JPH02152267A - Lead frame parallel-connected by cu alloy/fe-ni alloy - Google Patents

Abstract

PURPOSE:To obtain a newly-established head frame which is superior not only in heat radiating properties and mechanical strength but also in consistency of thermal expansion by installing band materials consisting of a low thermal expansive Fe-Ni alloy to both ends of a band material consisting of a highly conductive Cu alloy in one body in such a way that the above band materials of Fe-Ni alloys are connected to the Cu alloy in the plate width direction by causing them to have the same thickenss. CONSTITUTION:Each lead frame is formed into a tri-metal structure in which three band materials are united in one in parallel so that two band materials 2 consisting of a low thermal expansive Fe-Ni alloy are connected to both ends of a band material 1 consisting of a highly conductive Cu alloy in the plate width direction. In such a case, for example, a Cu-0.15% Sn alloy is used as the Cu alloy and an Fe-42% Ni alloy is used as the Fe-Ni alloy. Each band material is joined in parallel by performing an electron beam welding process and the like. Desired lead frame which are superior in heat radiating properties and mechanical strength and even in consistency of thermal expansion as well are obtained.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a composite metal material suitable for lead frames of semiconductor devices such as ICs and LSIs, and in particular to a composite metal material made of a parallel bond of two or more materials. Alloy/Fe-N
The present invention relates to a J-alloy parallel lead frame.

[Prior Art] In semiconductor devices such as ICs and LSIs, frames that support semiconductor chips such as Si and constitute a sorting section for information transmission have various characteristics as IC components. required. In other words, the main characteristics required are excellent thermal conductivity (electrical conductivity), relatively high strength, good repeated bendability, low coefficient of thermal expansion, and excellent plating properties. It will be done.

42 has traditionally been used as a material for lead frames because it has a small coefficient of thermal expansion and has good sealing properties with ceramics and glass.
Alloy (F e -42%Ni) has been widely used, and in recent years, due to the demand for heat dissipation (thermal conductivity) accompanying the trend toward lower cost and higher integration of ICs, it has become a relatively inexpensive and heat conductive material. The use of copper-based materials, which have good properties, is increasing.

As copper-based materials, Cu -0,15$ Sn alloy C
DA194 lCu-2,4%Fe-0,1! Zn1C
U-0, I%Fe alloy etc. are mainly used.

[Problems to be Solved by the Invention] Recently, there has been a remarkable increase in the integration of ICs, LSIs, etc., and semiconductor chips have become larger.

If the chip size is large, if there is a large gap in the coefficient of thermal expansion between the chip and the Riet frame, tie the chip to the sorting frame.
This is a problem that cannot be ignored, as cracks may occur in the chip when waxing at 00°C.

1) In order to meet the above requirements, it is difficult to achieve the desired characteristics by improving single materials, and some materials such as crat materials made of copper-based materials and iron-based materials have been developed or researched. In sandwich-type composite metal materials that have been proposed for use in frames or are conventionally known, it is difficult to achieve a high level of thermal conductivity and strength that meet the required levels.

[Means for Solving the Problems] The present invention was made for the purpose of solving the above-mentioned problems, and includes alloying Fe-N with low thermal expansion at both ends of a strip material made of a highly conductive Cu alloy. By making strips of the same thickness and integrally fixing them side by side in the width direction, we provide a glued ferreme with a new structure that has excellent heat dissipation, mechanical strength, and thermal expansion consistency. .

[Function] As described above, by integrally fixing the strip material made of a low thermal expansion Fe-Ni alloy to both ends of the strip material made of a highly conductive Cu alloy in parallel in the plate width direction, the third As shown in the figure, the heat dissipation property of the semiconductor chip support part 3 of the sort frame which is mainly made of Cu alloy is ensured, and the foot part (leat part) of the lead frame which is mainly made of Fe-Ni alloy is secured. 4) Mechanical strength is ensured. Since the lead portion 4 of the lead frame is used after being bent in semiconductor devices such as ICs and LSIs, it is necessary to have mechanical strength corresponding to the bending process.

The semiconductor chip support needs to have thermal expansion consistency as well as heat dissipation.
In the present invention, by arranging the Fe-Ni alloy at both ends of the Cu alloy, the thermal expansion of the Fe-Ni alloy or the Cu alloy at both ends is kept low. This ensures consistency in thermal expansion as a whole.

[Example] Fig. 2 shows a sorting frame having a structure in which a strip material 2 made of a low thermal expansion Fe-Ni alloy is fixed to one end of a strip material l made of a highly conductive Cu alloy in parallel in the sheet width direction. FIG. 1 shows a cross-sectional view of highly conductive Cu as an example of the present invention.
Low thermal expansion F e -N is applied to both ends of the strip material 1 made of alloy.
This is a cross-sectional view of a sorting frame having a trimetal structure in which three strips 2 made of i-alloy are integrally fixed in parallel in the strip width direction.

Here, a Cu-0.15% Sn alloy was used as the Cu alloy, and a Fe-42% Ni alloy was used as the Fe-Ni alloy. Further, in FIG. 1, the Wl material 1 used had a thickness of 0.2 mm and a width of Innm, and the strip material 2 had a thickness of 0.2 mm and a width of 7 mm.

In the case of Fig. 2, the strip material 2 made of Fe--Ni alloy is attached to only one end of the strip material L made of Cu alloy, so depending on the use of the lead frame, the heat dissipation performance may be affected. Even if mechanical strength can be ensured, there may be problems with thermal expansion consistency, or warping may occur due to thermal expansion mismatch.

On the other hand, in the case of Fig. 1, the strip material l made of Cu alloy
consists of a low thermal expansion Fe-Ni alloy at one end of the ?
1? By integrally fixing the members 2 side by side in the width direction of the plate, it is possible to obtain the desired thermal expansion consistency as well as heat dissipation and mechanical strength.

The strips may be joined in parallel by electron beam welding, laser beam welding, plasma arc welding, or the like.

[Effects of the Invention] Since the lead frame of the present invention is configured as described below, it exhibits the effects described below.

(1) High strength of Fe-Ni alloy (especially in the sorting part)
It has a new function that has never been seen before as a lead frame that has both the heat dissipation properties and low electrical resistance of a Cu alloy.

(2) Both ends of the strip can be easily joined by electron beam welding or the like, resulting in extremely high productivity and low cost.

(3) By changing the plate width, etc., it becomes easier to match the required performance, and the applicability as a lead frame is improved.

[Brief explanation of the drawing]

FIG. 2 is a cross-sectional view of a convex lead frame in which a Fe-Ni alloy strip is juxtaposed and integrated with one end of a Cu alloy strip as a comparative example. As an example, Fe-N is applied to both ends of a strip made of a Cu alloy.
FIG. 2 is a cross-sectional view of a sword frame having a structure in which strips made of i-alloy are joined together in parallel. FIG. 3 is a top view of the sorting frame shown in FIG. 1 which is punched out into a pattern shape. l... Band material 2 made of Cu alloy... Band material 3 made of Fe-Ni alloy

Claims (1)

[Claims] A Cu alloy/Fe- alloy, characterized in that a strip made of a highly conductive Cu alloy is integrated with strips made of a low thermal expansion Fe-Ni alloy of the same thickness and juxtaposed in the width direction of the plate on both ends of the strip made of a highly conductive Cu alloy.
Ni alloy parallel lead frame