JPS6138199Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to semiconductor devices, and particularly to improvements in mounting a temperature compensating plate in a pressure contact type semiconductor device.

In a pressure contact type semiconductor device for power use, which is an example of a semiconductor device, a thin metal foil is interposed between a silicon pellet and a pressure contact electrode body in order to withstand thermal fatigue.
There is one that has sliding contact. The reason for interposing the metal foil is as follows. That is, when a semiconductor device is operated with a metal film fixedly formed on a silicon pellet by vacuum evaporation or an alloying method for leading out an electrode being pressed against a press-contact electrode body, the metal film and press-contact electrode body are is alloyed and fixed. This alloying is caused by the heat generated by the operation of the semiconductor device,
Furthermore, sliding occurs due to the difference in thermal expansion coefficient between the silicon and the pressure-welding electrode body, and when alloyed and fixed, cracks occur in the silicon due to the mechanical stress of the sliding. In order to prevent this silicon from cracking, a thin metal foil that is susceptible to mechanical stress is inserted between the metal film and the pressure contact electrode body so that they do not come into direct contact with each other. In the case of power semiconductor devices, as the pellet diameter increases, the cathode pattern also becomes more complex, and the shape of the metal foil also becomes more complex. When assembling the element, the shape of the metal foil was matched to the cathode pattern, and electrodes were pressed onto it to create an airtight seal. In this case, the more complex the shape of the metal foil, the more difficult it is to assemble, and the more the metal foil may become misaligned with the cathode pattern, resulting in a loss of functionality.

Next, the above will be explained with reference to the drawings. Fig. 1 is a cross-sectional view showing an outline of a thyristor exemplifying a press-contact type semiconductor device, Fig. 2 is a front view of a metal foil, Fig. 3 is a front view of a pellet of the thyristor, and Fig. 4 is a pellet and a press-contact part of the thyristor. FIG. 3 is a cross-sectional view for explaining a contact portion of a press-contact electrode body. First, in Figure 1 showing the entire thyristor, 1 is a pellet, 2a, 2c
are the pressure contact electrode body on the anode side and the pressure contact electrode body on the cathode side, 3 is a temperature compensation plate, 4 is a metal foil,
The temperature compensation plate is soldered or slidably connected between the pressure contact electrode body 2a on the anode side, the metal film 2a for leading out the anode of the pellet, and the metal film 1a for leading out the anode of the pellet, and the metal foil is connected to the metal foil on the cathode side. Pressure contact electrode body 2c and pellet cathode lead metal film 1
Connect movably between c. Furthermore, as shown in FIG. 2, the metal foil 4 has an annular shape that contacts the cathode leading metal film 1c, and has a notch 4a for avoiding the gate leading metal film 1g (FIG. 3), and a peripheral edge. A plurality of claws 4 protrude radially from the
b, 4b', etc., and the claws are bent at a substantially right angle so as to be in contact with the circumferential surface of the press-contact electrode body. In addition, 5 is a surface protective agent layer of silicone resin applied to prevent surface contamination of the pellets, and 10 is an airtight envelope.

In the semiconductor device formed as described above, when the metal foil 4 and the cathode leading metal film 1c of the pellet do not match well, the cathode and the gate are short-circuited by the metal foil, and the thyristor is short-circuited. Functionality may be lost. Furthermore, the above-mentioned accidents often occur during actual assembly processes, and countermeasures are strongly desired. Second, corona discharge often occurs from the ends of the metal foil claws, often leading to damage when the thyristor is used.

This invention provides a structure for a semiconductor device that overcomes the conventional drawbacks.

This invention is a press-contact type semiconductor device having a metal foil slidably inserted between one electrode body and a pellet, and a plurality of pawls protruding from the periphery of the metal foil. The end of the electrode is rounded, some of the nails are bent to position one electrode body, and the tips of these nails and the remaining unbent nails are covered with a surface protective agent. This is a press-contact type semiconductor device.

Next, this invention will be explained in detail for one embodiment of a thyristor with reference to the drawings. Figures 5 to 7
The figure is a diagram for explaining the main parts of one embodiment, and the differences from the conventional thyristor structure will be explained in detail using these figures. FIG. 5 is a cross-sectional view illustrating a contact portion between a pellet and a press-contacting electrode body that is pressed into contact with the pellet, FIG. 6 is a front view of the metal foil, and FIG. 7 is a front view of the pellet. In this embodiment, parts that are the same as those in the conventional structure are denoted by the same reference numerals, and the explanation thereof is omitted. The metal foil 14 shown in FIG. 6 has a circular shape with a plurality of claws 14b, 14b', etc. projecting radially from the periphery.The tips of these claws are rounded, and a part of the claws is bent at a right angle to form a press-contact electrode. It is formed so as to be in contact with the circumferential surface of the body. FIG. 5 shows the main parts of the thyristor in cross section taken along lines X and X' in the figure. The tip of a bent claw (for example, 14b) of the metal foil is embedded in the surface protection agent layer 5, and the slightly bent claw (for example, 14b') is also embedded in the surface protection agent layer. In addition, the above-mentioned nails may be embedded in the surface protective agent layer from the beginning, but it is also possible to place the nails on the hardened surface protective agent layer, apply the surface protective agent layer on top of the hardened surface protective agent layer, and then embed the nails. It may be fixed.

By doing as described above, there are the following advantages.

(1) Part of the multiple claws on the periphery of the metal foil is bent to support one electrode body, and the tips of these claws and the remaining claws are covered with a surface protective agent, so the metal foil is firmly positioned. This can reliably prevent a short circuit between the cathode and the gate, which tends to occur in a semiconductor device having such a structure.

(2) The structure in which the tips of the claws are rounded and encapsulated in a surface protective agent reduces the occurrence of corona and prevents deterioration of the element, and the surface protective agent that envelops this part prevents damage. There is also the advantage of not giving

(3) Contact failure is eliminated and contact resistance between the cathode and pressure contact electrode can be reduced. Further, since there is no displacement of the metal foil and the surface protective agent is not caught, it is possible to prevent the occurrence of cracks in the element.

It goes without saying that this invention can also be used to provide pellets with notches as shown in FIG. 2, as shown in FIG. 3, and claws as shown in the invention. Furthermore, it is also possible to insert an auxiliary metal plate between the metal foil 4 or 14 and the cathode-side press-contact electrode body 2c for the purpose of preventing deformation of 2c due to press-contact.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of the thyristor, Fig. 2 is a front view of the metal foil, Fig. 3 is a front view of the pellet of the thyristor, Fig. 4 is a cross-sectional view of the contact portion between the pellet and the pressure contact electrode body, Fig. 5 Hereinafter, regarding the present invention, FIG. 5 is a cross-sectional view of the contact portion with the pellet press-contact electrode body, FIG. 6 is a front view of the metal foil, and FIG. 7 is a front view of the pellet of the thyristor. 1 ... Pellet, 2a... Pressure contact electrode body on the anode side, 2c... Pressure contact electrode body on the cathode side, 5...
Surface protective agent layer, 14 ...Metal foil, 14b, 14
b′...Metal foil nails.

Claims (1)

[Scope of utility model registration request] In a pressure contact type semiconductor device having a metal foil slidably inserted between one electrode body of the pressure contact type semiconductor device and a pellet, and a plurality of claws protruding from the periphery of the metal foil, the ends of the claws A press-contact type characterized in that the electrode body is formed into a round shape, some of the claws are bent to position one electrode body, and the tips of these claws and the remaining claws are coated with a surface protective agent. Semiconductor equipment.