JP2003204036A - Electrode plate for composite semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode plate for composite semiconductor device in which stress due to heat generated from a pair of semiconductor elements can be relaxed without increasing the quantity of insulation sealing material, and discharge between the element electrodes can be prevented by eliminating residual bubbles in a boundary groove between elements being filled with the insulation sealing material. <P>SOLUTION: An electrode plate 11 is formed in slab form in order to avoid increase in the injection quantity of an insulation sealing material due to presence of a projecting part. A plurality of through holes 11a being bored side by side in the direction along the boundary groove in a region corresponding to a boundary groove being filled with the insulation sealing material have an arcuate shape and the direction between the opposite ends thereof is set to intersect the direction along the boundary groove so that each through hole 11a is imparted with a stress relaxing function and a function for discharging bubbles in the insulation sealing material. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electrode plate for a composite semiconductor device having a stress relaxation function and a bubble discharging function.

[0002]

2. Description of the Related Art FIG. 8 shows a conventional composite semiconductor device to which an electrode plate having a stress relaxation function is applied. 81 in the figure
Is a single insulating substrate having electrode patterns (not shown) formed on the upper and lower surfaces thereof. On the insulating substrate 81, more specifically, on the electrode pattern (upper surface electrode pattern) on the upper surface of the insulating substrate 81, a pair of semiconductor elements 83, 8 is sandwiched with a boundary groove 82 filled with an insulating sealing material described later.
4 is connected and fixed.

A pair of semiconductor elements 83, 84 constitutes an essential part of a composite semiconductor device, and a common upper electrode plate 85 is connected and fixed on the pair of semiconductor elements 83, 84, so that both semiconductor elements are connected. 83 and 84 are electrically connected to each other. Here, the semiconductor element 83 is an IGBT, the semiconductor element 84 is a freewheel diode, and is a high voltage element with an applied voltage of about 650V.

The insulating substrate 81 is positioned and fixed on a heat dissipation plate 86 having thermal conductivity and conductivity. The upper surface electrode pattern of the insulating substrate 81 and the semiconductor elements 83, 8
4, the semiconductor elements 83, 84 and the upper electrode plate 85 are fixedly connected by the solder 87.

Fixing between the electrode pattern (lower surface electrode pattern) on the lower surface of the insulating substrate 81 and the heat radiating plate 86 is also performed by the solder 87. Therefore, the insulating substrate 81 and the heat radiating plate 86 are electrically and mechanically connected and fixed. . Moreover, since the upper and lower electrode patterns (not shown) of the insulating substrate 81 are electrically connected to each other as described above, the lower surfaces (electrodes) of the pair of semiconductor elements 83 and 84 and the heat dissipation plate 86 are electrically connected to each other. The heat sink 86 can function as a lower electrode plate of the composite semiconductor device.

The upper electrode plate 85, the semiconductor element 83,
The assembly consisting of 84, the insulating substrate 81 and the heat dissipation plate 86 is
The package is housed in a package interior 88 (indicated by a one-dot chain line indicates a package side wall), and an insulating sealant 89 such as silicone is injected into the package interior 88.

When the package 89 is filled with the insulating encapsulant 89, the insulating encapsulant 89 is filled with the insulating encapsulant 89 from the opening portions at both ends of the boundary groove 82 (both end portions in the direction perpendicular to the illustrated surface of the boundary groove 82). It flows around into the groove 82 and fills the boundary groove 82.

Here, the upper electrode plate 85 is formed to have a stress relaxation function. That is, when the semiconductor elements 83 and 84 in FIG. 8 actually operate, the semiconductor elements 83 and 84 generate a large amount of heat. Most of the generated heat is transmitted to the heat radiating plate 86 side and radiated into the air, but the upper electrode plate 8
The heat transmitted to the No. 5 side is easily accumulated in the upper electrode plate 85 portion, and stress acts on the upper electrode plate 85 in the directions indicated by arrows a and b in the figure.

Therefore, in the conventional upper electrode plate 85, as shown in the figure, a pair of semiconductor elements 83, 84 which are heat sources.
A downward U-shaped bent portion 85a projecting to the side opposite to the boundary groove 82 side (upper side in the drawing) is formed in the corresponding portion of the mutual groove portion, that is, in the region corresponding to the boundary groove 82. According to the bent portion 85a, when a stress is generated, the lower opening portion is bent in a closing direction to relax stress, particularly stress in the arrow B direction, and in turn, stress in the arrow A direction.

[0010]

However, in the above-mentioned conventional upper electrode plate 85, discharge occurs between the upper electrode plate 85 and the upper surface electrode pattern of the insulating substrate 81 at the inner wall portion of the boundary groove 82 (see the upward arrow in the figure). ) Occurs, and a short circuit occurs between the upper and lower electrodes of the semiconductor elements 83 and 84 (semiconductor element 8
There was a problem that the non-grounded electrodes 3, 84 were grounded.

That is, in the upper electrode plate 85 shown in FIG.
A tunnel-shaped cavity 90 is often formed below the opening edge of the bent portion 85a. this is,
It is considered that the largest cause is that when the insulating sealing material 89 is injected into the package interior 88, the insulating sealing material 89 is not sufficiently filled in the boundary groove 82 and bubbles remain in the boundary groove 82. In any case, when the tunnel-shaped cavity 90 is formed, the dielectric strength is reduced at that portion, and discharge easily occurs, causing the above-described problem.

Further, in the upper electrode plate 85 shown in FIG. 8, since the bent portion 85a protruding upward in the drawing is formed, more insulating sealing material 89 is required as compared with the case where the whole is formed in a flat plate shape. There was also a problem. This will be described with reference to FIG. 9. When insulating the upper electrode plate 85, the thickness of the insulating layer is set on the basis of the portion most protruding to the outside of the package. Therefore, even if the protruding portion is a part of the surface of the upper electrode plate 85, the insulating sealing material 89 must be injected to the depth d1 at which the required insulating layer thickness t1 is obtained. There is also a problem that the amount of insulating sealing material injected into the package interior 88 increases.

In order to deal with the problem of bubbles remaining in the boundary groove 82 in the upper electrode plate 85 shown in FIG. 8, conventionally, in a direction along the boundary groove 82 in a region corresponding to the boundary groove 82, As shown in FIG. 10, a plurality of circular through holes 91
There is an upper electrode plate 91 having a formed therein. According to this, in FIG. 8, the air and bubbles in the boundary groove 82 are discharged to the outside from the plurality of circular through holes 91a shown in FIG. 10 when or after the insulating sealing material 89 is injected into the package inside 88. To be done. Therefore, the tunnel-shaped cavity 90 is prevented from being formed in the boundary groove 82, and the above-mentioned problem is solved.

However, the upper electrode plate 91 shown in FIG.
It does not have a positive stress relaxation function. Therefore, the stress acting in the directions indicated by arrows a and b in the figure is not relaxed, and stress concentration occurs at the tip portions of the arrows a and b, particularly at the tip portion of the arrow a, causing peeling or the like on the upper electrode plate 91. I was afraid. This is as shown in FIG.
When a stress is generated, stress acts on the circular through holes 91a from the left and right directions in the drawing as indicated by arrows c and d, respectively. However, each circular through hole 91a is designed to allow the stress from the left and right to escape in an appropriate direction. It does not work, and therefore FIG.
Stress concentration occurred at the tip of arrow a in the figure.

The present invention has been made in view of the above situation, and positively reduces stress generated by heat generated from a semiconductor element without increasing the amount of insulating sealing material inside the package of the device. (EN) Provided is an electrode plate for a composite semiconductor device, which can be relaxed and which can prevent discharge between electrodes of a semiconductor element by preventing bubbles from remaining in a boundary groove filled with an insulating sealing material. The purpose is to

[0016]

In order to achieve the above object, the electrode plate for a composite semiconductor device according to claim 1 is
Placed and fixed on both sides of a boundary groove filled with an insulating encapsulant on a common substrate, connected and fixed to a surface opposite to the substrate of a pair of semiconductor elements forming a main part of the composite semiconductor device, A common flat electrode plate for electrically connecting the semiconductor elements to each other, in a direction along the boundary groove in a region corresponding to the boundary groove of the plate surface, and a direction between both ends is defined as a boundary groove. It is characterized in that a plurality of substantially arcuate or U-shaped through-holes oriented in a direction intersecting with the along direction are formed side by side.

According to a second aspect of the present invention, in the electrode plate for a composite semiconductor device according to the first aspect, the direction of the arcuate or U-shaped concave or convex of the through hole is substantially in the direction along the boundary groove. It is characterized in that they are formed in opposite directions with the central position sandwiched therebetween.

The invention described in claim 3 is the invention according to claim 1 or 2.
In the composite semiconductor device electrode plate according to, the plate surface shape of the end portion corresponding to the through hole located at the end of the through holes arranged in the direction along the boundary groove is a recess of the through hole located at the end. Alternatively, it is characterized in that it is formed in a concave or convex shape in the same direction as the convex direction.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an example of a composite semiconductor device to which the electrode plate of the present invention is applied. In the figure,
11 is the electrode plate of the present invention (herein referred to as the upper electrode plate).
The configuration of each part except the upper electrode plate 11 is
There is no particular difference from FIG. Therefore, in FIG. 1, the same or corresponding portions as those in FIG. 8 are designated by the same reference numerals, and the description thereof will be omitted, and the upper electrode plate 11 will be mainly described.

2 (a), 2 (b) and 2 (c) are a plan view showing the upper electrode plate 11 in FIG. 1 taken out, a right side view and a cross-section line cc line in FIG. 2 (a). It is a perspective view. Figure 2
As can be seen from (a), the upper electrode plate 11 has a substantially arc-shaped or U-shaped (hereinafter simply referred to as “arc-shaped”) through hole 11.
A plurality of a are formed. In this case, the plurality of through-holes 11a are formed on the plate surface of the upper electrode plate 11 in a direction along the boundary groove 82 in a region corresponding to the boundary groove 82 shown in FIG.
(A) Middle and up and down direction)
Are arranged in the direction intersecting with the direction (the same, left and right direction).

The arc-shaped through hole 11a may be formed only by punching, or may be formed by another method. For example, first, strip-shaped through holes are laterally punched at the positions where the arc-shaped through holes 11a are to be formed on the upper electrode plate material. Next, a rod-shaped tool is inserted into each of the strip-shaped through holes, and the tool or the upper electrode plate material is slightly pressed and moved in the arrangement direction of the strip-shaped through-holes to obtain the arc-shaped through-holes 11a. Good.

As shown in FIGS. 1 and 2, the through hole 11a
By arranging a plurality of them in a direction along the boundary groove 82 in a region corresponding to the boundary groove 82 on the plate surface of the upper electrode plate 11, the same effect as that of the conventional upper electrode plate 91 shown in FIG. 10 can be obtained. To be

That is, as shown in FIG. 3, when the insulating sealing material 89 is injected into the package inside 88, the insulating sealing material 89 is not sufficiently filled in the boundary groove 82, and the bubbles 31 remain in the boundary groove 82. In that case, the bubble 31 floats as shown by the arrow E and is discharged from the through hole 11a to the outside. As a result, the tunnel-shaped cavity 90 (see FIG. 8) is not formed in the boundary groove 82, and the dielectric strength at that portion is not lowered, so that discharge is not likely to occur. Therefore, the upper electrode plate 11 and the insulating substrate 81
Discharge occurs between the upper electrode patterns (not shown) of
The problem that the upper and lower electrodes of the semiconductor elements 83 and 84 are short-circuited (the non-grounded electrodes of the semiconductor elements 83 and 84 are grounded) is solved.

The shape of the through hole 11a of the upper electrode plate 11 is formed in an arc shape as shown in FIG. 2A so as to have a positive stress relaxation function. That is, when the semiconductor elements 83 and 84 of the composite semiconductor device configured as shown in FIG. 1 actually operate, the semiconductor elements 83 and 84 generate a large amount of heat and reach a high temperature. Most of the generated heat is transmitted to the heat radiating plate 86 side and is radiated into the air from the surface of the heat radiating plate 86. However, the heat transmitted to the upper electrode plate 11 side is likely to be accumulated in the upper electrode plate 11 portion, and the upper electrode plate 11
In the figure, stress acts in the directions indicated by arrows a and b in the figure. FIG. 4 shows this state using a plan view of the upper electrode plate 11.

In the upper electrode plate 11 of the present invention, a plurality of through-holes 11a formed in the above-mentioned position and arrangement direction are formed in an arc shape as shown in FIGS. . With such an arc-shaped through hole 11a, when a stress is generated, the stress acting on the through hole 11a portion in the arrow B direction in FIG. 4 is released in one direction to be relaxed, and the stress in the arrow A direction is also reduced. Will be alleviated.

A portion α surrounded by the one-dot chain line in FIG.
FIG. 5 which is an enlarged view of FIG.
As described above, the stress in the arrow B direction in FIG. 4 acts on the arc-shaped through hole 11a. At this time, the arc-shaped through hole 11
a bends from the original shape shown by the dotted line to the shape shown by the solid line,
At that portion, stress in the direction of arrow B in FIG. 4 is released in the direction of the end portion 11c (see arrow F in the figure). That is, the through hole 1
The stress acting on the portion 1a in the direction of arrow B in FIG. 4 is positively relaxed by the deforming action of the arc-shaped through hole 11a, and in turn the stress in the direction of arrow a is also relaxed, causing the upper electrode plate 11 to peel off or the like. Prevent that.

In this embodiment, as shown in FIG. 2A, the upper electrode plate 11 has end portions 11b corresponding to the through holes 11a, 11a located at the ends of the through holes 11a arranged in one direction. , 11c are formed in a concave or convex shape in the same direction as the concave or convex direction of the arc-shaped through holes 11a, 11a located at the end. According to this, when the stress acting on the arc-shaped through hole 11a is about to escape in the direction of the end portion 11c as shown by the arrow in FIG. 5, the stress acts on the edge portion of the upper electrode plate 11. Can be absorbed without imposing a burden on the outer edge, and damage to the edge portion can be suppressed as much as possible.

Through-holes 1 arranged in one direction on the upper electrode plate 11.
The upper electrode plate 11 is formed in a flat plate shape regardless of whether the plate surface shape of the end portions 11b, 11c corresponding to the through holes 11a, 11a located at the end of 1a ... Is formed to be concave or convex. Has been done. Therefore, the problem of requiring a large amount of insulating sealing material 89 in the conventional upper electrode plate 85 shown in FIG. 8 is solved.

This will be described with reference to FIG. 6. When the upper electrode plate 11 is insulated, the thickness of the insulating layer is set with reference to the most projecting portion on the outside of the package. Therefore, if there is a portion projecting on the plate surface like the conventional upper electrode plate 85 shown in FIG. 8, as shown in FIG.
Depth d1 at which the required insulating layer thickness t1 is obtained
The insulating sealing material 89 must be injected until (t1 <d1). However, since the upper electrode plate 11 of the present invention has a flat plate shape, as shown in FIG. 6, the required insulating layer thickness t1 and the injection depth d1 of the insulating sealing material 89 for obtaining the thickness t1 are set. Are equal to each other (t1 = d1), and therefore a large amount of insulating encapsulant 89 is not required.

In the above embodiment, the arcuate (U-shaped) concave or convex direction of the through hole 11a formed in the upper electrode plate 11 is aligned in one direction, but the invention is not limited to this. . For example, as shown in FIG. 7, the direction of the concave or convex may be the direction along the boundary groove on the surface of the upper electrode plate 11 (in FIG. 7,
They may be formed in mutually opposite directions with a substantially central position (up and down direction) interposed therebetween. According to this, the stress is evenly released in opposite directions, and there is an advantage that the stress relaxation can be realized without being biased in one direction. In the case of this example, the through hole 11d located at the center is, as shown in the figure,
It is desirable to form the end portion 11c (see FIG. 2) into a shape in which a pair of end portions 11c are joined face-to-face. In the above figures, the same symbols indicate the same or corresponding parts.

[0031]

As described above, according to the invention of claim 1,
The electrode plate for a composite semiconductor device was composed of a flat electrode plate. Then, in a direction along the boundary groove in a region corresponding to the boundary groove filled with the insulating sealing material on the plate surface, a substantially arcuate shape or a U direction in which a direction between both ends is oriented in a direction intersecting a direction along the boundary groove. A plurality of V-shaped through-holes were formed side by side to achieve both a stress relaxation function and a bubble discharging function in the insulating sealing material. With such a structure, the thickness of the insulating layer on the upper part of the electrode plate can be reduced, and the stress generated by the heat generated from the semiconductor element can be positively increased without increasing the amount of the insulating sealing material inside the device package. Can be relaxed. In addition, it is possible to prevent bubbles from remaining in the boundary groove filled with the insulating sealing material and prevent discharge between the electrodes of the semiconductor element.

According to the second aspect of the invention, the direction of the arcuate or U-shaped concave or convex of the through hole is formed to be opposite to each other with the substantially central position along the boundary groove interposed. Therefore, the stress relaxation can be realized without being biased in one direction.

According to the third aspect of the invention, since the plate surface shape of the end portion of the electrode plate corresponding to the through hole located at the end is formed in the same direction as the direction of the through hole, stress relaxation is achieved. At this time, when the stress acting on the through hole portion is released to the end portion side, it can be absorbed without putting a load on the end edge portion.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a composite semiconductor device to which an electrode plate of the present invention is applied.

FIG. 2 is a diagram showing an upper electrode plate taken out in FIG.

FIG. 3 is an explanatory diagram of a bubble discharging function in the upper electrode plate.

FIG. 4 is a diagram showing how stress acts on the upper electrode plate.

FIG. 5 is an enlarged view of an α part in FIG. 4 for explaining a stress relaxation function in the upper electrode plate.

FIG. 6 is an explanatory diagram of a required amount of an insulating sealing material in a composite semiconductor device to which the upper electrode plate is applied.

FIG. 7 is an explanatory diagram of another example of forming an arc-shaped through hole in the upper electrode plate.

FIG. 8 is a cross-sectional view of a composite semiconductor device to which a conventional electrode plate is applied.

FIG. 9 is an explanatory diagram of a required amount of an insulating encapsulant in a composite semiconductor device to which the upper electrode plate is applied.

FIG. 10 is a diagram showing how stress acts on the upper electrode plate.

FIG. 11 is a partial enlarged view for explaining the stress relaxation function of the upper electrode plate.

[Explanation of symbols]

11 Upper electrode plate (electrode plate) 11a Arc-shaped through hole (arc-shaped or U-shaped through hole) 11b, 11c Edge part of upper electrode plate 81 Insulating substrate (substrate) 82 boundary groove 83,84 Semiconductor element 89 Insulation sealing material

Claims (3)

[Claims] 1. A surface of a pair of semiconductor elements opposite to the substrate, which is arranged and fixed on a common substrate with a boundary groove filled with an insulating encapsulating material sandwiched therebetween, and which constitutes a main part of a composite semiconductor device. A common plate-shaped electrode plate that is fixedly connected to and electrically connects the semiconductor elements to each other, in a direction along the boundary groove in a region corresponding to the boundary groove on the plate surface, between both ends. An electrode plate for a composite semiconductor device, wherein a plurality of substantially arcuate or U-shaped through holes oriented in a direction intersecting a direction along a boundary groove are formed side by side. 2. A substantially arcuate or U-shaped concave or convex direction of the through hole is formed in opposite directions with a substantially central position in a direction along the boundary groove being sandwiched therebetween. 7. The electrode plate for a composite semiconductor device according to. 3. The plate surface shape of the end portion corresponding to the through hole located at the end of the through holes arranged in the direction along the boundary groove,
3. The concave or convex shape is formed in the same direction as the concave or convex direction of the through hole located at the end.
7. The electrode plate for a composite semiconductor device according to.