SEMICONDUCTOR MODULE RADIATOR PLATE FABRICATION METHOD, RADIATOR PLATE, AND SEMICONDUCTOR MODULE USING THE SAME
When insulating substrates of different shapes are soldered to a radiator plate, a third concave curve is previously formed on an insulating substrate side of the radiator plate. The third curve is determined by adding a second concave curve which is expected at the time of actually soldering the insulating substrates to the radiator plate to a first concave curve obtained by moving upside down a convex curve which appears at the time of soldering the insulating substrates to a flat radiator plate. A bottom of the third curve is positioned under the large insulating substrate, and a curvature of a portion where the distance between the bottom and a reference point of the radiator plate is longer is made smaller than a curvature of a portion where the distance between the bottom and a reference point of the radiator plate is shorter.
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This application is a continuation application of International Application PCT/JP2011/070035 filed on Sep. 2, 2011 which designated the U.S., which claims priority to Japanese Patent Application No. 2011-024610, filed on Feb. 8, 2011, the entire contents of which are incorporated herein by reference.
FIELDThe embodiments discussed herein are related to a semiconductor module radiator plate fabrication method, a radiator plate, and a semiconductor module using such a radiator plate.
BACKGROUNDIn order to cancel out the convex curve 67 illustrated in
When the insulating substrates 56 are soldered to the radiator plate 51 by which the reverse curve 69 indicated by a dashed line is formed, the convex curve 67 illustrated in
Furthermore, according to Japanese Laid-open Patent Publication No. 2007-88045, as illustrated in
In addition, according to Japanese Laid-open Patent Publication No. 2008-91959 (not illustrated), when an insulating substrate is adhered to a radiator plate by the use of solder, a concave curve (reverse curve) is formed in advance on an insulating substrate side of the radiator plate and then the insulating substrate is soldered. By doing so, the radiator plate is kept in a reversely curved state (having a concave curve on the insulating substrate side) even after the soldering. By attaching the radiator plate in a reversely curved state to a cooling fin, there appears no gap between the radiator plate and the cooling fin.
In
When the insulating substrates 81 and 82 are soldered to the radiator plate 83 having the curve 86, the radiator plate 83 is deformed into the radiator plate 83 having a concave curve 87 a bottom 87a of which is positioned under the insulating substrate 82.
With the method of forming the concave curve in this way, a position at which the left-hand and right-hand portions of the curve 86 which differ in curvature, that is to say, the curvatures of which are R3 and R4, respectively, connect deviates from the center and becomes unclear. Accordingly, it is difficult to manage the curve 86.
Furthermore, the curve 86 the left-hand and right-hand portions of which differ in curvature, that is to say, the curvatures of the left-hand and right-hand portions of which are R3 and R4, respectively, may be formed on the radiator plate 83 for canceling out the convex curve 85 which appears as a result of soldering the insulating substrates 81 and 82 of different shapes. Accordingly, the management of the curve 86 is complex.
As illustrated in
According to Japanese Laid-open Patent Publication No. 2007-88045, a curve corresponding to each of the insulating substrates 71 and 72 is formed without taking a curve of the entire radiator plate 73 into consideration. This may lead to considerable curve deformation of the entire radiator plate 73. If considerable initial curving is performed, the following problems, for example, tend to arise. A semiconductor chip mounted over the insulating substrate 71 or 72 at assembly time shifts, or a void appears in solder between the insulating substrate 71 or 72 and the radiator plate 73.
Furthermore, the insulating substrates 71 and 72 are simply placed over the radiator plate 73. Therefore, as described in
Furthermore, Japanese Laid-open Patent Publication No. 2008-91959 does not state that when the insulating substrates of different shapes are soldered to the radiator plate in order to prevent the above troubles, a bottom of the curve (initial curving) formed on the radiator plate before the soldering is positioned under clearance between the insulating substrate.
SUMMARYAccording to an aspect of the embodiments to be discussed herein, there is provided a semiconductor module radiator plate fabrication method which includes: soldering a plurality of insulating substrates of different shapes to a flat radiator plate, and forming a convex curve on an insulating substrate side of the radiator plate; obtaining a first concave curve by reversing the convex curve; setting a second concave curve on an insulating substrate side of a radiator plate after soldering, a bottom of the second concave curve being positioned under clearance between the plurality of insulating substrates; adding the first curve and the second curve to calculate a third concave curve on the insulating substrate side; and forming the third curve on a flat plate to form a radiator plate before soldering.
The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention.
Embodiments will be described by the following examples.
EXAMPLE 1First the flat radiator plate 3 and the two insulating substrates 1 and 2 of different shapes which differ in area are prepared for data acquisition. The insulating substrates 1 and 2 are soldered to determined positions on one of the radiator plate 3. As illustrated in part (a) of
The top 4a of the convex curve 4 is positioned under the large insulating substrate 2. The distance L11 between the top 4a and a reference point 5a on a small insulating substrate 1 side is longer than the distance L21 between the top 4a and a reference point 5b on a large insulating substrate 2 side.
As illustrated in
Next, as illustrated in part (b) of
Next, as illustrated in part (c) of
Furthermore, as indicated by dotted lines, two straight lines 9 and 10 may be drawn between the bottom 7a of the second curve 7 and the reference points 5a and 5b. In this case, a second plane is obtained as a surface. However, if the radiator plate 3 is concavely curved downward by the two straight lines 9 and 10, then clearance appears at the time of fixing the radiator plate 3 onto a cooling fin. It is preferable to avoid the appearance of clearance. If the second curve 7 is represented by the two straight lines 9 and 10, then the relationship “curvature R1<curvature R2” regarding a third curve 11 illustrated in part (d) of
Next, as illustrated in part (d) of
In addition, the position of the bottom 11a of the third curve 11 is approximately identical to that of the bottom 6a of the first curve 6.
When the insulating substrates 1 and 2 of different shapes are soldered to the determined positions on the radiator plate 3 having the third curve 11, then the radiator plate 3 having a fourth curve 21 (see
For the sake of simplicity one dimension has been described above, but in reality concave curves are two-dimensionally measured to obtain the first curve 6, the second curve 7, and the third curve 11.
In this example, as stated above, the shape of the third curve 11 is determined from a curve of the entire radiator plate 3. With Japanese Laid-open Patent Publication No. 2007-88045, curves are determined according to insulating substrates and these curves are combined to determine an entire curve. In this example, on the other hand, the third curve 11 does not become too sharp. Accordingly, when the radiator plate 3 is fixed onto the cooling fin, it is possible to prevent a crack from appearing in solder between the insulating substrates 1 and 2 and the radiator plate 3.
Furthermore, as stated above, the third curve is calculated from the first curve 6 found by the experiment and the set second curve 7. Therefore, the management of the third curve 11 is not so complex as the management of conventional curves and is easy.
EXAMPLE 2Part (d) of
On the radiator plate 3 in
The straight lines which connect the centers of the clamp holes 5 are needed for determining the reference points 5a and 5b (see
The semiconductor module 100 includes the radiator plate 3, insulating substrates with a conductive pattern (above insulating substrates 1 and 2) back conductive films (not illustrated) of which are adhered to the radiator plate 3 with solder 25 between, semiconductor chips 27 adhered to a conductive pattern (not illustrated) of the radiator plate 3 with solder 26 between, bonding wires 28 which connect surface electrodes (not illustrated) of the semiconductor chips 27 and the conductive patterns, wiring conductors 29 one end of each of which is connected to a conductive pattern, lead-out terminals 30 to each of which the other end of each of the wiring conductor 29 is adhered, a resin case 31 to which the lead-out terminals 30 are adhered, and gel 32 with which the resin case 31 is filled.
The insulating substrates 1 and 2 are soldered to the radiator plate 3 having the third curve. By doing so, a bottom 21a of the fourth concave curve 21 of the radiator plate 3 is positioned under the clearance 8 between the insulating substrates 1 and 2. The fourth curve 21 is very close to the above second curve 7.
The bottom 21a of the fourth concave curve 21 of the radiator plate 3 is positioned under the clearance 8 between the insulating substrates 1 and 2, so the radiator plate 3 having low rigidity is pressed against a cooling fin 33 with the bottom 21a of the fourth curve 21 and the clamp holes 5 of the radiator plate 3 as supporting points. At this time there is no supporting point (bottom 21a of the fourth curve 21) in the insulating substrate 2 having high rigidity. As a result, the whole of the back 15 of the radiator plate 3 adheres closely to the cooling fin 33 and the appearance of a gap between the radiator plate 3 and the cooling fin 33 is prevented.
As stated above, in this embodiment the shape of the third curve 11 is determined from a curve of the entire radiator plate 3, so the third curve 11 does not become too sharp. Accordingly, when the radiator plate 3 is fixed onto the cooling fin 33, the appearance of a crack in the solder 25 between the insulating substrates 1 and 2 and the radiator plate 3 is prevented.
A material for the above radiator plate 3 is copper, a copper alloy (C19220 or C19210, for example), or the like. Furthermore, insulating plates made of alumina, aluminum nitride, silicon nitride, or the like are used as the insulating substrates 1 and 2 mounted over the radiator plate 3.
According to the present invention, when insulating substrates of different shapes are soldered to a radiator plate, a third concave curve is formed in advance on an insulating substrate side of the radiator plate. The third curve is determined by adding a second concave curve which is expected at the time of actually soldering the insulating substrates of different shapes to the radiator plate to a first concave curve obtained by moving upside down a convex curve which appears at the time of soldering the insulating substrates of different shapes to a flat radiator plate. A bottom of the third curve is positioned under a large insulating substrate and a curvature of a portion of the third curve for which the distance between this bottom and a reference point determined on the basis of the clamping of the radiator plate is longer is made smaller than a curvature of a portion of the third curve for which the distance between the bottom and a reference point determined on the basis of the clamping of the radiator plate is shorter.
A bottom of a concave portion of the radiator plate is positioned between the insulating substrates. As a result, when the radiator plate is attached to a cooling fin, a crack does not appear in solder. In addition, a gap between the radiator plate and the cooling fin is made narrow. Accordingly, heat radiation properties can be improved.
Furthermore, the third curve is calculated from a first curve found by actual measurement and the set second curve. Accordingly, the management of the third curve is not so complex as the management of conventional curves and is easy.
All examples and conditional language provided herein are intended for the pedagogical purposes of aiding the reader in understanding the invention and the concepts contributed by the inventor to further the art, and are not to be construed as limitations to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although one or more embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.
Claims
1. A semiconductor module radiator plate fabrication method comprising:
- soldering a plurality of insulating substrates of different shapes to a flat radiator plate, and forming a convex curve on an insulating substrate side of the radiator plate;
- obtaining a first concave curve by reversing the convex curve;
- setting a second concave curve on an insulating substrate side of a radiator plate after soldering, a bottom of the second concave curve being positioned under clearance between the plurality of insulating substrates;
- adding the first curve and the second curve to calculate a third concave curve on the insulating substrate side; and
- forming the third curve on a flat plate to form a radiator plate before soldering.
2. A semiconductor module radiator plate having, on a side on which a plurality of insulating substrates of different shapes are soldered, a third concave curve obtained by adding a first concave curve obtained by reversing a convex curve formed, by soldering the plurality of insulating substrates of different shapes to a flat radiator plate, on an insulating substrate side of the radiator plate and a second concave curve which is set on an insulating substrate side of a radiator plate after soldering and a bottom of which is positioned under clearance between the plurality of insulating substrates.
3. The semiconductor module radiator plate according to claim 2, wherein:
- a bottom of the third curve is positioned under an insulating substrate which is the largest in area of the plurality of insulating substrates of different shapes; and
- a curvature of a portion of the third curve positioned under an insulating substrate which is the smallest in area of the plurality of insulating substrates of different shapes is smaller than a curvature of a portion of the third curve positioned under the insulating substrate which is the largest in area of the plurality of insulating substrates of different shapes.
4. The semiconductor module radiator plate according to claim 3, wherein a material is copper or a copper alloy.
5. A semiconductor module comprising:
- a plurality of insulating substrates of different shapes; and
- a semiconductor module radiator plate having, on a side on which the plurality of insulating substrates of different shapes are soldered, a third concave curve obtained by adding a first concave curve obtained by reversing a convex curve formed, by soldering the plurality of insulating substrates of different shapes to a flat radiator plate, on an insulating substrate side of the radiator plate and a second concave curve which is set on an insulating substrate side of a radiator plate after soldering and a bottom of which is positioned under clearance between the plurality of insulating substrates.
6. The semiconductor module according to claim 5, wherein:
- the curve of the semiconductor module radiator plate is concave on the insulating substrate side; and
- a bottom of the concave curve is positioned under clearance between the plurality of insulating substrates.
7. The semiconductor module according to claim 6, wherein a material for insulating plates used as the plurality of insulating substrates is alumina, aluminum nitride, or silicon nitride.
Type: Application
Filed: Jul 25, 2013
Publication Date: Nov 21, 2013
Applicant: FUJI ELECTRIC CO., LTD. (Kawasaki)
Inventors: Yoshinori Uezato (Kawasaki), Masayuki Soutome (Kawasaki), Rikihiro Maruyama (Kawasaki), Tomoaki Goto (Kawasaki)
Application Number: 13/950,928
International Classification: F28F 3/00 (20060101); B23P 15/26 (20060101);