JPH05206306A - High-power transistor vessel for high-frequency band - Google Patents

Abstract

PURPOSE:To reduce the occurrence of cracks in a vessel and the breakage of a mount member under heat environments, by forming a pedestal for mounting a semiconductor chip or a regulating circuit etc., with a material whose thermal expansion coefficient is similar to that. of a material mounted on the pedestal. CONSTITUTION:A pedestal part in a vessel is formed with a material such as CuW whose thermal expansion coefficient is about similar to that of a material mounted on the pedestal part. Also, the pedestal part is formed with the material whose thermal expansion coefficient is similar to that of the bonding face of a sidewall and a base of the vessel. When an impedance matching circuit substrate 3 made of ceramic and a semiconductor chip 2 of GaAs are mounted on a pedestal 1 formed with the material such as CuW, the difference of mutual thermal expansion coefficient is small as compared with the case of mounting them on the pedestal 1 formed with the single material of Cu. Thus, the occurrence of cracks of the impedance matching circuit substrate 3 or a semiconductor chip 4 caused by thermal stress is reduced. This is particularly effective when the vessel is large and the contact area is large. When a sidewall 5 of the vessel is made of ceramic, a contact part of the sidewall 5 of ceramic and the base is formed with the material whose thermal expansion coefficient is taken into consideration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a high power transistor container for high frequency band.

[0002]

2. Description of the Related Art As shown in FIG. 3, a conventional container is composed of a pedestal portion for mounting a semiconductor circuit such as a semiconductor element, a chip capacitor and an impedance matching circuit board, a base portion in consideration of a heat sink, and a side wall portion surrounding the semiconductor circuit. Has been done. The pedestal part and the base part are conventionally formed integrally with Cu as shown in FIG. 3B, the outer wall of Cu or ceramic is adhered on the Cu base, and the semiconductor circuit, impedance matching circuit board, etc. are mounted on the Cu pedestal. Has been done.

In FIG. 3, 2 is a Cu pedestal and a base,
Reference numeral 3 denotes an impedance matching circuit board, 4 a semiconductor circuit such as a semiconductor element and a chip capacitor, and 5 a Cu or ceramic side wall.

[0004]

The coefficient of thermal expansion of Cu is about 1.7 × 10 ^-5 ° C ^-1 , and the coefficient of thermal expansion of ceramics is about 6.0.
× 10 ^-6 ℃ ^-1 , the thermal expansion coefficient of GaAs is about 5.0 × 10 ^-6
℃ ^-1 .

A conventional high-power transistor container for a high frequency band has a thermal expansion between different materials when a ceramic side wall is adhered to a Cu base or when a semiconductor circuit or an impedance matching circuit board is mounted on a Cu pedestal. The difference in rates is remarkable. Therefore, there is a problem that cracks are generated due to thermal stress in the thermal environment tests such as the temperature cycle test and the heat shock test.

The generation of these cracks becomes more remarkable as the container is larger and the contact area between the semiconductor circuit, the impedance matching circuit and the pedestal is larger.

[0007]

The high-power transistor container for high frequency band according to the present invention is formed of a material such as CuW having a thermal expansion coefficient substantially equal to that of the material of which the pedestal portion is mounted.

Further, it is formed of a material having a small difference in coefficient of thermal expansion between the adhesive surface between the side wall and the container base.

[0009]

The present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.

As shown in FIG. 1, 1 is a material in consideration of thermal expansion coefficient such as CuW, 2 is Cu, 3 is an impedance matching circuit board, 4 is a semiconductor circuit, and 5 is a side wall.

The coefficient of thermal expansion of Cu is about 1.7 × 10 ^-5 ° C ^-1 ,
About 4.5 × 10 ^-6 ℃ ^{-1 for} W, about 6.0 × 1 for ceramic
The temperature is 0 ^-6 ° C ^-1 and that of GaAs is about 5.0 × 10 ^-6 ° C ^-1 .

For example, when a ceramic impedance matching circuit board or a GaAs semiconductor element is mounted on a pedestal made of CuW, the difference in the coefficient of thermal expansion is larger than that when mounted on a pedestal made of a single Cu material. Since it is small, it is possible to reduce the occurrence of cracks in the impedance matching circuit board and the semiconductor element caused by thermal stress. This is particularly effective when the container is large and the contact area with the impedance matching circuit board or the semiconductor circuit is large.

A second embodiment is shown in FIG. When the side wall of the container is made of ceramic, the contact portion between the ceramic side wall and the base portion is made of a material in consideration of the coefficient of thermal expansion, so that the occurrence of cracks at the contact portion is reduced.

Further, as shown in FIG. 2, by adopting a structure in which the material such as CuW of the base portion is sandwiched by Cu, the strength of the base portion itself against the strain due to heat is increased, and it becomes possible to suppress the generation of cracks.

[0016]

As described above, according to the present invention, the structure in which the difference in the coefficient of thermal expansion between the contact portions made of different materials is made small, the cracking of the container and the damage of the mounting member under the thermal environment are prevented. It is possible to obtain a high-power transistor container for a high frequency band which has a reduced thermal environment characteristic.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a high power transistor container for a high frequency band provided with a pedestal such as CuW of the present invention.

FIG. 2 is a cross-sectional view when the side wall of FIG. 1 is ceramic.

FIG. 3 is a cross-sectional view of a conventional high-power transistor container for high frequency band.

[Explanation of symbols]

 1 Material considering thermal expansion coefficient such as CuW 2 Cu 3 Impedance matching circuit board 4 Semiconductor circuit 5 Side wall

Claims (1)

[Claims] 1. A high-power transistor container for a high frequency band, characterized in that a pedestal for mounting a semiconductor element, an adjusting circuit, etc. is made of a material having a coefficient of thermal expansion close to that of the mounting material.