JPH1140716A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device which can prevent formation of such improper soldering as solder ball, insufficient solder strength or offset position. SOLUTION: A semiconductor device 1 includes a metallic base 2, an insulating substrate 3 having upper and lower electrodes formed on upper and lower surfaces, a soldering film 5 disposed between the lower electrodes and the base 2, and semiconductor elements 6 provided on an upper surface of the substrate 3 and electrically connected to the upper electrodes. Provided on the soldering film 5 are electrically conductive bumps which secure a constant spacing between the substrate 3 and the base 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device such as a giant transistor and a method for manufacturing the same.

[0002]

2. Description of the Related Art As shown in FIGS. 8 and 9, a semiconductor device C such as a giant transistor for connecting a large insulating substrate A to a metal base B by soldering.
Is a diagram in which a plurality of semiconductor elements D are arranged on an insulating substrate A, and the electrodes of the semiconductor element D and the electrodes provided on the insulating substrate A are connected by aluminum wires F. Are connected to the metal base B by the solder G. The material of the metal base B used at this time is generally copper, and its surface is plated with a nickel film. The metal base B is often used for heat radiation of the semiconductor device C, and its surface is generally flat to increase the contact area with the insulating substrate A.

[0003] Solder G used for soldering is used.
Is formed in a sheet shape. In the soldering method, a flux H is applied to the surface of the metal base B, and a sheet-like solder G is placed thereon. Further, a flux is applied to the sheet-like solder G, and after placing the insulating substrate A, the solder is heated to melt the solder, thereby making connection. As a heating method, there are (1) a method of directly heating from the metal base B side with a hot plate or the like, and (2) a method of heating the entire semiconductor device C itself to be soldered with a reflow furnace or the like.

[0004]

However, only the gap between the metal base B and the insulating substrate A of the conventional semiconductor device C is maintained by the solder G, and the amount of the solder G and the inclination of the insulating substrate A are different. The gap changes due to the like. At this time, the solder G in the narrowed portion protrudes from the gap between the metal base B and the insulating substrate A, and the solder ball J
Etc., or the amount of solder is insufficient,
Insufficient contact area occurs.

[0005] Further, a flux is applied before soldering. When the flux is applied to the outside of the insulating substrate A at the time of application, the flux is guided by the flux at the time of soldering, the solder G protrudes, and a solder ball or the like is formed. In addition to the failure, a flux may remain between the insulating substrate A and the metal base B, and outgas may be generated by heating, which may lead to generation of voids. The present invention has been made in view of the above circumstances, and has as its object to provide a semiconductor device and a method of manufacturing the same that solve the above-mentioned problems.

[0006]

According to a first aspect of the present invention, there is provided a semiconductor device, comprising: a metal base; an insulating substrate having an upper electrode provided on one surface and a lower electrode provided on the other surface; A solder film interposed between the metal base and
A semiconductor element electrically connected to the upper electrode is provided, and conductive particles for maintaining a constant distance between the metal base and the insulating substrate are mixed in the solder film.

According to a second aspect of the present invention, in the first aspect, the particles are made of metal. Thus, the semiconductor device according to claims 1 and 2 can prevent the formation of solder balls, insufficient soldering strength, misalignment, and occurrence of soldering defects such as solder voids. .

According to a third aspect of the invention, there is provided a method of manufacturing a semiconductor device, comprising: a metal base; an insulating substrate having an upper electrode provided on one surface and a lower electrode provided on the other surface; and electrically connected to the upper electrode. In the manufacture of a semiconductor device comprising a semiconductor element and conductive particles that keep the distance between the metal base and the insulating substrate constant in the solder film, the particles are mixed. A superposing step of interposing the solder member between the lower electrode side of the insulating substrate and the metal base, and a solder film obtained by melting the solder member after the superposing step. And a reflow soldering step of performing reflow soldering.

According to a fourth aspect of the present invention, in the method of the third aspect, the solder member has a sheet shape.
The method of manufacturing a semiconductor device according to claim 5, wherein the solder member is in the form of a paste in claim 3.

According to a third aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: preventing formation of solder balls, insufficient soldering strength, displacement, and occurrence of soldering defects such as solder voids. Is possible.

[0011]

An embodiment of the present invention will be described below in detail with reference to the drawings. 1 and 2 show a semiconductor device 1 of this embodiment. The semiconductor device 1 has a rectangular shape, for example, a metal base 2 having a length of 100 mm and a width of 30 mm, and a rectangular shape having a smaller area than the metal base 2 provided on the metal base 2 and having a length of, for example, 70 mm.
an insulating substrate 3 having a thickness of, for example, copper and a thickness of, for example, 200 μm provided on the lower surface of the insulating substrate 3;
Film 5 for bonding the metal base 2 to the insulating substrate 3
A plurality of semiconductor elements 6 such as transistors provided on the upper surface of the substrate and a material provided in an island shape on the upper surface of the insulating substrate 3 so as to surround the semiconductor elements 6 is, for example, copper and has a thickness of, for example, 200 μm. Upper electrode 7 and semiconductor element 6
And a wire 9 made of, for example, aluminum for electrically connecting between the electrode 8 and the upper electrode 7.
The lower electrode 4 is provided for the purpose of heat radiation and grounding, and is provided on substantially the entire lower surface of the rectangular insulating substrate 3. That is, the lower electrode 4
Is provided in a rectangular shape, for example, 1.5 mm inward from the edge of the insulating substrate 3. On the other hand, the upper electrode 7 is for electrically connecting the semiconductor element 6 and is formed in a predetermined pattern.

The metal base 2 has a thickness of, for example, 3
The main body 10 is formed to a thickness of about 5 mm and made of a metal having a small electric resistance such as copper, for example, and a coating 11 made of, for example, nickel or the like is applied on the surface of the main body to a thickness of about 5 μm. I have. Further, the material of the insulating substrate 3 is, for example, ceramic or the like.

The solder film 5 has a thickness of, for example, 1
The thickness of the solder film 5 is as shown in FIG.
As shown in FIG. 4, a large number of spherical particles 5p are mixed. The material of the particles 5p is preferably, for example, nickel (Ni) or copper (Cu). The average value of the size (diameter) of the particles 5p is preferably, for example, 50 μm to 100 μm. However, the variation (deviation value) of the diameter is preferably 5 μm to 10 μm. That is, the diameter of the particles 5p is preferably substantially constant.

Next, a method for manufacturing the semiconductor device 1 will be described. The method of manufacturing the semiconductor device 1 includes a covering portion forming step of applying a covering portion 11 of, for example, nickel to a surface of a metal plate having a low electric resistance such as copper to a thickness of, for example, about 5 μm by, for example, plating (see FIG. 5). (See S1)
And a metal base forming step of cutting the plated metal plate after the covering part forming step to obtain a plurality of metal bases 2 (see symbol S2 in FIG. 5). Fixing a semiconductor element with a high melting point solder or a conductive resin or the like (see symbol S3 in FIG. 5);
After the semiconductor element fixing step, a wire connecting step (see symbol S4 in FIG. 5) for electrically connecting the electrode 8 and the upper electrode 7 provided on the semiconductor element 6 with, for example, an aluminum wire 9 or the like; 2 and / or a flux application step of applying the flux 13 to the lower electrode 4 of the insulating substrate 3 (see S5 in FIG. 5 / see FIG. 6), and after this flux application step, the solder sheet 14 is placed on the metal base 2.
A solder sheet placing step for placing on the top (see S6 in FIG. 5 / see FIG. 6), and after the solder sheet placing step, the insulating substrate 3 is connected via the solder sheet 14 so that the lower electrode 4 contacts the solder sheet 14. A superimposing step (see S7 in FIG. 5 / see FIG. 6), and the metal base 2 and the insulating substrate 3 superimposed after the superimposing step are charged into a reflow furnace or placed on a hot plate. And
For example, there is a reflow soldering step of performing reflow soldering after heating at 275 ° C. for 130 seconds (see symbol S8 in FIG. 5).

The sheet 14 is made of, for example, a eutectic solder having a thickness of 100 μm, and contains the above-mentioned particles 5p. By the way, in the reflow soldering process, the solder sheet 14 is melted. However, when the insulating substrate 3 is inclined, when the amount of the molten solder is large, or when the gap is formed only by the solder, the insulation having the reduced gap is used. In the peripheral part of the substrate 3, a part of the molten solder 5a flows out. However, in this embodiment, since the insulating substrate 3 is mounted on the metal base 2 via the particles 5p, the gap (distance) between the insulating substrate 3 and the metal base 2 is constant, for example, 70 μm ± 10 μm. And the insulating substrate 3 is held horizontally without tilting. By eliminating the inclination of the insulating substrate 3 with respect to the metal base 2 in this manner, it is possible to prevent the molten solder 5a from flowing to the peripheral portion and to prevent the formation of solder balls.

As described above, the semiconductor device 1 of this embodiment
In the method for manufacturing the semiconductor device 1, since the particles 5 p are interposed between the metal base 2 and the insulating substrate 3,
By the action of keeping the distance between the insulating substrate 3 and the metal base 2 of the particles 5p constant, the application area of the flux 13 is reliably limited to the bonding area of the metal base 2 and the insulating substrate 3 by soldering. Becomes possible. Also,
By creating a gap between the metal base 2 and the insulating substrate 3,
The solder is filled between the metal base 2 and the insulating substrate 3 due to the surface tension of the solder, and the amount of solder is insufficient due to the inclination of the insulating substrate 3 or the like, so that the contact area due to soldering is insufficient and sufficient adhesive strength is obtained. It is possible to prevent the occurrence of soldering defects such as not being able to be performed. Furthermore, since the projections 12 are formed integrally with the metal base 2, the projections 12 also have a good effect in terms of heat dissipation for releasing heat generated in the semiconductor element 6 to the metal base 2 side.

In the above embodiment, the metal particles are mixed into the solder sheet. However, the same effect as in the above embodiment can be obtained in the paste (cream) solder. In this case, instead of the sheet placing process,
The solder paste (cream) containing the metal particles is applied to the metal base 2 or the insulating substrate 3 or both with a thickness of, for example, 10 mm.
It is necessary to provide a solder application step of applying a continuous thin film or an intermittent island shape to the portion to be soldered at 0 μm to 500 μm (FIG. 7). Further, the particles are not limited to metal particles, and may be, for example, ceramics or plastics having conductivity.

[0018]

According to a first aspect of the present invention, there is provided a semiconductor device comprising: a metal base; an insulating substrate having an upper electrode provided on one surface and a lower electrode provided on the other surface; A solder film interposed therebetween, and a semiconductor element electrically connected to the upper electrode, wherein the solder film has a conductive property for keeping a constant distance between the metal base and the insulating substrate. Particles are mixed.

According to a second aspect of the present invention, in the first aspect, the particles are made of metal. According to the semiconductor device of the first and second aspects of the present invention, the metal particles are mixed into the solder sheet interposed between the metal base and the lower electrode attached to the insulating substrate. Even if the substrate tilts and the gap between the metal base and the insulating substrate is narrowed, the gap is maintained by the metal particles so that the insulating substrate does not approach the metal base more than the height of the metal particles, and the solder flows between the metal base and the insulating substrate. It does not protrude. as a result,
The protruding solder becomes a solder ball due to the effect of surface tension, or the amount of solder for soldering the metal base and the insulating substrate is insufficient, so that the contact area due to soldering is insufficient, and sufficient adhesive strength cannot be obtained. , Etc., can be prevented. In addition, even when outgas is generated from the flux due to the gap when the solder is melted, the gas can be discharged and the generation of voids can be prevented.

According to a third aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: a metal base; an insulating substrate having an upper electrode provided on one surface and a lower electrode provided on the other surface; and electrically connected to the upper electrode. In the manufacture of a semiconductor device comprising a semiconductor element and conductive particles that keep the distance between the metal base and the insulating substrate constant in the solder film, the particles are mixed. A superposing step of interposing the solder member between the lower electrode side of the insulating substrate and the metal base, and a solder film obtained by melting the solder member after the superposing step. And a reflow soldering step of performing reflow soldering.

According to a fourth aspect of the present invention, in the method of the third aspect, the solder member has a sheet shape.
The method of manufacturing a semiconductor device according to claim 5, wherein the solder member is in the form of a paste in claim 3.

According to a third aspect of the present invention, in the method of manufacturing a semiconductor device, metal particles are mixed into a solder sheet provided at a position facing a metal base and a lower electrode attached to an insulating substrate. By mixing the metal particles into the solder sheet interposed at the position opposite to the set lower electrode, even if the insulating substrate is tilted and the gap between the metal base and the insulating substrate is narrowed, the metal particles are mixed. By keeping the gap, the insulating substrate does not approach the metal base more than the height of the metal particles, and the solder does not protrude from between the metal base and the insulating substrate. As a result, the protruding solder becomes solder balls due to the effect of surface tension, or the amount of solder for soldering the metal base and the insulating substrate is insufficient, so that the contact area due to soldering is insufficient and sufficient adhesive strength is obtained. It is possible to prevent the occurrence of soldering failure such as not being obtained. In addition, even when outgas is generated from the flux due to the gap when the solder is melted, the gas can be discharged and the generation of voids can be prevented.

[Brief description of the drawings]

FIG. 1 is a plan view of a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is an enlarged sectional view of a main part of the semiconductor device according to one embodiment of the present invention;

FIG. 4 is an enlarged sectional view of a main part of FIG.

FIG. 5 is a flowchart illustrating a method for manufacturing a semiconductor device according to an embodiment of the present invention.

FIG. 6 is a sectional view illustrating the method for manufacturing the semiconductor device according to the embodiment of the present invention;

FIG. 7 is an enlarged sectional view of a main part of a semiconductor device according to another embodiment of the present invention.

FIG. 8 is an explanatory diagram for explaining a conventional technique.

FIG. 9 is an explanatory diagram for explaining a conventional technique.

[Explanation of symbols]

1: semiconductor device, 2: metal base, 3: insulating substrate, 4:
Lower electrode, 5: solder film, 6: semiconductor element, 12: particle, 13: flux, 14: solder groove.

Claims (5)

[Claims] A metal base; an insulating substrate provided with an upper electrode on one surface and a lower electrode on the other surface;
A solder film interposed between the lower electrode and the metal base, and a semiconductor element electrically connected to the upper electrode, wherein the solder film includes a metal base and the insulating substrate. A semiconductor device comprising conductive particles for keeping a distance constant. 2. The semiconductor device according to claim 1, wherein the particles are made of metal. 3. A metal base, an insulating substrate having an upper electrode provided on one surface and a lower electrode provided on the other surface,
Manufacturing a semiconductor device comprising: a semiconductor element electrically connected to the upper electrode; wherein the solder film is mixed with conductive particles for maintaining a constant distance between the metal base and the insulating substrate. In doing so, an overlapping step of interposing the solder member mixed with the particles between the lower electrode side of the insulating substrate and the solder film obtained by melting the solder member after the overlapping step A reflow soldering step of reflow soldering the substrate to the metal base. 4. The method according to claim 3, wherein the solder member has a sheet shape. 5. The method according to claim 3, wherein the solder member is in the form of a paste.