JP2000277876A - Semiconductor device and method and apparatus for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain provide a high reliability semiconductor device and a method and apparatus for manufacturing the same, wherein solder crack resistance is improved by making uniform the solder layer thickness of a semiconductor substrate, having a metal base plate and an insulation plate soldered to the base plate. SOLUTION: Annular flat protrusions 1c, having the same projection height h and each having an annular flat face 1d at the top end, are formed on a main surface 1a of a metal base plate 1, a front and back metal patterns 2a, 2c are formed in one body respectively on the main front and back surfaces of an insulation plate 2A, an insulation plate 2 with a semiconductor element 3 mounted on the front metal pattern 2a is laid on the protrusions 1c, and the gap between the main surface 1a and the back metal pattern 2c is filled with solder 4 to bond them and form a uniform thickness layer of a solder 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device having a solder layer of a predetermined thickness formed by forming a plurality of projections on a solder joint surface between a metal base plate and an insulating substrate, and a method and apparatus for manufacturing the same. It is about.

[0002]

2. Description of the Related Art FIG. 6 is a view showing an insulating substrate part constituting a main part of a power module as a conventional semiconductor device, FIG. 6A is a plan view thereof, and FIG. 6B is a sectional view. FIG. 7 is a sectional view showing a conventional power module using the insulating substrate shown in FIG. In FIG. 6, reference numeral 1 denotes a metal base plate, and 2 denotes an insulating substrate mounted on one main surface 1a of the metal base plate 1 and soldered, and is provided on a ceramic insulating plate 2A and its front main surface. Surface metal pattern 2
a, 2b and a back metal pattern 2c provided on the back main surface, and the back metal pattern 2c and the main surface 1a are
And the semiconductor element 3 is mounted on the front metal pattern 2a and joined with the solder 4A.

In the power module shown in FIG. 7, reference numeral 5 denotes a resin case, 6 denotes an electrode terminal for external connection inserted into the resin case 5, and an end of the electrode terminal 6 exposed inside the resin case 5. The portion 6 a is soldered to the front metal pattern 2 b of the insulating substrate 2 with solder 7, and the edge 1 b of the metal base plate 1 is fitted to the open end of the resin case 5 and adhered by the adhesive 8. That is, when the resin case 5 is bonded to the metal base plate 1 with the adhesive 8 in a post-process of soldering the insulating substrate 2 and the metal base plate 1, the end 6 a also has a lower melting point than the solder 4. At 7, it is soldered to the front metal pattern 2 b.

In the conventional semiconductor device, when the main surface 1a of the metal base plate 1 and the back metal pattern 2c of the insulating substrate 2 are joined with the solder 4, the in-plane weight imbalance of the insulating substrate 2 is reduced. 6B, the thickness of the solder 4 is not uniform as shown in FIG. 6B due to the horizontality of the joining device (not shown), the unevenness of the solder wettability of the main surface 1a and the back metal pattern 2c. When the insulating substrate 2 is inclined with respect to the main surface 1a of the plate 1, the insulating substrate 2 is
a.

[0005] Even if the thickness of the solder 4 can be made uniform, when the end 6a of the electrode terminal 6 is soldered to the front metal pattern 2b using the solder 7 in a later step, this soldering is performed. Is performed in a heated environment, so that the solder 4 that has already joined the insulating substrate 2 and the metal base plate 1 is re-melted or re-softened, and in this state, one end of the electrode terminal 6 7A, the insulating substrate 2 is pressed by the pressing force, and as shown in FIG. 7, the thickness of the solder 4 on the side pressed by the end 6a becomes thinner than the side on which the semiconductor element 3 is mounted, and the insulating substrate 2 The protrusion 4a of the solder 4 is formed on the side of the edge of No. 2 and the insulation creepage distance may be insufficient.

As described above, when the semiconductor element 3 repeats the ON / OFF switching operation in a state where the layer thickness of the solder 4 is not uniform, heat fluctuation accompanying the ON / OFF operation occurs, and the metal base plate Due to the difference between the linear expansion coefficients of the solder substrate 1 and the insulating substrate 2, thermal stress repeatedly acts on the solder 4, and solder cracks generated in the solder 4 may grow.

FIG. 5 is a diagram showing the relationship between solder thickness and solder crack length using the number of heat cycles as a parameter. As is clear from FIG. 5, when thermal stress repeatedly acts on the solder 4, the growth of solder cracks in a portion having a small thickness of the solder is large, leading to a decrease in heat dissipation, and finally to a poor characteristic of the semiconductor element 3. On the other hand, even if the layer thickness of the solder 4 is intentionally increased, the thermal resistance increases or the heat dissipation decreases.

FIG. 8 is a cross-sectional view showing another conventional insulating substrate portion. In this conventional example, a plurality of protrusions 1b protruding from the main surface 1a are formed on the main surface 1a of the metal base plate 1 in order to secure a constant solder thickness, and an insulating material is provided on these protrusions 1b. The substrate 2 is placed and joined in a state where the solder 4 is filled in the gap between the main surface 1a and the back metal pattern 2c.

In this conventional example, due to the presence of the projection 1b,
Although an extremely thin solder layer in which solder cracks are easily generated does not occur, it is difficult to uniformly control the heights of the plurality of protrusions 1b, and as shown in FIG. In the case of a projection, the tip of the projection 1b is easily deformed by an external force such as a slight collision, and it is difficult to maintain the projection height at a constant value. It is difficult to obtain a solder layer.

Further, the metal base plate 1 having the projection 1b which is easily deformed by an external force is difficult to correct the displacement of the substrate at the time of soldering and to perform a scrub operation for discharging voids.

[0011]

Since the conventional power module as a semiconductor device is configured as described above, the thickness of the solder layer joining the metal base plate and the insulating substrate tends to be non-uniform. In the thin solder layer portion, the growth due to the thermal fatigue of the solder cracks is remarkable, while if the solder thickness is made thicker than necessary, the reliability of the product is reduced, such as poor characteristics due to the decrease in heat dissipation. There was a problem. Further, in a power module of a type in which electrode terminals inserted into a resin case are soldered to the insulating substrate, this soldering is performed in a heated environment, and the insulating substrate and the metal base plate are already joined. Since the end of the electrode terminal presses the insulating substrate toward the metal base plate in a state where the solder that has been re-melted or re-softened, the layer thickness of the solder on the pressed side becomes thinner and the solder becomes thinner. There is a problem in that the insulating substrate protrudes to the edge side of the insulating substrate, resulting in insufficient insulation creepage distance.

Further, as a countermeasure for solving the above problem, a plurality of projections are formed on the main surface of the metal base plate, and the gap formed between the metal base plate and the insulating substrate formed by the projections is filled with solder and solidified by melting. However, it is difficult to control the heights of the plurality of protrusions uniformly, and it is difficult to obtain a solder layer having a uniform thickness due to variations in the heights of the plurality of protrusions. was there.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a uniform thickness of the solder layer in a semiconductor device in which a metal base plate and an insulating substrate are joined by solder. An object of the present invention is to improve the crack resistance of the solder against a heat cycle and obtain a highly reliable semiconductor device, a method of manufacturing the same, and a manufacturing apparatus.

[0014]

According to a first aspect of the present invention, there is provided a semiconductor device in which a front metal pattern is formed integrally on a front main surface of a metal base plate and an insulating plate, and a back metal pattern is formed integrally on a back main surface of an insulating plate. A semiconductor element mounted on the front metal pattern and an insulating substrate soldered to the main surface of the metal base plate via the back metal pattern, and a plurality of predetermined surfaces facing the back metal pattern on the main surface. In the semiconductor device in which the projections in contact with the back metal pattern are formed at each of the positions, the plurality of projections each have a ring-shaped flat surface at a tip end in contact with the back metal pattern, and the height thereof is Are mutually equivalent.

A semiconductor device according to a second aspect of the present invention is the semiconductor device according to the first aspect, wherein the outer diameter of the ring-shaped flat surface is 0.5 mm or more and 3 mm or less.

A semiconductor device according to a third aspect of the present invention is the semiconductor device according to the first or second aspect, wherein a plurality of protrusions on the main surface of the metal base plate are formed in a state where an insulating substrate is mounted on the main surface. The plurality of protrusions are disposed so that the contact positions with the back metal pattern are located at least 2 mm inside the peripheral edge of the insulating substrate.

According to a fourth aspect of the present invention, there is provided an apparatus for manufacturing a semiconductor device, comprising: a front metal pattern for mounting a semiconductor element on a front main surface of an insulating plate; and a back metal pattern integrally formed on a rear main surface. Is mounted on the first flat surface of a plurality of projections formed on the main surface of the metal base plate and having a ring-shaped first flat surface at the tip and having the same height. In a semiconductor device manufacturing apparatus for soldering between a pattern and the main surface, a protrusion for pressing the main surface,
A second flat surface formed at the base periphery of the projection,
Pressing the protrusions into the main surface to squeeze the main surface and restricting the height of the main surface raised in a ring shape in the vicinity of the root periphery by the second flat surface. Means.

According to a fifth aspect of the present invention, in the semiconductor device manufacturing apparatus according to the fourth aspect,
Processing means has an opposing surface disposed opposite to the main surface,
The facing surface is brought into contact with the main surface so that the processing is completed.

According to a sixth aspect of the present invention, in the semiconductor device manufacturing apparatus according to the fifth aspect,
The peripheral edge of the root of the projection of the processing means is formed in a substantially truncated cone shape larger than its tip.

According to a seventh aspect of the invention, there is provided a method of manufacturing a semiconductor device, wherein a metal base plate, a front metal pattern for mounting a semiconductor element on a front main surface of an insulating plate, and a back metal pattern on a back main surface are integrally formed. A step of preparing the formed insulating substrate; a step of forming a projection having a ring-shaped first flat surface at the tip on the main surface of the metal base plate; and placing the back metal pattern on the projection. And a step of soldering the back metal pattern to the main surface.
When the protrusion is formed in the working head having a second flat surface formed on the entire periphery of the base of the protrusion by forming the protrusion into the main surface, the tip of the protrusion is set to the second position.
And the ring-shaped first flat surface is formed at the tip of the projection.

According to an eighth aspect of the present invention, in the method of manufacturing a semiconductor device, a metal base plate, a front metal pattern for mounting a semiconductor element on a front main surface of an insulating plate, and a back metal pattern on a back main surface are integrally formed. A step of preparing the formed insulating substrate; a step of forming a projection having a ring-shaped first flat surface at the tip on the main surface of the metal base plate; and placing the back metal pattern on the projection. And a step of soldering the back metal pattern to the main surface.
When the protrusion is formed in the working head having a second flat surface formed on the entire periphery of the base of the protrusion by forming the protrusion into the main surface, the tip of the protrusion is set to the second position.
A flat surface is formed, and a ring-shaped first flat surface is formed at the tip of the projection, and an opposing surface facing the main surface separately from the first flat surface is brought into contact with the main surface, This is a method for regulating the amount of indentation.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a cross-sectional view showing an insulating substrate part constituting a main part of a power module which is a semiconductor device according to a first embodiment of the present invention. FIG. 1A is an overall cross-sectional view, and FIG. FIG. 2 is a cross-sectional view showing a power module using the insulating substrate shown in FIG. In the drawings, the same reference numerals as those of the conventional example indicate the same or equivalent parts as those of the conventional example.

Referring to FIG. 1, reference numeral 1 denotes a metal base plate having a plurality of ring-shaped flat projections 1c at predetermined positions on a main surface 1a, that is, ring-shaped projections having a concave central portion, and a ring-shaped projection on a front end surface. And a plurality of projections formed at the same height as each other. 2 is a metal base plate 1
An insulating substrate soldered to the metal base plate 1 while being mounted on the plurality of ring-shaped flat protrusions 1c;
It comprises a ceramic insulating plate 2A, front metal patterns 2a and 2b provided on the front main surface thereof, and a back metal pattern 2c provided on the back main surface.
c, a gap formed by a plurality of ring-shaped flat protrusions 1c is filled with solder 4 and joined by melting and solidifying the solder 4, and the semiconductor element 3 is placed on the front metal pattern 2a. 4A.

In the power module shown in FIG. 2, reference numeral 5 denotes a resin case, and 6 denotes an electrode terminal for external connection inserted and fixed in the resin case 5. The exposed end 6a is soldered to the front metal pattern 2b of the insulating substrate 2 with solder 7, and the edge 1b of the metal base plate 1 is
And is adhered with an adhesive 8. That is, when the resin case 5 is bonded to the metal base plate 1 with the adhesive 8 in a post-process of soldering the insulating substrate 2 and the metal base plate 1, the end 6 a also has a lower melting point than the solder 4. At 7, it is soldered to the front metal pattern 2 b.

In the embodiment shown in FIG. 1, a plurality of ring-shaped flat protrusions 1c of the same height formed on the main surface 1a of the metal base plate 1 are used to separate the main surface 1a from the insulating substrate 2. A gap having a uniform width is formed on the entire surface between the back metal pattern 2c and the back metal pattern 2c. When the main surface 1a and the back metal pattern 2c are joined with the solder 4, the in-plane weight of the insulating substrate 2 is increased. Even if there is an imbalance, horizontality of the joining device (not shown) for the joining, variation in solder wettability of the metal base plate 1 and the back metal pattern 2c, etc., the solder 4
Can be joined uniformly.

In the power module shown in FIG. 2, after the insulating substrate 2 is soldered to the metal base plate 1 on which a plurality of ring-shaped flat protrusions 1c of the same height are formed by solder 4, When joining the end 6a of the electrode terminal 6 inserted into the resin case 5 to the front metal pattern 2b with the solder 7, this soldering is performed in a heated environment. The solder 7 is selected to have a lower melting point than the solder 4. The heating environment is set to a temperature higher than the melting point of the solder 7 and lower than the melting point of the solder 4. It is easy to re-melt or re-soften the solder 4 that has already joined the insulating substrate 2 and the metal base plate 1. In this state, the insulating substrate 2 is pressed by the end 6 a of the electrode terminal 6 and the insulating substrate 2 is pressed. 2 is pressed and pressed toward the metal base plate 1.

However, even if the insulating substrate 2 receives the pressing force,
Due to the presence of the plurality of ring-shaped flat protrusions 1c, the pressing force is applied to the metal base plate 1 via the ring-shaped flat protrusions 1c.
As a result, the thickness of the solder 4 can be made uniform, and as in the conventional example shown in FIG.
The layer thickness of the solder 4 on the side where a is abutted becomes thinner than the side on which the semiconductor element 3 is mounted, and there is no danger that the solder 4 protrudes 4a. A power module in which the creepage distance is not impaired is obtained.

As described above, in the power module according to the first embodiment, the main surface 1a of the metal base plate 1 is provided.
In addition, a plurality of ring-shaped flat protrusions 1c, that is, ring-shaped flat surfaces are formed, and the height of the protrusions is improved to improve the accuracy. It is difficult to be deformed, its protruding height is maintained at a predetermined value, and the thickness of the solder 4 is
Can be formed uniformly over the entire surface of the semiconductor device, and the uniform solder thickness can be stably maintained.
Even if thermal stress caused by the difference in the coefficient of linear expansion between the insulating substrate 2 and the metal base plate 1 repeatedly acts on the solder 4 due to the thermal fluctuation caused by repeating the switching operation of N and OFF, the solder 4 The generated solder cracks are less likely to grow, and good heat dissipation characteristics with excellent crack resistance are obtained.

That is, as is apparent from the relationship between the solder thickness and the solder crack length in the solder layer using the number of heat cycles as a parameter shown in FIG. 5, when the thermal stress repeatedly acts on the solder layer, the portion where the solder thickness is small is reduced. However, if the solder thickness is not less than a predetermined value, the solder crack growth tends to saturate even if the number of heat cycles increases, so that the solder 4 has a uniform and appropriate solder thickness. Therefore, it is difficult for solder cracks to grow, good heat dissipation characteristics excellent in crack resistance based on excellent uniformity of solder are obtained, and an increase in heat resistance or a decrease in heat dissipation is caused. There is no risk of characteristic failure.

The ring-shaped flat projection 1c has an appropriate projection height in a range of not less than a thickness at which the thickness of the solder 4 does not adversely affect the practical use and not more than a thickness which does not hinder an increase in thermal resistance. By forming the ring-shaped flat surface 1d at the tip of the ring-shaped flat projection 1c so as not to have a sharp angle, the insulating substrate 2 can be selected.
Has good conformability to the back metal pattern 2c, and a good void discharge property can be obtained at the time of joining with the solder 4.

The outer diameter of the ring-shaped flat surface 1d in the ring-shaped flat protrusion 1c is preferably about 0.5 mm to 3 mm, and if the diameter is smaller than 0.5 mm, the edge of the ring-shaped flat surface 1d Becomes sharp, causing stress concentration and voids. If the diameter is larger than 3 mm, a large pressing force is required when the ring-shaped flat protrusion 1c is formed.

The plurality of ring-shaped flat protrusions 1c on the main surface 1a of the metal base plate 1 are
c is 2 mm or more from the peripheral edge of the insulating substrate 2,
It was arranged to be located inside. That is, the internal stress of the solder 4 that has been melted and solidified by filling between the main surface 1a and the back metal pattern 2c is relatively large at the edges of each side of the insulating substrate 2, especially at the corners, and the ring-shaped flat When the projections 1c are present, stress is inevitably concentrated on the solder 4 on the peripheral edge. Therefore, when a plurality of ring-shaped flat projections 1c abut near the peripheral edge of the insulating substrate 2, the ring-shaped flat projections 1c are formed.
The stress concentration on the solder 4 at the periphery of c becomes extremely large. However, as a result of experiments, it has been confirmed by experiments that the stress concentration of the solder 4 at the peripheral edge of the insulating substrate 2 attenuates as the distance from the edge increases, and saturates at a distance of 2 mm or more. Flat protrusion 1
By forming c so as to be in contact with the inner edge of each side of the insulating substrate 2 by 2 mm or more, excessive stress concentration of the solder 4 on the peripheral edge of the plurality of ring-shaped flat protrusions 1c can be prevented.

Embodiment 2 FIG. FIG. 3 is a sectional view showing a ring-shaped flat protrusion forming jig in a semiconductor device manufacturing apparatus according to a second embodiment of the present invention. FIG. 4 is a metal base using the ring-shaped flat protrusion forming jig according to the second embodiment. It is a figure showing the method of forming a plurality of ring-shaped flat projections on the main surface of a board.

In the drawing, reference numeral 9 denotes a jig for forming a ring-shaped flat projection, which has an opposing surface 9a opposing the main surface 1a of the metal base plate 1, and a tip of the opposing surface 9a which is partly larger than the opposing surface 9a. A protruding truncated conical projection 9b is formed, a recess 9d is formed at the base periphery of the projection 9b, and a flat surface 9e is formed on the bottom surface of the recess 9d so as to surround the base periphery of the projection 9b. I have. The depth H of the recess 9d, that is, the dimension H of the step between the facing surface 9a and the flat surface 9e.
Are ring-shaped flat protrusions 1 formed on the main surface 1a.
c is formed to have substantially the same size as the protrusion height h. The jig 9 for forming a ring-shaped flat protrusion shown in FIG. 3 has only one protrusion 9b, but this is for explaining the shape of the protrusion 9b and its peripheral edge. The one that is put into practical use is, as shown in FIG.
Four projections 9b are formed on the top.

Next, a manufacturing method for forming a plurality of ring-shaped flat protrusions 1c on the main surface 1a of the metal base plate 1 using the ring-shaped flat protrusion forming jig shown in FIG. 3 will be described with reference to FIG. I do. First, as shown in FIG. 4A, the metal base plate 1 having been subjected to surface treatment by Ni plating is set on a horizontal plane, and then the jig 9 for forming a ring-shaped flat projection is formed on a plurality of truncated cones formed on the facing surface 9a. Are arranged so that the opposing surface 9a is opposed to the main surface 1a so that the projection 9b can contact a predetermined position on the main surface 1a from above.

Next, as shown in FIG. 4B, the ring-shaped flat projection forming jig 9 is lowered by driving means (not shown) of the ring-shaped flat projection forming jig 9, and a plurality of truncated conical projections 9b are formed. As shown in FIG.
C, the opposing surface 9a is further pressed to form the main surface 1a.
The plurality of truncated cone-shaped projections 9b are sunk into the main surface 1a to a depth where the projections 9b are brought into contact with the main surface 1a, so that the root periphery of the plurality of truncated cone-shaped projections 9b on the main surface 1a is raised in a ring shape. A flat surface 9e on the bottom surface of the recess 9d at the raised portion
, And the height of the protrusion is regulated by the flat surface 9e.

Next, as shown in FIG. 4D, when the jig 9 for forming a ring-shaped flat protrusion is raised and retracted from the main surface 1a, a ring-shaped flat surface 1d having a predetermined height is placed at a predetermined position on the main surface 1a. The metal base plate 1 having a plurality of ring-shaped flat protrusions 1c having the same height as each other is obtained by plastic deformation.

Thereafter, as shown in FIG. 1A, the insulating substrate 2
Is mounted on the tips of the plurality of ring-shaped flat protrusions 1c, and the main surface 1 formed by the plurality of ring-shaped flat protrusions 1c
The gap between a and the back metal pattern 2c of the insulating substrate 2 is filled with the solder 4 in a molten state and joined. In the subsequent process,
As shown in FIG. 2, the edge of the metal base plate 1 is inserted into the open end of the resin case 5 and adhered with an adhesive 8, and the electrode terminals 6 inserted into the resin case 5 are connected to the front metal pattern 2b. Is soldered with solder 7.

As described above, when the ring-shaped flat projection 1c having the ring-shaped flat surface 1d is formed by using the ring-shaped flat projection forming jig 9, the height h of the projection is determined with respect to the target value. Since it is formed accurately,
Since the height variation among the plurality of ring-shaped flat protrusions 1c is extremely small and uniformity is maintained, the uniformity of the solder thickness of the solder 4 joining the metal base plate 1 and the insulating substrate 2 is extremely good. Thus, the crack resistance of the solder 4 is improved, and a highly reliable semiconductor device can be obtained. That is,
Since the variation of the protrusion height h of the plurality of ring-shaped flat protrusions 1c is accurately formed to about ± 0.01 mm, when the target value of the solder thickness is tmm, the protrusion height h
= T-0.02 mm, a solder thickness almost equal to the target value can be obtained.

Further, the frusto-conical projection 9b of the ring-shaped flat projection forming jig 9 has a moderately chamfered edge at the tip end, and the formed ring-shaped flat projection 1c is formed.
Does not have a sharp corner, and particularly, if the outer diameter of the ring-shaped flat surface 1d is about 0.5 mm to 3 mm, the scrubbing work on the metal base plate 1 can be performed smoothly, and the wettability of the solder 4 Good adhesion, no voids,
A solder in which stress concentration hardly occurs in the solder around the ring-shaped flat protrusion 1c is obtained.

The method for forming the ring-shaped flat protrusion 1c according to the second embodiment is described in connection with the surface 9 of the ring-shaped flat protrusion forming jig 9 facing the main surface 1a of the metal base plate 1.
a, a truncated cone-shaped projection 9b is provided at a plurality of predetermined positions, and a recess 9 having a predetermined depth
d, the main surface 1a and the opposing surface 9a are brought into contact with each other to restrict the height h of the ring-shaped flat protrusion 1c. However, the main surface 1a of the metal base plate 1 and the ring-shaped flat protrusion forming jig are provided. It is not always necessary to contact the opposing surface 9a of the ring-shaped flat protrusion forming jig 9, and the height direction of the ring-shaped flat protrusion forming jig 9 is controlled by controlling the stroke of the upper die holding the ring-shaped flat protrusion forming jig 9, The protrusion height h of the flat protrusion 1c may be restricted.

Further, in the method of forming the ring-shaped flat protrusion 1c according to the second embodiment, the press-type dedicated ring-shaped flat protrusion forming jig 9 is used. A special jig is not necessarily required, and a metal mold (not shown) for forming the outer shape of the metal base plate 1 is provided with the opposing surface 9 of the ring-shaped flat projection forming jig 9.
a, a plurality of high-precision ring-shaped flat projections are formed simultaneously with the step of forming the outer shape of the metal base plate 1 even when the projections 9b, the recesses 9d, the flat surfaces 9e, etc. are formed. 1c can be formed, and a simple forming method with less cost increase factor can be obtained.

In the method of forming the ring-shaped flat protrusions 1c according to the second embodiment, the ring-shaped flat protrusions 1c are formed after the surface treatment of the metal base plate 1 by Ni plating.
However, the formation of the ring-shaped flat projections 1c is not necessarily required to be performed after the surface treatment step, and may be performed before or after the surface treatment of the metal base plate 1; There is no risk of delamination.

[0044]

As described above, according to the present invention, a ring-shaped flat surface is provided at the tip at a plurality of predetermined positions facing the vicinity of the inside of the periphery of the back metal pattern of the insulating substrate on the main surface of the metal base plate. A protrusion having a predetermined height is formed, and the ring-shaped flat surface is brought into contact with the back metal pattern, so that the protrusion has a uniform width dimension between the back metal pattern and the main surface. A gap of width is formed,
Due to the presence of the ring-shaped flat surface, the contact area between the projection and the back metal pattern is relatively large, and a stable gap size can be maintained. As a result, a crack-resistant crack having a substantially uniform predetermined thickness is obtained. Thus, there is an effect that a highly reliable semiconductor device can be obtained since a solder layer having excellent reliability can be formed.

Further, since the outer diameter of the ring-shaped flat surface at the tip of the projection is formed in the range of 0.5 mm or more and 3 mm or less, no excessive pressing force is required for forming the projection. At the same time, since the tip does not become sharp, the solder layer joining the back metal pattern of the insulating substrate and the main surface of the metal base plate does not have stress concentration or voids, and has a substantially uniform thickness. There is an effect that a highly reliable semiconductor device having a solder layer having excellent cracking properties can be easily and inexpensively obtained.

Further, when the plurality of projections on the main surface of the metal base plate are in contact with the back metal pattern when the insulating substrate is mounted on the main surface, the position of the plurality of protrusions is 2 mm from the periphery of the insulating substrate. As described above, since the solder layer is disposed inside, the concentration of stress in the solder layer can be reduced, and a highly reliable semiconductor device in which solder cracks are unlikely to grow can be obtained easily and inexpensively.

Further, the metal base plate has a protruding portion for pressing the main surface thereof, and a second flat surface formed on the periphery of the root of the protruding portion. The second flat surface restricts the height of the main surface raised in a ring shape in the vicinity of the base periphery by processing the second flat surface. There is an effect that an apparatus for manufacturing a semiconductor device can be obtained in which a plurality of protrusions having a ring-shaped first flat surface and having the same height can be formed in one step.

Further, the processing means has an opposing surface disposed opposite to the main surface, and the opposing surface is brought into contact with the main surface so that the processing is completed. A plurality of projections having a ring-shaped first flat surface at the tip and having the same height as each other can be formed in a single step with high precision in the height of the projections, and have a simple structure and easy operation. There is an effect that a manufacturing apparatus can be obtained.

Further, since the protruding portion of the processing means is formed in a substantially truncated cone shape whose root periphery is larger than the tip portion,
At a plurality of predetermined positions on the main surface, a high-efficiency ring-shaped protrusion forming apparatus capable of forming a plurality of protrusions having a stable shape without a sharp point in a central depression in one step and with a small pressing force is obtained. effective.

In order to form and process a projection having a ring-shaped first flat surface at the tip on the main surface of the metal base plate,
The protrusion in a processing head having a protrusion that is recessed into the main surface to form the protrusion and a second flat surface formed on the entire periphery of the root of the protrusion is recessed into the main surface. Is formed, the tip of the projection is applied to the second flat surface, and the ring-shaped first flat surface is formed at the tip of the projection. In addition to the above, the ring-shaped flat projection forms a uniform and stable gap of a predetermined width between the main surface and the back metal pattern, and has a substantially uniform thickness and excellent crack resistance. There is an effect that a method for manufacturing a semiconductor device in which a layer can be formed and a highly reliable semiconductor device can be manufactured by a simple operation can be obtained.

Further, in order to form a projection having a ring-shaped first flat surface at the tip on the main surface of the metal base plate, a projection portion which digs into the main surface to form the projection,
When the protrusion is formed in the working head having a second flat surface formed on the entire periphery of the base of the protrusion by forming the protrusion into the main surface, the tip of the protrusion is set to the second position.
And the ring-shaped first flat surface is formed at the tip of the projection, and an opposing surface that faces the main surface separately from the first flat surface is brought into contact with the main surface. Since the amount of digging is regulated, the height of the plurality of ring-shaped flat protrusions can be formed on the main surface in one step with high precision, and the main surface and the back metal can be formed by the ring-shaped flat protrusions. Since a uniform and stable gap of a predetermined width is formed between the pattern and the pattern, a solder layer having a uniform thickness and excellent crack resistance can be formed, and a highly reliable semiconductor device can be manufactured by an extremely simple operation. There is an effect that a method for manufacturing a semiconductor device can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an insulating substrate portion according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a semiconductor device using the insulating substrate shown in FIG.

FIG. 3 is a cross-sectional view showing a ring-shaped flat protrusion forming jig as Embodiment 1 of the present invention.

FIG. 4 is a diagram illustrating a method of forming a ring-shaped flat protrusion using a ring-shaped flat protrusion forming jig according to a second embodiment.

FIG. 5 is a diagram showing the influence of the solder thickness and the number of heat cycles on the solder crack length.

FIG. 6 is a plan view and a sectional view showing a conventional insulating substrate portion.

7 is a cross-sectional view illustrating a semiconductor device using the insulating substrate illustrated in FIG.

FIG. 8 is a sectional view showing another conventional insulating substrate portion.

[Explanation of symbols]

Reference Signs List 1 metal base plate, 1a main surface, 1b protrusion, 1c ring-shaped flat protrusion, 1d ring-shaped flat surface, 2 insulating substrate, 2a, 2b front metal pattern, 2c back metal pattern, 3 semiconductor element, 4 solder, 4a solder Protruding part, 5 resin case, 6 electrode terminals, 7 solder, 8
Adhesive, 9 Ring-shaped flat protrusion forming jig, 9a
Opposing surface, 9b Frustoconical projection, 9c Tip, 9d
Recess, 9e flat surface, h protrusion height

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshiaki Shinohara 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Sanishi Electric Co., Ltd. (72) Inventor Hironobu Nagata 4-1-1 Mizuhara, Itami-shi, Hyogo Conductor System Engineering Co., Ltd. F-term (reference) 5E315 AA09 BB01 BB14 BB18 CC29 DD19 DD29 GG16

Claims (8)

[Claims] 1. A metal base plate and a front metal pattern are integrally formed on a front main surface of an insulating plate, and a back metal pattern is integrally formed on a back main surface, and a semiconductor element is mounted on the front metal pattern and the back metal pattern is formed. An insulating substrate soldered to the main surface of the metal base plate via a metal pattern, and at each of a plurality of predetermined positions on the main surface facing the back metal pattern, a projection abutting on the back metal pattern. In the formed semiconductor device, the plurality of protrusions each have a ring-shaped flat surface at a tip portion in contact with the back metal pattern, and have the same height. 2. The semiconductor device according to claim 1, wherein the outer diameter of the ring-shaped flat surface is 0.5 mm or more and 3 mm or less. 3. A plurality of protrusions on a main surface of a metal base plate, and a contact position of the plurality of protrusions with a back metal pattern in a state where an insulating substrate is mounted on the main surface is 2 mm from a peripheral edge of the insulating substrate. The semiconductor device according to claim 1, wherein the semiconductor device is provided so as to be present inside. 4. An insulating substrate having a front metal pattern on which a semiconductor element is mounted on a front main surface of an insulating plate and a back metal pattern integrally formed on a back main surface is formed on a main surface of a metal base plate. A plurality of projections having a ring-shaped first flat surface at the tip and having the same height as each other are placed on the first flat surface, and the space between the back metal pattern and the main surface is soldered. In a semiconductor device manufacturing apparatus, the semiconductor device has a protrusion for pressing the main surface, and a second flat surface formed on a peripheral edge of a root of the protrusion, and presses the protrusion against the main surface to be fitted therein. Processing means for controlling the height of the main surface raised in a ring shape in the vicinity of the root periphery by the second flat surface and processing the semiconductor device. apparatus. 5. The processing means has an opposing surface disposed opposite to the main surface, and the opposing surface is brought into contact with the main surface to complete the processing. 4. The apparatus for manufacturing a semiconductor device according to item 3. 6. The semiconductor device manufacturing apparatus according to claim 4, wherein the protruding portion of the processing means is formed in a substantially truncated conical shape in which a root periphery is larger than a tip portion. 7. A step of preparing a metal base plate, an insulating substrate having a front metal surface on which a semiconductor element is mounted on the front main surface of the insulating plate, and a back metal pattern integrally formed on the back main surface, respectively. Forming a projection having a ring-shaped first flat surface at the tip on the main surface of the metal base plate; placing the back metal pattern on the projection and soldering the back metal pattern to the main surface; And a step of attaching the protrusion to the main surface to form the protrusion, and a second flat surface formed on the entire periphery of the base of the protrusion. When the protrusion is recessed into the main surface to form the protrusion, the tip of the protrusion is applied to the second flat surface, and the ring-shaped first flat surface is formed at the tip of the protrusion. Of semiconductor devices characterized by the following: Method. 8. A step of preparing a metal base plate, an insulating substrate having a front metal pattern on which a semiconductor element is mounted on the front main surface of the insulating plate, and a back metal pattern integrally formed on the back main surface. Forming a projection having a ring-shaped first flat surface at the tip on the main surface of the metal base plate; placing the back metal pattern on the projection and soldering the back metal pattern to the main surface; And a step of attaching the protrusion to the main surface to form the protrusion, and a second flat surface formed on the entire periphery of the base of the protrusion. When the protrusion is recessed into the main surface to form the protrusion, the tip of the protrusion is applied to the second flat surface, and a ring-shaped first flat surface is formed at the tip of the protrusion. Opposed to the main surface separately from the first flat surface Contact the opposite surface to the main surface,
A method of manufacturing a semiconductor device, wherein the amount of digging is regulated.