• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The present invention relates to a lead frame composed of a die pad made of an iron alloy material and an inner lead and an outer lead made of a copper alloy material to prevent bending of the die pad. Disclosure of Invention An object of the present invention is to provide a lead frame capable of preventing semiconductor chip warpage and package warpage due to a difference in thermal expansion coefficient with a die pad. Lead frame according to the present invention for achieving the above object Internal leads made of a first material; Outer leads made of the first material; And And a die pad made of a second material different from the first material.
    公开号:KR19990031589A
    申请号:KR1019970052370
    申请日:1997-10-13
    公开日:1999-05-06
    发明作者:최일흥
    申请人:윤종용；삼성전자 주식회사；
    IPC主号:
    专利说明:

    Leadframe
    The present invention relates to a lead frame, and more particularly, to a lead frame comprising a die pad made of an iron alloy material and an inner lead and an outer lead made of a copper alloy material to prevent bending of the die pad. will be.
    As is generally known, a copper-based alloy or an iron-based alloy has been mainly used as a material of a lead frame in consideration of electrical, thermal and physical properties. The lead frame of the copper-based alloy is mainly used in thin packages because of its excellent electrical characteristics, thermal conductivity, and cracking properties of solder joints.
    As shown in FIG. 1, the conventional leadframe 10 includes a die pad 11, inner leads 13, outer leads 15, side rails 17, tie bars 14, and a dam bar ( 16) consists of the same single material.
    Looking at the manufacturing process of the plastic package using a conventional lead frame having such a structure, first, a die attach process is performed, the semiconductor chip 1 is bonded to the die pad of the lead frame 10 by the adhesive 3 ( 11) to the top surface.
    Subsequently, in the die attach process, the adhesive 3 is cured at a predetermined temperature for a predetermined time, and then the lead frame 10 is cooled to room temperature.
    Thereafter, in the wire bonding process, the inner leads 13 of the lead frame 10 and the bonding pads (not shown) of the semiconductor chip 1 are electrically connected to each other by bonding wires (not shown).
    Then, in the molding process, the respective parts except for the outer lead 15 and the side rail 17 of the lead frame 10 are sealed by an encapsulation body (not shown) of a molding resin.
    However, since the conventional lead frame 10 is made of a single material of a copper-based alloy, it is not only easy to manufacture a lead frame for a thin package such as TSOP or TQFP, but also advantageous to manufacture a thin package.
    However, the conventional lead frame 10 has various problems as follows. That is, when the die pad 11 of the lead frame 10 has a large size, after the hardened lead frame 10 is cooled to room temperature, the die pad 11, the semiconductor chip 1, and the adhesive 3 Due to the severe thermal expansion coefficient difference between), as shown in FIG. 2, the center portion of the die pad 11 is bent upwards relative to the edge, and the edge of the semiconductor chip 1 is bent downwardly below the center portion.
    Furthermore, when the lead frame 10 is sealed by an encapsulation body (not shown) of the molding resin, an unbalance of the up and down flow of the molding resin occurs, so that a poor molding process of the package occurs and the package is completed even after the molding process is completed. Warping of was frequent.
    In order to improve this, it is necessary to adjust the downset of the die pad 11, but to prevent the bending of the package, it is necessary to deepen the downset depth. However, when the downset depth of the die pad 11 is deep, an imbalance in molding resin flow occurs between the upper and lower cavities of a molding die (not shown) in the molding process, thereby causing a large molding defect of the encapsulation body.
    As described above, in the conventional lead frame, since each part is made of a single material, there is a technical difficulty in solving two conflicting problems such as bending of a package and molding.
    Accordingly, an object of the present invention is to provide a lead frame capable of preventing semiconductor chip warpage and package warpage due to a difference in thermal expansion coefficient with a die pad.
    1 is a schematic view showing a structure in which a semiconductor chip is bonded to a lead frame in the prior art.
    Figure 2 is a cross-sectional view showing the occurrence of warpage of the die pad after curing the adhesive bonding the semiconductor chip to the lead frame according to the prior art.
    Figure 3 is a schematic diagram showing a structure in which a semiconductor chip is bonded to the lead frame according to the present invention.
    4A and 4B are cross-sectional views taken along lines A-A and B-B of FIG. 3.
    Explanation of symbols on the main parts of the drawing
    DESCRIPTION OF SYMBOLS 1 Semiconductor chip 3: Adhesive 10: Lead frame 11: Die pad 13: Inner lead 14: Tie bar 15: Outer lead 16: Dam bar 17: Side rail 30: Lead frame 31: Die pad 33: Inner lead 34: Tie bar 35: outer lead 36: dam bar 37: side rail 37a: upper layer of side rail 37b: lower layer of side rail 39: adhesive for side rail bonding
    Lead frame according to the present invention for achieving the above object
    Internal leads made of a first material;
    Outer leads made of the first material; And
    And a die pad made of a second material different from the first material.
    Hereinafter, a lead frame according to the present invention will be described in detail with reference to the accompanying drawings.
    3 is a schematic view showing a structure in which a semiconductor chip is bonded to a lead frame according to the present invention, and FIGS. 4A and 4B are cross-sectional views taken along lines A-A and B-B of FIG. 3.
    As shown in FIG. 3, the leadframe 30 of the present invention has an inner lead 33, an outer lead 35, a dam bar (not shown) and a side rail 37 as shown in FIG. 1. The upper layer 37a is made of the first material, and the die pad 31, the tie bar (not shown), and the lower layer 37b of the side rail 37 are made of the second material. Here, the first material is a copper alloy, and the second material is an iron alloy.
    Looking at the manufacturing method of the lead frame of the present invention configured as described above, first, the first lead frame of the first material of the copper-based alloy is formed and the plate material of the second material of the copper-based alloy to the second lead frame of the second material Form.
    In more detail, by etching or stamping a plate of the first material, which is a copper-based alloy, the die pad 31 and the tie bar 36 are absent, and the inner leads 33, the outer leads 35, and the dam bars ( 36 and a first lead frame having a pattern corresponding to the upper layer 37a of the side rail 37. In addition, a positive hole and a long hole are formed in the upper layer 37a. Subsequently, the plating layer 33a is plated on the inner ends of the inner leads 33.
    In addition, by etching or stamping the plate of the second material, which is a copper-based alloy, there are no inner leads 33, outer leads 35, or a dam bar 36, and a die pad 31, a tie bar 34, and a side rail. A second lead frame having a pattern corresponding to the lower layer 37b of 37 is formed. In addition, a positive hole and a long hole are formed in the lower layer 37b to correspond to the positive hole and the long hole of the upper layer 37a.
    Thereafter, the first lead frame and the second lead frame are adhered to each other through the adhesive 39 between the upper layer 37a and the lower layer 37b of the side rail 37 to complete the lead frame 30.
    In the lead frame 30 completed as described above, since the die pad 31 is made of an iron-based alloy, the die pad 31 is hardened even after curing the adhesive 3 that adheres the semiconductor chip 1 to the die pad 31 in the die attach process. The warpage of the pad 31 is prevented and the warpage of the semiconductor chip is prevented. This is because the die pad 31 has a small difference in coefficient of thermal difference between the semiconductor chip and the die attach adhesive.
    In addition, when the molding process is performed in a state where the die pad 31 is not warped, the warpage of the package is naturally prevented.
    In addition, since the inner lead 33 and the outer lead 35 are made of a copper alloy material, the electrical properties and the thermal conductivity of the lead frame 30 are excellent.
    As described above, the lead frame according to the present invention is made of an iron alloy in which a die pad is thermally stable, and an inner lead and an outer lead are made of a copper alloy having excellent electrical characteristics and thermal conductivity.
    Therefore, the present invention can prevent the bending of the die pad and prevent the bending of the package, thereby improving the reliability of the packaged product.
    权利要求:
    Claims (4)
    [1" claim-type="Currently amended] Internal leads made of a first material;
    Outer leads made of the first material; And
    A lead frame comprising a die pad made of a second material different from the first material.
    [2" claim-type="Currently amended] The method according to claim 1, further comprising a side rail having an upper layer made of the first material, a lower layer made of the second material, and an adhesive interposed between the upper and lower layers to bond the upper and lower layers. Leadframe.
    [3" claim-type="Currently amended] The lead frame according to claim 2, wherein the lower layer of the side rail is integrally connected with the tie bar.
    [4" claim-type="Currently amended] The lead frame according to claim 1 or 2, wherein the first material is a copper alloy and the second material is an iron alloy.
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    同族专利:
    公开号 | 公开日
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    1997-10-13|Application filed by 윤종용, 삼성전자 주식회사
    1997-10-13|Priority to KR1019970052370A
    1999-05-06|Publication of KR19990031589A
    优先权:
    申请号 | 申请日 | 专利标题
    KR1019970052370A|KR19990031589A|1997-10-13|1997-10-13|Leadframe|
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