JPH05202968A - Disk spring fixing method - Google Patents

Abstract

PURPOSE:To provide even pressure distribution with a desired pressing force, when multiple disk springs are used in a condition in which they are stacked in parallel with each other. CONSTITUTION:A No. 2 disk spring 2 is put on a No.1 disk spring in parallel with each other so that the recessed surface sides of both disk springs 1 and 2 are faced to each other and also the mating point 3 of both disk springs 1 and 2 is positioned at their outer periphery. Then they are fixed with silicone rubber 4 at four or three points on the outer periphery, and the silicone rubber 4 is allowed to be cured. Also, when four disk springs are stacked, two assembly bodies, each comprising two disk springs, are positioned in parallel with each other in vertical direction, and the silicone rubber is applied into the outer or inner peripheries of the adjacent disk springs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of fixing a disc spring used for pressing and holding a pressure contact type flat type semiconductor element for electric power.

[0002]

2. Description of the Related Art When pressing and holding a pressure contact type flat type power semiconductor device, it has been conventionally practiced to use a plurality of disc springs in parallel.

FIG. 4 is a sectional view showing a conventional disc spring superposition method. In the figure, 1 is a first disc spring, 2 is a second disc spring, and these disc springs 1 and 2 are substantially donut-shaped with one surface being concave and the other surface being convex. It is said that. And these two disc springs 1 and 2
Are superposed on each other via the peripheral adjacent points 3 so that the concave sides face each other. Further, when pressing and holding the semiconductor element, a load is applied in the direction indicated by arrow A in the figure. Note that T ₁ in the figure indicates the height of the disc springs in the superposed state.

[0004]

In the case where a plurality of disc springs are used in parallel, in the structure in which they are simply overlapped as described above, when a load is applied in the direction of arrow A, as shown in FIG. As shown, there is a problem that the adjacent point 3 is displaced inward from the outer peripheral portion of the other disc spring. When such a deviation occurs, the height T ₂ of the disc spring in the superposed state
Is lower than the initial height T ₁ or the parallelism between the first disc spring 1 and the second disc spring 2 cannot be secured, and in extreme cases, the pressure distribution of the semiconductor element is not uniform. There was a problem such as becoming.

When the height of the disc springs in the stacked state is lowered as described above, for example, in the case of a stack using several flat semiconductor elements in series, the total length in the series direction is shortened. There has been a problem that a predetermined pressure contact force corresponding to the set length dimension cannot be obtained.

Further, if the parallelism of the two disc springs cannot be ensured, the semiconductor elements will be non-uniformly pressure-contacted, and in the case of a flat type power semiconductor element such as a GTO thyristor which requires particularly uniform pressure-contact, it is turned on. The contact thermal resistance (R) is increased by increasing the voltage (V _TM ) and the gate trigger current (I _GT ).
_{th (cf)} ) increases, and the contact power loss increases as a whole, which accelerates the increase in heat generated inside the semiconductor element during energization, which may lead to permanent destruction of the semiconductor element. ..

The present invention has been made to solve the above-mentioned problems, and when a plurality of disc springs are piled up in parallel and used, a desired pressure contact force and a uniform pressure distribution are obtained. It is intended to be obtained.

[0008]

The disc spring fixing method according to the present invention is such that the outer peripheral portion or the inner peripheral portion of adjacent disc springs are mutually fixed with a resin such as silicone rubber.

[0009]

According to the present invention, since the outer peripheral portion or the inner peripheral portion of the adjacent disc springs is fixed by the soft resin such as silicon rubber, when the disc springs are pressed, the outer periphery of the disc springs adjacent to the resin is fixed. It is possible to flexibly deform even with a slight movement of the inner part or the inner peripheral part, to prevent a positional deviation between adjacent points between the disc springs, and to maintain a desired disc spring height.

[0010]

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

FIG. 1 is a sectional view showing a method of fixing a disc spring according to an embodiment of the present invention, and FIG. 2 is a plan view of the same.

In this embodiment, the first disc spring 1 and the second disc spring 2 have a concave surface on one side and a convex surface on the other side, similar to the conventional ones shown in FIGS. 4 and 5. It has a substantially donut shape. Then, when these two disc springs 1 and 2 are used in an overlapping manner, they are assembled and fixed as follows.

First, the first disc spring 1 is placed with the concave side facing upward, and the second disc spring 2 is placed on the first disc spring 1, both disc springs 1 and 2.
Stack them in parallel so that the concave surfaces of are facing each other.
At this time, the alignment is performed so that the adjacent point 3 of the disc springs 1 and 2 is located on the outer peripheral portion.

Next, using a jig (not shown), both disc springs 1 and 2 are fixed to prevent displacement, and then four portions of the outer periphery are made of silicone rubber 4 at an angle that divides the outer periphery into four equal parts. Fix it. Here, as the fixing silicone rubber 4, a non-fluid material having a relatively high viscosity is used so that the silicone rubber 4 does not flow out to portions other than the outer peripheral portions of the disc springs 1 and 2. Is desirable. Further, the outer peripheral portion does not have to be fixed at four places, and for example, the outer periphery is fixed at three places.
It is also possible to fix the three parts at equal angles.

Next, in this state, the silicone rubber 4 is cured. The silicone rubber 4 is usually a one-component room temperature curing type. Such a silicone rubber 4 can be sufficiently cured by leaving it in the room for 8 hours or more.

Then, using the assembly of the disc springs 1 and 2 fixed as described above, an assembly for pressing and holding the semiconductor element is performed.

According to this embodiment, since the first disc spring 1 and the second disc spring 2 can be fixed to each other at a desired position by using the silicone rubber 4, both discs can be pressed at the time of pressurization. Positional deviations do not occur in the outer peripheral portions of the springs 1 and 2, so that a predetermined disc spring height can be obtained. Further, since the parallelism between the first disc spring 1 and the second disc spring 2 is maintained, it is possible to avoid the occurrence of a defect in the electrical characteristics due to the imbalance of the pressure distribution of the semiconductor element.

In the above embodiment, the case where two disc springs are stacked in parallel has been described, but the present invention is
It can also be applied to the case where four disc springs are stacked in parallel as shown in FIG. When stacking four disc springs, as shown in the figure, two sets of disc springs 1 and 2 and the other two disc springs 1'and 2'are vertically arranged in parallel. To do it. And in that case, 4
As for the disc springs of one sheet, the outer peripheral portion or the inner peripheral portion of each adjacent disc spring is fixed to each other with the silicone rubber 4. With such a configuration, it is possible to prevent the disc springs from being displaced, as in the above embodiment.

[0019]

As described above, according to the present invention, when a plurality of disc springs are stacked and used, the outer peripheral portion or the inner peripheral portion of the adjacent disc springs is fixed with a resin such as silicone rubber. Therefore, the disc spring can be prevented from being displaced, and the semiconductor element can be uniformly pressed and held with a desired pressure contact force.

[Brief description of drawings]

FIG. 1 is a sectional view showing a method of fixing a disc spring according to an embodiment of the present invention.

FIG. 2 is a plan view showing a disc spring fixing method according to an embodiment of the present invention.

FIG. 3 is a sectional view showing a method of fixing a disc spring according to another embodiment of the present invention.

FIG. 4 is a sectional view showing a conventional disc spring superposition method.

FIG. 5 is a cross-sectional view showing a defect example due to a conventional disc spring overlapping method.

[Explanation of symbols]

 1 First disc spring 2 Second disc spring 3 Adjacent point 4 Silicon rubber

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[Procedure amendment]

[Submission date] June 5, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

Further, if the parallelism of the two disc springs cannot be ensured, the semiconductor elements will be non-uniformly pressure-contacted, and in the case of a flat type power semiconductor element such as a GTO thyristor which requires particularly uniform pressure-contact, it is turned on. This causes an increase in the voltage (V _TM ) and an increase in the contact thermal resistance (R _{th (cf)} ), resulting in an increase in the contact power loss as a whole, thereby increasing the heat generated inside the semiconductor element during energization. May be accelerated, and the semiconductor element may be permanently destroyed in some cases.

Claims (1)

[Claims] 1. A method of fixing adjacent disc springs to each other when a plurality of disc springs are stacked in parallel and used, wherein the outer peripheral portion or the inner peripheral portion of the adjacent disc springs is made of a resin such as silicone rubber. A method for fixing disc springs, which is characterized in that they are fixed to each other.