COATINGS IMPROVEMENTS

专利摘要:
An electronic or electrical device or component thereof having a coating formed thereon by exposing the electronic or electrical device or component thereof to a plasma comprising one or more monomer compounds for a period of time sufficient to leave a protective polymeric coating on a surface thereof to shape; wherein the protective polymeric coating forms a physical barrier on a surface of the electronic or electrical device or component thereof; wherein each monomer is a compound of formula I (a): R1R2C = CR3-CO-OCR4R5-CR6R7- (CR8R9) a- (CX2) b- (CXCX3) c-CX3 (I (a)), or a compound with formula I is (b) R1R2C = CR3O-CO-CR4R5-CR6R7- (CR8R9) a- (CX2) b- (CXCX3) c-CX3 (I (b)), wherein each of R1 to R9 is independently selected from hydrogen or halogen or an optionally substituted C1-C6 branched or straight chain alkyl group; each X is independently selected from hydrogen or halogen; a is from 0 to 6; b is from 2 to 14; and c is 0 or 1; and where when each X is F or when at least one X is halogen, especially F, the FTIR / ATR intensity ratio of CX3 / C = O of the coating is less than (c + 1) 0.6e -0.1n wherein n is a + b + c + 1; and wherein when each X is H, the FTIR / ATR intensity ratio of CX3 / C = O is less than (c + 1) 0.25 ± 0.02, optionally wherein the barrier is a conformal physical barrier.
公开号:BE1023776B1
申请号:E2016/5426
申请日:2016-06-08
公开日:2017-07-20
发明作者:Stephen Coulson；Delwyn Evans；Thomas Hellwig；Frederick Hopper；Neil Poulter；Angeliki Siokou；Clive Telford
申请人:P2I Ltd；
IPC主号:

专利说明:

Improvements with regard to coatings
FIELD OF THE INVENTION
This invention relates to protective coatings. In particular, although not exclusively, the invention relates to substrates with protective coatings formed thereon, as well as to methods for forming protective coatings on substrates.
BACKGROUND OF THE INVENTION
It is known that electronic and electrical devices are very sensitive to damage caused by contamination with liquids such as ambient liquids, in particular water. Contact with liquids, whether in the course of normal use or as a result of accidental exposure, can lead to a short circuit between electronic components, and irreparable damage to printed circuit boards, electronic chips, etc.
The problem is particularly acute in relation to small portable electronic devices, such as mobile phones, smartphones, pagers, radios, hearing aids, laptops, notebooks, tablet computers, phablets and personal digital assistants (PDAs) that can be exposed to significant liquid contamination when used indoors or outdoors in the presence of liquids. Such devices are also susceptible to accidental exposure to liquids, for example when falling into liquid or splashing.
Other types of electronic or electrical devices can be susceptible to damage mainly due to their location, for example outdoor lighting, radio antenna and other forms of communication equipment.
Protective coatings are known to reduce the vulnerability of electrical and electronic devices to liquids. WO2007 / 083122 describes electrical and electronic devices with a polymeric coating formed thereon by exposure to pulsed plasma comprising a particular monomer compound, for a sufficient period of time to cause a polymeric coating to form on the surface of the electrical or electronic devices. In general, an article to be treated is placed in a plasma chamber together with material to be deposited in the gaseous state, a glow discharge is ignited in the chamber and a suitable voltage is applied which may be pulsed. While the coating of internal components of electronic or electrical equipment, such as printed circuit boards (PCBs) is casually considered in WO2007 / 083122, this is not illustrated and the focus of the disclosure is on coating entire devices, especially those that contain microphones.
It is known that the application of a protective coating on electronic substrates presents particular difficulties. An electronic substrate can in principle be any electronic or electrical device or component that includes at least one exposed electrical or electronic contact point. On the one hand, such substrates are particularly vulnerable, e.g. due to electrochemical migration, and require highly effective protection as a barrier and water-repellent against liquids, often on complex surfaces, e.g., print topographies. On the other hand, electrical or electronic contact points of such substrates may lose their function if coated with a too thick protective layer due to increased electrical resistance. Similarly, microphones or speakers on or in the vicinity of electronic substrates can be blocked or damaged if they are overcoated.
Known coating technologies, such as sprays, dips, gas phase processing systems such as Parylene, and even plasma deposition, have so far been unable to form protective coatings, especially on complex surfaces, which have sufficient thickness and resistance to provide a high degree of protection against liquids. without compromising contact point functionality. One known approach to overcoming the paradox between protection and contact point functionality is the splash proof (Splashproof (TM)) technology of P2i, where an ultra-thin water-repellent protective coating is applied to both the outside and the inside of a composite electronic or electrical device. This limits the penetration of liquids, while moreover preventing penetrated liquid from spreading inside the device. Thus, in the first place, it is prevented that the majority of a contamination with liquid penetrates the device, while there is some extra protection inside the device that does not interfere with the functionality of contact points. However, this technology generally only offers protection against splashing liquid and not against immersion of the device in liquid.
Another known approach has been to apply relatively thick protective coatings to electronic substrates, for example on the basis of Parylene technology, while masking contact points and / or microphones and loudspeakers to prevent coating depositing thereon. However, this leads to complex processing that has been proven to be impractical / unaffordable for mass production of portable electronic devices and the like.
There remains a need in the art for highly effective protective coatings that can be applied to electronic substrates without adversely interfering with contact points. Such coatings can further improve the resistance of substrates to liquids and / or enable more efficient manufacture of protected substrates, in particular in the electronics industry. It is an object of the invention to provide a solution to this problem and / or at least one other problem of the prior art.
Summary of the invention
The inventors have now developed highly effective protective coatings, and methods for producing them, that can be suitably used for the purpose of preventing water ingress into a treated electronic device or preventing and preventing electrochemical migration on a surface comprising an electronic circuit. but do not require masking during application. These coatings are based on plasma deposited monomer compounds.
Explanation of the invention
An aspect of the present invention provides an electronic or electrical device or component thereof with a coating formed thereon by exposing the electronic or electrical device or component thereof to a plasma comprising one or more monomeric compounds for a sufficient period of time to provide a protective polymeric coating on forming a surface thereof; wherein the protective polymeric coating forms a physical barrier over a surface of the electronic or electrical device or component thereof; wherein each monomer is a compound of formula I (a): (Ia)
wherein each of R 1 to R 9 is independently selected from hydrogen or halogen or a C 1 -C 6 branched or straight chain alkyl group; each X is independently selected from hydrogen or halogen; a is from 0-10; b is from 2 to 14; and c is 0 or 1; and wherein when each XF is the FTIR / ATR intensity ratio of the peaks attributed to stretching -CX3 and stretching C = 0, CXs / C = 0, the coating is lower than (c + 1) 0.6e "° 'hl ± 0.01 where n is a + b + c + 1; and where when each X is H, the FTIR / ATR intensity ratio of CX3 / C = 0 is lower than (c + 1) 0.25+ 0.02 or a compound of formula I (b): I (b)
wherein each of R 1 to R 9 is independently selected from hydrogen or halogen or a Q-C 6 branched or straight chain alkyl group; each X is independently selected from hydrogen or halogen; a is from 0-10; b is from 2 to 14; and c is 0 or 1; and wherein when each XF is the FTIR / ATR intensity ratio of the peaks attributed to stretching -CX3 and stretching C = 0, CXs / C = 0, the coating is lower than (c + 1) 0.6e N is ± 0.01 where n is a + b + c + 1; and wherein when each X is H, the FTIR / ATR intensity ratio of CX3 / C = 0 is lower than (c + 1) 0.25 + 0.02.
When at least one X is halogen, in particular F, the FTIR / ATR intensity ratio of the peaks attributed to stretching -CX3 and stretching C = 0, CX3 / C = 0, of the coating may be lower than (c + 1) 0.6e0nln ± 0.01 where n is a + b + c + 1.
Optionally, when each X is F, or when at least one X is halogen, especially F, the FTIR / ATR intensity ratio of CX3 / C = 0 of the coating is lower than (c + 1) 0.56th "°" III where n is a + b + c + 1, and where when each X is H, the FTIR / ATR intensity ratio of CX3 / C = 0 is lower than (c + 1) 0.16 + 0.01.
The coating protects the electronic or electrical device or component thereof by forming a physical barrier against mass and electron transport. The physical barrier limits diffusion of water, O 2 or other ions with time / voltage. This physical barrier layer differs from the liquid-repellent, typically water-repellent, layer described in the prior art. It will be appreciated that the physical barrier layer of the present invention may be liquid-repellent in addition to being a physical barrier, although the coating of the invention may be a physical barrier without being liquid-repellent.
The halogen can be chlorine or bromine, but fluorine is preferred in accordance with RoHS regulations (Restriction of Hazardous Substances). a is from 0 to 10, preferably from 0 to 6, optionally 2 to 4, most preferably 0 or 1. b is from 2 to 14, optionally from 2 to 10, preferably 3 to 7.
Each of R 1 to R 9 is independently selected from hydrogen or halogen or an optionally substituted C 1 -C 6 branched or straight chain alkyl group. The alkyl group can be substituted or unsubstituted, saturated or unsaturated. When the alkyl group is substituted, the location or type of substituent is not particularly critical provided that the resulting polymer provides a suitable barrier layer. The skilled person would be aware of suitable substituents. If the alkyl group is substituted, a preferred substituent may be halogen, i.e., any of R 1 to R 9 may be haloalkyl, preferably fluoroalkyl. Each of the alkyl groups can also be substituted with one or more hydroxyl groups. If the alkyl group is unsaturated, it may comprise one or more alkene or alkyne groups. Each of R 1 to R 9 can be independently selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, n-pentyl, neopentyl, n-hexyl, isohexyl and 3- methyl pentyl. Preferably, each of R1 to Rg is independently selected from hydrogen or methyl.
In a preferred embodiment, a and c are each independently 0 or 1; and b is from 3 to 7.
In one preferred embodiment, each X is H. In an alternative preferred embodiment, each X is F.
Optionally, R 1 and R 2 are both hydrogen.
Optionally, R 3 is hydrogen or methyl. Preferably, R 1 and R 2 are both hydrogen and R 3 is hydrogen or methyl.
In a preferred embodiment, R8 is hydrogen and R9 is C1 -C6 branched or straight chain alkyl group. In a particularly preferred embodiment, R9 is methyl.
Preferably, each of R4 to R7 is hydrogen.
Optionally, each of R 1 to R 9 is hydrogen, each X is H, a = 0 and c = 0.
In a particularly preferred embodiment, the compound of formula I (a) has the following formula:
wherein n is from 2 to 10.
In another preferred embodiment, the compound of formula I (a) has the following formula:
wherein n is from 2 to 10.
The compound of formula I (a) can be selected from 1H, 1H, 2H, 2H-perfluorohexyl acrylate (PFAC4), 1H, 1H, 2H, 2H-perfluorooctyl acrylate (PFAC6), 1H, 1H, 2H, 2H-perfluorocyl acrylate (PFAC8) and 1 H, 1 H, 2 H, 2 H perfluorododecyl acrylate (PFAC10).
The compound of formula I (a) can be selected from 1H, 1H, 2H, 2H-pefluorohexyl methacrylate (PFMAC4), 1H, 1H, 2H, 2H-perfluorooctyl methacrylate (PFMAC6) and 1H, 1H, 2H, 2H-perfluorodecyl methacrylate (PFMAC4) .
In another embodiment, the compound of formula I (a) has the following formula:
wherein a and c are each independently 0 or 1, b = 3-7, wherein n = a + b + c + 1.
In a further embodiment, the compound of formula I (a) has the following formula:
wherein n is 2 to 12.
The compound of formula I (a) can be selected from ethyl hexyl acrylate, hexyl acrylate, decyl acrylate, lauryl dodecyl acrylate and isodecyl acrylate.
In a further preferred embodiment, the compound of formula I (b) has the following formula:
wherein n is 3 to 13. Preferably n is 9.
The compound of formula I (b) most preferably has the following formula:
wherein η is 3 to 13. n can be 6 to 10, preferably n is 9, i.e., vinyl decanoate.
Various alkenyl alkyl alkanoates are considered as monomers for the present invention. Preferred monomers are vinyl alkyl alkanoates, such as vinyl hexanoate, vinyl heptanoate, vinyl octanoate, vinyl nonanoate, most preferably vinyl decanoate. The hydrogen atoms can be replaced by another chemical group at one or more positions. For example, the hydrogen atoms can be replaced with halogen atoms, preferably fluorine.
The outer surfaces may include the outer surface of the electronic or electrical device or component thereof, for example, the housing of a device, such as a smartphone, or outer surfaces of individual components that will later be assembled into a device such as PCB As and microphones. When an electronic or electrical device or component thereof comprises a housing, inner surfaces may, for example, comprise the inner surface of a housing or the surface of the components contained in the housing.
In one embodiment, the electronic or electrical device or component thereof comprises a housing and wherein the coating forms a conforming physical barrier over an inner surface of the housing and / or surfaces of components within the housing. In this embodiment, suitable protection is provided by the coating on the inner surfaces; the outer surface of the housing need not be provided with a coating, which can be advantageous for cosmetic areas as well as for reducing processing steps.
The FTIR / ATR intensity ratios of peaks attributed to stretch mode of CX3 and C = Q groups, CX3 / C = 0, of the coating are indicative of sufficient contamination in the coating to form a physical barrier. CX3 refers to the terminal groups in the side chain of the compounds of formulas I (a) and I (b).
The coating formed by the present invention is more cross-linked than its conventionally polymerized counterpart, which explains the surprisingly good barrier properties. In some embodiments, the polymeric coating also provides fluid repellency or fluid permeability resistance. The coating can be electrically insulating. The combination of the barrier properties and optionally additionally the liquid repellency of the coating of the present invention allows the coated electronic device or print plate assembly (PCBA) to be submerged in water for at least 30 minutes without adverse effects. The electronic or electrical device or component thereof can usually withstand immersion in up to 1 meter of water for more than 30 minutes without interference or corrosion, while the electronic or electrical device or component is powered.
The effectiveness of the coating can be determined by measuring the electrical resistance at a fixed voltage when immersed in water during a certain period; for example, when the protective polymeric coating is applied to a test circuit board (PCB). If it has a resistance of 8 MOhm or higher when immersed in water, while a voltage of at least 16V / mm (for example 8V over a 0.5 mm between electrodes) is applied for at least 13 minutes, the coating is an effective barrier coating and will the coated electronic or electrical device or component thereof comply with an IPX7 test. The IPX7 test is the Ingress Protection Marking that classifies and assesses the degree of protection against water. In the IPX7 test for telephones, the device is immersed in water under defined conditions of pressure and time (up to 1 m immersion) for a duration of 30 minutes. The device must be switched on during testing and functional after 24 hours.
Formation of the barrier coatings of the present invention is believed to be caused by a mixture of crosslinking and controlled fragmentation of the monomer during polymerization. Crosslinking is believed to proceed predominantly through the CX2-CX3 chain, while fragmentation is thought to occur predominantly through loss of the C = O group during polymerization and to a lesser extent shortening the CX2 chain.
Cross-linking affects the abundance of -CX3 groups in the coating and controlled fragmentation controls the amount of C = 0 groups in the coating. The ratio of these two functional groups is an indication that sufficient cross-linking and fragmentation has taken place and can be expressed as the ratio of the intensities of the corresponding FTIR / ATR peaks.
Possible mechanisms for crosslinking the monomer in the present invention are shown in Figure 14 in which 1H, 1H, 2H, 2H-perfluorocyl acrylate (PFAC8) is used as an example. Schemes 1-3 give a CF3: C = 0 ratio of 1: 1; Scheme 4 provides a polymer without CF3 groups; and scheme 5 yields a CF 3: C = 0 ratio of 1: 2. Scheme 2 would have a CF3: C = 0 ratio of 1: 2 if the CF3 group was activated instead of CF2. Cross-linking between CF2 and CF3 is considered the most likely mechanism (i.e., scheme 3).
The degree of crosslinking and fragmentation in the polymer can be found by measuring the FTIR / ATR peak intensities of the C = 0 and CX3 functional groups. The ratios of C = 0 intensity / total intensity (area) of the ATR spectmm and CX3 / total intensity both correlate with the performance of the coating. Figures 15 and 16 show graphs of the FTIR / ATR ratios against coating resistance (after applying 8V when immersed in water for 13 minutes) for C = 0 / total area and CX3 / total area, respectively. Reduced CX3 and C = 0 intensities give higher resistance values, which means improved coating performance with increased crosslinking (for CX3) and fragmentation (for C = 0).
But their ratio (CX3 / C = 0) gives the best correlation with coating resistance because it describes the combination of fragmentation and contamination (see Figure 17).
For X = F, the FTIR / ATR intensity ratio of CX3 / C = 0 in the monomer increases with chain length (ie value of a + b + c in formula I (a) or I (b) or n due to the dipole change with change in chain length The actual ratio of CX3 / C = O groups in the polymer has not changed with monomer chain length.
In one embodiment, the compound of formula I (a) comprises a compound of formula (II)
wherein n is 4 to 10 and wherein the FTIR / ATR intensity ratio of CF3 / C = 0 of the coating is less than 0.6 "" in.
The compound of formula (II) can be selected from 1H, 1H, 2H, 2H-perfluorohexyl acrylate (PFAC4), 1H, 1H, 2H, 2H-perfluorooctyl acrylate (PFAC6), 1H, 1H, 2H, 2H-perfluorocyl acrylate (PFAC8) and 1 H, 1 H, 2 H, 2 H perfluorododecyl acrylate (PFAC10).
In another embodiment, the compound of formula I (a) comprises a compound of formula (III).
wherein a and c is either 0 or 1 and b = 3-7; n is 4 to 10 (n = a + b + c + 1) and wherein the FTIR / ATR intensity ratio of CH3 / C = 0 of the coating is lower than (c + 1) 0.25.
The compound of formula (III) can be selected from ethyl hexyl acrylate, hexyl acrylate, decyl acrylate, dodecyl (or lauryl) acrylate and isodecyl acrylate.
In another embodiment, the compound of formula I (a) comprises a compound of formula (IV)
wherein n is 4 to 8; and wherein the FTIR / ATR intensity ratio of CF3 / C = 0 of the coating is less than 0.6 "0.11.
The compound of formula (IV) can be selected from 1H, 1H, 2H, 2H-pefluorohexyl methacrylate (PFMAC4), 1H, 1H, 2H, 2H-perfluorooctyl methacrylate (PFMAC6) and 1H, 1H, 2H, 2H-perfluorodecyl methacrylate (PFMAC8).
In a further embodiment, the compound of formula (I) comprises a compound of formula (V)
wherein n is 4 to 8; and wherein the FTIR / ATR intensity ratio of CH3 / C = 0 of the coating is less than 0.25.
The coating is preferably substantially free of holes to provide a physical barrier. Zooming in on the coating is preferably A7./d <0.15, where ΔΖ is the average height variation on an AFM line scan in nm (see Figure 2) and d is coating thickness in nm.
The value of ΔΖ / d tells the extent to which defects / cavities on the surface of the coating extend into the coating, i.e. the percentage value of the depth of defect on the total coating thickness. For example, ΔΖ / d = 0.15 means that the cavities on the surface extend only down to 15% of the coating thickness. A coating with a ΔΖ / d <0.15 is defined herein as substantially without holes.
The coating is preferably in conformity, which means that it takes on the 3D shape of the electronic or electrical device or component thereof and substantially covers an entire surface of the device. This has the advantage of ensuring that the coating has sufficient thickness to provide optimum functionality over an entire surface of the device or component. The meaning of the term "substantially covers an entire surface" will depend somewhat on the type of surface to be covered. For example, for some components it may be necessary to have complete coverage of the surface, so that the component will function after immersion in water. However, for other components or housings, small holes in the cover can be tolerated.
The coating can have a thickness of 50 to 10,000 nm, optionally 50 to 8000 nm, 100 to 5000 nm, more preferably 250 nm - 5000 nm, most preferably 250 nm - 2000 nm.
The coating can be electrically insulating and sufficiently flexible that electrical connectors can be connected to the electronic or electrical device or component thereof and an electrical connection can be made between the electrical connectors and electronic or electrical device or component thereof without the need to first apply the coating to delete. In this case, the force that the electrical connector exerts on the coating is sufficient to change the structure of the coating or even break the coating, close to the electrical connector, allowing the electrical connection to be made. Electrical connectors can usually be connected in this way to the electronic or electrical device or component for coating thicknesses of less than 5000 nm, and for high-quality coatings below 2000 nm.
In one embodiment, the coating is electrically insulating and has a thickness of less than 1 micron and a force of 5-20 g applied to the coating via a round probe with a diameter of 1 mm makes it possible to make an electrical connection to the electronic or electrical device or component thereof in the local area where the force is applied.
In another embodiment, the coating is electrically insulating and has a thickness of 1-2.5 microns and wherein a force of 20-100 g applied to the coating via a round probe with a diameter of 1 mm makes it possible to make an electrical connection in the local area of the coating when the force is applied.
The coating may have a higher density than that of the corresponding monomer from which they are formed. For example, the increase in density may be at least 0.1 g / cm 3. The increase in density is explained by the highly cross-linked coating. The high density of the coating improves the barrier properties of the coating.
The coating can form a surface defined by a static water contact angle (WCA) of at least 70 °. Coatings with a WCA of at least 90 ° can be described as liquid-repellent (typically water-repellent). In this case, the coating achieves liquid repellency in addition to providing a physical barrier. For fluorinated polymers, the coating can have a static water contact angle of at least 100 °. The contact angle of a liquid on a solid substrate gives an indication of the surface energy, which in turn illustrates the liquid-repellent properties of the substrate. Contact angles can be measured on a VCA Optima contact angle analyzer, using drops of 3 µl deionized water at room temperature.
The desired degree of crosslinking and fragmentation in the polymeric coating to achieve the barrier performance is achieved by adjusting the process parameters. For example, applicants have found that continuous wave (CW) conditions and / or pulsing under conditions of high power causes fragmentation and loss of C = 0 groups, while low ratios of power / flow have been found to produce effective crosslinking.
Another aspect of the invention provides a method for treating an electronic or electrical device or component as defined above, comprising: exposing the electronic or electrical device or component thereof to a plasma, comprising one or more monomeric compounds for a sufficient period of time to cause a protective polymeric coating to form on the electronic or electrical device or component thereof, wherein the protective polymeric coating forms a physical barrier over a surface of the electronic or electrical device or component thereof; wherein each monomer is a compound of formula I (a): (Ia)
wherein each of R 1 to R 9 is independently selected from hydrogen or halogen or an optionally substituted C 1 -C 6 branched or straight chain alkyl group; each X is independently selected from hydrogen or halogen; a is from 0-10; b is from 2 to 14; and c is 0 or 1; or a compound of formula I (b):
wherein each of R 1 to R 9 is independently selected from hydrogen or halogen or an optionally substituted C 1 -C 8 branched or straight chain alkyl group; each X is independently selected from hydrogen or halogen; a is from 0-10; b is from 2 to 14; and c is 0 or 1.
The chemical structures of the monomers are described in detail above.
To achieve that a polymeric coating forms a physical barrier over a surface of the electronic or electrical device, the process parameters can be changed, e.g. power, monomer flow rate and monomer flow to power ratio.
The physical barrier is preferably a conforming physical barrier.
The step of exposing the electronic or electrical device or component thereof to a plasma can include a two-step process, the first and second steps comprising different plasma conditions.
The step of exposing the electronic or electrical device or a component thereof to a plasma can take place in a reaction chamber.
In a preferred embodiment, the step of exposing the electronic or electrical device or component thereof to a plasma comprises a first continuous wave (CW) deposition step and second pulsed (PW) deposition step.
In one embodiment, a first step may include optimizing process parameters to allow surface treatment and crosslinking to take place and a second step may include adjusting the process parameters so that further crosslinking and further fragmentation occurs. Thus, optimum cross-linking (shown by lower CX3 peak intensities in the FTIR / ATR spectra) and increased fragmentation (shown by lower C = 0 peak intensity in the FTIR / ATR spectra) are achieved. For example, the step of exposing the electronic or electrical device or component thereof to a plasma may include a first continuous wave (CW) deposition step and second pulsed (PW) deposition step.
The continuous wave (CW) deposition step has been found to act as a substrate priming step which optimizes the performance of the coating. Applicants have discovered that incorporation of a CW step optimizes the interface between the substrate surface and growing coating, which causes both some etching of the substrate surface and growth of the polymer coating. Inclusion of the CW deposition step leads to homogeneous growth of the coating and minimizes the chance of defects forming in the coating.
The pulsed (PW) deposition step has been found to be important in achieving good penetration of the coating in hard-to-reach areas. The applicants have surprisingly discovered that the quality and thickness of the coating on inner surfaces can be optimized by adjusting the flow and power parameters. Increased power provides good quality coatings with the desired functionality on inner surfaces. Increased flow provides good quality coatings with the desired functionality on outer surfaces.
The power / flow ratio (W / F) of the PW deposition step can be adjusted depending on the desired properties of the coated substrate: increasing W / F causes an increase in the resistance and quality of the internal coating but a decrease in external resistance and quality.
FLOW SPEED
The flow rate of the monomer compound into the chamber can be much higher (on a per volume basis of the chamber) than that described in the method of WO2007 / 083122. It has been found that this high flow rate of the monomer compound surprisingly facilitates the formation of polymeric coatings with desirable liquid-repellent and / or barrier properties even at thicknesses that offer low electrical resistance.
The exact flow rate of the monomer compound into the chamber may depend to some extent on the nature of the specific monomer compound used, the nature of the substrate, and the desired properties of the protective coating. In some embodiments of the invention, the monomer compound is introduced into the chamber at a gas flow rate in the range of at least 1.5 sccm and preferably in the range of 1.5 to 2500 sccm, optionally from 1.5 to 250 sccm, optionally from 1.5 to 200 sccm, although this depends on room volume. For a 2.5 L chamber, the gas flow rate can be in the range of 1.5 to 20 sccm. The monomer gas stream is calculated from the liquid monomer stream since the monomer in the chamber acts as an ideal gas.
In a further embodiment the invention relates to a method for forming a coating on an electronic or electrical device or component thereof, which method comprises the following: exposing the electronic or electrical device or component thereof in a chamber to a plasma comprising a monomer compound as defined above, preferably a pulsed plasma, for a sufficient period of time to form a protective polymeric coating on the substrate, wherein during exposure of the substrate the monomer compound is introduced into the chamber at a rate in the range of 100 -10,000 sccm / m3, more preferably in the range of 600-8000 sccm / m3.
PEAK POWER
To achieve the desired level of crosslinking and fragmentation for optimum coating properties, higher powers can be used than commonly used in the prior art. Figure 18 shows the FTIR / ATR intensity ratios of (A) C = 0 / total and (B) CF3 / total against power for PFAC4 coatings. The C = 0 / total data indicates increased fragmentation with increased power and the CF3 / total data indicates increased cross-linking with increased power.
For pulsed plasmas, higher average powers can be achieved by using higher peak powers and varying the pulsed regime (ie on / off times).
In a further embodiment, the invention relates to a method for forming a coating on an electronic or electrical device or component thereof, the method comprising the following: exposing the substrate in a chamber to a plasma comprising a monomer as defined above , preferably a pulsed plasma, for a sufficient period of time to form a protective polymeric coating on the substrate, wherein during exposure of the substrate the pulsed plasma has a peak power (e.g. on-phase) of at least 2 W / liter.
It has been found that this high average power density of the plasma surprisingly facilitates the formation of polymeric coatings with desired liquid-repellent and / or barrier properties even at thicknesses that offer low electrical resistance. This is due to the increased cross-linking and / or fragmentation that occurs at higher powers.
The exact average power density of the plasma depends to a certain extent on the nature of the specific monomer compound used, the nature of the substrate and the desired properties of the protective coating. In some embodiments of the invention, the plasma may have an average power density in the range of 0.001 to 20 W / liter. An average power density in the range of 0.001-1 W / liter is particularly preferred for some types of compounds, for example compounds of formula Π or formula ΙΠ, n> 8. For other compounds, for example compounds of formula II or formula III for n <8 or when X = H, an average power density in the range of 2-12 W / liter may be preferred.
In one embodiment, the plasma is a pulsed plasma in which pulses are applied in a sequence that yields a time-on: time-out ratio in the range of 0.001 to 1, optionally 0.002-0.5. For example, time-on may be 10-500 ps, preferably 35-45 ps or 30-40 ps, such as about 36 ps, and time-out may be 0.1 to 30 ms, preferably 0.1 to 15 ms, optionally 5 to 15 ms, for example 6 ms. Time on can be 35 ps, 40 ps, 45 ps. Timeout can be 0.1, 1, 2, 3, 6, 8, 10, 15, 20, 25 or 30 ms.
The term pulsed may mean that the plasma cycles between a state of no (or virtually no) plasma emission (off state) and a state in which a certain amount of plasma is emitted (on state). Alternatively, pulsed may mean that there is continuous plasma emission, but that the amount of plasma cycles between an upper limit (on-state) and lower limit (off-state).
In a further embodiment the invention relates to a method for forming a coating on an electronic or electrical device or component thereof as defined above, which method comprises the following: exposing the substrate in a chamber to a plasma comprising a monomer compound , preferably a continuous plasma, for a sufficient period of time to form a protective polymeric coating on the substrate, wherein during continuous exposure of the substrate the continuous plasma has a power density of at least 2 W / liter, preferably 20 W / liter.
RATIO POWER TO FLOW
The ratio of power to monomer current during the pulsed plasma can be between 2-60 W / sccm, preferably 2-40 W / sccm, 2-25 W / sccm, 5-20 W / sccm.
In a further embodiment the invention relates to a method for forming a coating on an electronic or electrical device or component thereof as defined above, which method comprises: exposing the electronic or electrical device or component thereof in a chamber to a plasma comprising a monomer compound, preferably a pulsed plasma, for a sufficient period of time to form a protective polymeric coating on the substrate, wherein during exposure of the substrate the pulsed plasma has a peak power to flow ratio between 2 to 60 W / sccm, at preferably 2 to 40 W / sccm, more preferably 2-25 W / sccm, optionally 5-20 W / sccm.
It has been found that this range of power-to-flow ratio surprisingly facilitates the formation of polymeric coatings with desired liquid-repellent and / or barrier properties, even at thicknesses that offer low electrical resistance.
In a further embodiment the invention relates to a method for forming a coating on an electronic or electrical device or component thereof, which method comprises the following: exposing the electronic or electrical device or component thereof in a chamber to a plasma comprising a monomer compound, preferably a continuous plasma, for a sufficient period of time to form a protective polymeric coating on the substrate, wherein during exposure of the substrate the continuous plasma has a power to flow ratio between 2 to 60 W / sccm, preferably 2 to 40 W / sccm, more preferably from 2-25 W / sccm, optionally 5-20 W / sccm.
PULSE / CW
The step of exposing the electronic or electrical device or component thereof to a plasma may include a pulsed (PW) deposition step. Alternatively, or additionally, the step of exposing the electronic or electrical device or component thereof to a plasma may include a continuous wave (CW) deposition step.
The aspects of the invention provide methods that each facilitate the formation of highly effective protective coatings that can be applied to electronic substrates without adversely interfering with contact points. An advantage is that the resulting coating is sufficiently flexible, so that electrical connectors after coating the device during or after fabrication and assembly. In one embodiment, the method comprises the step of connecting electrical connectors to the electronic or electrical device or component thereof after the coating has been applied. This has the advantage that electrical connectors can be easily connected to the electronic or electrical device or component thereof after coating the device or component during manufacture or assembly.
In particular, the features of the aspects of the invention operate in synergy and lead to preferred embodiments of the invention when combined. All such combinations, with or without the preferred and optional functions listed herein, are explicitly considered in accordance with the invention.
For example, in one preferred embodiment of the invention, a method of forming a coating on a substrate comprises: exposing the substrate in a chamber to a pulsed plasma for a sufficient period of time to leave a protective polymeric coating on the substrate. wherein the plasma has a peak phase on power of at least 2 W / liter and comprises a hydrocarbon or fluorocarbon or methacrylate monomer compound, e.g., the compound of formula (Ia) introduced into the chamber during exposure of the substrate at a speed of at least 1.5 sccm or 2-100 sccm or 2.5-20 sccm.
In another preferred embodiment of the invention, a method of forming a coating on a substrate comprises exposing the substrate in a chamber to a continuous plasma for a sufficient period of time to form a protective polymeric coating on the substrate, the plasma has a peak power of at least 15 W / l and comprises a hydrocarbon or fluorocarbon or methacrylate monomer compound, for example the compound of formula (Ia), introduced into the chamber during exposure of the substrate of at least 2.5 sccm.
The monomer can comprise a hydrocarbon or fluorocarbon or methacrylate. In particular, the monomer may be a compound of Formula I (a):
wherein R 1 and R 2 are both H, R 3 is hydrogen or methyl, R 4 to R 8 are each hydrogen, R 9 is an alkyl group, X is hydrogen or fluoro, a and c are 0 or 1, b = 3-7, and n 4 to 10 (where n = a + b + c + 1).
For X = F, the FTIR / ATR intensity ratio of CX3 / C = 0 of the resulting coating is preferably lower than (c + 1) 0.6e "° 'nn, where n is as defined as a + b + c + 1.
For X = H, the FTIR / ATR intensity ratio of CX3 / C = 0 of the resulting coating is preferably lower than (c + 1) 0.25, where n is as defined as a + b + c + 1.
An embodiment of the invention provides a method for treating an electronic or electrical device or component, comprising: exposing the electronic or electrical device or component thereof to a plasma comprising one or more monomeric compounds for a sufficient period of time to provide a protective polymeric coating to form on the electronic or electrical device or component thereof, wherein the protective polymeric coating forms a physical barrier; wherein each monomer is a compound of formula I (a):
is, where R | and R2 are both H, R3 is hydrogen or methyl, R4 to Rg are each hydrogen, R9 is an alkyl group, X is hydrogen or fluoro, a and c are 0 or 1, b = 3-7, and n is 4 to 10 (wherein n = a + b + c + 1); and wherein the step of exposing the electronic or electrical device or component thereof to a plasma comprises a first continuous wave (CW) deposition step and second pulsed (PW) deposition step.
The compound can be selected from 1H, 1H, 2H, 2H-pefluorohexyl acrylate (PFAC4), 1H, 1H, 2H, 2H-perfluorooctyl acrylate (PFAC6), 1H, 1H, 2H, 2H-perfluorocyl acrylate (PFAC8) and 1H, 1H, 2H 1 H perfluorododecyl acrylate (PFAC10).
In one embodiment, n is 8, X is F, and R 3 is H, wherein the compound of formula I is (a) 1H, 1H, 2H, 2H-heptadecafluorodecyl acrylate.
The compound can be selected from 1H, 1H, 2H, 2H-pefluorohexyl methacrylate (PFMAC4), 1H, 1H, 2H, 2H-perfluorooctyl methacrylate (PFMAC6) and 1H, 1H, 2H, 2H-perfluorodecyl methacrylate (PFMAC8).
The compound of formula I (a) can be selected from ethyl hexyl acrylate, hexyl acrylate, decyl acrylate, lauryl dodecyl acrylate and isodecyl acrylate.
SUBSTRATE
Although the invention is useful in the context of a large number of substrates, the substrate can advantageously be an electronic substrate in all aspects of the invention.
In some embodiments of the invention, the electronic substrate may comprise an electronic or electrical device, i.e., any piece of electrical or electronic device. Non-limiting examples of electrical and electronic devices include communication devices such as cellular phones, smartphones and pagers, radios, and sound and audio systems such as speakers, microphones, ringers or buzzers, hearing aids, personal audio equipment such as personal CD, tape cassette or MP3 players, televisions, DVD players including portable DVD players, video recorders, digital and other set-top boxes such as Sky, computers and related components such as laptop, notebook, tablet, phablet or palmtop computers, personal digital assistants (PDAs), keyboards, or instrumentation, games consoles in particular handheld Playstations and the like, data storage devices, outdoor lighting systems or radio antennas and other forms of communication equipment.
In preferred embodiments of the invention, the substrate may contain or consist of an electronic component, e.g., a printed circuit board (PCB), a printed circuit board array (PCBA), a transistor, resistor, or semiconductor chip. The electronic component can thus be an internal component of an electronic device, e.g. a mobile telephone. The coatings of the invention are particularly valuable in preventing electrochemical migration in such components.
In all aspects of the invention, the exact conditions under which the protective polymeric coating is effectively formed will vary depending on factors such as, but not limited to, the nature of the monomer compound, the substrate, and the desired properties of the coating. These conditions can be determined using routine methods or preferably using the techniques and preferred features of the invention as described herein, which operate in particular synergy with the invention.
Suitable plasmas for use in the methods of the invention include non-equilibrium plasmas such as those generated by radio frequencies (Rf), microwaves or direct current (DC). They can operate at atmospheric or sub-atmospheric pressures as known in the art. In particular, however, they can be generated by radio frequencies (Rf).
Different forms of equipment can be used to generate gaseous plasmas. In general, these include containers or plasma chambers in which plasmas can be generated. Specific examples of such equipment are described, for example, in WO2005 / 089961 and WO02 / 28548, the contents of which are incorporated herein by reference, but many other conventional plasma-generating equipment are available.
In general, the substrate to be treated is placed in the plasma chamber together with the monomer compound, a glow discharge is ignited in the chamber, and a suitable voltage is applied. The voltage can be continuous or pulsed. Monomer can be introduced from the start or after a period of prior plasma continuous power.
The monomer compound will suitably be in a gaseous state in the plasma. The plasma may simply comprise a vapor of the monomer compound if present. Such vapor can be formed in situ, the compounds being introduced into the chamber in liquid form. The monomer can also be combined with a carrier gas, in particular an inert gas such as helium or argon.
In preferred embodiments, the monomer can be delivered to the chamber by means of an aerosol device such as a nebulizer or the like, as described, for example, in WO2003 / 097245 and WO003 / 101621, the contents of which are incorporated herein by reference. In such an arrangement, a carrier gas need not be needed, which advantageously helps to achieve high flow rates.
In some cases, a prior plasma continuous power may be created in the chamber for, for example, from 10 seconds to 10 minutes, e.g. This can act as a surface pre-treatment step, so that the monomer compound easily adheres to the surface, so that when polymerization takes place, the coating "grows" on the surface. The pre-treatment step can be performed before monomer is introduced into the chamber, for example in the presence of inert gas, or simply in a residual atmosphere. Monomer can then be introduced into the chamber to allow polymerization to take place, whereby the plasma is either exchanged for a pulsed plasma, continued with a continuous plasma or a sequence of both continuous and pulsed plasma is used.
In all cases, a glow discharge is suitably ignited by applying a high-frequency voltage, for example at 13.56 MHz. This is suitably applied with electrodes that are inside or outside the chamber.
Gasses, vapors or aerosols can be drawn or pumped into the plasma chamber or plasma area. Particularly when a plasma chamber is used, gases or vapors may be drawn into the chamber due to a reduction in the pressure in the chamber caused by the use of an evacuation pump, or they may be pumped or injected into the chamber as is customary when working with liquid.
Suitably the gas, vapor or gas mixture can be supplied at a rate of at least 1.5 sccm and preferably in the range of 1.5 to 100 sccm, more preferably 2.5 to 20 sccm, although this will depend on room volume.
These amounts can be scaled up to larger systems on a chamber volume basis in accordance with the teachings described herein.
Polymerization is conveniently carried out using vapors of the monomer compound, which are maintained at pressures of 0.1 to 200 mTorr, suitably at about 15-150 mTorr.
The applied fields can preferably provide a relatively high peak power density, e.g. as defined above in the method according to the invention. The pulses can also be applied in a sequence that produces a lower average power, for example in a sequence in which the time-on: time-out ratio is in the range of 20: 100 to 20: 20,000. Sequences with shorter time-out periods may be preferred to maintain good power density. One example of a sequence is a sequence in which power is on for 20 to 50 microseconds, for example 30 to 40 microseconds, such as about 36 microseconds, and off for 5 to 30 milliseconds, for example 5 to 15 milliseconds, such as 6 milliseconds. It has been found that this can be especially advantageous when the monomer is a compound of formula (I).
Preferred average powers obtained in a 2.5 liter chamber in this way were in the range of 0.05 to 30 W. In some embodiments, especially when compound of formula (I), wherein n is greater than or equal 8 is used as a monomer, relatively low average powers are preferred, e.g. in the range of 0.1 to 5 W, e.g. 0.15 to 0.5 W in a 2.5 liter chamber. Higher average powers, for example more than 10 W, have been shown to have the advantage of assisting with monomer fragmentation. These ranges can be increased or decreased on a volume basis for larger or smaller chambers and will depend on the selected peak power and the selected pulse sequence.
The process temperatures, e.g., measured within the chamber, may be ambient temperature or preferably slightly above ambient temperature, such as in the range of 30 to 60 ° C, e.g., 35 to 55 ° C. In some embodiments, the process temperature is kept below 40 ° C.
Suitably, a used plasma chamber can be of sufficient volume to accommodate multiple substrates, especially when they are small in size, for example, up to 20,000 PCB can be easily processed simultaneously with equipment of the correct size. A particularly suitable apparatus and method for manufacturing coated substrates according to the invention are described in WO2005 / 089961, the contents of which are incorporated herein by reference.
The dimensions of the chamber will be chosen to accommodate the whole of the specific substrate to be treated. For example, generally cubic chambers may be suitable for a variety of applications, but if required, elongated or rectangular chambers may be constructed or even cylindrical or of any other suitable shape. The volume of the chamber can for instance be at least 1 liter, preferably at least 2 liters. In some applications, relatively small chambers with a volume of up to 13 liters or up to 10 liters are preferred. For large-scale production, the volume of the chamber can suitably be up to 400 liters or higher. The chamber may be a closable container to allow batch processes, or may include inlets and outlets for substrates so that it can be used in a continuous process. Particularly in the latter case, the pressure conditions required for creating a plasma discharge within the chamber are maintained with the use of high volume pumps, as is customary in, for example, a device with a "whistle leak". However, it may also be possible to process certain substrates at atmospheric pressure or close thereto, so that "whistle leaks" are not necessary.
Advantageously, electronic or electrical contact points of the substrate need not be masked during the treatment, in particular for coating with a thickness below 5 µm, more preferably below 2 µm. Indeed, in one embodiment of the invention, these contacts and / or microphones / speakers are not masked during the formation of the coating by any of the methods described herein, leading to an advantageously simplified process.
The invention has led to coatings that offer protective properties while maintaining contact and microphone / speaker functionality. In a further embodiment, the invention relates to an electronic or electrical device or component thereof with a polymeric coating formed thereon by exposing the substrate to pulsed plasma comprising a monomer compound of formula (I) for a sufficient period of time to provide a protective polymeric coating on forming the substrate (e.g., according to any of the methods described herein), wherein the coating has a thickness of at least 50 nm and / or a surface defined by a static water contact angle (WCA) of at least 70 °.
More generally, from a further aspect, the invention relates to a substrate with a polymeric coating formed by any of the methods described herein. The invention also includes coated substrates obtainable by any of the methods described herein. One particular advantage of the invention is that electronic or electrical devices as a whole can be made resistant to liquids, even during complete immersion, by coating only internal components such as PCBs, so that an external coating is no longer necessary. Thus from a further aspect the invention relates to an electronic or electrical device, for example a mobile telephone, comprising a housing and one or more internal electronic or electrical components having a coating thereon formed by any of the methods described herein. Advantageously, the housing does not have to include a coating. The device can advantageously meet standard IEC 60529 14.2.7 (IPX7).
More generally, any of the coated electronic substrates described herein can preferably continue to function even after complete immersion in water for at least 2 minutes, preferably at least 5 minutes. The electronic substrate will preferably continue to function for at least 30 minutes or more, preferably at least two days.
As used herein, the term "in gaseous state" refers to gases or vapors, alone or in mixture, and optionally aerosols.
As used herein, the term "protective polymeric coating" refers to polymeric layers that provide some protection against fluid damage, for example, by forming a barrier and optionally by being fluid-repellent (such as oil and / or water-repellent). Sources of liquids against which the substrate is protected include environmental liquids such as water, in particular rain, and liquids that are accidentally spilled.
As used herein, the term "during exposure of the substrate" refers to a period in which the substrate is within the chamber together with the plasma. In some embodiments of the invention, the term may refer to the entire period in which the substrate is within the chamber together with the plasma.
Through the description and claims of this specification, the words "include" and "contain" and variations of the word, for example "comprising" and "includes", have the meaning "including but not limited to", and include other groups, additives, components, integers or steps. In addition, the singular includes the plural unless the context requires otherwise: in particular when the indefinite article is used, the specification should be considered as both plural and singular, unless the context requires otherwise. In addition, when upper and lower limits are mentioned for a property, then a range of values defined by a combination of each of the upper limits with each of the lower limits can also be implied.
As used herein, the term "FTIR / ATR" refers to Fourier Transform infrared spectroscopy (FTIR) using a muted total reflection (ATR) sampling technique. This is a known technique that is understood by a person skilled in the art. Typically, the ATR sampling is performed with a diamond crystal.
Preferred features of any aspect of the invention may be as described in connection with any of the other aspects. Other features of the invention will become apparent from the following examples. In general, the invention extends to any new feature, or to any new combination of features described in this specification (including all appended claims and drawings). Thus, it is to be understood that features, numbers, characteristics, compounds, chemical units or groups described in connection with a specific aspect, embodiment or example of the invention are applicable to any other aspect, embodiment or example described herein. unless this is incompatible with it. In addition, unless otherwise specified, any feature described herein may be replaced by an alternative feature serving the same or similar purpose.
In this description, references to compound properties - unless otherwise indicated - refer to properties measured under ambient conditions, i.e. at atmospheric pressure and at a temperature of 16 to 22 or 25 ° C, or 18 to 22 or 25 ° C, e.g. about 20 ° C C or about 25 ° C.
Listed parameters, e.g. with regard to thickness, hydrophobicity, density and mwness of the coating, can be measured by any of the techniques mentioned in the examples, using standard techniques. Unless otherwise specified, all values listed herein may be measured or determined using standard techniques known to those skilled in the art.
The present invention will now be further described with reference to the following non-limiting examples and the accompanying illustrative drawings, in which:
Figure 1 illustrates the electrical testing device for determining the resistance of the coating;
Figure 2 shows a tapping mode image of the coatings over 5x5 pm2 field of view (left) and a representative contour line indicating height variation (z-axis) of the coating (right);
Figure 3 is an FTIR / ATR spectrum of a 1000 nm thick coating formed from PFAC8 monomer;
Figure 4 is a graph of the water resistance of PW PFAC8 coatings at 8V after 13 min interruption with respect to the FTIR / ATR-CF3 / C = 0 peak area ratio;
Figure 5 is a graph of the water resistance of PW PFAC10 coatings at 8V after 13 min interruption with respect to the FTIR / ATR-CF3 / C = 0 peak area ratio;
Figure 6 is a graph of the water resistance of PW PFAC® coatings at 8Y after 13 min interruption with respect to the FTIR / ATR-CF3 / C = 0 peak area ratio;
Figure 7 is a graph of the water resistance of PW PFAC4 coatings at 8V after 13 min interruption with respect to the FTIR / ATR-CF3 / C = 0 peak area ratio;
Figure 8 is a graph showing the ATR surface ratios for the different perfluoroacrylate monomers;
Figure 9 is a graph showing the critical ATR ratio as a function of the side chain length of the initial monomer;
Figure 10 is a graph showing the resistance in water of PW PFMAC8 coatings at 8V after 13 min interruption to the FTIR / ATR-CF3 / C = 0 peak area ratio;
Figure 11 is a graph showing the resistance in water of PW PFMAC® coatings at 8V after 13 min interruption to the FTIR / ATR-CF3 / C = 0 peak area ratio;
Figure 12 is a graph showing the resistance in water of PW PFMAC4 coatings at 8V after 13 min interruption to the FTIR / ATR-CF3 / C = 0 peak area ratio; and
Figure 13 is a graph showing the critical FTIR / ATR ratio as a function of the side chain length of the initial perfluoroacrylate (PFACn) or perfluoromethacrylate (PFMACn) monomer;
Figure 14 illustrates possible cross-linking mechanisms for PFAC8; and
Figure 15 is a graph of resistance (with 8V applied for 13 minutes) to FTIR / ATR-C = 0 / total area for PFAC8; and
Figure 16 is a graph of resistance (with 8V applied for 13 minutes) to FTIR / ATR-CF3 / total area for PFAC8; and
Figure 17 is a graph of resistance (with 8V applied for 13 minutes) to FTIR / ATR-CF3 / C = 0;
Figure 18 is a graph of (A) FTIR / ATR-C = 0 / total against power and (B) FTIR / ATR-CF3 / total against power, both for PFAC4 coatings;
Figure 19 is a graph of the contact force Fc against coating thickness;
Figure 20 is a graph of the water resistance of ethylhexyl acrylate coatings at 8V after 13 min interruption to the FTIR / ATR-CH3 / C = 0 peak area ratio;
Figure 21 is a graph of the water resistance of hexyl acrylate coatings at 8V after 13 min interruption to the FTIR / ATR-CH3 / C = 0 peak area ratio;
Figure 22 is a graph of the water resistance of isodecyl acrylate coatings at 8V after 13 min interruption with respect to the FTIR / ATR-CH3 / C = 0 peak area ratio;
Figure 23 is a graph of the resistance in water of various non-fluorinated coatings at 8V after 13 min interruption to the FTIR / ATR-CH3 / C = 0 peak area ratio; ethylhexyl acrylate coating represented by diamonds; hexyl acrylate represented by squares; decyl acrylate represented by triangles; lauryl (dodecyl) acrylate represented by crosses; isodecyl acrylate represented by crossed-out crosses.
Example 1
Process design and parameters
Plasma polymerization experiments were performed in a cylindrical glass reactor vessel with a capacity of 2.5 liters. The vessel was in two parts coupled with a Viton O ring to seal the two parts together under vacuum. One end of the reactor was connected to a liquid flow controller, which was heated at 70 ° C and this was used to deliver monomer at a controlled flow rate.
The other end of the reactor was connected to a metal pump pipeline equipped with manometers, pressure control valve, liquid nitrogen trap and a vacuum pump. A copper coil electrode was wound around the outside of the reactor (11 turns of 5 mm diameter pipe) and connected to an RF power supply via an L-C matching network. For pulsed plasma deposition, the RF power supply was controlled by a pulse generator.
The monomer used for this example was PFAC-8, i.e. 1H, 1H, 2H, 2H-heptadecafluorodecyl acrylate (CAS # 27905-45-9) of formula
A series of experiments were performed with the parameters shown in Tables 1A-1D. In each experiment, a sample was placed in the glass reactor vessel so that it was at the bottom of the reactor vessel and within the volume surrounded by the copper coil electrode. The reactor was evacuated to the basic pressure (typically <10 mTorr). The monomer was delivered to the chamber using the flow controller, with typical monomer gas flow values between 2-25 sccm. The chamber was heated to 45 ° C. The pressure in the reactor was kept at 30 mTorr.
The plasma was produced using RF at 13.56 MHz and the process usually consisted of two steps; the continuous wave (CW) plasma and the pulsed wave (PW) plasma. The CW plasma was for 2 minutes and the duration of the PW plasma varied in different experiments. The peak power setting was 50 W in each case, and the pulse conditions were time on (Taan) = 37 ps and time out (Tout) = 6 ms. Two coatings were formed using Taan = 37 ps and Tuit = 20 ms. At the end of the deposition, the RF power was turned off, the flow controller stopped and the chamber pumped empty to basic pressure. The chamber was vented to atmospheric pressure and the coated samples removed.
Two test PCBs and two Si waffles were used for each experiment. Si wafers allow physical properties of the coating formed to be measured, for example AFM for surface morphology and XRR for coating density. The metal traces of the test PCBs were gold clad copper. Si waffles were placed on the top front of the PCBs.
Tables 1A-1D show the different process parameters for coatings formed in this example and the measured properties of these coatings.
Example 2
A number of properties of examples of coated substrates formed according to the invention were investigated.
Resistance to fixed voltage in the time
This test method has been developed to evaluate the ability of different coatings to provide an electrical barrier on printed circuit boards and to predict the ability of a smart phone to meet the IEC 60529 14.2.7 (IPX7) test. The method has been developed to be used with tap water. This test includes measuring the current-voltage (IV) characteristics of a standardized printed circuit board (PCB) in water. The PCB is designed with a distance of 0.5 mm between the electrodes to be able to judge when electrochemical migration takes place over the traces in water. The degree of electrochemical activity is quantified by measuring current; low current is indicative of a coating with good quality. The method appears to be very effective at differentiating between different coatings. The performance of the coatings can be quantified, e.g. as a resistance at 4 and 8 V and 21 V. The measured resistance on the untreated test device is approximately 100 ohms when 16 V / mm is applied.
The coated PCB 10 to be tested is placed in a beaker 12 with water 14 and connected to the electrical tester via connections 16, 18 as shown in Figure 1. The plate is centered horizontally and vertically in the beaker to minimize effects of local ion concentration ( vertical location of the place is very important; water level must be up to the blue line). When the PCB is connected, the power source is set to the desired voltage and the current is monitored immediately. The applied voltage is for example 8 V and the PCB is kept at the set voltage for 13 minutes, the current being continuously monitored during this period.
The coatings formed by the different process parameters are tested and the results are shown in Tables 1A-1D. It has been found that when coatings have resistance values higher than 8 MOhm, the coated device successfully passes an IPX7 test. The nature of the device that is covered (for example the type of smartphone) will influence the test, for example by variations in materials, intrusion points, power consumption, etc.
Critical power (Fc)
The electrical conductivity of a coating can change considerably when a compressive voltage is applied to the coating. The change in the electrical conductivity depends on the amplitude of the stress experienced by the coating, amount of defects and type of polymer matrix of the coating. This behavior is explained on the basis of the formation or destruction of a conductive network, which further depends on the viscosity (stiffness) of the polymer matrix. To evaluate the ability of the coating to provide electrical contact under a relatively low force, a contact force test is performed.
The contact force test is an electrical test procedure that includes measuring the critical force (Fc) or pressure (Pc) to be applied to the insulating coating via a flat probe to cause electrical breakthrough through the coating. The test can be used either on smart phone PCBs or on strip plates (Test PCBs) that are placed as testimony samples during processes.
The test uses a flat probe, for example, 1 mm in diameter (or, for example, a spherical probe with a diameter of 2 mm), which contacts the flat surface of the film. The probe is mounted on a support leg and the arrangement is such that variations in the force applied by the probe to the surface of the sample are immediately recorded by a scale (or load cell) on which the sample is placed. With this arrangement, the resolution in applied pressure is approximately 15 kPA (force 5 g).
The normal procedure is to manually increase the force applied by the probe to the flat surface of the sample, taking into account the resistance between the probe and the conductive substrate. The force is manually or automatically increased to the point (Fc) when a film breakthrough occurs.
This test allows the electrical insulation properties of the sample to be analyzed at a number of different points across the surface, thereby providing an idea of the uniformity of the surface layer.
The Fc values for the coated PCB coatings formed in Example 1 are shown in Tables 1A-1D.
Figure 19 is a graph of Fc against coating thickness for PFAC8 made according to Example 1. It appears that a force of 20-100 g can be applied to the coating with a thickness of 1-2.5 microns to make an electrical connection.
Typical Fc values for a coating with a thickness of approximately 1000 nm is approximately 35 g. The coating can achieve protective functionality at a relatively low (250-800 nm) thickness, making it possible to achieve electrical contact after applying relatively low (<15 g) force. This is the advantage that the coating of the present invention can offer over other standard barrier coatings.
Coatin thickness
The thickness of the coatings formed in Example 1 was measured with a spectroscopic reflectometry device (Filmetrics F20-UV) using optical constants verified by spectroscopic elipsometry.
Spectroscopic Ellipsometry
Spectroscopic ellipsometry is a technique for measuring the change in polarization between incident polarized light and the light after interaction with a sample (i.e. reflected, transmitted light, etc.). The change in polarization is quantified by the amplitude ratio Ψ and the phase difference Δ. A broadband light source is used to measure this variation in a range of wavelengths and the default values of Ψ and Δ are measured as a function of the wavelength. The ITAC MNT Ellipsometer is an AutoSE from Horiba Yvon that has a wavelength range of 450 to 850 nm. Many optical constants can be derived from the Ψ and Δ values, such as film thickness and refractive index.
Data collected from the sample measurements include the harmonics intensities of the reflected or transmitted signal in the predefined spectral range. These are mathematically treated to extract intensity values called Is and Ic as f (I). The software calculates Ψ and Δ from Ic and Is. To extract parameters of interest, such as thickness or optical constants, a model must be set up to allow theoretical calculation of Ψ and Δ. The parameters of interest are determined by comparing the theoretical and experimental data files to obtain the best fit (MSE or X2). The best fit for a thin layer must be an X2 <3, for thicker coatings this value can be as large as 15. The model used is a three-layer Laurentz model comprising PTFE on Si substrate ending with a mixed layer (PTFE + cavities) to account for surface density.
Examples of optical properties of coatings formed in Example 1 are given in Table 2. This data relates to coatings 9 and 10 in Tables 1A-1D.
Spectroscopy Reflectrometry
Thickness of the coating is measured with a Filmetrics F20-UV spectroscopy-reflectrometry device. This instrument (F20-UV) measures properties of the coating by reflecting the light from the coating and analyzing the resulting reflection coefficient spectrum over a range of wavelengths. Light reflected from different interfaces of the coating can be in or out of phase so that these reflections add or subtract, depending on the wavelength of the incident light and the thickness and index of the coating. The result is intensity oscillations in the reflection coefficient spectrum that are characteristic of the coating.
To determine the thickness of the coating, the Filmetrics software calculates a theoretical reflection coefficient spectrum that corresponds as much as possible to the measured spectrum. It starts with an initial estimate of what the reflection coefficient spectrum should look like, based on the nominal coating stack (layered structure). This includes information about the thickness (accuracy 0.2 nm) and the refractive index of the different layers and the substrate from which the sample is made (refractive index values can be derived from spectroscopic ellipsometry). The theoretical reflection coefficient spectrum is then adjusted by adjusting the properties of the coating until a best fit with the measured spectrum is found. Measured coatings should be optically smooth and set within the thickness range set by the system configuration requirements is shown in Table 3.
The thicknesses of the coatings produced in Example 1 are shown in Tables 1A-1D, which is typically 750-3500 nm thick.
Alternative techniques for measuring thickness are pen profilometry and cross-sections of coatings measured with SEM.
Surface morphology
The surface morphology of the coatings is measured using atomic force microscopy (AFM). Analyzes are performed with a Veeco Park Autoprobe AFM instrument, used in tapping imaging mode, using Ultrasharp NSC12, diving board levers with spring constants in the range of 4-14 N / m, and with resonance frequencies in the range of 150-310 kHz. A high aspect ratio probe with a radius of curvature on the tipapex of <10 nm and aperture angle <20 ° was used. 10x10, 5x5 and lxl pm2 fields of view were depicted, with the larger field of view being more informative. Surface roughness, RMS (root mean square), was calculated by standard software, for each field of view. The images obtained were 256 x 256 pixels in all cases.
Two parameters can be extracted from the AFM morphological analysis of the coatings; (a) the RMS roughness (r) of the coating and b) the ratio AZ / d where d is the thickness of the coating and ΔΖ is explained below.
Figure 2 shows a tapping mode image 10x10 pm2 field of view (left) of a sample example (thickness d = 1230 nm) prepared according to Example 1 and a contour line plot (right) showing the data used for RMS roughness calculation. The ΔΖ value indicated on the plot is taken over an area of the graph that represents most of the coating. Peaks above the ΔΖ range indicate large particles and troughs that fall below the ΔΖ range show cavities or holes in the coating. The width of the peaks also gives an indication of the particle size. The example shown is sample 7 in Tables 1A-1D whose RMS roughness (r) was 35 + 3 nm and ΔΖ = 80 ± 10 nm giving ΔΖ / d = 0.065.
It has been shown that ΔΖ / d <0.15 indicates a hole-free coating. Morphological parameters are good indicators for hole-free coatings. However, this property alone does not take into account the high performance of the coating.
Chemical analysis
For samples with a thickness greater than 200 nm, a Fourier Transform Infrared Spectroscopy (FTIR) using a damped total reflection (ATR) sampling technique is used for chemical characterization and quality assessment of the coating (FTIR / ATR analysis). The spectrometer used was a MIR Standard Perkin Eimer Frontier fitted with the Frontier UATR Diamond / ZnSe with 1 reflection top plate, which produces high-quality spectra through the use of a pressure arm, allowing good contact of the sample with the diamond crystal. Scanning range of all measurements was 4,000-650 cm'1 with 0.4 cm'1 resolution and 10,000 / 1 HP-HP for a 5-second scan.
For the technique to be successful, the sample must be in direct contact with the ATR crystal. As with all FT-IR measurements, an infrared background is collected, in this case from the clean ATR diamond crystal. The crystals are usually cleaned with a piece of tissue soaked in solvent. After the crystal area has been cleaned and the background has been collected, the solid sample is placed on the small crystal area. The pressure arm must be positioned above the sample. Force is applied to the sample, thereby dampening it on the diamond surface. After the spectmm is collected, the user must check that the crystal area is clean before the next sample is placed on the crystal.
A typical FTIR / ATR spectmm of a 1000 nm thick coating prepared as described in Example 1 is shown in Figure 3. Assignments of the absorption peaks are also shown.
To analyze the data, a baseline is automatically subtracted from the spectrum, the integrated area is measured under certain interesting peaks, followed by the calculation of certain peak area ratios. The peak areas used for this analysis are shown in Figure 3 by rectangles around the interesting peaks. The band assignments and the integration limits are shown in Table 4.
The ratio between these two peak areas A (1335) / A (1737) is an important parameter that characterizes the chemistry and more particularly the degree of contamination in the coating. It appears that coatings with thickness d> 800 nm and A (1335) / A (1737 <0.23 ± 0.01) have undergone sufficient contamination to have the desired functionality, provided that they uniformly cover the surface of the piece to be protected It has been determined that plasma treatment would lead to the formation of a polymeric material that is much more cross-linked than the conventionally polymerized counterpart, and crosslinking would affect the abundance of -CF3 functionalities in the coating.
Coatings with thickness d <800 nm require a correction to be applied to the measured ratio value A (1335) / A (1737) to take into account the effect of the reduced thickness of the intensity of the selected FTIR / ATR peaks.
In this case: the corrected ratio = measured A (1335) / A (1737) - 000, 0003 * d + 0.255), where d = coating thickness in nm.
Physical density measurements
The physical density of the coatings prepared in Example 1 was estimated gravimetrically and also by XRR for more accuracy on very thin coatings. The polymeric coating with the desired properties was found to have a higher density than the corresponding monomer due to crosslinking, which is in accordance with the FTIR / ATR findings.
Table 5 shows the densities of three monomers and the resulting coatings, measured by X-ray reflectometry (XRR). The coating formed from (I) is formed using the present method, while the coating formed from (II) is formed using a known method. The density values for Parylene C are derived from the literature [1],
It can be seen that the coating (I) formed from PFAC8 according to the present invention is considerably denser than coating (III) formed from the same monomer using known methods. This is also considerably denser than Parylene C coating, a conventionally used barrier coating.
Relationship between resistance and FTIR / ATR data
The relationship between the resistance value of the coating and the FTIR / ATR ratio of the CF3 / C = 0 intensities is shown in Figure 4, using the data from Tables 1A-1D. The resistance value is resistance at 8V for 13 minutes in tap water and the FTIR / ATR ratio refers to A (1535) / A (1737).
As previously discussed, coatings with values for R greater than 8MOhm will pass an IPX7 test. Figure 4 shows that the coatings with FTIR / ATR-CF3 / C = 0 values of less than 0.23 ± 0.01 meet this criterion. It can be seen from the results in Tables 1A-1D that coatings 1, 2, 3 and 4 do not meet these criteria. These coatings are produced with the lowest current settings (~ 2.2 sccm) while coatings 1 and 2 have the lowest average power setting.
From the Fc results in Tables 1A-1D, it is also clear that the coatings can be produced such that they provide Fc values below 45 g. These values can become even lower (<10 g) if the coatings are thinner than 800 nm.
Other perfluoroacrylate monomers
Comparable high performance coatings have been produced with other perfluoracrylate and methyl acrylate monomers with different side chain lengths (n = 4.6.8 and 10), which are described in the following examples.
Example 3 - PFAC10
The experiment of Example 1 was repeated with PFAC10 (1H, 1H, 2H, 2H perfluorododecyl acrylate; CAS No. 17741-60-5) instead of PFAC8.
Figure 5 is a graph of the water resistance of PW PFAC10 coatings at 8V after 13 min interruption with respect to the FTIR / ATR-CF3 / C = 0 peak area ratio.
Looking at coatings with values for R higher than 8MOhm (that will pass an IPX7 test), the critical value of the ATR CF3 / C = 0 area ratio is 0.19 + 0.01.
Example 4 - PFAC6
The experiment of Example 1 was repeated with PFAC6 (1H, 1H, 2H, 2H-perfluorooctyl acrylate; CAS No. 17527-29-6) instead of PFAC8.
Figure 6 is a graph of resistance in water at 8V after 13 min interruption relative to the FTIR / ATR-CF3 / C = 0 peak area ratio shown.
Looking at coatings with values for R higher than 8MOhm (which will pass an IPX7 test), the critical value of the ATR CF3 / C = 0 area ratio is 0.3 ± 0.01.
Example 5 - PFAC4
The experiment of Example 1 was repeated with PFAC 4 (1H, 1H, 2H, 2H-perfluorohexyl acrylate; CAS No. 52591-27-2) instead of PFAC8.
Figure 7 is a graph of resistance in water at 8V after 13 min interruption with respect to the FTIR / ATR-CF3 / C = 0 peak area ratio shown.
Looking at coatings with values for R higher than 8MOhm (that will pass an IPX7 test), the critical value of the ATR CF3 / C = 0 area ratio is 0.36 ± 0.02
Analysis of perfluoroacrylate monomers
For Examples 3-5, the FTIR / ATR surface ratio between the peak representing the stretch mode of the end CF3 terminal group and the stretch mode of the C = O ester bond of the acrylate is measured for each monomer and produced for each plasma polymer from those monomers.
The surface boundaries used for these measurements are shown in Table 6. The monomers PFAC4 - PFAC10 have all the formula (II) below,
(Π) wherein n is 4 for PFAC4, 6 is for PFAC6, 8 is for PFAC8 and 10 is for PFAC10.
Figure 8 is a graph of the FTIR / ATR critical ratio (i.e., under which the coating provides good barrier functionality) against n and shows that the selected ATR surface ratio for each monomer increases exponentially with the length of the side chain. This is to be expected because during the ATR measurement the quenching wave will interact with dipoles in the film in all orientations defining the C-F binding envelope of each measured substance. As the length of the side chain increases, the intensity of the peak representing the CF3 stretch will increase along with the signal of peaks representing CF2 and CF2-CF3 vibration modes.
For each type of the plasma polymer prepared, there is a corresponding functionality line such as that shown in Figure 4 for PFAC8 and a critical ATR ratio value. Figure 9 shows these critical values for each polymer, as a function of the side chain length n of the monomer used to prepare this polymer.
It can be clearly seen that the values are related to the length (s) of the side chain through an exponential relationship. Applicants have realized that a coating with an FTIR / ITR ratio A (1) / A (2) <0.56e '°' parts (integration limits given in Table 8) is a polymer with the desired functionality.
The ATR spectrum can be used to identify the monomer from which the plasma polymer is produced. Table 7 shows the most important properties that distinguish the ATR spectra from the polymers.
Perfluoromethacrylate monomers
High performance coatings have also been produced with perfluoromethyl acrylate monomers with different side chain lengths as defined in formula (IV)
(IV) wherein n = 4, 6, 8 and 10. The coatings obtained are described in the following examples. The surface boundaries used for these measurements are shown in Table 8.
Example 6 - PFMAC8
The experiment of Example 1 was repeated with PFMAC8 (1H, 1H, 2H, 2H-perfluorodecyl methacrylate; CAS No. 1996-88-9) instead of PFAC8.
A graph of the water resistance of PW PFMAC8 coatings at 8V after 13 min interruption with respect to the FTIR / ATR-CF3 / C = 0 peak area ratio is shown in Figure 10.
The critical value of the ATR CF3 / C = 0 surface ratio is 0.19 ± 0.01 Example 7 - PFMAC6
The experiment of Example 1 was repeated with PFMAC6 (1H, 1H, 2H, 2H-perfluorooctyl methacrylate; CAS No. 2144-53-8) instead of PFAC8.
A graph of the water resistance of PW PFMAC® coatings at 8V after 13 min interruption with respect to the FTIR / ATR-CF3 / C = 0 peak area ratio is shown in Figure 11.
The critical value of the ATR CF3 / C = 0 surface ratio is 0.24 ± 0.02 Example 8 - PFMAC4
The experiment of Example 1 was repeated with PFMAC4 (1H, 1H, 2H, 2H-pefluorohexyl methacrylate; CAS No. 1799-84-4) instead of PFAC8.
A graph is of the resistance in water of PW PFMAC4 coatings at 8V after 13 min interruption with respect to the FnR / ATR-CF3 / C = 0 peak area ratio is shown in Figure 12.
The critical value of the ATR CF3 / C = 0 surface ratio is 0.31 ± 0.02 Analysis of PFACn monomers and PFMACn monomers
Figure 13 shows the critical FTIR / ATR ratio values as a function of the side chain length for the initial perfluoracrylate (PFACn) or perfluoromethacrylate (PFMACn) monomer and the resulting plasma polymers.
It can be seen that the critical FTIR / ATR-CF3 / C = 0 values for PFMACn coatings with the desired behavior follow the same trend as PFACn coatings with an exponential relationship. For compounds of formula III, the applicants have realized that a value of the FTIR / ATR ratio A (1) / A (2), 0.50th "°" 12n results in a coating with the desired functionality.
Example 9 - Parylene
The properties of Parylene coatings prepared by chemical vapor deposition (CVD) on the same substrates as the coatings described in Examples 1 and 3-8 are shown in Table 16 for comparative purposes.
As shown in Table 9, Parylene coatings with resistance values above 8MOhm can only be achieved with coatings thicker than 2500 nm. When these high thicknesses are achieved, the coating has an adverse effect on the operation of the device, as evidenced by the high critical force of more than> 250 g. With such a high thickness, the coating does not allow sufficient electrical contact to be made under typical contact forces, making masking contacts a necessary operation prior to applying the coating.
High performance coatings have also been produced with non-fluorinated monomers such as in Examples 10 to 12.
Example 10
The experiment of Example 1 was repeated with ethylhexyl acrylate (CAS No. 103-11-7) instead of PFAC8.
(VII)
A graph of the water resistance of ethylhexyl acrylate coatings at 8V after 13 min interruption with respect to the FTIR / ATR-CH3 / C = 0 peak area ratio is shown in Figure 20.
The critical value of the ATR CH3 / C = 0 surface ratio is 0.16 ± 0.01. Example 11
The experiment of Example 1 was repeated with hexyl acrylate (CAS No. 2499-95-8) instead of PFAC8.
(VIII)
A graph of the water resistance of hexyl acrylate coatings at 8V after 13 min interruption with respect to the FTIR / ATR-CH3 / C = 0 peak area ratio is shown in Figure 21.
The critical value of the ATR CH3 / C = 0 surface ratio is 0.16 ± 0.01. Example 12
The experiment of Example 1 was repeated with isodecyl acrylate (CAS No. 1330-61-6) instead of PFAC8.
(IX)
The process parameters and coating properties are given in Table 10.
A graph is of the water resistance of isodecyl acrylate coatings at 8V after 13 min interruption with respect to the FTIR / ATR-CH3 / C = 0 peak area ratio is shown in Figure 22.
The critical value of the ATR CH3 / C = 0 surface ratio is 0.30 ± 0.01. Overview of non-fluorinated monomers
A graph of the resistance in water of various coatings at 8V after a 13 minute interruption to the FTIR / ATR-CH3 / C = 0 peak area ratio is shown in Figure 23. This graph contains data of coatings formed from the following monomers: ethylhexyl acrylate, hexyl acrylate, decyl acrylate, lauryl dodecyl acrylate and isodecyl acrylate.
The structures of decyl acrylate (CAS No. 2156-96-9) and deodecyl (lauryl) acrylate (CAS No. 2156-97-0) are given below:
Decyl acrylate (X)
Dodecyl (lauryl) acrylate FTIR / ATR analysis of the CH3 / C = 0 peaks for the monomers in Figure 23 show that, apart from isodecyl acrylate (IDA), they all produce the desired coatings (ie with resistance values higher than 1 × 1 O7 Ohm ) at the same critical ATR ratio CH3 / C = 0 = 0.16 ± 0.01. This critical ATR ratio is independent of the chain length. The surface boundaries used for these measurements are shown in Table 11.
The only exception is IDA for which the critical ATR ratio = 0.30 ± 0.01, namely double that of the coatings formed from the other monomer in
Figure 23. This is explained by the fact that IDA has two CH3 terminal groups at the end of the side chain.
Applicants have been able to identify a general chemical structure for both fluorinated and non-fluorinated monomers that gives the desired performance. The monomer is a compound of formula I (a):
wherein each of R | until R 9 is independently selected from hydrogen or a C 1 -C 6 branched or straight chain alkyl group; each X is independently selected from hydrogen or halogen; a is from 0-10; b is from 2 to 14; and c is 0 or 1; and wherein when each XF is the FTIR / ATR intensity ratio of CX3 / C = 0 of the coating is lower than (c + 1) 0.6e '°' n ± 0.01 where n a + b + c + 1 ; and wherein when each X is H, the FTIR / ATR intensity ratio of CX3 / C = 0 is lower than (c + 1) 0.25 + 0.02; or the monomer a compound of formula I (b):
wherein each of R 1 to R 9 is independently selected from hydrogen or a C 1 -C 4 branched or straight chain alkyl group; each X is independently selected from hydrogen or halogen; a is from 0-6; b is from 2 to 14; and c is 0 or 1; and wherein when each XF is the FTIR / ATR intensity ratio of CX3 / C = 0 of the coating is lower than (c + 1) 0.6e '°' n ± 0.01 where n a + b + c + 1 ; and wherein when each X is H, the FTIR / ATR intensity ratio of CX3 / C = 0 is lower than (c + 1) 0.25 + 0.02.
Example 13
The experiment of Example 1 was repeated with vinyl decanoate (CAS No. 4704-31-8). The process parameters and coating properties are shown in Table 12.
All coatings in the examples have a coating thickness in the range of 250 nm to 5000 nm. After examination, the coatings were found to be compliant and the fact that all coatings either exceed or come close to the IPX7 test is an indication that they form physical barriers. The use of plasma polymerization to deposit the coating has the advantage that the coating can be made thick enough to provide a physical barrier while being significantly thinner than prior art conformal coatings. This thickness range has the advantage that the coating is sufficiently thick to form a physical barrier and yet thin enough to allow electrical connections to be made without first removing the coating.
The use of plasma polymerization also has the advantage that good intrusion of the monomer during the plasma polymerization technique ensures that the coating covers all desired areas, for example the entire outer surface. When the electronic or electrical device comprises a housing, the entire inner surface of the housing can be coated (by exposing the open housing to the plasma) to protect the electronic components in the housing when the device is assembled.
Table IA: Process parameters and coating properties for coatings formed from PFAC8
Table 1B: Process parameters and coating properties for coatings formed from PFAC8
Table IC: Process parameters and coating properties for coatings formed from PFAC8
Table 1D: Process parameters and coating properties for coatings formed from PFAC8
Table 2: Example of optical properties of coatings
1 Standard deviation of 100 thickness readings of 500 nm S102 film on silicon substrate
Table 3: Configuration requirements for thickness measurements (F20 UV)
Table 4: Band allocations and integration limits
Table 5: Monomer and coating densities (measured by XRR for PFAC8 coatings) and by gravimetric analysis for Parylene C
Table 6: Integration limits for the calculation of ATR ratios of different perfluoroacrylate monomers and associated polymers
Table 7: ATR characteristics of different PFACn polymers
Table 8: Integration limits for the calculation of ATR ratios of different perfluoromethacrylate monomers and associated polymers
Table 9: Properties of CVD-prepared Parylene coatings
Table 10: Process parameters and coating properties for coatings formed from isodecyl acrylate
Table 11: Integration limits for the calculation of ATR ratios of different non-fluorinated monomers and the corresponding polymers
Table 12: Process parameters for forming coatings from vinyl decanoate and obtained coating properties

权利要求:
Claims (50)
[1]
Conclusions
An electronic or electrical device or component thereof with a coating formed thereon by exposing the electronic or electrical device or component thereof to a plasma comprising one or more monomeric compounds for a sufficient period of time to apply a protective polymeric coating on a surface thereof. to form; wherein the protective polymeric coating forms a physical barrier over a surface of the electronic or electrical device or component thereof; wherein each monomer is a compound of formula I (a):

is, wherein each of R | until R 9 is independently selected from hydrogen or halogen or an optionally substituted Q-C 0 branched or straight chain alkyl group; each X is independently selected from hydrogen or halogen; a is from 0-10; b is from 2 to 14; and c is 0 or 1; and wherein when each XF is or when at least one X is halogen, especially F, the FTIR / ATR peak intensity ratio of CX3 / C = 0 of the coating is lower than (c + 1) 0.6e 'o ln ± 0.01 wherein n is a + b + c + 1; and wherein when each X is H, the FTIR / ATR intensity ratio of CX3 / C = 0 is lower than (c + 1) 0.25 + 0.02; or a compound of formula I (b):

wherein each of R 1 to R 8 is independently selected from hydrogen or halogen or an optionally substituted C 1 -C 6 branched or straight chain alkyl group; each X is independently selected from hydrogen or halogen; a is from 0-10; b is from 2 to 14; and c is 0 or 1; and wherein when each XF is or when at least one X is halogen, especially F, the FTIR / ATR intensity ratio of CX3 / C = 0 of the coating is lower than (c + 1) 0.6e "o ln where n is a + b + ci -1, and wherein when each X is H, the FTIR / ATR intensity ratio of CX3 / C = 0 is lower than (c + 1) 0.25 + 0.02, optionally wherein the barrier is a conforming physical barrier.
[2]
The electronic or electrical device or component thereof of claim 1, wherein the halogen is fluorine.
[3]
The electronic or electrical device or component thereof according to claim 1 or claim 2, wherein each of R1 to Rg is independently selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec- butyl, n-pentyl, neopentyl, n-hexyl, isohexyl, and 3-methylpentyl.
[4]
The electronic or electrical device or component thereof according to claim 3, wherein each of R 1 to R g is independently selected from hydrogen or methyl.
[5]
An electronic or electrical device or component thereof according to any one of the preceding claims, wherein a and c are each independently 0 or 1; and b is from 3 to 7.
[6]
The electronic or electrical device or component thereof according to any of the preceding claims, wherein each X is H.
[7]
The electronic or electrical device or component thereof according to any of claims 1 to 5, wherein each X is F.
[8]
The electronic or electrical device or component thereof according to any of the preceding claims, wherein R 1 and R 2 are both hydrogen.
[9]
The electronic or electrical device or component thereof according to any of the preceding claims, wherein R 3 is hydrogen or methyl.
[10]
The electronic or electrical device or component thereof of any one of the preceding claims, wherein R 5 is hydrogen and R 9 is C 1 -C 6 branched or straight chain alkyl group.
[11]
The electronic or electrical device or component thereof of claim 10, wherein R 9 is methyl.
[12]
The electronic or electrical device or component of any one of the preceding claims, wherein each of R 4 to R 7 is hydrogen.
[13]
The electronic or electrical device or component of any one of the preceding claims, wherein each of R 1 to R 9 is hydrogen, each X is H, a = 0 and c = 0.
[14]
The electronic or electrical device or component thereof according to any of claims 7 to 12, wherein the compound of formula I (a) has the following formula:

wherein n is from 2 to 10.
[15]
The electronic or electrical device or component thereof according to any of claims 7 to 12, wherein the compound of formula I (a) has the following formula:

wherein n is from 2 to 10.
[16]
The electronic or electrical device or component thereof according to claim 14, wherein the compound of formula I (a) is selected from 1H, 1H, 2H, 2H-perfluorohexyl acrylate (PFAC4), 1H, 1H, 2H, 2H-perfluorooctyl acrylate (PFAC6) 1 H, 1 H, 2 H, 2 H-perfluorocyl acrylate (PFAC 8) and 1 H, 1 H, 2 H, 2 H-perfluorododecyl acrylate (PFAC 10).
[17]
The electronic or electrical device or component thereof according to claim 15, wherein the compound of formula I (a) is selected from 1H, 1H, 2H, 2H-pefluorohexyl methacrylate (PFMAC4), 1H, 1H, 2H, 2H-perfluorooctyl methacrylate (PFMAC6) and 1H, 1H, 2H, 2H-perfluorodecyl methacrylate (PFMAC8).
[18]
The electronic or electrical device or component thereof according to any of claims 8 to 13, wherein the compound of formula I (a) has the following formula:

wherein a and c are each independently 0 or 1, b = 3-7 and n is 4 to 10, where n = a + b + c + 1.
[19]
The electronic or electrical device or component thereof according to any of claims 8 to 13, wherein the compound of formula I (a) has the following formula:

wherein n is 2 to 12.
[20]
The electronic or electrical device or component thereof according to claim 18 or claim 19, wherein the compound of formula I (a) is selected from ethyl hexyl acrylate, hexyl acrylate, decyl acrylate, lauryl dodecyl acrylate and isodecyl acrylate.
[21]
The electronic or electrical device or component thereof according to any of claims 1 to 13, wherein the compound of formula I (b) has the following formula:

wherein n is from 3 to 13.
[22]
The electronic or electrical device or component thereof of claim 21, wherein

the compound of formula I (b) has the following formula: wherein n is from 3 to 13.
[23]
The electronic or electrical device or component thereof of any one of the preceding claims, wherein the physical barrier is a conformal physical barrier.
[24]
The electronic or electrical device or component thereof according to any of the preceding claims, wherein the electronic or electrical device or component comprises a housing and wherein the coating forms a conforming physical barrier over an inner surface of the housing.
[25]
Electronic or electrical device or component thereof according to one of the preceding claims, wherein the coating is substantially free of holes.
[26]
The electronic or electrical device or component thereof of claim 25, wherein ΔΖ / d is less than 0.15, wherein ΔΖ is the average length variation on an AFM line scan in nm and d is coating thickness in nm.
[27]
An electronic or electrical device or component thereof according to any one of the preceding claims, wherein the coating is electrically insulating.
[28]
An electronic or electrical device or component thereof according to any of the preceding claims, wherein the electronic or electrical device or component thereof can withstand immersion in up to 1 meter of water for more than 30 minutes without failure or corrosion while power is applied to the electronic or electrical electrical device or component.
[29]
An electronic or electrical device or component according to any preceding claim, wherein the coating has a resistance of 8 MOhm or higher when immersed in water and a voltage of 8V is applied for 13 minutes.
[30]
An electronic or electrical device or component according to any one of the preceding claims, wherein the coating has a thickness of 50 nm-10,000 nm.
[31]
An electronic or electrical device or component according to any one of the preceding claims, wherein the coating has a thickness of 250 nm - 2000 nm.
[32]
An electronic or electrical device or component according to any one of the preceding claims, wherein the coating is electrically insulating and wherein the coating is sufficiently flexible that electrical connectors can be connected to the electronic or electrical device or component thereof and an electrical connection between the electrical connectors and electronic or electrical device or component thereof can be made without the need to first remove the coating.
[33]
An electronic or electrical device or component according to any one of the preceding claims, wherein the coating is electrically insulating and has a thickness of 1-2.5 microns and wherein a force of 20-100 g applied to the coating allows an electrical connection with the electronic or electrical device or component thereof is made in the local environment where the force is applied.
[34]
An electronic or electrical device or component according to any one of the preceding claims, wherein the coating is electrically insulating and has a thickness of less than 1 micron and wherein a force of less than 5-20 g applied to the coating allows an electrical connection to be made is in the local environment where the power is applied.
[35]
An electronic or electrical device or component thereof according to any of the preceding claims, wherein the coating forms a water-repellent surface defined by a static water contact angle (WCA) of at least 90 °.
[36]
An electronic or electrical device or component thereof according to any one of the preceding claims, wherein X is F and wherein the coating forms a water-repellent surface defined by a static water contact angle (WCA) of at least 100 °.
[37]
An electronic or electrical device or component thereof according to any one of the preceding claims, wherein the electronic or electrical device or component thereof is selected from mobile telephones, smartphones, pagers, radios, sound and audio systems such as loudspeakers, microphones, ringers and / or buzzers, hearing aids, personal audio equipment such as personal CD, cassette tape or MP3 players, televisions, DVD players including portable DVD players, VCRs, digital and other set-top boxes, computers and related components such as laptop, notebook, tablet, phablet or palmtop computers, personal digital assistants (PDAs), keyboards, or instrumentation, game consoles, data storage devices, outdoor lighting systems, radio antennas and other forms of communication equipment, and printed circuit boards.
[38]
A method of treating an electronic or electrical device or component thereof according to any of the preceding claims, comprising: exposing the electronic or electrical device or component thereof to a plasma comprising one or more monomeric compounds for a sufficient period of time to provide a protective forming a polymeric coating on the electronic or electrical device or component thereof, wherein the protective polymeric coating forms a physical barrier over a surface of the electronic or electrical device or component thereof; wherein each monomer is a compound of formula (Ia): (Ia)

wherein each of R 1 to R 9 is independently selected from hydrogen or halogen or an optionally substituted C 1 -C 6 branched or straight chain alkyl group; each X is independently selected from hydrogen or halogen; a is from 0-10; b is from 2 to 14; and c is 0 or 1; or a compound of formula (Ib):

wherein each of R 1 to R 9 is independently selected from hydrogen or halogen or an optionally substituted C 1 -C 6 branched or straight chain alkyl group; each X is independently selected from hydrogen or halogen; a is from 0-10; b is from 2 to 14; and c is 0 or 1.
[39]
The method of claim 38, wherein the barrier is a conformal physical barrier.
[40]
The method of claim 38 or claim 39, wherein the step of exposing the electronic or electrical device or component thereof to a plasma comprises a first continuous wave (CW) deposition step and second pulsed (PW) deposition step.
[41]
The method of claim 40, wherein the pulsed plasma pulses are arranged in a sequence that yields a time-to-time ratio in the range of 0.001 to 1.
[42]
The method of claims 40 to 41, wherein the pulsed conditions are time-on = 10-500 microseconds and time-out = 0.1 to 30 ms.
[43]
The method of any one of claims 40 to 42, wherein the monomer is introduced during pulsing at a flow rate between 1.5 to 2500 sccm.
[44]
The method of any one of claims 40 to 44, wherein the ratio of power to monomer current during the pulsed plasma is between 2-60 W / sccm.
[45]
The method of any one of claims 38 to 44, wherein the compound of formula I (a) is selected from 1H, 1H, 2H, 2H-perfluorohexyl acrylate (PFAC4), 1H, 1H, 2H, 2H-perfluorooctyl acrylate (PFAC6), 1H, 1H, 2H, 2H-perfluorocyl acrylate (PFAC8) and 1H, 1H, 2H, 2H-perfluorododecyl acrylate (PFAC10).
[46]
The method of any one of claims 38 to 44, wherein the compound of formula I (a) is selected from 1H, 1H, 2H, 2H-pefluorohexyl methacrylate (PFMAC4), 1H, 1H, 2H, 2H-perfluorooctyl methacrylate (PFMAC6) and 1H, 1H, 2H, 2H-perfluorodecyl methacrylate (PFMAC8).
[47]
The method of any one of claims 38 to 44, wherein the compound of formula I (a) is selected from ethyl hexyl acrylate, hexyl acrylate, decyl acrylate, lauryl dodecyl acrylate, and isodecyl acrylate.
[48]
The method of any one of claims 38 to 47, further comprising a prior activation step of applying a CW plasma in the presence of an inert gas.
[49]
An electronic or electrical device comprising a housing and an internal electronic or electrical component, wherein the internal component comprises a coating, wherein the coating is formed by one of the methods according to claims 38 to 48 and / or the internal component is a component according to one of claims 1 to 37.
[50]
The method of any one of claims 38 to 49, wherein the electronic or electrical device or component thereof is selected from mobile phones, smartphones, pagers, radios, sound and audio systems such as speakers, microphones, ringers and / or buzzers, hearing aids, personal audio equipment such as personal CD, cassette tape or MP3 players, televisions, DVD players including portable DVD players, video recorders, digital and other set-top boxes, computers and related components such as laptop, notebook , tablet, phablet or palmtop computers, personal digital assistants (PDAs), keyboards, or instrumentation, game consoles, data storage devices, outdoor lighting systems, radio antennas and other forms of communication equipment.

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公开号 | 公开日

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BR112017026582A2|2018-08-14|

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EP3799542A1|2021-03-31|

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US20210368632A1|2021-11-25|

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US20190335592A1|2019-10-31|

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GB201800281D0|2018-02-21|

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CN108029198A|2018-05-11|

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GB2556246A|2018-05-23|

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IL256182D0|2018-02-28|

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BE1023776A1|2017-07-18|

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GB2556246B|2019-06-12|

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AU2016275276A1|2018-02-01|

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MX2017015916A|2018-08-21|

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GB2556246C|2019-06-26|

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EP3308613B1|2020-08-05|

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EP3308613A1|2018-04-18|

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ES2821323T3|2021-04-26|

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JP2018522097A|2018-08-09|

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KR20180016559A|2018-02-14|

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GB2556246A8|2020-08-19|

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TW201706369A|2017-02-16|

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GB2556246B8|2020-08-19|

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PL3308613T3|2020-11-16|

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WO2016198855A1|2016-12-15|

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WO2022008859A1|2020-07-07|2022-01-13|The Secretary Of State For Defence|New and improved substrates for raman spectroscopy|

法律状态:
2017-10-30| FG| Patent granted|Effective date: 20170720 |

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2020-03-27| MM| Lapsed because of non-payment of the annual fee|Effective date: 20190630 |

优先权:

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申请号 | 申请日 | 专利标题

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EP15386018|2015-06-09|

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EP15386018.4|2015-06-09|

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