JP2020092239A - Heat sink, semiconductor module, and manufacturing method of heat sink - Google Patents

Abstract

To provide a heat sink with excellent heat dissipation performance, a semiconductor module, and a manufacturing method of the heat sink.SOLUTION: A heat sink 1 according to the present invention includes a metal plate 2 made of copper or a copper alloy, a fin portion 3 provided on the surface of the metal plate 2 and made of copper or a copper alloy, and a metal bonding layer 4a which is interposed between the surface of the metal plate 2 and the fin portion 3 and bonds the fin portion 3 to the metal plate 2.SELECTED DRAWING: Figure 5

Description

The present invention relates to a heat sink having a fin portion provided on the surface of a metal plate, a semiconductor module, and a method for manufacturing the heat sink, and particularly proposes a technique capable of realizing excellent heat dissipation performance. ..

Some heat sinks are provided with fin portions of various shapes on the surface of a metal plate for increasing the heat transfer area for the purpose of increasing heat exchange efficiency.
Most heat sinks having such a fin portion are made of aluminum, and in general, a metal plate made of aluminum and the fin portion are integrally formed by extrusion molding, and then, if necessary, a fin portion such as a plate is formed. It is manufactured by performing a predetermined process.

Note that, as a technique related to the manufacturing of this type of heat sink, for example, there is one described in Patent Document 1. Patent Document 1 discloses that "a fin of an aluminum extruded profile having a plurality of fins that are vertically erected at intervals on a substrate is formed by cutting into a substrate in a lateral direction orthogonal to the extrusion direction. Divide each fin into a plurality of rows in the extrusion direction, and simultaneously enclose a plurality of fins in the same row over a certain range in the height direction from the tip side of the fin, and insert the machining die in the lateral direction orthogonal to the extrusion direction. A fin processing method for a heat sink made of an aluminum extruded profile characterized in that only a portion between the root of the fin and the processing die is bent obliquely by moving the fin by a predetermined distance.

JP, 2010-225621, A

By the way, in recent years, it has been required to greatly improve the heat dissipation performance of a heat sink used in a vehicle-mounted or other semiconductor module such as an electromechanical integrated type. In order to meet this requirement, it is considered effective to change the material of the heat sink to copper or a copper alloy, which has better heat dissipation than aluminum.

However, copper or a copper alloy is inferior to aluminum in workability. Therefore, it is difficult to integrally form a heat sink having a fin portion and a metal plate made of copper or a copper alloy by extrusion molding. Therefore, up to now, it has not been easy to realize a heat sink having a metal plate and a fin portion made of copper or a copper alloy to improve the heat radiation performance.

The present invention has an object to solve such a problem, and an object thereof is to provide a heat sink having excellent heat dissipation performance, a semiconductor module, and a method for manufacturing the heat sink.

The heat sink of the present invention includes a metal plate made of copper or a copper alloy, a fin portion provided on the surface of the metal plate, made of copper or a copper alloy, and interposed between the surface of the metal plate and the fin portion. A metal bonding layer for bonding the fin portion to the metal plate.

In the heat sink of this invention, it is preferable that the metal bonding layer has a shape that widens toward the metal plate side.
Further, it is preferable that the heat sink of the present invention has a plurality of fin portions and a metal joining layer interposed between the surface of the metal plate and each fin portion and joining each fin portion to the metal plate. .. In this case, in the cross section in the thickness direction of the metal plate, the metal bonding layers that bond the fin portions to the metal plate are arranged at intervals at least at positions farthest from the metal plate. Preferably.

In the heat sink of the present invention, the metal bonding layer contains copper, the metal bonding layer is made of a sintered body, the metal bonding layer contains voids, and the metal bonding layer contains carbon. Each is suitable.
When the metal bonding layer includes voids, the porosity of the metal bonding layer is preferably less than 0.5.

In the heat sink of the present invention, it is preferable that the fin portion has a column shape provided on the surface of the metal plate in an upright state.

The semiconductor module of the present invention has any one of the heat sinks described above.

The method for manufacturing a heat sink of the present invention provides a metal plate made of copper or a copper alloy, a fin portion made of copper or a copper alloy, and a metal powder paste, and the surface of the metal plate and/or the end face of the fin portion is provided. A paste applying step of applying a metal powder paste, a fin arranging step of arranging a fin portion on the surface of the metal plate via the metal powder paste, and an intervening step between the surface of the metal plate and the fin portion. The heating step of heating and sintering the metal powder paste is performed.

In the heat sink manufacturing method of the present invention, a plurality of fin portions are prepared in the paste applying step, and the metal powder paste interposed between the surface of the metal plate and each fin portion is heated in the heating step. It is preferable to sinter.

In the method for manufacturing a heat sink of the present invention, in the paste applying step, only the fin placement region in which the fin portion is placed in the fin placement step on the surface of the metal plate, of the surface of the metal plate and the end surface of the fin portion, is formed. , A metal powder paste can be applied.
Alternatively, in the paste applying step, the metal powder paste can be applied to the end surface of the fin portion among the surface of the metal plate and the end surface of the fin portion.

In the heat sink manufacturing method of the present invention, the metal powder paste contains a copper-containing powder made of copper or a copper alloy, and the average particle diameter D50 of the copper-containing powder is less than 1.0 μm. It is preferable to heat the powder paste to a temperature of 400° C. or higher.

According to the present invention, the heat sink has the metal bonding layer which is interposed between the surface of the metal plate and the fin portion to bond each fin portion to the metal plate, so that the metal plate and the fin portion are made of copper or copper alloy. It can be manufactured, and thereby excellent heat dissipation performance can be realized.

It is a perspective view showing a heat sink of one embodiment of this invention. It is a perspective view which shows the heat sink of other embodiment. It is a side view which shows the paste application process and fin arrangement process at the time of manufacturing the heat sink of FIG. It is sectional drawing of the thickness direction of a metal plate which follows the IV-IV line of FIG. It is a partial expanded sectional view of FIG. It is an expanded sectional view showing a modification of a metal joining layer which a heat sink has, and a modification of a metal plate and a metal joining layer. It is a SEM image of the cross section of a metal joining layer as an example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(Outline of heat sink)
The heat sink 1 illustrated in FIG. 1 dissipates heat due to heat generated by a flat metal plate 2 or other plate-shaped metal plate 2 and a semiconductor chip of a semiconductor module (not shown) in which the heat sink 1 is provided, so that the heat transfer area is increased. And a fin portion 3 provided on the surface of the metal plate 2.
Here, the illustrated metal plate 2 has a flat plate shape having a substantially square planar contour shape, but it has various planar contour shapes such as a rectangular shape and other polygonal shapes, and includes a bent or curved portion. It can be in the form of various plates such as objects.

Further, here, in this heat sink 1, one or more fin portions 3 that are provided in a state of standing upright substantially perpendicular to the surface of the metal plate 2, more specifically, one or more columnar fin portions 3 are provided with a predetermined shape. They are arranged at intervals. Such a columnar fin portion 3 is excellent in heat dissipation because a cooling medium such as cooling water passes between the plurality of fin portions 3 and circulates.
However, the fin portion is not limited to this as long as the shape has a large surface area. For example, as shown in FIG. 2, a plurality of thin-walled rectangular parallelepiped plate-shaped fin portions 3a are arranged on the surface of the metal plate 2 in parallel at equal intervals. There is also a fin portion that is a curved flat plate. Although not shown, one fin member having one or a plurality of blades may be used.
Here, the fin portion 3 shown in FIG. 1 will be mainly described as an example.

Here, the metal plate 2 and the fin portion 3 of the heat sink 1 are made of copper or copper alloy. As a result, it is possible to exhibit excellent heat dissipation performance as compared with that made of aluminum. As a result, the heat sink 1 can be preferably used in other vehicle-mounted semiconductor modules such as an electromechanical integrated type, which have strict requirements for heat dissipation performance.
Specific examples of the copper or copper alloy forming the metal plate 2 and the fin portion 3 include oxygen-free copper, tough pitch copper, high-purity copper, tin-containing copper or zirconium-containing copper, silver-containing copper, and chromium-containing copper. Can be mentioned. Of these, oxygen-free copper is particularly preferable from the viewpoint that hydrogen embrittlement does not occur at high temperatures.

However, since copper or a copper alloy is inferior to aluminum in workability, it is difficult to integrally form the metal plate and the fin portion by extrusion molding or the like. Further, when a copper or copper alloy ingot or the like is carved out to form the metal plate and the fin portion, the productivity and the material yield are remarkably low.
Therefore, in the manufacturing method of this embodiment, the metal plate 2 and the fin portion 3 are joined together by using a metal powder paste. According to this, the metal plate 2 and the fin portion 3 can be joined with required strength, and the heat sink 1 having excellent heat dissipation performance can be manufactured relatively easily.

(Production method)
To describe the method of manufacturing the heat sink 1 in detail, first, a metal plate 2 made of copper or a copper alloy, one or more, for example, a plurality of fin portions 3 made of copper or a copper alloy, and a metal powder paste are prepared.
Of these, the metal plate 2 and the fin portion 3 are relatively simple in shape, so that they can be easily processed by, for example, pressing, drawing, wire cutting, cutting, header processing, or the like. Can be manufactured.

As the metal powder paste, a publicly known one can be used without particular limitation, but if it can be sintered at a low temperature, the heat sink 1 can be manufactured more easily. The metal powder paste contains, for example, metal powder, a solvent, and a binder resin, and may further contain an additive in some cases. As these solvents, binder resins and additives, it is preferable to use compounds that can be removed as much as possible by sintering.

From the viewpoint of heat dissipation and cost, the metal powder contained in the metal powder paste preferably contains copper-containing powder made of copper or a copper alloy. The heat sink 1 is manufactured using a metal powder paste containing copper-containing powder made of copper or a copper alloy similarly to the metal plate 2 and the fin portion 3, so that a metal described later between the metal plate 2 and the fin portion 3 is formed. The change in heat conduction in the bonding layer can be suppressed to a small level, and the heat dissipation performance can be further improved.
As the copper-containing powder, for example, a powder made of pure Cu or a Cu-Ag alloy, a powder made of Cu and coated with Ag, and the like can be mentioned. Moreover, these powders may be surface-treated with a predetermined coupling agent.

The average particle diameter D50 of the metal powder contained in the metal powder paste is preferably less than 1.0 μm. As a result, the porosity of the metal bonding layer between the metal plate 2 and the fin portion 3 can be reduced, and the heat dissipation performance can be greatly improved. The average particle size D50 of the metal powder can be, for example, 0.1 μm to 0.9 μm, preferably 0.2 μm to 0.6 μm. The average particle diameter D50 of the metal powder is measured, for example, as a median diameter that can be obtained from a particle size distribution (volume basis) obtained by a laser diffraction method.
The shape of the metal powder is not particularly limited, but may be, for example, a spherical shape, a spheroidal shape, a flattened shape thereof, or a mixture of these shapes.

As the solvent contained in the metal powder paste, those known as those used in the metal powder paste can be used. Examples of such a solvent include α-terpineol, pentylcarpitol and the like. As the binder resin, those known as those used for metal powder paste can be used. The binder resin is preferably one that decomposes at a predetermined heating temperature, and examples thereof include cellulose-based, acrylic-based, epoxy-based, and phenol-based binder resins. Further specific examples of such a binder resin include polyvinyl propylal resin and ethyl cellulose.

The paste applying step is performed using the metal powder paste as described above.
In the paste application step, whether the metal powder paste 4 is applied to the surface of the metal plate 2 as shown in FIG. 3(a) or the end surface of the fin portion 3 as shown in FIG. 3(b). Alternatively, although not shown, it is applied to both the surface of the metal plate 2 and the end surface of the fin portion 3. By using the metal powder paste 4, it is possible to allow the metal powder to exist in a predetermined area relatively uniformly, so that it is possible to improve the heat dissipation performance and ensure the required bonding strength.

Since the metal powder paste 4 is often expensive, it is desirable to minimize the amount of the metal powder paste 4 used from the viewpoint of suppressing cost increase. Therefore, when the metal powder paste 4 is applied to the surface of the metal plate 2, it is also possible to apply the metal powder paste 4 to the entire surface of the metal plate 2. It is preferable to apply only to the fin arrangement region where the fin portion 3 is arranged in the fin arrangement step. This means that, for example, the metal powder paste 4 is applied in a state where a sheet as a mesh or a mask is arranged on the surface of the metal plate 2 so that only the fin arrangement area on the surface of the metal plate 2 is exposed. It can be realized by such things.

The metal powder paste 4 is applied to the surface of the metal plate 2 and/or the end surface of the fin portion 3 so that the maximum thickness is preferably 0.03 mm to 0.2 mm. More preferably, the maximum thickness is 0.15 mm or less. If the coating thickness of the metal powder paste 4 is too thin, the bonding strength between the metal plate 2 and the fin portion 3 may be insufficient. On the other hand, if the coating thickness is too thick, the heat sink 1 as a product may crack. In addition to the possibility of occurrence, there is an inconvenience that the use of a large amount of metal powder paste 4 causes an increase in cost.

When the metal powder paste 4 is applied to the end surface of the fin portion 3 having a columnar shape, the fin portion 3 is put into an unillustrated rocking type transfer machine or an automatic aligning machine, and the plurality of fin portions 3 are connected. The coating can be performed in a state where the fins 3 are arranged in a predetermined arrangement in a transfer jig such as the swing transfer machine and the end surface of the fin portion 3 is exposed from the transfer jig.

Then, the fin placement step is performed. In the fin arranging step, as shown by an arrow in FIG. 3, the surface of the metal plate 2 coated with the metal powder paste and/or the end faces of the fin portions 3 are brought close to each other, and are placed at predetermined positions on the surface of the metal plate 2. A plurality of fin portions 3 are arranged via the metal powder paste 4.

Such arrangement of the plurality of fin portions 3 on the surface of the metal plate 2 is performed by aligning the plurality of fin portions 3 with the plurality of fin portions 3 fitted in the fitting holes of the transfer jig described above. It is advantageous from the viewpoint of improving workability that the work is carried out by bringing it close to the surface of the metal plate 2 together with the transfer jig.

And after that, a heating process is performed. More specifically, in this heating step, for example, in the state where the end faces of the plurality of fin portions 3 are pressed against the surface of the metal plate 2 under the action of a predetermined pressing force, the fin portions 3 are pressed between the end faces and the surface. By heating the intervening metal powder paste 4, the solvent or the like of the metal powder paste is vaporized and removed, and at the same time, the metal powder is sintered between each of the plurality of fin portions 3 and the metal plate 2. When an oscillating transfer machine or the like is used, the transfer jig that holds the plurality of fin portions 3 can be heated together.

The metal powder paste 4 is preferably heated to a temperature of 200° C. or higher, further 400° C. or higher. For example, a metal powder such as a copper-containing powder having a predetermined small particle diameter of D50 of about 0.4 μm is heated to, for example, 400° C. or higher, more preferably 600° C. or higher, further preferably 800° C. or higher. By heating at such a high temperature, the metal powder paste 4 becomes a dense metal bonding layer with a small porosity, whereby a further excellent heat dissipation performance can be obtained.
On the other hand, if the heating temperature is too high, it is necessary to use equipment capable of withstanding the heating temperature, which may impair the ease of manufacturing. Therefore, the heating temperature of the metal powder paste is preferably 200°C to 900°C.
On the other hand, if the heating temperature is too low, the binder resin is not sufficiently decomposed and the proportion of the binder resin-derived component in the metal bonding layer increases, which may deteriorate the heat dissipation of the heat sink 1. Further, if the heating temperature is too low, the sintering between the metal powders does not proceed sufficiently and the porosity increases, which may deteriorate the heat dissipation property of the heat sink 1.

The heating process may include two or more heating processes depending on the paste composition used. This has the advantage that the thickness of the paste can be made uniform. As an example, when a copper-containing powder having a D50 of about 0.4 μm is used, the heating process may include three heating processes. In such a case, the first heating process is performed mainly for the purpose of removing the solvent and the like of the metal powder paste, and can be heated at 100°C to 150°C for 0.05 hours to 0.5 hours. The second heating process is performed for the purpose of desorbing the binder resin, and can be performed at 350° C. to 450° C. for 0.25 hours to 1.5 hours. The third heating step is performed for the purpose of sintering the metal powder, and can be heated at 550 to 900° C. for 0.25 hours to 1.5 hours.

At the time of heating, each fin portion 3 can be pressed against the metal plate 2 at, for example, 0 MPa to 1.5 MPa, preferably 0 MPa to 1.0 MPa. As a result, the ratio of voids in the metal bonding layer can be reduced, the heat dissipation of the heat sink 1 can be improved, and the fin portion 3 can be firmly bonded onto the surface of the metal plate 2. If the applied pressure is too large, the fin portion 3 containing copper may be deformed. The applied pressure may be 0 MPa, that is, no pressure may be applied.
When the metal powder paste 4 contains a metal such as Ag whose surface oxide is unstable, the heating can be performed in an air atmosphere, but when the metal oxide paste 4 contains a metal such as Cu whose surface oxide is stable, It is preferable to heat in an inert gas atmosphere or a reducing gas atmosphere. Moreover, by heating in a reducing gas atmosphere (for example, nitrogen gas containing 2 to 5% hydrogen), the sintering of the metal powder can be promoted, that is, the porosity in the sintered body can be reduced.

However, various metal powder pastes 4 can be used here, and appropriate conditions such as temperature and time can be set according to the metal powder paste 4 to be used.

(heatsink)
Through the heating process as described above, the metal powder paste between the metal plate 2 and the fin portion 3 becomes the metal bonding layer 4a as shown in the sectional views of FIGS. The metal bonding layer 4a, which is generally made of a sintered body of metal powder contained in the metal powder paste, functions to bond the metal plate 2 and the fin portion 3 with required strength.
Therefore, the heat sink 1 of this embodiment is provided between the surface of the metal plate 2 and the fin portion 3 in addition to the metal plate 2 and the one or more fin portions 3 described above, and the fin portion 3 is made of metal. It has a metal bonding layer 4a bonded to the plate 2.

The metal bonding layer 4a preferably contains copper. With this, since the metal plate 2 and the fin portion 3 contain copper, it is possible to suppress a change in heat conduction due to a difference in material in the metal bonding layer 4a, and it is possible to more effectively improve heat dissipation performance. .. Further, since copper is less affected by migration, it is possible to suppress a decrease in heat dissipation performance due to use. When the metal powder paste contains copper-containing powder, the metal bonding layer 4a usually contains copper.

The metal bonding layer 4a may have a mesh structure and may include voids due to the fact that the metal powder is sintered and connected when melted. However, the porosity of the metal bonding layer 4a is preferably less than 0.5. When the porosity of the metal bonding layer 4a is low, the density of the metal bonding layer 4a is high, so that the heat dissipation performance is further enhanced. From this viewpoint, the porosity of the metal bonding layer 4a is more preferably less than 0.1.

The metal bonding layer 4a may contain carbon due to residual components such as the binder resin contained in the metal powder paste. Carbon may remain in the voids of the metal bonding layer 4a.
FIG. 7 is an example of an SEM image of a cross section of the metal bonding layer 4a. As shown in FIG. 7, most of the metal bonding layer 4a is calcined copper (light gray portion), and a void is included in a part thereof. More specifically, the portion indicated by the two-dot broken line portion (dark black portion) of FIG. 7 corresponds to the void portion in which carbon does not remain, and the portion indicated by the one-dot broken line portion (darker than copper , A portion thinner than the void in which carbon does not remain) corresponds to the void in which carbon remains. It can be confirmed that carbon remains in the void portion (the portion indicated by the one-dot broken line portion) of the metal bonding layer 4a by performing a component analysis using EPMA, for example.

For the porosity of the metal bonding layer 4a, a cross section obtained by cutting the metal bonding layer 4a along the thickness direction of the metal plate 2 is observed by a scanning electron microscope (SEM), and a black region (a void in the metal bonding layer 4a ( It is calculated as the ratio of the area of the black region, which is a void, to the total of the area of the void region in which carbon remains) and the area of the gray region filled with metal.

The metal plate 2 and the fin portion 3 joined by the metal joining layer 4a preferably have a joining strength of 1 MPa to 20 MPa, more preferably 2 MPa to 15 MPa. For example, when the heat sink 1 is a water-cooled type (when at least a part of the fin portion 3 is immersed in water), the joint strength between the metal plate 2 and the fin portion 3 is 5 MPa or more in order to withstand the water pressure. Preferably. The joint strength is measured as the shear strength of the central portion of the fin portion 3.
An example of the shear strength measurement conditions is shown below.
Device: Precision load measuring device Sweep speed: 5 mm/min
Position where the tool is pressed: Position of the fin portion 3 at a height of 4 mm with reference to the surface of the metal plate 2 to be joined to the fin portion 3

The thickness Tc of the metal bonding layer 4a is preferably 0.01 mm to 0.15 mm, more preferably 0.05 mm to 0.1 mm, measured along the thickness direction of the metal plate 2. If the thickness Tc of the metal bonding layer 4a is too thin, there is a concern that the metal plate 2 and the fin portion 3 cannot be bonded sufficiently firmly. On the other hand, if the thickness Tc of the metal bonding layer 4a is too large, the heat dissipation may be deteriorated and cracks may occur.

The heat sink 1 has the metal bonding layer 4a, as illustrated in FIG. 5, due to the fin portion 3 being pressed against the metal plate 2 with a predetermined pressing force in the above-described heating process during manufacturing. However, it may have a shape that widens toward the metal plate 2 side. In FIG. 5, the metal bonding layer 4a for bonding the cylindrical fin portion 3 to the metal plate 2 has a shape in which the diameter thereof gradually increases from the cylindrical fin portion 3 side toward the metal plate 2 side. Has become. In other words, the metal bonding layer 4a has a taper shape in which the cross-sectional area decreases and the taper as the distance from the metal plate 2 increases.

The divergent shape of the metal bonding layer 4a is not limited to the linear shape in the cross section in the thickness direction of the metal plate 2 as shown in FIG. 5, and the inside has the same cross section as shown in FIG. 6(a). There is also a case where the metal bonding layer 14a has a curved shape which is narrowed to the end and spreads toward the end.
Alternatively, as shown in FIG. 6B, the tip portion including the end face of the fin portion 3 is embedded in the metal joining layer 24a by the pressure applied in the heating step, and the metal joint surrounding the tip portion of the fin portion 3 is joined. It may be the layer 24a.

The metal bonding layers 4a, 14a, and 24a are spaced apart from each other at a position Pa (shown by broken lines in FIGS. 5 and 6) at least at a position Pa farthest from the metal plate 2 in the cross section in the thickness direction of the metal plate 2. It is preferably arranged. This is because the metal powder paste is interposed only between the fin portion 3 and the metal plate 2 in the above-mentioned paste application process, which can reduce the amount of expensive metal powder paste used. The manufacturing cost can be reduced.
The metal bonding layers 4a, 14a, 24a shown in FIGS. 5 and 6(a) and (b) are not only located at the position Pa farthest from the metal plate 2, but also adjacent ones are entirely separated from each other, Each is independent. On the other hand, in the metal bonding layer 34 a shown in FIG. 6C, adjacent ones have a distance Dc from each other at the position Pa farthest from the metal plate 2, but contact each other at the position close to the metal plate 2. And integrated.

Further, as shown in FIG. 6( d ), when the metal plate 12 in which the recess 13 is previously provided in the fin disposition region is used, the fin portion 3 slightly inserted into the recess 13 and the metal part 12 in the recess 13 are used. The metal bonding layer 44a may be interposed between the plate 12 and the fin 12, and the metal bonding layer 44a may have a shape that spreads toward the metal plate 12 side around the tip portion of the fin portion 3.

(Semiconductor module)
The heat sink 1 described above can be arranged, for example, on the back side of an insulating substrate on which a semiconductor chip is attached, and can form a part of a semiconductor module. In this case, it is used to cool the semiconductor chip by water cooling or the like. Be done.

DESCRIPTION OF SYMBOLS 1 Heat sink 2, 12 Metal plate 3, 3a Fin part 4 Metal powder paste 4a, 14a, 24a, 34a, 44a Metal joining layer 13 Recess Tc Thickness of metal joining layer Pa Position farthest from metal plate Dc Farthest from metal plate Distance between metal bonding layers at different positions

Claims (16)

A metal plate made of copper or a copper alloy, provided on the surface of the metal plate, a fin portion made of copper or a copper alloy, and interposed between the surface of the metal plate and the fin portion, and the fin portion is made of the metal. A heat sink having a metal bonding layer bonded to a plate. The heat sink according to claim 1, wherein the metal bonding layer has a shape that widens toward the metal plate side. 3. The method according to claim 1, further comprising a plurality of fin portions and a metal joining layer interposed between the surface of the metal plate and each fin portion and joining each fin portion to the metal plate. Heat sink. 4. In the cross section in the thickness direction of the metal plate, the metal bonding layers that bond the fin portions to the metal plate are arranged at least at positions farthest from the metal plate and spaced from each other. The heat sink described in. The heat sink according to claim 1, wherein the metal bonding layer contains copper. The heat sink according to claim 1, wherein the metal bonding layer is made of a sintered body. The heat sink according to claim 1, wherein the metal bonding layer includes voids. The heat sink according to claim 7, wherein the porosity of the metal bonding layer is less than 0.5. The heat sink according to claim 1, wherein the metal bonding layer contains carbon. The heat sink according to any one of claims 1 to 9, wherein the fin portion has a columnar shape that is provided upright on the surface of the metal plate. A semiconductor module comprising the heat sink according to claim 1. A method of manufacturing a heat sink, comprising:
Prepare a metal plate made of copper or a copper alloy, a fin portion made of copper or a copper alloy, and a metal powder paste, and apply the metal powder paste to the surface of the metal plate and/or the end face of the fin portion. A fin placing step of arranging a fin portion on the surface of the metal plate via the metal powder paste, and heating and baking the metal powder paste interposed between the surface of the metal plate and the fin portion. A method of manufacturing a heat sink, including a heating step of binding. The plurality of fin portions are prepared in the paste applying step, and the metal powder paste interposed between the surface of the metal plate and each fin portion is heated and sintered in the heating step. A method for manufacturing the heat sink described. In the paste applying step, of the surface of the metal plate and the end surface of the fin portion, the metal powder paste is applied only to the fin arrangement area in which the fin portion is arranged in the fin arrangement step on the surface of the metal plate. Item 14. A method for manufacturing a heat sink according to item 12 or 13. The heat sink manufacturing method according to claim 12 or 13, wherein, in the paste applying step, the metal powder paste is applied to the end surface of the fin portion of the surface of the metal plate and the end surface of the fin portion. The metal powder paste contains a copper-containing powder made of copper or a copper alloy, and the average particle diameter D50 of the copper-containing powder is less than 1.0 μm,
The method for manufacturing a heat sink according to claim 12, wherein the metal powder paste is heated to a temperature of 400° C. or higher in the heating step.

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