JP5141371B2 - Coating method and pattern forming mask - Google Patents

Description

  The present invention relates to a coating method and a mask for pattern formation, and in particular, a coating method and a pattern for coating a contact material interposed between a base substrate of a semiconductor device and a cooling body on either main surface of the base substrate or the cooling body. The present invention relates to a forming mask.

  In order to cool semiconductor devices such as IGBTs (Insulated Gate Bipolar Transistors), power MOSs (Metal Oxide Semiconductors), and FWDs (Free Wheel Diodes), a method of dissipating heat by bringing a cooling body into contact with a semiconductor device that generates heat has been performed. Yes.

  A cooling body is installed in the semiconductor device via a high thermal conductive grease applied to the heat generating main surface of the semiconductor device (see, for example, Patent Document 1). At this time, the high thermal conductive grease is applied in a grid pattern on the heat generating main surface. Note that Patent Document 1 discloses a case where a high thermal conductive grease is applied radially from the center and the center point. When the cooling body comes into contact with the semiconductor device, the high thermal conductive grease is spread out so as not to trap air on the heat generating main surface. For this reason, the semiconductor device and the cooling body are connected with air removed, the thermal conductivity between the semiconductor device and the cooling body is improved, and the heat generated from the semiconductor device passes through the high thermal conductive grease. Dissipated from the cooling body.

Since the contact surfaces of the semiconductor device and the cooling body have undulations of several μm from each other, when the semiconductor device and the cooling body are brought into contact with each other and screwed, a high thermal conductive grease or The compound is applied. The compound is obtained by mixing heat conductive fine particles such as ceramics (for example, alumina) with an oil component in order to increase the thermal conductivity of the compound. By screwing the semiconductor device and the cooling body through such a compound, the adhesion between the semiconductor device and the cooling body is improved, and the cooling performance of the semiconductor device can be improved.
Japanese Patent Laid-Open No. 9-293811

However, when the compound is applied to the contact surface of the semiconductor device (or the cooling body) in a lattice pattern as in Patent Document 1 and the semiconductor device and the cooling body are screwed, there are the following problems.
The compound between the contact surfaces of the semiconductor device and the cooling body is pressed and spread by screw tightening. However, each compound applied in a grid pattern does not spread evenly, and depending on the position of the contact surface, the compound spreads. When spots occur, air or the like accumulates, the thermal conductivity between the semiconductor device and the cooling body decreases, and the cooling performance of the semiconductor device decreases.

  Moreover, the compound contains ceramic fine particles as described above. The ceramic fine particles are intended to increase the thermal conductivity of the compound, but have a lower thermal conductivity than a cooling body or the like. When the compound spread by screw tightening is thicker than a predetermined thickness, the thermal resistance from the semiconductor device to the cooling body increases, and the cooling performance of the semiconductor device decreases.

  The present invention has been made in view of these points, and an object of the present invention is to provide a coating method and a pattern forming mask that improve the thermal conductivity from a semiconductor device to a cooling body.

  In order to achieve the above object, there is provided a coating method in which a contact material interposed between a base substrate of a semiconductor device and a cooling body is applied to either main surface of the base substrate or the cooling body.

The coating method is between the center of the hole for inserting a fastener for installing the cold却体the base over scan substrate to a first distance, the first contact pattern touch corresponding to one of arbitrary shape The contact of the second pattern corresponding to one arbitrary shape having at least one material and having an area larger than that of the first pattern between the first distance and the second distance. the wood at least one disposed, wherein in the second distance or more, the larger area than the second pattern, arranging a plurality of the contact member of the third pattern corresponding to the one of any shape, The contact material is arranged in a fourth pattern corresponding to one arbitrary shape having an area smaller than that of the third pattern between the contact materials of the third pattern adjacent to each other .

According to such a coating method, the contact of the first pattern corresponding to one arbitrary shape between the center portion of the hole for inserting the stopper for installing the cooling body on the base substrate and the first distance. At least one material is disposed, and at least a second pattern contact material corresponding to one arbitrary shape having a larger area than the first pattern between the first distance and the second distance. A plurality of contact materials of a third pattern corresponding to one arbitrary shape having a larger area than the second pattern and a plurality of third contact materials are disposed adjacent to each other at a second distance or more. The contact material is disposed between the contact materials in a fourth pattern corresponding to one arbitrary shape having an area smaller than that of the third pattern .

  In order to achieve the above object, a mask for pattern formation is provided in which a contact material interposed between a base substrate of a semiconductor device and a cooling body is applied to either main surface of the base substrate or the cooling body. The

In the pattern forming mask, at least one first opening is disposed between the end of the mask member and the first distance , and the first and second distances are disposed between the first distance and the second distance. the first larger area than the opening, at least one disposed a second opening, the second in the distance or more, the larger area than the second opening, a third plurality of apertures of the A fourth opening having a smaller area than the third opening is disposed between the adjacent third openings .

According to such a pattern forming mask, between the end of the mask member of the first distance, the first opening is at least one disposed, from the first distance to the second distance In the meantime, at least one second opening having a larger area than the first opening is disposed, and a third opening having a larger area than the second opening is provided at the second distance or more. A plurality of fourth openings having a smaller area than the third openings are disposed between the adjacent third openings .

  In the coating method, the thermal conductivity from the semiconductor device to the cooling body is improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the technical scope of the present invention is not limited to these embodiments. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

First, an outline of the present embodiment will be described.
FIG. 1 is a diagram for explaining an outline of the coating method of the present embodiment, in which (A) is a schematic cross-sectional view of a cooling body and a base substrate, and (B) is a schematic plan view of the base substrate.

  As shown in FIG. 1A, in order to bring the base substrate 11 and the cooling body 13 into contact with each other, three types of shapes of contact material patterns 12a, 12b, and 12c are applied to the base substrate 11. Note that the contact material of the patterns 12a, 12b, and 12c is composed of the above-described compound. The contact material patterns 12 a, 12 b, and 12 c may be applied to the cooling body 13. Further, the base substrate 11 and the cooling body 13 are respectively formed with stop holes 11a and 13a into which stoppers (not shown) for contacting and fixing each other are fastened. For example, screws and screw holes or bolts and nuts correspond to the stoppers and the stopper holes 11a and 13a. In a state where the patterns 12a, 12b, and 12c are applied to the base substrate 11, the cooling body 13 and the base substrate 11 are brought into contact with each other and fixed with a stopper.

  Here, the base substrate 11 is provided on the heat dissipation surface of the semiconductor device 110. A semiconductor element is disposed on the opposite side of the joint surface of the base substrate 11 with the cooling body 13, but the illustration is omitted here.

Next, the patterns 12a, 12b, and 12c applied to the base substrate 11 will be described.
As shown in FIG. 1B, the base substrate 11 is coated with three types of patterns 12a, 12b, and 12c.

  Here, the pattern refers to the shape of one contact material when the contact material is applied. When a contact material having the same pattern (same shape) is applied to a plurality of locations, the pattern is applied in an array described later. .

  The pattern 12 a is applied to a region up to a distance ra from the center of the stop hole 11 a formed in the base substrate 11. The contact material of the pattern 12a has a substantially uniform application area. Further, the pattern 12a is not applied in the vicinity of the stop hole 11a.

  The pattern 12b is applied to a region from the distance ra to the distance rb from the center of the stop hole 11a. The application area of each contact material of the pattern 12b is substantially equal and wider than that of the pattern 12a.

The pattern 12c is applied to a region outside the distance rb. The application area of each pattern 12c is substantially equal and wider than that of the pattern 12b.
In this example, the patterns 12a, 12b, and 12c each have a circular shape.

  In this way, the base substrate 11 coated with the patterns 12a, 12b, and 12c is brought into contact with the cooling body 13, and the base plate 11 and the cooling body 13 are fixed by tightening a stopper in the stopper holes 11a and 13a. . Then, the base substrate 11 and the cooling body 13 receive stress due to tightening of the stoppers and crush the patterns 12a, 12b, and 12c. The patterns 12a, 12b, and 12c are spread between the base substrate 11 and the cooling body 13, and evenly fill the contact surface between the base substrate 11 and the cooling body 13 so that the base substrate 11 and the cooling body 13 are in close contact with each other. .

  Then, the application position of the pattern of the contact material with respect to a cooling body or a base substrate is demonstrated below. Below, the case where a pattern is apply | coated to a base substrate is demonstrated. The same applies when the contact material is applied to the cooling body.

First, the case where one kind of substantially uniform pattern is applied to the cooling body in a grid pattern will be described.
2 is a schematic cross-sectional view (comparative example) showing contact between a base substrate coated with a substantially uniform pattern in a grid pattern and a cooling body, and FIG. 3 shows a base substrate coated with a substantially uniform pattern in a grid pattern. It is a plane schematic diagram (comparative example) shown.

  As shown in FIG. 2, a contact material pattern 502 is applied to the base substrate 501 in order to bring the base substrate 501 into contact with the cooling body 503. Note that the contact material of the pattern 502 is composed of the compound described above. A predetermined mask member and a squeegee or a roller are used for applying the compound pattern 502. The base substrate 501 and the cooling body 503 are formed with stop holes 501a and 503a for fastening fasteners (not shown) for contacting and fixing each other. With the pattern 502 applied to the base substrate 501, the cooling body 503 and the base substrate 501 are brought into contact with each other and fixed with a stopper.

  The patterns 502 applied to the base substrate 501 are arranged in a lattice pattern as shown in FIG. The shape of the pattern 502 is, for example, a substantially square of about 5 mm × about 5 mm.

  The cooling body 503 is brought into contact with the base substrate 501 coated with such a pattern 502, and a stopper is tightened and fixed in the stopper holes 501a and 503a. A description will be given of the pattern 502 that spreads in response to the stress caused by fastening of the stopper at this time.

FIG. 4 is a schematic plan view (comparative example) for explaining the spread of the contact material when the cooling body is brought into contact with the base substrate and fixed with a stopper.
As shown in FIG. 4, the contact material pattern 502 applied to the stressed base substrate 501 covers the base substrate 501 in the vicinity of the stop hole 501 a by spreading the patterns 502 together. . On the other hand, in the central portion of the base substrate 501, the stressed pattern 502 spreads at the applied position, but does not spread until adjacent patterns 502 are combined.

Furthermore, the result of analyzing the stress distribution on the base substrate 501 by tightening the stopper at this time will be described.
FIG. 5 is an analysis diagram schematically showing the result of analyzing the stress distribution on the base substrate by tightening the stopper.

  As shown in FIG. 4, when the cooling body 503 is brought into contact with the base substrate 501 and fixed with a stopper, the contact surfaces of the base substrate 501 and the cooling body 503 are subjected to stress by tightening the stopper. An analysis diagram 510 in FIG. 5 shows an analysis result by a finite element method (FEM) of the stress distribution generated in the base substrate 501 at this time.

In the analysis diagram 510, a line connecting the positions where stress magnitudes ([N / m ² ]) are equal to the base substrate 501 is depicted for each stress received. The magnitude of each received stress is shown at the edge of analysis diagram 510. The positions of the stop holes 501a are shown at the four corners of the analysis diagram 510. As shown in FIG. 5, the x direction and the y direction are defined as the horizontal direction and the vertical direction of the paper, respectively.

  According to the analysis diagram 510, as shown in FIG. 5, the stress in the vicinity of the stopper hole 501a into which the stopper is tightened is the largest. The stress attenuates toward the center of the base substrate 501 with the stop hole 501a as the center, and the stress is constant.

  As described above, it is considered that the difference in the stress distribution with respect to the position of the base substrate 501 caused a difference in how the pattern 502 of the base substrate 501 shown in FIG. 4 spreads. That is, since the stress is large in the vicinity of the stop hole 501 a of the base substrate 501 to which stress is applied by tightening the stopper, the pattern 502 spreads more conspicuously than the center portion of the base substrate 501. On the other hand, since the stress decreases from the stop hole 501a toward the central portion of the base substrate 501, the pattern 502 in the central portion of the base substrate 501 is small.

Further, another reason why the pattern 502 at the center of the base substrate 501 is small will be described.
FIG. 6 is an enlarged schematic cross-sectional view for explaining the contact material applied to the contact surface between the base substrate and the cooling body.

  As shown in FIG. 6, the contact substrate pattern 502 is applied to the base substrate 501 in order to bring the base substrate 501 and the cooling body 503 into contact as described above. In FIG. 6, the particles 502a constituting the pattern 502 are drawn. The base substrate 501 and the cooling body 503 are formed with stop holes 501a and 503a, respectively, into which stoppers 503b for fixing the base substrate 501 and the cooling body 503 are brought into contact with each other. In a state where the pattern 502 is applied, the cooling body 503 and the base substrate 501 are brought into contact with each other, and the stopper 503b is tightened and fixed.

  As described above, the contact material pattern 502 applied to the base substrate 501 is obtained by mixing ceramic particles 502a such as alumina with an oil component. When the base substrate 501 and the cooling body 503 are brought into contact with each other, it is desirable that the contact material having low thermal conductivity is applied to the base substrate 501 as thinly as possible. Since the contact material contains the particles 502a, the contact material can be thinned to a thickness at least about the diameter of the particles 502a. However, when the contact material containing the particles 502a is applied in the vicinity of the stopper 503b, the contact material may cling to the stopper 503b. The contact material particles 502a clinging to the stopper 503b may be stacked in the vertical direction as shown in FIG. When the particles 502a are stacked in the vertical direction, even if the base substrate 501 and the cooling body 503 are brought into contact with each other and the stopper 503b is tightened, it is difficult to make the height of the stacked particles 502a or less. Therefore, for example, the particles 502a in the central portion of the base substrate 501 other than the region near the stop hole 501a are difficult to spread.

For the above reason, as shown in FIG. 4, it is considered that there is a difference between the vicinity of the stop hole 501 a and the center portion of the base substrate 501 in how the pattern 502 spreads.
A case where a contact material pattern is applied will be described in consideration of how the contact material spreads depending on the position of the contact surface of the base substrate 501.

FIG. 7 is a schematic plan view showing a base substrate on which a substantially uniform pattern is applied in a grid pattern except for the vicinity of the stopper holes.
FIG. 7 shows a case where a contact material pattern is not applied around the stop hole (comparative example) as compared to the case shown in FIG. 3. In addition, although description about a cooling body is abbreviate | omitted, about the structure of a cooling body, the stop hole is formed as above-mentioned.

  In order to bring the base substrate 511 into contact with the cooling body (not shown), a contact material pattern 512 is applied to the base substrate 511. The contact material is composed of the compound described above. A predetermined mask member and squeegee or roller are used for applying the compound pattern 512. Further, the base substrate 511 and the cooling body are formed with a stopper hole 511a into which a stopper (not shown) for fixing the base substrate 511 and the cooling body is fastened. In a state where the pattern 512 is applied, the base substrate 511 and the cooling body are brought into contact with each other, and are fastened and fixed with a stopper.

  The patterns 512 applied to the base substrate 511 are arranged in a lattice pattern as shown in FIG. The shape of the pattern 512 is, for example, a substantially square of about 5 mm × about 5 mm. However, unlike the base substrate 501 shown in FIG. 3, the contact material pattern 512 is not applied around the stopper hole 511a.

  In this way, the cooling body is brought into contact with the base substrate 511 to which the pattern 512 is applied, and the stopper is tightened and fixed in the stopper hole 511a. The pattern 512 that spreads under the stress at this time will be described below.

FIG. 8 is a schematic plan view (comparative example) for explaining the spread of the contact material when the cooling body is brought into contact with the base substrate and fixed with a stopper.
As shown in FIG. 8, the stressed pattern 512 spreads out in the central portion of the base substrate 511 until the adjacent patterns 512 are joined to each other. In the case of the base substrate 501, as shown in FIG. 4, the pattern 502 at the center of the base substrate 501 spreads only at the position where it was applied, and was not coupled to adjacent patterns 502.

The reason why the spread of the pattern 512 at the center of the base substrate 511 is improved will be described with reference to the drawings.
FIG. 9 is a schematic enlarged cross-sectional view for explaining the contact material applied to the contact surface between the base substrate and the cooling body.

  As shown in FIG. 9, the contact substrate pattern 512 is applied to the base substrate 511 in order to bring the base substrate 511 into contact with the cooling body 513 as described above. In FIG. 9, the particles 512a constituting the pattern 512 are drawn. Further, the base substrate 511 and the cooling body 513 are formed with stop holes 511a and 513a into which stoppers 513b for contacting and fixing each other are fastened. In a state where the pattern 512 is applied, the base substrate 511 and the cooling body 513 are brought into contact with each other, and are fastened and fixed by a stopper 513b.

  The contact material pattern 512 applied to the base substrate 511 contains the particles 512a as described above. The contact material pattern 512 is not applied to the vicinity of the stop hole 511 a of the base substrate 511. For this reason, the particles 512a that have received stress due to the fastening of the stopper 513b of the base substrate 511 and the cooling body 513 can also move to the vicinity of the stopper hole 511a. Therefore, the particles 512a constituting the contact material can spread in all directions.

  Therefore, in the case where the pattern 512 is not applied in the vicinity of the stop hole 511a, the particles 512a can be moved by the stress applied to the central portion of the base substrate 511 due to the fastening of the stopper 513b, compared to the case of the base substrate 501. And contact material spreads. For this reason, it is considered that the adjacent contact material patterns 512 applied to the central portion of the base substrate 511 are bonded to each other.

  From the above description using FIGS. 2 to 9, the stress applied to the base substrate (or the cooling body) by the stopper is attenuated as it proceeds from the center of the stopper hole to the center of the base substrate. And it was shown that the pattern of the contact material applied in the vicinity of the stop hole may hinder the spread of the pattern of the contact material.

  In view of these results, the density of the contact material decreases as it approaches the vicinity of the stop hole of the base substrate, and the density of the contact material increases from the stop hole toward the center of the base substrate to apply the pattern. In this case, the contact material can be uniformly and thinly filled into the base substrate.

  Therefore, as shown in FIG. 1, the pattern 12a is applied to the base substrate 11 in a region from the center of the stop hole 11a formed in the base substrate 11 to the distance ra, and the pattern 12a is formed in the vicinity of the stop hole 11a. Do not apply. A pattern 12b having a larger area than the pattern 12a is applied to a region from the distance ra to a distance rb from the center of the stop hole 11a. Then, the pattern 12c having a larger area than the pattern 12b is applied to the region outside the distance rb. By applying the contact material patterns 12a, 12b, and 12c in this manner, when the cooling body 13 is brought into contact with the base substrate 11 and tightened with a stopper, the contact material is uniformly and thinly filled into the contact surface. it can. Accordingly, the adhesion between the base substrate 11 and the cooling body 13 is improved, and an increase in thermal resistance from the base substrate 11 to the cooling body 13 can be suppressed, and the base substrate 11 can be cooled.

As specific examples of the area of the pattern 12a, 12b, 12c, the pattern 12a is approximately 3～51Mm ^2, the pattern 12b about 113～201Mm ^2, the pattern 12c about 201 mm ² or more, and there is a case of.

Next, a pattern coating method when the stop holes are adjacent to each other will be described.
FIG. 10 is a schematic plan view for explaining a coating method in the case where a stop hole is formed adjacently according to the present embodiment. Hereinafter, a case where a pattern is applied to the base substrate will be described. A pattern may be applied to the cooling body.

  As shown in FIG. 10, stop holes 41 a 1 and 41 a 2 are formed in the base substrate 41. Three types of patterns 42a1, 42b1, and 42c1 are applied around the stop hole 41a1.

  The pattern 42a1 is applied to a region up to a distance ra1 from the center of the stop hole 41a1 formed in the base substrate 41. The pattern 42a1 is not applied in the vicinity of the stop hole 41a1.

  The pattern 42b1 is applied to a region from the distance ra1 to the distance rb1 from the center of the stop hole 41a1. The application area of each pattern 42b1 is wider than that of the pattern 42a1.

The pattern 42c1 is applied to a region outside the distance rb1. The application area of each pattern 42c1 is made wider than that of the pattern 42b1.
On the other hand, three types of patterns 42a2, 42b2, and 42c2 are applied in the same manner as the patterns 42a1, 42b1, and 42c1, respectively, around the stop hole 41a2. The distances ra2 and rb2 are the same as the distances ra1 and rb1, respectively.

  In this base substrate 41, when each pattern is applied, an overlapping region is generated between a predetermined distance from the stop holes 41a1 and 41a2. In that case, the applied pattern is applied to an area within a short distance. For example, an overlapping region (region X1 in the drawing) is generated between the distance ra1 and the distance rb2. In this case, as shown in FIG. 10, a pattern 42a1 that has been applied up to a short distance ra1 is applied to the region X1. Further, in the region overlapping between the distance rb1 and the distance ra2 (region X2 in the figure), the pattern 42a2 is applied to the region X2.

  In this way, when the stop holes are adjacent to each other, if there is a part that overlaps with other areas in the area from each stop hole, the pattern applied to the area within a short distance in that part. Apply.

1 and 10 will be described with reference to an example of how to determine a distance for determining a region for forming a pattern.
As shown in FIG. 5, as described above, the stress attenuates from the center of the stop hole 501 a toward the center of the base substrate 501. In FIG. 5, the stress at the end of the base substrate 501 was about 10 N / m ² . From there, the stress gradually attenuates toward the center of the base substrate 501, and becomes about 5-4 N / m ² . Further, when proceeding to the center, the stress is attenuated more than before, and becomes about 1 N / m ² . Thus taking into account the attenuation of the stress, the stress is about 5~4N / m ² near distances ra, ra1, ra2, further stress is set to about 1N / m ² distance rb, rb1, rb2 and Also good. By setting the distance for each stress as described above, a contact material having a low density can be reliably applied in the vicinity of the stop hole where the stress is large. In addition, a contact material having a higher density than that of the vicinity of the stop hole can be reliably applied to the central portion of the base substrate having a stress smaller than that of the vicinity of the stop hole.

Next, a method for applying an elliptical pattern will be described.
In the above description, the case where the pattern has a circular shape has been described. Here, the case where the shape of the pattern is an ellipse will be described with reference to the drawings.

FIG. 11 is a schematic plan view of an essential part of a base substrate to which an elliptical pattern is applied.
Similar to the above, three types of patterns 52a1, 52b1, and 52c1 are applied to the base substrate 51. Similarly to the patterns 12a, 12b, and 12c, the patterns 52a1, 52b1, and 52c1 are applied to the region from the center to the distance ra3, the region from the distance ra3 to the distance rb3 from the center, and the outside of the distance rb3, respectively. The application area is different. However, the shapes of the patterns 52a1, 52b1, and 52c1 are ellipses. Note that the distances ra3 and rb3 in this case are set for each stress as described above. In addition, as described with reference to FIG. 5, the stress applied to the base substrate 51 due to tightening of the stopper is attenuated as the center proceeds from the stopper. Therefore, as shown in FIG. 11, the patterns 52a1, 52b1, and 52c1 are spread by receiving the stress due to tightening of the fasteners efficiently by applying the direction of the short side of the ellipse toward the center. Can do. Alternatively, as shown in the analysis diagram 510 of FIG. 5, it can be seen that the stress on the base substrate 51 becomes constant when a predetermined distance is exceeded. For this reason, for example, the shapes of the patterns 52a1 and 52b1 of the base substrate 51 may remain elliptical, and the shape of the pattern 52c1 may be circular.

Next, an embodiment based on the above outline will be described.
First, the first embodiment will be described.
1st Embodiment demonstrates the case where a radiation fin is made to contact with the power module which has four screw holes in four corners. In the first embodiment, the compound is applied to the power module side with the pattern of the present embodiment. The power module includes a base substrate (heat dissipation base) on the heat dissipation surface. The metal mask is a pattern forming mask used when applying a compound to the base substrate. Therefore, the metal mask is formed with a size that fits the contact surface of the base substrate of the power module with the radiating fin. In addition, comb-shaped grooves may be formed in the radiating fins, and a cooling coolant may be brought into contact with the gaps of the grooves or a water channel may be formed.

  FIG. 12 is a schematic plan view of a metal mask for pattern formation according to the first embodiment. As shown in FIG. 12, the x direction and the y direction are defined as a horizontal direction and a vertical direction on the paper surface, respectively. Further, the base substrate 70 of the power module is indicated by a dotted line, and a state in which the metal mask 60 for pattern formation is placed on the base substrate 70 is shown.

  As shown in FIG. 12, the metal mask 60 for pattern formation has a substantially rectangular shape and includes screw regions 61 at four corners that are superposed on screw holes of the base substrate 70 when installed on the base substrate 70. ing. The length R1 in the x direction of the metal mask 60 is about 120 mm, the length R2 in the x direction between the centers of the screw regions 61 is about 110 mm, the length R3 in the y direction is about 60 mm, and the length between the centers of the screw regions 61. The length R4 in the y direction is about 50 mm, the diameter of the screw region 61 is about 5.5 mm, the distance R5 of the screw region 61 from the outer edge of the metal mask 60 is about 2 mm, and the thickness of the metal mask 60 is about 100 μm.

The metal mask 60 has a plurality of openings 65 (radius: about 7 mm, area: about 154 mm ² ) at the center, and a plurality of openings 64 (radius: about 5 mm, area: about 79 mm ² ) so as to surround the opening 65. A plurality of openings 62 (radius: about 3 mm, area: about 28 mm ² ) are formed outside the openings 64. Therefore, the areas of the openings 62, 64, 65 increase from the screw region 61 toward the center. The length R7 in the x direction between the outermost openings 65 is about 47 mm, and the length R10 in the y direction is about 39 mm. Between the openings 65, the openings 66 (radius: about 3 mm, area) : About 28 mm ² ), and an opening 63 (radius: about 2 mm, area: about 13 mm ² ) is formed between the openings 64. The opening 64 is formed so as to surround the opening 65. R11 is about 8 mm, and R8 is about 15 mm. The opening 62 is formed between the metal mask 60 and a length R9 (about 19 mm) in the x direction. The distance R6 from the end of the screw region 61 to the end of the opening 62 closest to the screw region 61 is about 3 mm. The aperture ratio of the metal mask 60 is about 40 to 55%.

The finished compound thickness when the base substrate 70 of the power module is attached to the heat radiating fins can be adjusted by selecting the thickness of the metal mask and the aperture ratio.
Using the metal mask 60 having such a configuration as a mask for pattern formation, a compound pattern is applied to the contact surface of the base substrate 70 of the power module with the radiation fins.

FIG. 13 is a schematic plan view of the contact surface of the base substrate of the power module coated with the patterned compound according to the first embodiment.
As shown in FIG. 13, screw holes 71 are formed at four corners of the contact surface of the base substrate 70 of the power module. Further, the undulations of the contact surfaces of the base substrate 70 and the radiation fins of the power module are several μm or less.

  The screw hole 71 and the screw region 61 are aligned with the base substrate 70 of such a power module, and the compound is applied using the metal mask 60 installed on the contact surface of the base substrate 70 of the power module as a mask. Is done. The pattern of the compound applied to the contact surface of the base substrate 70 of the power module is also applied to the patterns 75, 74, 72 corresponding to the openings 65, 64, 62 formed in the metal mask 60. . Similarly, a pattern 76 is applied between the patterns 75, and a pattern 73 is applied between the patterns 74. The area of each pattern applied to the base substrate 70 of the power module corresponds to each opening formed in the metal mask 60.

  The power module is brought into contact with the base substrate 70 of the power module to which the compound thus patterned is applied, and the screw is fastened to the screw hole 71 to be fixed.

FIG. 14 is a schematic plan view of a compound filled in the contact surface of the radiating fin according to the first embodiment.
The radiating fin was brought into contact with the base substrate 70 of the power module to which the patterned compound was applied, and the screw was fastened to the screw hole 71 to fix the radiating fin to the base substrate 70 of the power module. The screw tightening pressure at this time is about 1 to 5 N / m ² .

  The patterned compound subjected to the stress generated in the base substrate 70 of the power module by tightening the screw spreads at the contact surface. Then, as shown in FIG. 14, the compound 77a is evenly filled in the contact surface of the base substrate 70 of the power module with the heat dissipating fins. The average thickness of the compound 77a filled in the contact surface of the base substrate 70 of the power module is about 55 μm.

  If there is a gap between the patterns, the gap may not be filled when the patterned compound is spread. In the first embodiment, for example, the openings are formed in the metal mask 60 so that the pattern 76 is applied between the patterns 75 and the pattern 73 is applied between the patterns 74. When the pattern is applied finely in this way, it is possible to evenly fill the contact surface with the compound by spreading the patterned compound.

Moreover, in the above, the case where the pattern apply | coated between patterns is circular is shown. You may apply | coat the compound patterned as follows.
FIG. 15 is a schematic diagram showing a pattern example of a compound applied to the contact surface according to the first embodiment.

  As shown in FIGS. 12 and 13, the compound pattern 75 is applied to the grid-like intersections on the contact surface of the base substrate 70 of the power module. A circular pattern 76 was applied to the area surrounded by the four patterns 75, and the patterned compound could be finely applied.

  On the other hand, instead of the pattern 76, as shown in FIG. 15A, a substantially rectangular pattern 76a may be applied to a region surrounded by the pattern 75. The area surrounded by the pattern 75 may become a substantially rectangular gap when the pattern 75 is expanded under stress. Therefore, by applying a substantially rectangular pattern 76a in advance, the contact surface can be evenly filled with the compound spread by the stress.

  As shown in FIG. 15B, when the pattern 75a is applied to each vertex of the honeycomb lattice, the substantially triangular pattern 76a1 is applied to the region surrounded by the pattern 75a. That's fine.

  In FIGS. 15A and 15B, the patterns 76a and 76a1 have rounded corners. This is because if a metal mask having an opening having a small area is used as a mask for compound transfer, the compound accumulates at the corners of the opening, and transfer may not be successful. Therefore, the transfer to the contact surface can be easily performed by rounding the corners.

On the other hand, a comparative example of the compound 77a filled in the contact surface of the base substrate 70 shown in FIG. 14 will be described below.
FIG. 16 is a schematic plan view of a contact surface of a base substrate of a power module to which a patterned compound is applied.

  As shown in FIG. 16, the base substrate 80 of the power module has screw holes 81 formed at four corners, and a compound 82 patterned into a substantially square pattern in a lattice shape using a metal mask as in FIG. Is applied to the contact surface.

  The power module is brought into contact with the base substrate 80 of the power module coated with the compound 82 thus patterned, and the screw is fastened to the screw hole 81 to be fixed.

FIG. 17 is a schematic plan view of the compound filled in the contact surface of the base substrate of the power module.
The radiating fin was brought into contact with the base substrate 80 of the power module to which the patterned compound 82 was applied, and the screw was fastened to the screw hole 81 to fix the radiating fin to the base substrate 80. The screw tightening pressure at this time is about 1 to 5 N / m ² .

  The patterned compound 82 subjected to the stress generated in the base substrate 80 of the power module by tightening the screws spreads at the contact surface. However, as shown in FIG. 17, the contact surface of the base substrate 80 of the power module is filled with the expanded compound 87, but gaps 88a and 88b are generated.

  As described above, in the first embodiment, by applying a patterned compound, the compound can be thinly and evenly filled on the contact surface of the radiating fin. Therefore, the adhesiveness between the radiation fin and the base substrate of the power module is improved, the thermal conductivity from the power module to the radiation fin is improved, and the power module can be cooled.

Next, a second embodiment will be described.
2nd Embodiment demonstrates the case where a radiation fin is made to contact with the power module in which a pair of screw hole was formed facing. In the second embodiment, a patterned compound is formed on the base substrate of the power module. Similar to the first embodiment, a metal mask formed so as to conform to the contact surface of the base substrate of the power module is used for applying the compound to the base substrate of the power module.

  FIG. 18 is a schematic plan view of a metal mask for pattern formation according to the second embodiment. As shown in FIG. 18, the x direction and the y direction are defined as the horizontal direction and the vertical direction, respectively. Further, the base substrate 70a of the power module is indicated by a dotted line, and a state in which the metal mask 90 for pattern formation is placed on the base substrate 70a is shown.

  As shown in FIG. 18, the metal mask 90 for pattern formation has a substantially rectangular shape, and when installed on the base substrate 70a of the power module, a screw that is overlapped with a screw hole of the base substrate 70a of the power module. Regions 91 are provided facing each other. The length S1 in the x direction of the metal mask 90 is about 104 mm, the length S2 in the y direction is about 38 mm, the diameter of the screw region 91 is about 6 mm, and the thickness of the metal mask 90 is about 100 μm.

The metal mask 90 has a plurality of openings 95 (radius: about 7 mm, area: about 154 mm ² ) in the center, and a plurality of openings 93 (radius: about 5 mm, area: so as to sandwich the plurality of openings 95 from both sides. about 79 mm ^2), a plurality of openings 92 so as to sandwich the further sides of the opening 93 (radius about 3 mm, area: about 28mm ²⁾ is formed. Therefore, the areas of the openings 92, 93, and 95 increase as the distance from the screw region 91 toward the center increases. The outermost opening 95 has a length S3 of about 39 mm, and openings 92 and 94 (radius: about 2 mm, area: about 13 mm ² ) are formed between the openings 95. The length 93 of the opening 93 in the x direction is about 9 mm, and the length S5 of the opening 92 in the x direction is about 27 mm. The distance S3 from the end of the screw region 91 to the end of the opening 92 closest to the screw region 91 is about 3 mm. The aperture ratio of the metal mask 90 is about 40 to 55%.

  Using the metal mask 90 having such a configuration as a mask, a compound is applied to the contact surface of the power module base substrate 70a with the heat dissipating fins as in the first embodiment. Then, a patterned compound having the same shape as the opening of the metal mask 90 is applied to the contact surface of the base substrate 70a of the power module with the radiation fin. Then, when the radiation fins are brought into contact with the base substrate 70a of the power module to which the patterned compound is applied, the compound is spread to fill the contact surface evenly. In the second embodiment, by applying a patterned compound, it is possible to fill the contact surface of the base substrate 70a of the power module almost uniformly and thinly. Therefore, it is possible to cool the power module by improving the adhesion between the base substrate 70a of the power module and the heat dissipating fins and suppressing the decrease in thermal conductivity from the base substrate 70a of the power module to the heat dissipating fins.

  In the first and second embodiments, the case of four and two screw holes has been described as an example. In addition, even when the number of screw holes is 6, 8 or the like, the patterned compound can be applied in the same manner.

Next, a third embodiment will be described.
In the outline of the embodiment and the first and second embodiments, a circle or an ellipse has been described as the contact material (compound) pattern. In the third embodiment, other pattern shapes will be described.

FIG. 19 is a schematic plan view showing the shape of a pattern according to the third embodiment.
As a shape of the pattern of the compound applied to the contact surface of the radiating fin with the power module, for example, a substantially hexagonal shape can be mentioned. As shown in FIG. 19A, the area of the contact surface of the base substrate of the power module increases from the screw hole (not shown) to the substantially hexagonal pattern 112, 113, 114 toward the center. Can be applied in a large size. If it is a substantially hexagonal pattern shape, the patterned compound can be finely applied to the contact surface of the radiation fin. Therefore, when the heat dissipating fins are fixed in contact with the base substrate of the power module, the contact surface can be filled with the compound evenly.

  On the other hand, as shown in FIG. 19B, the substantially hexagonal patterns 112a, 113a, and 114a can be applied in a similar manner as the area advances toward the center of the contact surface. However, the arrangement of the patterns 112a, 113a, and 114a is different from that in FIG. Even with such an arrangement, the patterned compound can be finely applied to the contact surface of the radiating fin. Various other arrangements are possible. Further, the patterns 112a, 113a, and 114a are shown when the corners are rounded as described with reference to FIG.

  As described above, the substantially hexagonal shape is an example of the pattern shape. In addition, a compound patterned into a substantially polygonal shape of approximately a triangular shape or more can be finely applied to the contact surface of the radiating fin in the same manner. The compound thus patterned can be applied in a lattice or honeycomb lattice. The same effect can be obtained with a compound that is patterned by combining substantially polygons.

  The above merely illustrates the principle of the present invention. In addition, many modifications and changes can be made by those skilled in the art, and the present invention is not limited to the precise configuration and application shown and described above, and all corresponding modifications and equivalents may be And the equivalents thereof are considered to be within the scope of the invention.

It is a figure for demonstrating the outline | summary of the coating method of this Embodiment, (A) is a cross-sectional schematic diagram of a cooling body and a base substrate, (B) is a plane schematic diagram of a base substrate. It is a cross-sectional schematic diagram (comparative example) which shows the contact with the base substrate which apply | coated the substantially equal pattern to the grid | lattice form, and a cooling body. It is a plane schematic diagram (comparative example) which shows the base substrate which apply | coated the substantially equal pattern to the grid | lattice form. It is a plane schematic diagram (comparative example) for demonstrating the breadth of a contact material when a cooling body is made to contact a base substrate and it fixes with a stopper. It is an analysis figure which shows typically the result of having analyzed the stress distribution with respect to the base substrate by fastening of a fastener. It is a cross-sectional enlarged schematic diagram (the 1) for demonstrating the contact material apply | coated to the contact surface between a base substrate and a cooling body. It is a plane schematic diagram which shows the base substrate which apply | coated the substantially uniform pattern in the grid | lattice form except the vicinity of the stop hole. It is a plane schematic diagram (comparative example) for demonstrating the breadth of a contact material when a cooling body is made to contact a base substrate and it fixes with a stopper. It is a cross-sectional enlarged schematic diagram (2) for demonstrating the contact material apply | coated to the contact surface between a base substrate and a cooling body. It is a plane schematic diagram for demonstrating the application | coating method in case the stop hole which adjoins this Embodiment is formed. It is a principal part plane schematic diagram of the base substrate in which the pattern of the ellipse was apply | coated. It is a plane schematic diagram of the metal mask for pattern formation which concerns on 1st Embodiment. It is a plane schematic diagram of the contact surface of the base substrate of the power module coated with the patterned compound according to the first embodiment. It is a plane schematic diagram of the compound with which the contact surface of the radiation fin which concerns on 1st Embodiment was filled. It is a schematic diagram which shows the example of a pattern of the compound apply | coated to the contact surface which concerns on 1st Embodiment. It is a plane schematic diagram of the contact surface of the base substrate of the power module to which the patterned compound is applied. It is a plane schematic diagram of the compound with which the contact surface of the base substrate of the power module was filled. It is a plane schematic diagram of the metal mask for pattern formation which concerns on 2nd Embodiment. It is a plane schematic diagram which shows the shape of the pattern which concerns on 3rd Embodiment.

Explanation of symbols

11 Base substrate 11a, 13a Stop hole 12a, 12b, 12c Pattern 13 Cooling body ra, rb Distance

Claims (10)

An application method for applying a contact material interposed between a base substrate of a semiconductor device and a cooling body to either the main surface of the base substrate or the cooling body,
At least one contact material having a first pattern corresponding to one arbitrary shape is formed between a center portion of a hole for inserting a stopper for installing the cooling body on the base substrate and a first distance. Arranged,
Between the first distance and the second distance, at least one contact material of the second pattern corresponding to one arbitrary shape having a larger area than the first pattern is disposed,
Wherein in the second distance or more, the larger area than the second pattern, arranging a plurality of the contact member of the third pattern corresponding to the one of any shape,
Between the contact materials of the third pattern adjacent to each other, the contact material is disposed in a fourth pattern corresponding to one arbitrary shape having a smaller area than the third pattern;
The coating method characterized by the above-mentioned.   Between the contact material of the second pattern and the third pattern, or between the contact materials of the second pattern adjacent to each other by arranging a plurality of the contact materials of the second pattern. The coating method according to claim 1, wherein the contact material is arranged in a fifth pattern corresponding to one arbitrary shape having an area smaller than that of the second pattern.   The coating method according to claim 1, wherein the first pattern, the second pattern, and the third pattern are circular.   When the contact materials of the second pattern and the third pattern are respectively arranged in a grid pattern,
  Between the contact materials of the third pattern adjacent to each other by arranging a plurality of the contact materials of the third pattern, the fourth pattern of the fourth pattern having a smaller area than the third pattern and having a quadrangular shape. Arrange the contact material,
  Between the contact material of the second pattern and the third pattern, or between the contact material of the second pattern adjacent to the plurality of contact materials of the second pattern, The coating method according to claim 3, wherein the contact material having a fifth pattern having a smaller area than the second pattern and having a quadrangular shape is disposed.   When the contact materials of the second pattern and the third pattern are arranged in a honeycomb lattice shape,
  Between the contact materials of the third pattern adjacent to each other by arranging a plurality of the contact materials of the third pattern, the area of the fourth pattern is smaller than the third pattern and the shape of the fourth pattern is triangular. Arrange the contact material,
  Between the contact material of the second pattern and the third pattern, or between the contact material of the second pattern adjacent to the plurality of contact materials of the second pattern, The coating method according to claim 3, wherein the contact material having a fifth pattern having a smaller area than the second pattern and a triangular shape is disposed.   The coating method according to claim 1, wherein the first pattern, the second pattern, and the third pattern are elliptical or polygonal.   In the region where the hole and another hole are adjacent to each other, the first predetermined distance from the center of the hole and the second predetermined distance from the center of the other hole overlap. The coating method according to claim 1, wherein the contact material having a pattern disposed in a region up to a shorter distance is disposed.   2. The coating according to claim 1, wherein the first and second distances are distances in which stresses transmitted from a central portion of the hole to the contact surface of the contact material by insertion of the stopper are equal. Method.   A mask for pattern formation in which a contact material interposed between a base substrate of a semiconductor device and a cooling body is applied to a main surface of either the base substrate or the cooling body,
  At least one first opening is disposed between the end of the mask member and the first distance,
  At least one second opening having a larger area than the first opening is disposed between the first distance and the second distance,
  Above the second distance, a plurality of third openings having a larger area than the second openings are disposed,
  A pattern forming mask, wherein a fourth opening having an area smaller than that of the third opening is disposed between the adjacent third openings.   It is installed on the main surface of either the base substrate or the cooling body, and the end of the mask member is aligned with a hole for inserting a stopper for installing the cooling body on the base substrate. Item 10. The pattern forming mask according to Item 9.

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