JPS6339968Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device in which electrical and thermally conductive contact between members having different coefficients of thermal expansion is made by pressurized contact.

In semiconductor devices, for example, approximately 2×10 ^-6 /℃
A semiconductor body made of silicon having a coefficient of thermal expansion of about 17×10 ^-6 /°C and a conductive member made of copper having a coefficient of thermal expansion of about 17×10 -6 /°C are used, and good flow of electricity and heat between them must be ensured. No. Moreover, since heat is generated during operation of the semiconductor device, if the two are fixed together by brazing or the like, there is a risk of damage due to thermal fatigue. In order to prevent such accidents, especially in semiconductor devices for large currents, a method is adopted in which members having different coefficients of thermal expansion are brought into contact with each other under pressure. During such pressurized contact,
In order to prevent fluctuations in contact resistance and to reduce contact resistance, a silver plate is interposed between the members. This is because silver has the following properties.

(1) Chemically stable.

(2) Good electrical conductivity.

(3) Good thermal conductivity.

(4) Soft and able to absorb mechanical shock.

FIG. 1 shows a flat semiconductor device as an example of such a semiconductor device. A semiconductor board 1 is fixed with aluminum, for example, on a support plate 2 made of molybdenum, tungsten, or the like having a coefficient of thermal expansion similar to that of the semiconductor board 1. End plate 3 made of copper and silver plate 4
Opposing through. The upper electrode of the semiconductor board 1 is opposed to an end plate 7 similarly made of copper via an electrode plate 5 made of molybdenum and tungsten and a silver plate 6.
Since the end plates 3 and 7 are connected to the annular ceramic body 9 by the flexible metal annular plate 8,
By applying pressure from both end plates 3 and 7, the silver plate 4
Contact can be made between the end plate 3 and the semiconductor support plate 2 via the silver plate 6, between the semiconductor plate 1 and the electrode plate 5, and between the end plate 7 via the silver plate 6. The silver plates 4, 6 may be brazed to the end plates 3, 7 in advance.

However, since the use of expensive silver plates increases the price of semiconductor devices, it is desirable to reduce the amount of silver used. An object of the present invention is to provide a pressure contact type semiconductor device that meets this demand.

The purpose of this is to create a pressurized contact structure in which a semiconductor board is held between support plates having a coefficient of thermal expansion similar to that of this board, and further sandwiched between an end plate serving as an external lead-out electrode plate on the outside of both support plates. type semiconductor device, there is a 1μ thick layer on both sides between the support plate and the end plate.
This is achieved by forming a pressure contact type semiconductor device with a copper plate coated with a silver layer of m or more.

Embodiments of the present invention will be described below with reference to the drawings. In Figure 2, the copper plate 11 has a plating thickness on both sides.
A silver plating layer 12 with a thickness of 1 μm or more is provided.
Such a silver-coated copper plate satisfies all of the properties of the conventional silver plate described above, such as chemical stability, electrical conductivity, thermal conductivity, and mechanical shock absorption ability. It can be used in place of plates 4 and 6. In particular, annealing the copper plate is effective for absorbing mechanical shock. The silver layer 12 can be provided not only by silver plating but also by laminating it with a silver plate.

FIG. 3 shows a fourth section between the semiconductor support plate 2 and the end plate 3.
Silver-coated copper plate 13 shaped as shown in the figure
This silver-coated copper plate has an upright peripheral edge 14 as well as a protrusion 15 to the opposite side,
By arranging the semiconductor support plate 2 in contact with the inner wall of the peripheral portion 14 and inserting the protrusion 15 into the recess 16 of the end plate 3, the semiconductor plate 1 can be positioned at the center of the device. Since the silver-coated copper plate according to the present invention has higher rigidity than a silver plate, the protrusion 15 has appropriate strength and is less likely to be deformed during assembly of the device.

As described above, the semiconductor device according to the present invention uses a silver-coated copper plate instead of the silver plate interposed in the pressurized contact portion, which reduces the amount of silver used and reduces the cost of the semiconductor device. It is extremely effective against

[Brief explanation of drawings]

FIG. 1 is a sectional view of an example of a conventional pressure contact type semiconductor device, FIG. 2 is a sectional view of a silver-coated copper plate in one embodiment of the present invention, and FIG. 3 is a schematic diagram of a semiconductor device in another embodiment. FIG. 4 is a plan view of a silver-coated copper plate used in the semiconductor device of FIG. 3. DESCRIPTION OF SYMBOLS 1... Semiconductor board, 2... Support plate, 3, 7... End plate, 11... Copper plate, 12... Silver layer, 13... Silver coated copper plate.

Claims (1)

[Scope of utility model registration request] A pressure contact type semiconductor device having a structure in which a semiconductor board is held between support plates having a coefficient of thermal expansion similar to that of the support plate, and is further held by an end plate serving as an external lead-out electrode plate on the outside of both support plates. A pressure contact semiconductor device characterized in that a copper plate having a silver layer of 1 μm or more thick is interposed between the support plate and the end plate on both sides.