JPH1197587A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device such as a power module, etc., wherein the amount of warpage of an aluminum base plate is reduced and also the variation of the amount of the warpage is suppressed. SOLUTION: In a power module formed by filling epoxy resin in a case, which is constructed to include an IGBT chip, etc., and which uses as the bottom plate thereof an aluminum base plate 20 consisting of a nearly rectangular rolled aluminum plate on one surface of which the IGBT chip, etc., are mounted, and then thermosetting the epoxy resin, the rolling direction of the aluminum base plate 20 is nearly matched with the short side direction. Thus, the amount of the warpage of the aluminum base plate 20 caused by the heating of the epoxy resin is suppressed to be relatively small, and the stress developed when it is screwed to a radiating fin is made relatively small so that the cracks are hardly developed in an insulating layer to assure a higher insulation resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in warpage of a base plate made of a rolled metal material due to thermosetting of a filling resin such as an epoxy resin in a semiconductor device such as a power module.

[0002]

2. Description of the Related Art FIG. 6 is a view showing the appearance of a power module as a conventional example. In the figure, reference numeral 1 denotes a power module, and 2 denotes an aluminum base plate as a base plate made of a cold-rolled metal material. The rolling direction is configured to match the long side direction. 3 is aluminum base plate 2
Is a bottom plate, 4 is an input signal terminal, 5 is an output electrode terminal, and 6 is an epoxy resin filled in the case 3 as a thermosetting resin.

FIG. 7 is a view showing the appearance of the power module 1 shown in FIG. 6 before filling it with an epoxy resin 6, wherein 7 denotes an IGBT as a semiconductor chip.
A chip 8 is an IC as a semiconductor chip. In addition,
The electronic components other than the IGBT chip 7 and the IC 8, the copper pattern described later, the input signal terminal 4, the output electrode terminal 5, and the like are omitted to avoid complication of the drawing.

FIG. 8 is a sectional view of a portion of the aluminum base plate 2 in the power module 1 shown in FIGS.
In the figure, 9A and 9B are insulating plates, 10 is an adhesive layer, 11
A and 11B are thin foil type copper patterns, and 12 is a thick foil type copper pattern.

[0005] An insulating plate 9A is joined to one surface of the aluminum base plate 2, and a power element I is formed on a thick foil type copper pattern 12 formed on the insulating plate 9A.
The GBT chip 7 is soldered via a heat sink 7A, and a two-layer thin foil type copper pattern 11 formed via an insulating plate 9A, an adhesive layer 10, and an insulating plate 9B.
A control circuit component such as an IC 8 is soldered to the copper pattern 11B of A and 11B. The aluminum base plate 2, the insulating plates 9A and 9B, the adhesive layer 10, the thin foil type copper patterns 11A and 11B, Thick foil type copper pattern 12
The aluminum substrate portion (double-layer aluminum substrate) 13 is formed by the above-described method.

FIG. 9 is an explanatory view relating to the attachment of the power module 1 to the radiating fins. In the drawing, 14 is a radiating fin, 15 is a mounting screw, and 16 is four corners of a case including the aluminum base plate 2. Reference numeral 17 denotes a through hole for the screw 15 that penetrates, and 17 denotes a screw hole (female screw) corresponding to the screw 15 provided in the heat radiation fin 14.

The power module 1 has one surface side of the aluminum base plate 2 in the aluminum substrate portion 13, that is, the copper patterns 11, 12 on which the input signal terminal 4, the output electrode terminal 5, the IGBT chip 7, the IC 8 and the like are soldered. A case 3 having an aluminum base plate 2 as a bottom plate is formed by bonding one end of an outer frame to an outer peripheral portion on the side of the surface on which the resin is formed. The power module 1 is manufactured by screwing
5 is tightened and fixed.

In such a structure, the aluminum base plate 2 is affected by the shrinkage of the epoxy resin 6 at the time of thermosetting, and warps such that the base surface joined to the radiation fin 14 becomes convex. .

As described above, the base surface of the aluminum base plate 2 that is warped convexly with respect to the mounting surface of the radiating fins 14 is tightened with the screws 15 so that the power module between the base surface of the aluminum base plate 2 and the radiating fins 14 is formed. The heat generation of the power module 1 is dissipated by closely contacting the mounting surface.

[0010]

As described above, the power module according to the prior art is mounted on the radiating fin 14 in a state in which it is warped in a convex manner on the base surface side of the aluminum base plate 2, that is, on the mounting surface side to the radiating fin 14. To tighten and fix with screws 15,
A stress is applied to the aluminum base plate 2 in a direction in which the warped state is corrected, and this stress causes cracks in the insulating plates 9A and 9B joined directly or indirectly to the aluminum base plate 2 to cause insulation. There is a problem that the proof strength is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is intended to reduce the amount of warpage of an aluminum base plate and to prevent cracks in an insulating plate when the aluminum base plate is fastened and fixed to radiation fins. It is an object of the present invention to provide a semiconductor device which prevents generation and has high reliability regarding dielectric strength.

[0012]

According to a first aspect of the present invention, there is provided a semiconductor device including a base plate made of a substantially rectangular rolled metal material having a semiconductor chip mounted on one surface as a bottom plate and enclosing the semiconductor chip. In a case where a thermosetting resin is filled in a case configured as described above and is thermoset, the rolling direction of the metal rolled material on the base plate is substantially coincident with the short side direction.

In a semiconductor device according to a second aspect of the present invention, there is provided a case in which a semiconductor chip is mounted on one surface and a base plate made of a substantially rectangular rolled metal material is used as a bottom plate to house the semiconductor chip. Is filled with thermosetting resin,
In the thermoset, the rolling direction and the diagonal of the rolled metal material on the base plate are substantially matched.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Embodiment 1 of the first invention is shown in FIG.
It will be described based on. FIG. 1 is a plan view showing an aluminum base plate constituting an aluminum substrate part in the power module. In the figure, those denoted by the same reference numerals as those of the conventional example indicate the same or equivalent parts as those of the conventional example.

In FIG. 1, reference numeral 18 denotes a roller rolling trace remaining on the base surface of the aluminum base plate.
Is made to coincide with the direction of the short side. That is, the die punching direction with respect to the rolling direction of the aluminum base plate material is such that the rolling direction matches the short side direction, and is hereinafter referred to as an aluminum base plate 20 to distinguish it from the conventional aluminum base plate 2.

FIG. 2 shows the "direction" when measuring the amount of warpage of the aluminum base plates 2 and 20 in the aluminum substrate portion 13.
And a "dimension" in the "direction" is defined, where a indicates a dimension in a long side direction, and b indicates a dimension in a short side direction (a direction orthogonal to the long side direction). Dimensions a and b are screws 1 opened at four corners of aluminum base plates 2 and 20, respectively.
It is determined from the distance between the centers along the long and short sides of the through hole 16 for 5.

FIG. 3 defines measurement points of the amount of warpage in the long side direction and the short side direction. FIG. 3a) shows a conventional aluminum sheet in which the rolling direction of the aluminum base plate material coincides with the long side direction. FIG. 3B) shows the amount of warpage in the base plate 2 and FIG. 3B) shows the amount of warpage in the aluminum base plate 20 in which the rolling direction and the short side direction of the aluminum base plate are matched. The centers A and B of the through holes 16 at both ends of the aluminum base plate 2 and the center point C between the holes A and B are used as measurement points of the amount of warpage. It is determined from the distances c and d between the line connecting B and the center point C on the aluminum base plate surface.

FIG. 3 shows that the rolling direction of the aluminum base plate is the same as that of the conventional one in which the rolling direction of the aluminum base plate coincides with the long side direction of the aluminum base plate, and that of the first embodiment in which the rolling direction of the aluminum base plate is orthogonal. As a result of comparing the effect of heating in the curing step, that is, the degree of warpage of the aluminum base plates 2 and 20, the aluminum base plate 20 according to the first embodiment of the present invention in which the rolling direction is orthogonal to the long-side direction is obtained. It has been confirmed that the absolute amount of warpage is smaller than that of the conventional aluminum base plate 2. As described above, the warpage of the aluminum base plate 20 in which the die punching direction with respect to the rolling direction of the aluminum base plate material coincides with the short side direction is relatively small, and there is little variation.

In the first embodiment, since the direction of the punching die is determined so that the rolling direction coincides with the short side direction of the aluminum base plate 20, the warpage of the aluminum base plate 20 is relatively small, and the radiation fins are formed. 14 is relatively small in stress when it is screwed to the insulating plates 9A, 9A.
There is an effect that cracks of B hardly occur and a high dielectric strength can be secured. In the first embodiment, the aluminum base plate 2 has a relatively large aspect ratio, for example, the aspect ratio is 1.
A remarkable effect can be obtained when it is applied to a material having a factor of 5 or more.

Embodiment 2 Next, a second embodiment of the present invention will be described with reference to FIGS. FIG.
FIG. 2 is a plan view showing an aluminum base plate constituting an aluminum substrate part in the power module 1, and reference numeral 21 denotes an aluminum base plate whose rolling direction is made to coincide with a diagonal direction. That is,
Roller rolling trace 1 remaining on the base surface of aluminum base plate 21
As is clear from FIG. 8, the rolling direction and the diagonal direction are matched.

FIG. 5 shows the aluminum base plate 21 shown in FIG.
It is an explanatory view showing a tightening order of four screws 15 when screwing the power module 1 provided with the heat radiating fins 14, firstly tightening diagonal screws 15 A, 15 C orthogonal to the rolling direction, Thereafter, the screws 15B and 15D on the diagonal side corresponding to the rolling direction are tightened.

Although the amount of deformation in the diagonal direction coincident with the rolling direction is relatively large, first, the diagonal screws 15A, 1A, 1A,
Since 5C is tightened, when tightening the diagonal screws 15B and 15D that match the rolling direction in which the deformation amount is relatively large,
The central convex portion of the aluminum base plate 21 is fixed to the radiation fins 14, so that the stress applied to the substrate portion 13 due to screw tightening can be reduced, and a decrease in the dielectric strength due to the occurrence of cracks in the insulating plates 9A and 9B can be prevented. It should be noted that the second invention has a remarkable effect when applied to an aluminum base plate 2 having a relatively small aspect ratio, for example, one having an aspect ratio of 1.5 or less.

In the first or second embodiment, the example in which the aluminum substrate 13 is a two-layer aluminum substrate has been described. However, cracks in the insulating plates 9A and 9B due to the reduction of the stress applied to the aluminum substrate are reduced. The effect of preventing the occurrence and the deterioration of the dielectric strength is effective even when the copper pattern layer is a single layer, or when the multilayer aluminum substrate has two or more layers.

Further, as the base plate, an aluminum base plate 2 made of a substantially rectangular rolled metal material is shown as an example. However, the present invention is not limited to a rolled aluminum material, but may be made of copper, brass, or any other material having a predetermined malleability. The effect can be obtained even with a metal having thermal conductivity.

[0025]

According to the first aspect of the present invention, since the rolling direction and the short side direction of the rolled metal material in the base plate made of the substantially rectangular rolled metal material are substantially coincident with each other, the warpage of the base plate is relatively small. In addition, since the stress received when screwed to the radiation fin is relatively small, cracks in the insulating layer 9 are less likely to occur, and an effect that a high dielectric strength can be ensured can be obtained.

According to the second invention, the rolling direction and the diagonal line of the metal rolled material in the base plate made of the substantially rectangular metal rolled material are substantially coincident with each other, and the screw on the diagonal side perpendicular to the rolling direction is first set. Is tightened, and then the screws on the diagonal side that match the rolling direction are tightened, so that the stress applied to the substrate portion can be reduced, and there is an effect that cracks can be generated and dielectric strength can be reduced.

[Brief description of the drawings]

FIG. 1 is a plan view showing an aluminum base plate constituting an aluminum substrate part in a power module according to an embodiment of the first invention.

FIG. 2 is a diagram showing a definition example of “direction” and “dimension” in the “direction” when measuring the amount of warpage of an aluminum base plate.

FIG. 3 is a diagram illustrating an example of definitions of measurement points of the amount of warpage in a long side direction and a direction orthogonal to the long side direction.

FIG. 4 is a plan view showing an aluminum base plate constituting an aluminum substrate in a power module according to an embodiment of the second invention.

5 is a diagram showing a tightening order of screws for screwing the aluminum base plate 2 shown in FIG. 4 to the radiation fins.

FIG. 6 is a diagram showing an appearance of a conventional power module.

FIG. 7 is a view showing an appearance of the power module shown in FIG. 6 before filling with a thermosetting resin.

FIG. 8 is a cross-sectional view of an aluminum substrate part in the power module shown in FIGS. 6 and 7.

FIG. 9 is an explanatory view of attaching a power module to a radiation fin.

[Explanation of symbols]

1 power module, 2 aluminum base plate, 3 case, 4 input signal terminal, 5 output electrode terminal, 6 epoxy resin, 7 IGBT chip, 8 IC, 9A insulating plate,
9B insulating plate, 10 adhesive layer, 11 thin foil type copper pattern, 12 thick foil type copper pattern, 13 aluminum substrate part, 14 heat radiation fin, 15 screw, 16 through hole,
17 screw holes, 18 roller rolling marks, 19 grooves, 20,
21 aluminum base plate.

Claims (2)

[Claims] 1. A thermosetting resin is filled in a case configured to enclose the semiconductor chip with a base plate made of a substantially rectangular rolled metal material having a semiconductor chip mounted on one surface as a bottom plate, In the thermoset semiconductor device, a rolling direction of the rolled metal material substantially coincides with a short side direction of the base plate. 2. A thermosetting resin is filled in a case configured to include the semiconductor chip with a base plate made of a substantially rectangular rolled metal material having a semiconductor chip mounted on one surface as a bottom plate, In the thermoset semiconductor device, a rolling direction of the rolled metal material substantially coincides with a diagonal line of the base plate.