JPH0572135U - Semiconductor device - Google Patents

Abstract

(57) [Summary] (Modified) [Objective] The present invention aims to reduce the occurrence rate of voids in a semiconductor chip, a metal plate, and a solder layer for fixing a metal member, and improve the thermal fatigue performance of a semiconductor device. The present invention provides a semiconductor device combined with a radiation fin or a printed wiring board. [Structure] A semiconductor chip 1 is fixed to one surface of a metal plate 3 having convex and curved surfaces formed on the upper and lower surfaces, and a metal member 2 is fixed to the other surface via a solder layer 5, and the thickness of the solder layer 5 is The height is made larger in the peripheral portions than in the central portions of the convex curved surfaces 3a, 4a.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to the structure of a semiconductor device, a radiation fin, and a semiconductor device mounted on a printed wiring board.

[0002]

[Prior Art]

 Conventionally, when a semiconductor device is configured using semiconductor chips such as diodes and transistors, for example, as shown in the cross-sectional structure diagram of FIG. 1, metal members 2 and metal plates 3 and semiconductor chips 1 and 4 are connected. The members are placed one after another and fixed to each other by 5 solder layers. The metal plate of No. 3 is used for supporting means, spacing maintaining means, thermal fatigue preventing means, heat radiating means, etc. As the metal material, molybdenum, tungsten, copper, silver or the like is selected and used as required.

However, since the brazing surface of the metal plate 3, that is, the surface facing the semiconductor chip 1 side and the metal member 2 side is flat, there are the following drawbacks.

In soldering a metal plate, a flux is applied to improve the wetting property of the solder, and the flux is fixed by heating and cooling. However, until the solder is melted and solidified, the flux is dispersed in the solder layer. Remaining, voids (cavities) are likely to occur in the solder layer. The generation of such voids weakens the solder bond and deteriorates the reliability of the semiconductor device.

Under the environment of long-term cooling / heating cycle, since the peripheral thickness of the solder layer is thin, the thermal buffering effect is small, and cracks are easily generated in the peripheral portion due to the thermal fatigue phenomenon, and the thermal fatigue life is short.

[0006]

[The purpose of the device]

 The present invention solves the above-mentioned drawbacks of the conventional device, provides a semiconductor device having a reduced occurrence rate of voids and a long thermal fatigue life. We also provide semiconductor devices mounted on heat dissipation fins and printed wiring boards.

[0007]

【Example】

 FIG. 2 is a sectional structural view of an embodiment of the present invention, in which the same symbols as in FIG. 1 indicate the same parts. The metal member 2 constitutes an aluminum or copper radiating fin having a recess for accommodating the metal plate and the semiconductor chip 1.

Further, as shown in a plan view of FIG. 3A and a side view of FIG. 3B, the metal plate 3 has convex curved surfaces 3 a formed on both upper and lower surfaces.

In the manufacture, the first solder chip, the metal plate 3, the second solder chip, the semiconductor chip 1, the third solder chip, and the connecting member 4 are laminated in the concave portion of the metal member 2 (radiation fin). The first, second, and third solder chips are melted by housing and heating, and the solder layer 5 is formed by subsequent solidification.

Since the metal plate 3 has convex curved surfaces 3a formed on both upper and lower surfaces, flux or the like which causes voids from the melting to solidification of the solder is generated in the peripheral portion from the central portion of the metal plate 3a. On the other hand, it becomes easier to escape, and the occurrence of voids after solidification of the solder layer is significantly reduced.

Further, the solder layers 5 on the upper and lower surfaces of the metal plate 3 are thicker in the peripheral portion than in the central portion (excluding the portion which is thinned by the spreading effect to the outer periphery when the solder layer 5 is melted). The occurrence of cracks in the solder layer, which is a phenomenon of thermal fatigue under a long-term thermal cycle environment, is reduced as compared with the conventional device of FIG.

Further, the heat dissipation effect is improved by increasing the area of the semiconductor chip 1, the metal plate 3, and the metal member 2 in this order.

In FIG. 2, a convex curved surface 4a is formed at a connection portion of the connection member 4 such as a connection piece or a header lead wire with the semiconductor chip 1, so that the same effect as that of the metal plate 3a can be obtained. Occurs.

FIG. 4 is a sectional view of another embodiment of the present invention, in which the same reference numerals as those in FIGS. 1, 2 and 4 denote the same parts. The second metal member is a conductive layer disposed on the substrate 6 of the printed wiring board. There are various types of printed wiring boards, such as ceramic substrates, aluminum base copper clad boards, glass, and epoxy copper clad laminates. The present invention can be applied to any printed wiring board. Reference numeral 7 is another electronic component provided on the substrate 6, which constitutes various composite or hybrid integrated circuit devices.

The embodiment shown in FIG. 4 also exhibits the same operation and effect as described in the embodiment shown in FIG.

In the embodiments of the present invention, the shapes, materials and the like described can be modified, changed, added, deleted and changed within the scope of the present invention. For example, the metal plate 3 can be selected from copper, molybdenum, tungsten, etc. according to need.

[0017]

[Effect of the device]

 As described above, the semiconductor device of the present invention can reduce voids in the solder layer and improve the thermal fatigue performance of the solder layer, and can be used as a semiconductor device mounted on a radiation fin or a printed wiring board. It is effective and has a great practical effect when it is used in electrical equipment and various types of electrical equipment that require high reliability.

[Brief description of drawings]

FIG. 1 is a cross-sectional structure diagram of a conventional semiconductor device.

FIG. 2 is a sectional structural view showing an embodiment of the present invention.

3A and 3B are structural views of the metal plate used in FIG. 2, where FIG. 3A is a plan view and FIG. 3B is a side view.

FIG. 4 is a sectional structural view showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor chip 2 Metal member 3 Metal plate 3a Convex curved surface of metal plate 4 Connecting member 4a Convex curved surface of connecting member 5 Solder layer 6 Board 7 Other electronic components

Claims (4)

[Scope of utility model registration request] 1. A semiconductor chip is fixed to one surface of a metal plate having convex and curved surfaces formed on both upper and lower surfaces, and a metal member is fixed to the other surface via solder layers, which are a semiconductor chip, a metal plate, and a metal member. The semiconductor device is characterized in that the area is increased in this order, and the thickness of the solder layer is larger in the peripheral portion than in the central portion of the convex curved surface. 2. The semiconductor device according to claim 1, wherein the metal member is a metal radiation fin. 3. The semiconductor device according to claim 1, wherein the metal member is a metal layer on a printed wiring board. 4. The semiconductor device according to claim 1, wherein the convex curved surface of the connecting member is soldered to the surface of the semiconductor chip opposite to the surface soldered to the metal plate.