JPH06196614A - Lead frame - Google Patents

Abstract

PURPOSE:To provide a lead frame having excellent stress resisting crack property, maintaining property of a lead shape, mechanical strength and heat dissipation property. CONSTITUTION:A heat dissipating base stage 4, a stress buffering member 6, which is bonded on the upper part of the heat dissipating base stage 4 through an insulating bonding layer 5, and an outer lead member 9 comprising rigid metal, which is bonded to the edge part of the heat dissipating base stage 4 with an insulating bonding agent 5, are provided. A semiconductor device is fixed on the upper part of the stress buffering member 6 through a bonding agent layer 10. A lead frame is constituted of these parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame, and more particularly to a lead frame which is excellent in stress crack resistance, lead shape retention, mechanical strength and heat dissipation.

[0002]

2. Description of the Related Art A semiconductor device such as an IC or LSI is mounted on a lead frame and then housed in a housing made of metal, ceramic or resin, or is put into practical use as a package entirely sealed with a resin mold. To be done. This package is mounted on a printed wiring board or the like and is commercially available. As this package,
Taking a resin-molded package as an example,
As shown in the schematic cross-sectional view of FIG. 2, a semiconductor device 21, a lead frame 22 mounted with the semiconductor device 21, and having a role of connecting a wiring pattern of the semiconductor device 21 and an external circuit, and the semiconductor device 21. It is composed of a resin mold 23 that encloses the lead frame 22. The lead frame 22 is a base 2 on which the semiconductor device 21 is mounted.
4 and an outer lead member 26 connected to the end portion 25 of the base 24. The semiconductor device 21 is adhered and fixed to the upper part of the base 24 by an insulating adhesive layer 27. The outer lead member 26 is connected to the end portion 25 of the base 24 by an insulating adhesive layer 28. Also, the base 24
Also serves as a heat dissipation plate that absorbs heat generated during operation of the semiconductor device 21 and radiates heat to the outside.
It is formed of a metal having high thermal conductivity, such as copper.
The outer lead member 26 is electrically connected to the semiconductor device 21 by wire bonding or the like (not shown). Further, in FIG. 2, the outer lead member 26 is shown alone, but normally, in the lead frame, a plurality of lead members 26 are provided corresponding to the input / output ends of the semiconductor device 21 to be mounted, and when there are many lead pins, there are several hundred pins. The outer lead member is provided on the base 24.

[0003]

However, in the above conventional lead frame, the base and the semiconductor device, for example,
In the semiconductor device made of a copper plate and the semiconductor device made of a Si wafer, the thermal expansion coefficients of the two are significantly different, and stress is generated due to heat generated during the operation of the semiconductor device, which causes a problem that the semiconductor device is cracked. . Therefore, the conventional lead frame cannot handle the amount of heat generated during operation, which increases with the recent trend toward higher integration and higher speeds of semiconductor devices, and special adhesives for bonding the base and the semiconductor device. However, there was a problem that the cost was increased. Also, in the conventional lead frame, the outer lead member is formed of a material such as copper that is soft and has low mechanical strength, so that it may be bent during handling and the shape may not be retained, or when mounted on a wiring board or the like. In addition, there is a problem that mounting work becomes difficult due to bending.

Therefore, an object of the present invention is to provide a lead frame which is excellent in stress crack resistance, lead shape retention, mechanical strength and heat dissipation.

[0005]

In order to solve the above-mentioned problems, the present invention provides a heat-dissipating base, and a stress buffer member adhered to the upper part of the heat-dissipating base via an insulating adhesive layer. An outer lead member made of a rigid metal, which is adhered to an end of the heat dissipation base via an insulating adhesive layer, and a semiconductor device is fixed on the stress buffer member via an adhesive layer. The present invention provides a lead frame as described above.

It is preferable that the stress buffering member is formed of a material having a coefficient of thermal expansion equal to or close to that of the substrate of the semiconductor device.

Hereinafter, the lead frame of the present invention will be described in detail with reference to FIG. 1 showing a schematic partial sectional view of a semiconductor device package using the lead frame according to the embodiment of the present invention.

The semiconductor device package shown in FIG. 1 comprises a semiconductor device 1, a lead frame 2 of the present invention for mounting the semiconductor device 1, and a resin mold 3 for sealing the semiconductor device 1.

The lead frame 2 basically has a heat-dissipating base 4, a stress buffer member 6 adhered to the heat-dissipating base 4 via an insulating adhesive layer 5, and the heat-dissipating base 4. Outer lead member 9 adhered to the end 7 of the insulating layer 8 by an insulating adhesive layer 8.
It consists of and.

The heat dissipating base 4 is not particularly limited as long as it absorbs heat generated during the operation of the semiconductor device and can dissipate the heat to the outside of the package. For example, Cu or the like having high thermal conductivity. It may be formed of a thing.

The stress buffer member 6 has an adhesive layer 1 on the upper portion thereof.
The semiconductor device 1 is adhered to the semiconductor device 1 via 0, and the semiconductor device 1 is fixed.
This is to alleviate the stress caused by the difference between the thermal expansion of the above and the thermal expansion of the heat dissipation base 4 and prevent the occurrence of cracks in the semiconductor device 1 due to the relaxation. The material of the stress buffering member is such that heat generation during operation of the semiconductor device or thermal expansion of the semiconductor device 1 due to heating in a reliability test or the like and the heat dissipation base 4
There is no particular limitation as long as it is made of a material that can alleviate the stress generated by the difference in thermal expansion of the semiconductor device 1 and prevent the semiconductor device 1 from cracking. For example, the semiconductor device 1 may be made of a material having a thermal expansion coefficient equal to or close to that of the material forming the semiconductor device 1. Specifically, when the semiconductor device 1 is made of a Si wafer, this stress buffering member may be made of a Si plate or the like having a thermal expansion coefficient equal to or substantially equal to that of Si.

The thickness, shape, area, etc. of the stress buffer member are appropriately determined according to the shape, size, amount of heat generated during operation, etc. of the mounted semiconductor device.

The outer lead member 9 is connected to the input / output end of the wiring pattern of the semiconductor device 1 by a bonding wire (not shown), and electrically connects this semiconductor device and an external circuit.

In the lead frame of the present invention, the outer lead member 9 is made of a rigid metal in order to prevent defects due to bending deformation. As the rigid metal, for example, iron, copper-nickel alloy (for example,
42 alloy) and the like.

In the lead frame of FIG. 1, the insulating adhesive layer 5, the insulating adhesive layer 8 and the adhesive layer 10 are
There is no particular limitation, and a conventional adhesive can be used. Particularly, in the present invention, since the stress buffering member 6 can relieve the stress caused by the difference in thermal expansion between the semiconductor device and the base, the difference in thermal expansion between the semiconductor device and the base is large. Since the adhesive agent that can be used for the adhesion is limited and an expensive adhesive agent is required, it is possible to solve the conventional problem that causes an increase in cost.

In the production of the lead frame of the present invention, constituent members such as a base and an outer lead member are formed by etching, pressing or the like according to a conventional method, and these are adhered to each other to be assembled into a predetermined structure, and further stress buffering is performed. This can be performed by adhering the member on the base, and can be easily performed by adding the adhering step of the stress buffering member to the normal lead frame manufacturing step.

[0017]

The lead frame of the present invention is excellent in stress crack resistance, lead shape retention, mechanical strength and heat dissipation. Therefore, the lead frame of the present invention is useful as a lead frame of a semiconductor device in which the heat generation during operation becomes a problem due to the higher integration and higher speed in recent years. Further, there is an advantage that it is not necessary to use a special adhesive, and a commonly used adhesive is sufficient.

[Brief description of drawings]

FIG. 1 is a schematic partial sectional view illustrating a semiconductor device package including a lead frame according to an embodiment of the present invention.

FIG. 2 is a schematic partial cross-sectional view illustrating a conventional lead frame.

[Explanation of symbols]

 1 Semiconductor Device 2 Lead Frame 3 Resin Mold 4 Heat Dissipating Base 5 Insulating Adhesive Layer 6 Stress Buffer Member 7 End 8 Insulating Adhesive 9 Outer Lead Member 10 Adhesive Layer 21 Semiconductor Device 22 Lead Frame 23 Resin Mold 24 Units Stand 25 End 26 Outer Lead Member 27 Insulating Adhesive Layer 28 Insulating Adhesive Layer

Claims (2)

[Claims] 1. A heat dissipation base, a stress buffer member adhered to an upper portion of the heat dissipation base via an insulating adhesive layer, and an end of the heat dissipation base via an insulating adhesive layer. An outer lead member made of a rigid metal that is adhered, and a semiconductor device is fixedly mounted on the stress cushioning member via an adhesive layer. 2. The lead frame according to claim 1, wherein the stress buffering member is formed of a material having a coefficient of thermal expansion equal to or close to that of the substrate of the semiconductor device.