JP2008066374A - Heat radiating substrate, method for manufacturing the same, and power module using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat radiating substrate which includes a heat conductive sheet provided with thin material pieces assuring higher heat conductivity within the resin material where the thin material pieces are arranged without any displacement from a heat spreading range. <P>SOLUTION: The heat radiating substrate includes: a heat conductive sheet having insulated thin material pieces within a resin composition; a heat sink provided in contact with one surface of the heat conductive sheet; and a base plate provided in contact with the other surface of the heat conductive sheet. A recessed part for preventing displacement of the entire part, a part, or respective portions of the thin material pieces, is provided at least to one of the surface in contact with the heat conductive sheet of the heat sink and the surface in contact with the heat conductive sheet of the base plate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heat dissipation substrate that facilitates heat dissipation from a heating element such as a power semiconductor element, a method for manufacturing the heat dissipation substrate, and a power module that uses the heat dissipation substrate.

  In a power module having a power semiconductor element therein, the operation of the power semiconductor element may become unstable due to an increase in temperature due to the heat generated by the power semiconductor element through which a large current flows. Therefore, in order to prevent this, a structure that facilitates heat dissipation is employed to suppress the temperature rise of the power module.

For example, a ceramic plate excellent in insulation and thermal conductivity, such as Al ₂ O ₃ , AlN, BeO, etc., is bonded to the opposite surface of the lead frame on which the power semiconductor element is mounted to the surface on which the power semiconductor element is mounted. (See Patent Document 1).

  Ceramic plates with excellent thermal conductivity are used by adhering to heat spreaders or lead frames with adhesives, etc., but ceramic plates have a coefficient of thermal expansion with the heat spreader or lead frame due to heat generated from heating elements such as power semiconductor elements. There is a problem that the heat conduction from the heating element is hindered due to peeling at the interface with the adhesive under the stress due to the difference between the two.

  In addition to thermal conductivity, there is a composite ceramic sheet that has multiple thermal polyconducting ceramic polyhedrons in a polymer film to provide both insulation and flexibility. (See Patent Document 2).

JP 2001-156253 A (page 3) JP-A-9-314747 (pages 6 to 7)

  When a composite ceramic sheet is bonded to a heat spreader or lead frame, the resin composition between the polyhedrons of the ceramic improves adhesion to the heat spreader or lead frame. Since the treatment is performed, the positional deviation of the ceramic polyhedron in the composite ceramic sheet may occur. When the position of the ceramic polyhedron is shifted, there is a problem that desired heat dissipation cannot be obtained.

  This invention is made | formed in order to solve this subject, and it aims at obtaining the heat dissipation board | substrate which has the outstanding thermal conductivity, and a power module using the same.

  The heat dissipating substrate according to the present invention includes a heat conductive sheet having an insulating thin piece inside a resin composition, a heat sink provided in contact with one surface of the heat conductive sheet, and the other of the heat conductive sheets. And a base plate provided in contact with the surface of the heat sink, and has a recess for accommodating the thin piece on at least one of the surface contacting the heat conductive sheet of the heat sink and the surface contacting the heat conductive sheet of the base plate.

  In addition, the method for manufacturing a heat dissipation substrate according to the present invention includes a step of attaching an insulating thin body to an adhesive sheet, a step of dividing the thin body into a thin piece in a state of being attached to the adhesive sheet, and a recess Placing and adhering the first resin sheet to the base plate having adhesive, arranging the thin piece adhered to the adhesive sheet at a predetermined position inside the recess of the base plate, and adhering the adhesive sheet A step of peeling from the thin piece affixed to the sheet, a step of placing the second resin sheet and the heat sink on the thin piece, and a step of curing the first and second resin sheets at a high temperature while applying pressure. It is equipped with.

  Moreover, the power module according to the present invention is disposed on the heat dissipating substrate of the present invention, the power semiconductor element disposed on the heat sink on one surface of the heat dissipating substrate, and the base plate on the other surface of the heat dissipating substrate. The heat spreader is provided.

  The thin piece can be disposed at a desired position by preventing the thin piece from being displaced, and a heat dissipating substrate having excellent thermal conductivity can be provided.

Embodiment 1 FIG.
FIG. 1 is a perspective view from above showing a schematic configuration of a heat dissipating substrate according to Embodiment 1 of the present invention. 2 is a cross-sectional view showing a schematic configuration of the heat dissipating substrate 1 according to Embodiment 1 of the present invention, and is a cross-sectional view of the heat dissipating substrate 1 taken along the line ab in FIG.

As shown in FIG. 1 and FIG. 2, the heat dissipating substrate in the present embodiment includes a heat conductive sheet 2 including a thin piece 31 inside a resin composition 21, and the heat conductive sheet 2 is a base plate 4. And the heat sink 5. The base plate 4 is formed with a concave portion 41 for accommodating a plurality of thin body pieces 31, and the outer peripheral portion of the concave portion 41 is a convex portion 40. The convex portion 40 extends to all regions except the concave portion 41 on the surface of the base plate 4. A resin composition 21 is continuously provided on the upper and lower surfaces of the thin piece 31 in the heat conductive sheet 2 to form a resin layer 22. Note that the resin layer 22 is provided much thinner than the thin piece 31 so as not to impair the thermal conductivity of the thin piece 31, but is shown thick in FIG. 2 for easy understanding.
The base plate 4 and the heat sink 5 are made of a conductive metal material such as copper, and the heat sink 5 has an electric conduction function as an electrode as well as a heat radiation function.

  Next, the manufacturing method of the heat dissipating substrate according to the present embodiment will be described step by step with reference to FIG. First, as shown in FIG. 3A, the insulating thin body 30 is attached to the adhesive sheet 11. Next, as shown in FIG. 3B, the thin body 30 of FIG. Subsequently, the thin piece 31 affixed to the pressure-sensitive adhesive sheet 11 is opposed to the base plate 4 in which the resin sheet 25 is bonded to the concave portion 41 in advance, and the thin piece 31 is placed on the inner side of the concave portion 41 of the base plate 4. Place and glue at the position of. After peeling the adhesive sheet 11 from the thin piece 31, another resin sheet 26 and the heat sink 5 are disposed on the thin piece 31 as shown in FIG. The resin sheet 25, 26 is melted and cured by heating the structure shown in FIG. 3D while applying pressure between the base plate 4 and the heat sink 5 to obtain a heat dissipation substrate shown in FIG.

  The heat conductive sheet 2 of the heat dissipating substrate according to the present embodiment may be provided with a plurality of thin body pieces 31 as shown in FIGS. 1 and 2, but for example, it is not always necessary that the heat dissipating substrate has a small area. The thin piece 31 does not need to be plural, and the thin piece 31 may be single.

  Moreover, as the insulating thin piece 31 in the heat conductive sheet 2 of the heat dissipating substrate according to the present embodiment, a ceramic sheet having heat conductivity is used. The ceramic material is not particularly limited as long as it is a material having a high thermal conductivity of 10 W / mK or higher, but a material having a thermal conductivity of 30 W / mK or higher, such as alumina, boron nitride, aluminum nitride or the like. It is preferable to use it. Further, the thin piece 31 may be made of a plurality of materials such as a surface of aluminum nitride coated with alumina as an oxide film.

  It is preferable that the space | interval between the thin body pieces 31 in the heat conductive sheet 2 of the thermal radiation board | substrate concerning this Embodiment is 0.1 mm or more and 3 mm or less. When the thin piece 31 and the resin composition 21 are compared, the thin piece 31 has a higher thermal conductivity. Therefore, the higher the area ratio of the thin piece 31 when viewed from the top, the higher the thermal conductivity of the heat dissipation substrate. Get higher. Therefore, it is preferable that the distance between the thin pieces 31 is narrow because the thermal conductivity of the heat dissipation substrate is high. However, if the distance between the thin pieces 31 is too small, the resin composition 21 is interposed between the thin pieces 31. It becomes difficult to enter, and voids remain in the heat conductive sheet 2, so that the withstand voltage is reduced. For this reason, it is preferable that the space | interval of the thin body piece 31 is 0.1 mm or more. On the contrary, if the interval between the thin pieces 31 exceeds 3 mm, the heat resistance of the heat dissipating substrate increases.

  The thickness of the thin piece 31 of the heat conductive sheet 2 of the heat dissipation substrate according to the present embodiment is preferably about 0.1 mm to 2 mm. The thinner the thin piece 31 is, the smaller the thermal resistance of the heat dissipating substrate is. Therefore, the thickness of the thin piece 31 is more preferably about 0.1 mm to 0.8 mm. In addition, the size of the thin piece 31 in the surface direction is desirably 3 mm square or more and 30 mm square or less from the viewpoint of preventing cracking of the heat-radiating substrate and ensuring withstand voltage and thermal conductivity. In the case where there are a plurality of thin pieces 31, the smaller the size of the thin piece 31 in the surface direction is to reduce the stress, which is advantageous for preventing cracks. In the case of 3 mm square or less, the heat resistance of the heat-dissipating substrate 1 is increased by increasing the volume ratio of the resin composition 21 in the heat conductive sheet 2, and the interface between the resin composition 21 and the thin piece 31 is increased. Increasing the density increases the probability of dielectric breakdown and lowers the withstand voltage. Further, if the size of the thin piece 31 that is a highly rigid ceramic sheet is increased to 30 mm square or more, cracks may occur in the thin piece 31 during the manufacturing process or due to impact or stress during use. Get higher.

The resin composition 21 of the heat conductive sheet 2 of the heat dissipating substrate according to the present embodiment is mainly composed of a resin composition, for example, a thermosetting resin such as epoxy resin, phenol resin, silicone rubber, polyethylene, polyimide, An acrylic thermoplastic resin or the like is used. Further, the resin composition may be further filled with an inorganic filler such as alumina, boron nitride, or aluminum nitride having good thermal conductivity. The resin composition 21 filled with the inorganic filler is preferable because its thermal conductivity is improved and thermal stress with the thin piece 31 of the ceramic material can be reduced. The filler preferably has a diameter of 1 to 100 μm, and has a diameter equal to or smaller than the final thickness of the resin to be the resin layer 22.
Further, the thickness of the resin layer 22 formed on the upper surface and the lower surface of the thin piece 31 is preferably thin for increasing the thermal conductivity of the thermal conductive sheet 2, but thick for improving the adhesiveness. Better. Therefore, the thickness of the resin layer 22 is preferably about 1/7 to 1/20 of the thickness of the thin body piece 31 when the thin body piece 31 is vertically aligned.

  The depth of the concave portion 41 of the base plate 4 of the heat dissipating substrate according to the present embodiment is desirably 20% to 80% of the thickness of the thin body piece 31. When the depth of the recess 41 is 20% or less of the thickness of the thin piece 31, the flow of the resin during the pressing process cannot be suppressed, and the thin piece 31 is displaced. On the other hand, when the depth of the concave portion 41 is 80% or more of the thickness of the thin piece 31, there is a concern that a void remains in the resin composition 21 during manufacturing and the dielectric breakdown voltage decreases.

  The area of the recess 41 of the base plate 4 of the heat dissipation substrate according to the present embodiment is desirably 104% or more and 144% or less of the total area of the thin piece 31. When the area of the recess 41 is 104% or less of the total area of the thin piece 31, the distance between the side surface of the recess 41 and the thin piece 31, and between the adjacent thin pieces 31 when there are a plurality of thin pieces 31. Since the interval becomes narrow, it becomes difficult for the resin to enter, so that a void is easily generated in the resin composition 21, which is not desirable in terms of ensuring thermal conductivity. Moreover, when the area of the recessed part 41 exceeds 144% of the total area of the thin body piece 31, the space | interval of the adjacent thin body piece 31 and the space | interval of the side surface of the recessed part 41 of the base board 4, and the thin body piece 31 become large. For this reason, the resin flows and the positional deviation is likely to occur. For this reason, it is desirable that the area of the recess 41 is 104% to 144% of the total area of the thin piece 31.

  The recess 41 provided in the base plate 4 of the heat dissipation substrate according to the present embodiment is preferably obtained by machining from the viewpoint of uniformity in the dimensional surface, but can also be formed by polishing or etching. It is.

  As a method of dividing and arranging the thin body 30 in the method for manufacturing a heat dissipation substrate according to the present embodiment, the thin body 30 is divided into thin pieces 31 in advance, and the thin body is once placed on a pallet having a desired interval. A method of arranging the pieces 31 and sucking the thin pieces 31 arranged on the pallet and transferring them onto the resin sheet 25 can also be used. In addition, the ceramic sheet as the thin body 30 is bonded to the dicing sheet as the adhesive sheet 11 and cut to a desired size, and the dicing sheet is expanded to widen the distance between the thin pieces 31 to the desired distance. A method of sticking the thin piece 31 on the resin sheet 25 can also be adopted.

  According to Embodiment 1 of the present invention, when the insulating thin piece 31 in the heat conductive sheet 2 is disposed at a predetermined position due to the effect of the recess 41 provided in the base plate 4, a heating press is used. It is possible to prevent the thin piece 31 from flowing together with the resin during the process and to prevent the thin piece 31 from being displaced, and to suppress the generation of voids in the resin composition 21. Therefore, it is possible to obtain a heat dissipating substrate excellent in thermal conductivity, flexibility, and insulation.

  In the present embodiment, the recess 41 provided on the surface of the base plate 4 of the heat dissipating substrate 1 has been shown to accommodate all of the plurality of thin pieces 31 as shown in FIG. As shown in FIG. 5, the concave portion 41 provided on the surface of the base plate 4 may accommodate a group of the plurality of thin body pieces 31 instead of all of the plurality of thin body pieces 31. Moreover, as shown in FIG. 6, the recessed part 41 is good also as what can accommodate each thin piece 31 independently.

  Further, as shown in FIG. 7, the recess 51 for accommodating the thin piece 31 may be provided on the surface of the heat sink 5, or may be provided on both surfaces of the base plate 4 and the heat sink 5.

Embodiment 2. FIG.
FIG. 8 is a perspective view from above showing a schematic configuration of the heat dissipating substrate in the second embodiment of the present invention. The heat dissipating substrate in the present embodiment includes a heat conductive sheet 2 provided with a thin piece 31 inside the resin composition, and the heat conductive sheet 2 is provided between the base plate 4 and the heat sink 5. . As shown in FIG. 8, the base plate 4 is formed with recesses 41 for accommodating a plurality of thin body pieces 31, and the outer periphery of the recesses 41 is a plurality of discrete protrusions 40. Other configurations and manufacturing methods are the same as those shown in the first embodiment, and thus description thereof is omitted.

  According to the second embodiment of the present invention, when the insulating thin piece 31 in the heat conductive sheet 2 is arranged at a predetermined position due to the effect of the convex portions 40 provided discretely on the base plate 4. In addition, the displacement of the thin piece 31 can be prevented, and further, the effect of releasing the pressure during the press treatment is produced, so that the generation of voids in the resin composition 21 can be more effectively suppressed. Therefore, it is possible to obtain a heat dissipating substrate excellent in thermal conductivity, flexibility, and insulation.

  In the present embodiment, the projections 40 provided on the surface of the base plate 4 of the heat dissipation substrate 1 are provided on the outer peripheral portion of the entire thin body piece 31. You may provide corresponding to the outer peripheral part of the body piece 31. FIG. Moreover, you may provide the convex part 40 in the outer peripheral part of the group of the some thin body piece 31. FIG.

Embodiment 3 FIG.
FIG. 9 is a cross-sectional view showing a schematic configuration of the heat dissipating substrate according to Embodiment 3 of the present invention.
As shown in FIG. 9, the heat dissipation substrate of the present embodiment includes a heat conductive sheet 2 in which a thin piece 31 having heat conductivity is bonded by a resin composition 21, and the heat conductive sheet 2 is a base. It is provided between the plate 4 and the heat sink 5. A recess 41 is formed in the base plate 4 so that the thin piece 31 can be accommodated, and a groove 42 having a depth that is one step deeper than the bottom surface of the recess 41 is provided in the periphery of the bottom surface of the recess 41. Since this is the same as that shown in the first embodiment, description thereof is omitted.

  Also in the present embodiment, when the insulating thin piece 31 in the heat conductive sheet 2 is arranged at a predetermined position, the thin piece 31 flows together with the resin during the heating press step, and the position of the thin piece 31 is reached. Generation of gaps in the resin composition 21 can be prevented more effectively because the occurrence of deviation can be prevented, and the effect of releasing the pressure during the pressing process is produced by the groove 42 provided at the bottom of the recess 41 of the base plate 4. Can be suppressed. Therefore, it is possible to obtain a heat dissipating substrate that is excellent in thermal conductivity, flexibility, and insulation.

Embodiment 4 FIG.
FIG. 10 is a cross-sectional view illustrating a schematic configuration of the heat dissipation substrate 1 according to the fourth embodiment of the present invention.
As shown in FIG. 10, the heat dissipation substrate of the present embodiment includes a heat conductive sheet 2 in which a thin piece 31 having heat conductivity is bonded by a resin composition 21, and the heat conductive sheet 2 is a base. It is provided between the plate 4 and the heat sink 5. A recess 41 is formed in the base plate 4 so that the thin piece 31 can be accommodated, and the bottom surface of the recess 41 is formed with an inclined surface in which the depth of the recess 41 increases toward the periphery of the recess 41. Since it is the same as that shown in Embodiment 1, the description thereof is omitted.

  Also in the present embodiment, when the insulating thin piece 31 in the heat conductive sheet 2 is arranged at a predetermined position, the thin piece 31 flows together with the resin during the heating press step, and the position of the thin piece 31 is reached. The occurrence of deviation can be prevented, and the inclined surface provided at the bottom of the concave portion 41 of the base plate 4 has an effect of releasing the pressure during the pressing process, so that more voids are generated in the resin composition 21. It can be effectively suppressed. Therefore, it is possible to obtain a heat dissipating substrate excellent in thermal conductivity, flexibility, and insulation.

  In addition, although the example in which the thin piece 31 in the heat dissipation substrate 1 is single in Embodiment 3 and Embodiment 4, the thin piece 31 in the heat dissipation substrate may be plural.

Embodiment 5. FIG.
FIG. 11 is a cross-sectional view showing a schematic configuration of the heat dissipation substrate in the fifth embodiment of the present invention. FIG. 12 is a perspective view of a part of the overlapping relationship between the thin piece 31 and the heat sink 5 of the heat dissipating substrate according to the fifth embodiment of the present invention from the top surface of the heat dissipating substrate.
As shown in FIG. 11, the heat dissipation substrate of the present embodiment includes a heat conductive sheet 2 in which a plurality of thin body pieces 31 having heat conductivity are bonded by a resin composition 21, and the heat conductive sheet 2 is It is provided between the base plate 4 and the plurality of heat sinks 5. A recess 41 is formed in the base plate 4 so that the thin piece 31 can be accommodated. The thin piece 31 is completely overlapped with the heat sink 5 or is overlapped with the plurality of heat sinks 5, and as shown in FIGS. In all cases where an arbitrary straight line on the same plane passing through the center of gravity 311 on the surface is drawn, at least a part of the thin piece 31 is overlapped with the heat sink 5 on both sides divided by the straight line. A piece 31 and a heat sink 5 are provided.

  According to the present embodiment, the pressure applied to the thin piece 31 during press working does not greatly deviate, so that the thin piece 31 can be prevented from being lifted during press working, and the positional deviation of the thin piece 31 can be prevented.

  FIG. 13 is a perspective view of the overlapping relationship between the thin piece 31 and the heat sink 5 as seen from the top surface of the heat dissipation substrate, for comparison with the embodiment of the present invention. As shown in FIGS. 13A and 13B, a straight line on the same plane passing through the center of gravity 311 on the surface of the thin piece 31 is drawn, and the heat sink 5 and the thin body are at least on one side divided by the straight line. When the thin piece 31 and the heat sink 5 are disposed so that the pieces 31 do not overlap with each other, the pressure applied to the thin piece 31 is greatly biased during the pressing process. There is a possibility that displacement of the thin piece 31 occurs during processing.

Embodiment 6 FIG.
FIG. 14 is a cross-sectional view showing a schematic configuration of the power module 7 according to Embodiment 6 of the present invention, in which the heat dissipation substrate 1 of Embodiment 1 is used.
In the power module 7 of the present embodiment, a power semiconductor element 6 serving as a heating element is mounted on a heat sink 5 of the heat dissipation substrate 1, and the electrode 12 on the power semiconductor element 6 and the heat sink 5 of the heat dissipation substrate 1 are connected to a lead frame. 8, and the constituent members are sealed with a mold resin 9. The base plate 4 of the heat dissipation substrate 1 is bonded to the heat spreader 10. Here, the heat spreader 10 has a metal heat dissipation structure. The heat dissipating substrate 1 includes a heat conductive sheet 2 between a base plate 4 and a heat sink 5, and the heat dissipating substrate 2 includes a thin piece 31 inside a resin composition 21. Further, a recess 41 is provided on the surface of the base plate 4 that contacts the heat conductive sheet 2.

  In the present embodiment, it is possible to obtain the power module 7 in which the operation is prevented from becoming unstable during use.

  In the power module in the present embodiment, the heat radiating substrate 1 is the one in the first embodiment, but the heat radiating substrate 1 may be any one in the second to fifth embodiments.

  As described above, the embodiment of the present invention has been described on the assumption that the shape of the thin piece 31 is a square. However, the present invention is not limited to this, and the shape of the thin piece 31 may be a rectangle or a triangle. , Hexagonal or indeterminate.

  Next, the manufacturing method of the heat dissipation substrate in the present invention and the heat dissipation substrate obtained thereby will be specifically described.

Examples 1-5.
As an example of the heat dissipating substrate according to the first embodiment, a thin heat dissipating substrate having a plurality of thin pieces and a manufacturing method thereof will be described. The base plate, thin piece, and heat sink constituting the heat dissipating substrate were subjected to surface treatment. Copper was used for the base plate and the heat sink. The base plate and heat sink surface were subjected to an acid treatment, and then a silane coupling treatment and a heat treatment at 110 ° C. for 5 minutes. A resin sheet with a thickness of about 100 μm is placed in a 30 × 33.3 mm recess formed on the base plate, and a 3 mm square aluminum nitride plate with a thickness of 0.350 mm is placed as a thin piece on the resin sheet at a distance of 0.3 mm. Were arranged in 9 rows and 10 rows. The distance between the thin piece and the concave end was 0.3 mm. As the surface treatment of the thin piece, silane coupling treatment was performed in the same manner as the base plate.

  As a method of arranging the thin pieces, a method was used in which the thin pieces were once arranged on a pallet having a desired interval, and the thin pieces arranged on the pallet were sucked and transferred onto the resin sheet. The resin composition used an epoxy resin and contained alumina as a filler.

A resin sheet having a thickness of 100 μm and a heat sink are further arranged on thin pieces arranged at a desired interval, and vacuum pressing is performed under the conditions of 100 kg / cm ² pressure, 100 ° C., 5 minutes and 180 ° C., 30 minutes. Thus, a heat dissipating substrate was obtained. The thickness of the resin layer after the vacuum pressing was 15 μm in each of the upper and lower sides. At this time, the area of the recess of the base plate was 123% of the total area of the thin piece.
Here, the depth of the recess of the base plate of the heat dissipation substrate in Example 1 was 0.075 mm, and the ratio of the depth of the recess to the thickness of the thin piece was 21%. Hereinafter, the depths of the recesses in Examples 2 to 5 (ratio of the depth of the recesses to the thickness of the thin piece) were 0.1 mm (29%), 0.15 mm (43%), and 0.2 mm (respectively). 57%) and 0.25 mm (71%).

  In the case of the heat dissipating substrates according to Examples 1 to 5, the position shift of the thin piece and the void of the resin composition did not occur. Due to the effect of the recesses, it was possible to prevent the displacement of the thin piece due to the resin flow during pressing, and it was possible to obtain a heat dissipating substrate in which the insulating thin piece was arranged inside the recess. In addition, about the thermal conductivity of the heat dissipation board | substrate of Examples 1-5, the thing about 1.3 times as high as the composite ceramic sheet which has arrange | positioned the ceramic polyhedron to the polymeric material was obtained.

Example 6
As an example of the heat dissipating substrate according to the first embodiment, the heat dissipating substrate has a space between thin pieces and a distance between the thin piece and the end of the recessed portion of 0.5 mm, and the recesses of the base plate with respect to the total area of the thin pieces. The area was 140%. Conditions other than the above were the same as in Example 2.

  In the case of the heat dissipating substrate according to Example 6, the displacement of the thin piece and the void of the resin composition did not occur. Due to the effect of the recesses, it was possible to prevent the displacement of the thin piece due to the resin flow during pressing, and it was possible to obtain a heat dissipating substrate in which the insulating thin piece was arranged inside the recess.

Examples 7-8.
As an example of the heat dissipating substrate according to the first embodiment, a heat dissipating substrate in the case of one thin piece will be described.
Surface treatment is applied to the base plate, thin piece, and heat sink that make up the heat-dissipating substrate, and a resin sheet is placed on the base plate on which the recesses are formed, and a 30 mm square and 0.350 mm thick aluminum nitride piece is formed thereon. A plate was placed. A resin sheet having a thickness of 100 μm was placed thereon, a heat sink having a concave portion was placed at a predetermined position, and vacuum pressing was performed to obtain a heat dissipation substrate. Since the depth of the recess was formed at 0.1 mm, the ratio of the depth of the recess to the thickness of the thin piece at this time was 29%. The resin composition used an epoxy resin and contained alumina as a filler. In the case of Example 7, the distance between the thin piece and the end of the concave portion was 0.3 mm, and the area of the concave portion of the base plate was 104% of the area of the thin piece 31. In the case of Example 8, the distance between the thin piece and the end of the concave portion was 0.5 mm, and the area of the concave portion of the base plate was 107% of the area of the thin piece.

  In the case of the heat dissipating substrates according to Examples 7 to 8, there was no displacement of the thin piece and no voids in the resin composition. Due to the effect of the recesses, it was possible to prevent the displacement of the thin piece due to the resin flow during pressing, and it was possible to obtain a heat dissipating substrate in which the insulating thin piece was arranged inside the recess.

Examples 9-12.
As an example of the heat dissipating substrate according to the first embodiment, in the heat dissipating substrate according to the present example, the configuration other than the thickness of the thin piece and the depth of the recess is the same as that of the first example. Description is omitted. In the heat dissipating substrates of Examples 9 to 12, the thickness of the thin piece was 0.635 mm. About the depth of the recessed part 41, since the depth of the recessed part was 0.15 mm in the case of Example 9, the ratio of the depth of the recessed part with respect to the thickness of a thin piece was 24%. In the case of Example 10, since the depth of the recess was 0.20 mm, the ratio of the depth of the recess to the thickness of the thin piece was 31%. In the case of Example 11, since the depth of the recess was 0.30 mm, the ratio of the depth of the recess to the thickness of the thin piece was 47%. In the case of Example 12, since the depth of the recess was 0.35 mm, the ratio of the depth of the recess to the thickness of the thin piece was 55%.

  In the case of the heat dissipating substrates according to Examples 9 to 12, the positional deviation of the thin piece and the voids of the resin composition did not occur. Due to the effect of the recesses, it was possible to prevent the displacement of the thin piece due to the resin flow during pressing, and it was possible to obtain a heat dissipating substrate in which the insulating thin piece was arranged inside the recess.

Example 13
As an example of the heat dissipating substrate according to the third embodiment, an example in the case of one thin piece will be described. Surface treatment of the base plate, thin piece, and heat sink constituting the heat-dissipating substrate is performed, and a resin sheet having a thickness of 100 μm is placed on the base plate in which a recess having a groove is formed in the peripheral portion, and the thin piece is formed thereon. One piece of aluminum nitride having a 30 mm square and a thickness of 0.350 mm was placed. A resin sheet having a thickness of 100 μm was placed thereon, a heat sink was placed at a predetermined position, and vacuum pressing was performed to obtain a heat radiating substrate. The area of the recess of the base plate was 104% of the total area of the thin piece, the depth of the recess was 0.1 mm, and the depth of the groove provided around the recess was 0.2 mm. Other configurations were the same as those of the heat dissipation substrate of Example 1.

  The adhesive strength between the resin and the base plate can be improved by changing the depth of the recess depending on the location, the amount of resin can be controlled by the effect of the recess, the displacement of the thin piece due to the resin flow during pressing, and the gap of the resin composition Generation | occurrence | production can be prevented and the heat dissipation board | substrate which has arrange | positioned the thin piece inside the recessed part was able to be obtained.

Example 14 FIG.
As an example of the heat dissipating substrate according to the fourth embodiment, an example in the case of one thin piece will be described. Thickness is applied to the base plate that forms the base plate, the thin piece, and the heat sink that constitute the heat-dissipating substrate, and the bottom surface of the recess has an inclined recess that increases in depth from the center to the periphery of the recess. A resin sheet having a thickness of 100 μm was placed, and a piece of aluminum nitride having a thickness of 30 mm square and a thickness of 0.350 mm was placed thereon as a thin piece. A resin sheet having a thickness of 100 μm was placed thereon, a heat sink was placed at a predetermined position, and vacuum pressing was performed to obtain a heat radiating substrate. The area of the concave portion of the base plate was 104% of the total area of the thin piece, and the depth of the concave portion was 0.1 mm at a shallow portion. Other configurations were the same as those of the heat dissipation substrate of Example 1.

  By inclining the bottom surface of the concave portion of the base plate, the amount of resin can be controlled by the effect of the concave portion and the pressure can be relieved, so that the displacement of the thin piece due to the resin flow during pressing can be prevented. It was possible to obtain a heat dissipating substrate in which a thin piece was disposed at a predetermined position in the interior of the substrate.

Example 15.
As an example of the heat dissipating substrate according to the first embodiment, an example in which a concave portion is provided in a heat sink will be described. As in Example 1, surface treatment of the base plate, thin piece, and heat sink constituting the heat-dissipating substrate was performed, and a resin sheet having a thickness of 100 μm was placed on the base plate without a recess, and a 10 × 30 mm square was placed thereon. Two pieces of aluminum nitride having a thickness of 0.350 mm were placed. A resin sheet having a thickness of 100 μm was placed thereon, a heat sink having a 10.6 × 30.6 mm recess was placed at a predetermined position, and vacuum pressing was performed to obtain a heat dissipation substrate. The area of the recess of the heat sink was 108% of the total area of the thin piece, and the depth of the recess was 0.1 mm. The resin composition used an epoxy resin and contained alumina as a filler.

  In the case of the heat dissipating substrate according to Example 15, the displacement of the thin piece and the void of the resin composition did not occur. Due to the effect of the recesses, it was possible to prevent the displacement of the thin piece due to the resin flow during pressing, and it was possible to obtain a heat dissipating substrate in which the insulating thin piece was arranged inside the recess.

Example 16
As an example of the heat dissipating substrate according to the first embodiment, an example in which a recess is provided corresponding to each thin piece will be described. The base plate, thin piece, and heat sink that make up the heat-dissipating substrate are subjected to surface treatment, and a 3.6 mm square recess (9 rows by 10 rows) is formed at intervals of 0.3 mm. A resin sheet was placed, and 3 mm square and 0.35 mm thick aluminum nitride was placed as a thin piece in each recess. A resin sheet having a thickness of 100 μm was placed thereon, a heat sink was placed at a predetermined position, and vacuum pressing was performed to obtain a heat dissipation substrate. The area of each recess was 144% of the area of each thin piece, and the depth of the recess was 0.1 mm. The resin composition used was an epoxy resin containing alumina as a filler.

  In the case of the heat dissipating substrate according to Example 16, the displacement of the thin piece and the void of the resin composition did not occur. Due to the effect of the concave portion provided corresponding to each thin piece, the displacement of the thin piece due to the resin flow during pressing can be prevented, and a heat dissipating substrate having an insulating thin piece disposed inside the concave portion is obtained. I was able to.

Example 17.
As an example of the heat dissipation substrate according to the fifth embodiment, an example of a heat dissipation substrate in which a thin piece overlaps a plurality of heat sinks will be described.
As in Example 2, surface treatment of the base plate, thin piece, and heat sink constituting the heat-dissipating substrate was performed, a resin sheet having a thickness of about 100 μm was placed in the recess formed in the base plate, and a thin sheet was placed thereon. As body pieces, aluminum nitride plates having a size of 3 mm square and a thickness of 0.350 mm were arranged in 9 rows and 10 rows at intervals of 0.3 mm. A resin sheet having a thickness of 100 μm was placed thereon, a heat sink was placed at a predetermined position, and vacuum pressing was performed to obtain a heat radiating substrate. At this time, the position of the heat sink was determined so that there was always one thin piece between the heat sink and the heat sink. By always having one thin piece between the heat sinks, it is possible to uniformly apply the pressure of the vacuum press and prevent the thin piece from being inclined. The resin composition used an epoxy resin and contained alumina as a filler.

  In the case of the heat dissipating substrate according to Example 17, the positional deviation of the thin piece and the void of the resin composition did not occur. Due to the effect of the arrangement of the recess and heat sink and thin piece, it is possible to prevent the displacement of the thin piece due to the resin flow during pressing, and it is possible to obtain a heat dissipation substrate with an insulating thin piece arranged inside the concave portion It was.

Example 18
As an example of the power module according to the sixth embodiment, an example of a power module manufactured using the heat dissipating substrate of Example 1 will be described. The power semiconductor element is installed on the heat sink of the heat dissipating substrate of Example 2, the lead frame is connected to the heat sink of the heat dissipating substrate and the upper electrode of the power semiconductor element, and then molded with resin. A heat spreader was bonded to obtain a power module.

  For the power module of the present embodiment manufactured using the heat-dissipating substrate of Example 2, 300 cycles were performed with “holding at −40 ° C. for 30 minutes and holding at 125 ° C. for 30 minutes” as one cycle. When the heat cycle test was performed, the base plate and the resin layer in the heat radiating substrate, the heat sink and the resin layer, the peeling of the thin piece and the resin layer in the heat conductive sheet were not recognized, and the heat dissipation can be maintained. High capacity can be achieved.

Comparative Examples 1-4.
As a comparative example of the heat dissipation substrate according to the first embodiment, the thickness of the thin piece is 0.635 mm, the depth of the concave portion provided on the surface of the heat sink is 0.05 mm, and the thickness of the concave portion with respect to the thickness of the thin piece is The heat dissipation board | substrate of the comparative example 1 whose depth ratio is 14% was produced. Further, as Comparative Example 2, a heat radiating substrate having a recess depth of 0.05 mm, a thin piece thickness of 0.635 mm, and a ratio of the concave portion depth to the thin piece thickness of 8% was compared. As Example 3, a heat-radiating substrate having a recess depth of 0.075 mm, a thin piece thickness of 0.635 mm, and a ratio of the concave portion depth to the thin piece thickness of 12% is referred to as Comparative Example 4. A heat-dissipating substrate having a recess depth of 0.10 mm, a thin piece thickness of 0.635 mm, and a ratio of the concave portion depth to the thin piece thickness of 16% was produced. The rest was the same as in Example 1.

  In the case of the heat dissipating substrates according to Comparative Examples 1 to 4, no gaps in the resin composition occurred, but the thin piece was displaced.

Comparative Example 5
As a comparative example, the same heat dissipating substrate as in Example 1 was produced except that the depth of the concave portion of the heat dissipating substrate was 0.3 mm. At this time, the ratio of the depth of the recess to the thickness of the thin piece was 86%.

  In the case of the heat dissipating substrate according to Comparative Example 5, the thin piece was not displaced, but voids were generated in the resin composition.

  Table 1 summarizes the results of Examples 1 to 12 and Comparative Examples 1 to 5. As shown in Table 1, when the ratio of the depth of the recess to the thickness of the thin piece is 20% or less, the thin piece is displaced, and when it is 80% or more, the resin composition has When the ratio of the depth of the concave portion to the thickness of the thin piece is 20 to 80%, the thin piece can be prevented from being displaced due to the resin flow during pressing, and the inside of the concave portion is insulative. The heat dissipation board | substrate which has arrange | positioned the thin-body piece of this was able to be obtained.

It is a perspective view from the upper surface which shows schematic structure of the heat dissipation board | substrate in Embodiment 1 of this invention. It is sectional drawing which shows schematic structure of the heat dissipation board | substrate in Embodiment 1 of this invention. It is sectional drawing which shows the manufacturing method of the heat dissipation board | substrate in Embodiment 1 of this invention. It is a perspective view from the upper surface which shows schematic structure of the heat dissipation board | substrate in Embodiment 1 of this invention. It is a perspective view from the upper surface which shows schematic structure of the heat dissipation board | substrate in Embodiment 1 of this invention. It is a perspective view from the upper surface which shows schematic structure of the heat dissipation board | substrate in Embodiment 1 of this invention. It is sectional drawing which shows schematic structure of the heat dissipation board | substrate in Embodiment 1 of this invention. It is sectional drawing which shows schematic structure of the heat dissipation board | substrate in Embodiment 2 of this invention. It is sectional drawing which shows schematic structure of the heat dissipation board | substrate in Embodiment 3 of this invention. It is sectional drawing which shows schematic structure of the heat dissipation board | substrate in Embodiment 4 of this invention. It is sectional drawing which shows the one part schematic structure of the heat dissipation board | substrate in Embodiment 5 of this invention. It is a perspective view from the upper surface which shows the schematic structure of a part of heat dissipation board | substrate in Embodiment 5 of this invention. It is a perspective view from the upper surface which shows schematic structure of a part of heat dissipation board | substrate for the comparison with Embodiment 5 of this invention. It is sectional drawing which shows schematic structure of the power module in Embodiment 6 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Heat dissipation board, 2 Thermal conductive sheet, 21 Resin composition, 22 Resin layer, 25, 26 Resin sheet, 30 Thin body, 31 Thin piece, 311 Center of gravity of thin piece surface, 4 Base plate, 40 Convex part , 41 recess, 42 groove, 5 heat sink, 51 recess, 6 power semiconductor element, 7 power module, 8 lead frame, 9 mold resin, 10 heat spreader, 11 adhesive sheet, 12 electrode

Claims (12)

A heat conductive sheet comprising an insulating thin piece inside the resin composition; and
A heat sink provided in contact with one surface of the heat conductive sheet;
A base plate provided in contact with the other surface of the heat conductive sheet,
A heat dissipating substrate, comprising: a concave portion in which the thin piece is accommodated in at least one of a surface of the heat sink that contacts the heat conductive sheet and a surface of the base plate that contacts the heat conductive sheet. The heat conductive sheet has a plurality of thin body pieces, and a concave portion in which a group of the thin body pieces is collected is provided on a surface of the heat sink or base plate that contacts the heat conductive sheet. The heat dissipation board of description. 2. The heat conductive sheet has a plurality of thin pieces, and an independent recess corresponding to each thin piece is provided on a surface of the heat sink or base plate that contacts the heat conductive sheet. The heat-dissipating board described in 1. The convex part located in the outer peripheral part of the recessed part provided in the surface which contact | connects the heat conductive sheet of a heat sink or a base board is cut off at least partially, The Claim 1 thru | or 3 characterized by the above-mentioned. Heat dissipation board. The heat-radiating substrate according to claim 1, wherein a groove having a depth larger than that of the concave portion is provided in a peripheral portion of the concave portion provided on a surface of the heat sink or the base plate that contacts the heat conductive sheet. The bottom surface of the concave portion provided on the surface of the heat sink or the base plate that contacts the heat conductive sheet has an inclination in which the depth of the concave portion increases from the center to the periphery of the concave portion. Heat dissipation board. 2. The heat dissipating substrate according to claim 1, wherein a depth of a concave portion provided on a surface of the heat sink or the base plate contacting the heat conductive sheet is 20% or more and 80% or less of the thickness of the thin piece. . 2. The heat dissipating substrate according to claim 1, wherein an area of a recess provided on a surface of the heat sink or the base plate in contact with the heat conductive sheet is 104% to 144% of the total area of the thin piece. The heat-radiating substrate according to claim 1, wherein the plurality of thin pieces of the heat conductive sheet are made of a ceramic plate having a thickness of 0.1 mm or more and 2 mm or less. At least a part of the thin piece is superimposed on a heat sink on both sides separated by any straight line on the same plane passing through the center of gravity on the surface of the thin piece of the heat conductive sheet. The heat-radiating substrate according to any one of claims 1 to 4. A process of attaching an insulating thin body to an adhesive sheet;
Dividing the thin body into a thin piece in a state of being stuck to the adhesive sheet;
Arranging and bonding the first resin sheet to the base plate having the recesses;
Arranging and bonding the thin piece affixed to the adhesive sheet at a predetermined position inside the concave portion of the base plate;
Peeling the pressure-sensitive adhesive sheet from the thin piece affixed to the pressure-sensitive adhesive sheet;
Disposing a second resin sheet and a heat sink on the thin piece;
And a step of curing the first and second resin sheets at a high temperature while applying pressure. The heat dissipating substrate according to claim 1, a power semiconductor element disposed on a heat sink on one surface of the heat dissipating substrate, and a base plate on the other surface of the heat dissipating substrate. A power module comprising: a heat spreader disposed in the housing.