JP2011035219A - Composite heat sink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure that suppresses mountain-shaped distortion of a metal heat sink joined to an insulating heat sink. <P>SOLUTION: The composite heat sink is used to dissipate heat of an electronic component, and includes an insulating substrate and a first metal plate 4. The first metal plate 4 is joined to the insulating substrate, and has a larger coefficient of thermal expansion than the insulating substrate. On a first surface 4s, a plurality of first grooves 41 are linearly formed and on a second surface 4t, a plurality of second grooves 42 are linearly formed. Center line parts of the respective first grooves 41 and center line parts of the respective second grooves 42 are not positioned on the same straight line along a direction (vertical direction D) perpendicular to the first surface 4s. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a composite heat dissipation plate used for heat dissipation of electronic components.

  Patent Document 1 discloses a conventional semiconductor device. In this semiconductor device, an IGBT module is mounted on the surface of a DBA substrate (insulating heat dissipation plate; an aluminum nitride plate joined to an aluminum plate), and the DBA substrate is interposed via a solder layer. It joins on the heat sink made from Cu-Mo alloy.

JP 2007-141948 A

The insulating heat sink is required to have high thermal conductivity, and further, high insulating properties are required in order to prevent electric leakage from electronic components. As the material of the insulating heat sink, the above-mentioned AlN (thermal conductivity: 150 W / (m · K), thermal expansion coefficient: 4.7 × 10 ⁻⁶ [1 / K]), diamond (thermal conductivity: 500) ˜1000 W / (m · K), coefficient of thermal expansion: 2.2 × 10 ⁻⁶ [1 / K]) and the like are used. The thermal expansion coefficient of such a material is smaller than that of a metal heat sink such as aluminum or copper.

  And since the thermal expansion amount (length, area, or volume change) of the insulating heat sink during heat generation of the electronic component is smaller than the thermal expansion amount of the metal heat sink, the metal heat sink generates heat. The portion is distorted in a mountain shape with the apex at the top (that is, warping deformation occurs). In the state where such distortion occurs in the metal heat sink, the following problems may occur. First, (i) it becomes difficult to join these heat radiating plates (insulating heat radiating plate and metal heat radiating plate) to other members. (Ii) Further, thermal stress is generated between these heat radiating plates, resulting in damage to the heat radiating plate (insulating heat radiating plate or metal heat radiating plate). Such a problem of warpage deformation also occurs when the insulating heat sink is disposed between the metal heat sink and the electronic component.

(Task)
The problem to be solved by the present invention is to suppress the mountain-shaped distortion of the metal heat sink joined to the insulating heat sink.

(1) In order to solve the above problems, a composite heat sink according to the present invention is used for heat dissipation of an electronic component, and is joined to an insulating heat sink and the insulating heat sink, and A metal heat radiating plate having a larger coefficient of thermal expansion than the insulating heat radiating plate.
The metal heat sink has a first surface and a second surface that are parallel to each other, and a plurality of first grooves are linearly formed on the first surface, and the second surface A plurality of second grooves are formed in a linear shape, and each of the first grooves includes a center line portion and two end portions formed at both ends of the center line portion. Each of the second grooves includes a center line portion and two end portions formed at both ends of the center line portion, and the center line portion of each of the first grooves and each of the second grooves. The plurality of first grooves and the plurality of second grooves are arranged so that the center line portion of the plurality of first grooves is not located on the same straight line along a direction perpendicular to the first surface.

In this configuration, a plurality of first grooves and a plurality of second grooves are formed on both sides of the metal heat radiating plate in most parts in the perspective plan view (plan view including hidden lines; see through plan view) of the metal heat radiating plate. It is arranged not to become. Further, in this perspective plan view, the grooves that become folds during heat generation do not intersect with the cross. Therefore, when the metal heat radiating plate is heated, the metal heat radiating plate is bent with the groove portion as a crease, and has a shape corrugated like a bellows.
When the insulating heat sink and the metal heat sink are heated with the heat generation of the electronic component, the difference in thermal expansion coefficient between the insulating heat sink and the metal heat sink causes the electronic heat sink The metal heat sink is deformed not only in the vicinity of the parts but also in the direction parallel to the surface of the metal heat sink when viewed as a whole. Therefore, a mountain-shaped warp deformation does not occur in the metal heat sink.
As described above, with this configuration, the mountain-shaped distortion of the metal heat sink joined to the insulating heat sink is suppressed.

  In addition, when grooves are formed on both sides of a metal heat sink, if the grooves overlap in a perspective plan view, the thickness of the overlapped portion will become thin, which will become a heat dam and cooling efficiency will decrease. Resulting in. In this configuration, the plurality of first grooves and the plurality of second grooves are arranged so as not to overlap most parts in the perspective plan view of the metal heat radiating plate, resulting in the formation of the grooves. A decrease in cooling efficiency is suppressed.

  The “joining” between the insulating heat sink and the metal heat sink is to join the two together while maintaining the thermal conductivity between them. Includes contact (soldering, brazing) and the like.

  As a material for the metal heat sink, a material having a thermal conductivity at room temperature (20 ° C.) of 100 W / (m · K) or more is desirable. Specifically, aluminum, gold, silver, copper, magnesium, tungsten, Molybdenum, zinc, etc. can be used. The material of the metal heat sink may be a single material or an alloy. In addition, the thickness of the metal layer is preferably 100 μm to 3 mm.

“Electronic components” to be radiated include semiconductor elements, LEDs, and the like. Moreover, Si, SiC, GaN, Ge, GaAs, etc. can be utilized as the material of the semiconductor element.
The electronic component may be a power semiconductor element (power device). Specific examples include an IGBT (Insulated Gate BipolarTransistor), a rectifier diode, a power transistor, a power MOSFET, a thyristor, and a gate turn-off. A thyristor (GTO), triac, or the like may be used.

Electronic components may be directly joined to the metal heat sink. That is, the insulating heat sink may be joined to the surface of the metal heat sink that does not face the electronic component.
An insulating heat sink may be disposed between the metal heat sink and the electronic component. That is, the electronic component may be attached to the insulating heat sink, and the metal heat sink may be joined to the surface of the insulating heat sink that is not suitable for the electronic component. The “joining” method here includes diffusion bonding, brazing (soldering, brazing) and the like.

As a material of the insulating heat sink, AlN (thermal conductivity: 150 W / (m · K), thermal expansion coefficient: 4.7 × 10 ⁻⁶ [1 / K]), diamond (thermal conductivity: 500 to 1000 W) / (M · K), coefficient of thermal expansion: 2.2 × 10 ⁻⁶ [1 / K]) (and those containing a small amount of impurities). Further, the insulating heat sink may be a DBA (Direct Brazing Aluminum) substrate made of AlN (aluminum nitride).

The insulating heat sink is formed by PVD, CVD (microwave plasma CVD, hot filament CVD, etc.) as a thin film layer on the surface of the metal heat sink. Further, the metal heat radiating plate and the insulating heat radiating plate may be formed as separate plate members.
The thickness of the insulating heat sink is preferably 10 μm to 3 mm.

  The insulating heat radiating plate may be a printed board (printed wiring board; a board having an electric wire pattern formed on the surface) having a heat radiating function.

  In this configuration, the center line portion of the first groove and the center line portion of the second groove do not overlap in the perspective plan view of the metal heat sink, but the end portion of the first groove and the center line portion of the second groove And may overlap. In the perspective plan view of the metal heat sink, the center line portion of the first groove and the end portion of the second groove may overlap.

The groove is “linear”, but this indicates a state of being connected thinly, not in a planar shape. There is some extent in the range of groove widths that are recognized as linear.
Moreover, a groove | channel is formed in a metal heat sink using an end mill and a rotary saw, for example.

The shape of the first groove and the second groove in plan view may be a straight line or a curved line. A plurality of first grooves (or a plurality of second grooves) may be formed continuously. Further, in this case, when the curvature of the groove changes discontinuously (changes rapidly), the change point becomes a boundary between the two first grooves (or the second grooves).
Further, in one first groove (or second groove), it is assumed that the curvature of the groove continuously changes (or is constant).

  The cross section of the first groove and the second groove (cross section orthogonal to the direction in which the groove extends) may be V-shaped, U-shaped, or the like. Further, the cross-sectional shape of the groove may be an angular shape or a rounded shape.

Regarding the “center line portion” and the two “end portions”: the length ratio of one groove (the first groove or the second groove) to the entire length is 80% to 95% in the center line portion, and two It is assumed that it is 5% to 20% at one end (total).
And, “(length ratio of center line portion) and (length ratio of two end portions)” are, for example, “80% and 20%”, “85% and 15%”, “90% and 10%” Or “95% and 5%”. It is assumed that the lengths of the two ends are the same.

  In addition to the metal heat sink and the insulating heat sink, the composite heat sink may include other metal heat sinks.

  (2) In the composite heat radiation plate according to (1) according to the present invention, each of the first grooves and each of the second grooves are in the same straight line along a direction perpendicular to the first surface. You may arrange | position so that it may not be located on a line.

  In this configuration, the plurality of first grooves and the plurality of second grooves are arranged so as not to overlap at all in the perspective plan view of the metal heat sink. For this reason, a decrease in cooling efficiency due to the formation of the grooves can be more reliably suppressed.

  (3) In the composite heat radiation plate according to the above (1) or (2) according to the present invention, a planar region to which an electronic component is bonded is formed on the first surface, and the plurality of first The groove may be formed around the planar region.

  In this configuration, since the groove is not formed in the planar region, the heat radiation effect by the metal heat radiating plate can be obtained without being obstructed by the groove.

  In the second surface, the second groove may be formed on the entire surface. Moreover, it is desirable that the area of the planar region is larger than the area of the installation surface of the electronic component.

  “Join” between an electronic component and a planar region is to join the two while maintaining thermal conductivity between them. The “joining” method here includes diffusion bonding, brazing (soldering, soldering, Brazing) and the like.

  The “planar area” may be a circular area or an area having another shape. The area of the planar region is preferably larger than the area of the installation surface of the electronic component, but the area of the planar region may be smaller than the area of the installation surface of the electronic component.

  (4) In the composite heat sink according to any one of (1) to (3) according to the present invention, the material of the insulating heat sink may be diamond.

Since the thermal conductivity of diamond is high (thermal conductivity: 500 to 1000 W / (m · K)), a composite heat dissipation plate with higher heat dissipation performance can be obtained.
On the other hand, since the thermal expansion coefficient of diamond is small (thermal expansion coefficient: 2.2 × 10 ⁻⁶ [1 / K]), when diamond is used as an insulating heat sink, the metal accompanying the heat generation of electronic components The problem of warp deformation of the heat sink becomes significant.
By using diamond as the material of the insulating heat sink in the composite heat sink of the present invention, high heat dissipation performance can be obtained and distortion of the metal heat sink can be suppressed.

  (5) In the composite heat radiating plate according to any one of (1) to (4) according to the present invention, the plurality of first grooves are swirl radially around a central circular region of the first surface. The plurality of second grooves may be formed in a swirling radial pattern around a circular area in the center of the second surface.

  In this configuration, the first groove and the second groove are formed in a swirling radial shape on both surfaces of the metal heat radiating plate, so when the electronic component is arranged in the center of the metal heat radiating plate, the peripheral region of the circular region is Deformation in a direction parallel to the surface of the metal heat radiating plate and warpage deformation in a circular region are suppressed. Therefore, the mountain-shaped distortion of the metal heat sink is reliably suppressed.

  Hereinafter, “swivel radial” will be described with reference to FIG. In FIG. 6A, a circle 4C is arranged at the center of the surface of the metal plate 4p. A plurality of lines extend radially from the circle 4C. The plurality of lines all extend radially from the center 4Z of the circle 4C. Hereinafter, an example of one line 41P among a plurality of radially extending lines will be described. The line 41P connects the end point 4F and the end point 4D. The end point 4F is located at the end of the metal plate 4p. In FIG. 6A, the end point 4D corresponds to the intersection of the line 41P and the circle 4C. Here, it is assumed that the end point 4D can move (that is, turn) along the circumference of the circle 4C.

  FIG. 6B shows a state after the end point 4D has moved on the circumference of the circle 4C. In this state, a line 41V connects the end point 4D and the end point 4F. The angle formed by the line 41V and the line 41P is α [degree]. The turning of the end point 4D from the state of FIG. 6A to the state of FIG. 6B is referred to as “turning of the angle α”.

  And not only the line 41P but all the lines extending radially, the state after turning the intersection of the circle and the line (corresponding to the end point 4D) by the angle α by the same concept is “turning radial” It is. The arrangement of the plurality of lines in FIG. 6B is a “turning radial” arrangement. And the several line segment of FIG.6 (b) is equivalent to the turning radial groove | channel in the metal heat sink which concerns on this invention.

  In this way, when a plurality of radial lines centered on the center of the circle are arranged, the intersection of each radial line and this circle (corresponding to the end point 4D before rotation) is along the circumference. A plurality of lines are arranged so as to connect each point after rotation (corresponding to the end point 4D after rotation) and each end point (fixed point; corresponding to the end point 4F) of the plate when rotated. The state is assumed to be “turning radial”. Here, the turning angle α is more than 0 degree and less than 90 degrees.

  Note that the end point 4D may be a contact point between the circle 4C and the line 41V, or may not be a contact point. Further, the above description is for explaining the shape of the “swivel radial” groove, and not for the manufacturing process. For example, it is not necessary to form a groove along the line 41P in the manufacturing process. “Swirl radial” is explained as described above.

  The groove (the first groove or the second groove) and the circular region may be in contact with each other at a contact point, or may be in contact at a point closer to the end point (corresponding to the end point 4F in FIG. 6) than the contact point.

  The area of the circular region is preferably larger than the area of the installation surface of the electronic component, but the area of the circular region may be smaller than the area of the installation surface of the electronic component.

  (6) In the composite heat dissipation plate according to any one of (1) to (5) according to the present invention, the plurality of first grooves include a first central groove, a first inclined groove, and a second inclined surface. A plurality of second grooves include a second central groove, a third inclined groove, and a fourth inclined groove, and each of the first central groove and the second central groove includes The first inclined groove and the third inclined groove are formed in a first direction along the first surface, and each of the first inclined groove and the third inclined groove is a direction inclined with respect to the first direction, and the first surface The second inclined groove and the fourth inclined groove are directions inclined with respect to the first direction and the second direction, respectively, and The angle formed by the first direction and the second direction is defined by the first direction and the third direction. 3 equal to the angle between the directions, in perspective plan view, a plurality of the first groove, and by a plurality of the second grooves may have a plurality of parallelogram is formed.

  In this configuration, the plurality of first grooves and the plurality of second grooves are arranged on both surfaces of the metal heat sink so as not to overlap in the perspective plan view of the metal heat sink. Therefore, for example, a crease similar to Miura fold (see Japanese Utility Model Publication No. 56-25023) is formed in the metal heat sink, and the crease becomes a plurality of parallelogram division lines. And when a metal heat sink is heated, it will bend using a groove part as a crease | fold, and will become the shape which wavy in the shape of a bellows in one cross section perpendicular | vertical to a heat sink. Therefore, the mountain-shaped distortion of the metal heat sink is reliably suppressed.

  It should be noted that the formation of the folds of the present configuration includes folds other than Miura folds. The first central groove, the first inclined groove, and the second inclined groove may be continuous or separated. Further, the second central groove, the third inclined groove, and the fourth inclined groove may be continuous or separated.

  A plurality of first central grooves (or a plurality of second central grooves) may be arranged at intervals along the first direction. The plurality of first central grooves (or the plurality of second central grooves) are arranged at intervals along a direction perpendicular to the first direction and along the first surface. It may be.

With respect to the second direction above;
“Inclined direction” with respect to the first direction does not include (i) a direction in which the first direction and the second direction are parallel, and (ii) a direction in which they are orthogonal to each other. To do.

Regarding the third direction above;
In the “inclined direction” with respect to the first direction and the second direction, (i) a direction in which the first direction and the third direction are parallel, and (ii) the second direction and the third direction are parallel. Such a direction, (iii) a direction in which the first direction and the third direction are orthogonal, and (iv) a direction in which the second direction and the third direction are orthogonal are not included.

(7) In order to solve the above problems, the composite heat sink according to the present invention is used for heat dissipation of electronic components, and is joined to the insulating heat sink and the insulating heat sink, and A metal heat radiating plate having a larger coefficient of thermal expansion than the insulating heat radiating plate.
The metal heat sink has a first surface and a second surface that are parallel to each other, and a plurality of first annular grooves are formed concentrically on the first surface, and the second surface A plurality of second annular grooves are concentrically formed on the surface, and the plurality of first annular grooves and the plurality of second annular grooves are arranged concentrically, and each of the first annular grooves The grooves and the respective second annular grooves are arranged so as not to be positioned on the same straight line along a direction perpendicular to the first surface.

In this configuration, the plurality of first annular grooves and the plurality of second annular grooves are arranged concentrically on both surfaces of the metal heat radiating plate so as not to overlap in the perspective plan view of the metal heat radiating plate. That is, all the annular grooves have different diameters. Therefore, when the metal heat sink is heated, the metal heat sink is bent with the groove portion as a crease, and has a corrugated shape in a cross section perpendicular to the heat sink.
When the insulating heat sink and the metal heat sink are heated with the heat generation of the electronic component, the difference in thermal expansion coefficient between the insulating heat sink and the metal heat sink causes the electronic heat sink The metal heat sink is deformed not only in the vicinity of the parts but also in the direction parallel to the surface of the metal heat sink when viewed as a whole. Therefore, a mountain-shaped warp deformation does not occur in the metal heat sink.
As described above, with this configuration, the mountain-shaped distortion of the metal heat sink joined to the insulating heat sink is suppressed.

  Further, in this configuration, the plurality of first annular grooves and the plurality of second annular grooves are arranged so as not to overlap at all in the perspective plan view of the metal heat radiating plate, resulting in the formation of the grooves. A decrease in cooling efficiency is suppressed.

  In addition, it is desirable that a circular plane region for installing an electronic component is formed in the center of the first surface.

  Moreover, the V-shaped, U-shaped, etc. may be sufficient as the shape of the cross section (cross section orthogonal to the direction where a groove | channel is extended) of a 1st annular groove and a 2nd annular groove. Further, the cross-sectional shape of the groove may be an angular shape or a rounded shape.

For example, the first annular groove and the second annular groove may be alternately arranged one by one from the inside, or may be alternately arranged by a plurality from the inside.
The annular groove is formed in the metal heat radiating plate using, for example, an end mill or a rotary saw.

  For matters other than the groove shape (“joining”, “material of metal heat sink”, “electronic component”, “positional relationship between metal heat sink and electronic component”, and “insulating heat sink”) (1 ), The description is omitted.

  (8) The composite heat radiating plate according to any one of (1) to (7) according to the present invention may further include at least one of the metal heat radiating plates. The metal heat sinks are stacked and joined to each other, and each of the metal heat sinks may be partially joined to the adjacent metal heat sink at a plurality of joint locations.

In this configuration, a plurality of metal heat sinks are stacked, and each metal heat sink deforms in a direction parallel to the plate surface when the electronic component generates heat. As a result, in the entire heated radiator plate assembly, the mountain-like distortion of the metal radiator plate is efficiently suppressed.
Moreover, since metal heat sinks are partially joined, the bending deformation of a metal heat sink is not inhibited.
Moreover, the high heat dissipation effect is acquired by the several metal heat sink being stacked.

  Note that “partially” joined does not mean that the entire surface of the plate surface is a joined part, but the joined part is partially formed in the entire surface.

  The method of “joining” a plurality of metal heat sinks includes diffusion bonding, brazing (soldering, brazing) and the like.

  The composite heat dissipation plate according to the present configuration is not limited to a combination of metal heat dissipation plates of the same type among the metal heat dissipation plates having the characteristics (1) to (6) described above, and (1) to (6) above. Among the metal heat sinks having the above characteristics, a plurality of types of metal heat sinks may be combined.

  It is desirable that the metal heat radiation plate is joined at a position corresponding to the top in the bellows shape after heat deformation. Thereby, the bellows-shaped deformation | transformation of a metal heat sink is not inhibited.

1 is a schematic side view showing a composite heat dissipation plate according to a first embodiment of the present invention. It is a perspective view of the metal heat sink which concerns on 1st Embodiment. It is a perspective top view of the metal heat sink which concerns on 1st Embodiment. It is a perspective view which shows the state of the metal heat sink at the time of a heating. It is a reference perspective view for demonstrating the deformation | transformation state of a metal heat sink. It is a reference top view for demonstrating "turning radial form", (a) shows the state before turning, (b) shows the state after turning. It is a reference top view for demonstrating the groove shape of a metal heat sink. It is a figure which shows the Example of the metal heat sink which concerns on a 1st modification, (a) is a perspective view, (b) is A-A 'sectional drawing. It is a figure which shows the Example of the metal heat sink which concerns on a 2nd modification, (a) is a perspective view, (b) is A-A 'sectional drawing. It is a figure which shows the Example of the metal heat sink which concerns on 1st Embodiment, (a) is a perspective view, (b) is A-A 'sectional drawing. It is a figure which shows the conventional metal heat sink as a comparative example, (a) is a perspective view, (b) is A-A 'sectional drawing. It is a perspective view which shows the metal heat sink which concerns on 2nd Embodiment. It is a perspective top view of the metal heat sink which concerns on 2nd Embodiment. It is a perspective view for demonstrating the deformation | transformation state of a metal heat sink. It is a perspective view which shows the metal heat sink which concerns on 3rd Embodiment. It is a perspective top view of the metal heat sink which concerns on 3rd Embodiment. It is a perspective view which shows the heat sink coupling body which concerns on 4th Embodiment. It is a see-through | perspective top view which shows the 2nd, 4th layer metal heat sink based on 4th Embodiment. It is a perspective view which shows the metal heat sink which concerns on 5th Embodiment. It is a perspective top view of the metal heat sink which concerns on 5th Embodiment. It is a perspective view which shows the metal heat sink which concerns on 6th Embodiment. It is a perspective top view of the metal heat sink which concerns on 6th Embodiment. It is a figure which shows the metal heat sink which concerns on 7th Embodiment, (a) is a perspective top view, (b) is C-C 'sectional drawing. It is a figure which shows the Example of the metal heat sink which concerns on 7th Embodiment, (a) is a perspective view, (b) is A-A 'sectional drawing.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. In the following description, “up / down / left / right” refers to up / down / left / right in the figure.

(overall structure)
First, the composite heat sink 1 will be described with reference to FIG. In FIG. 1, only the water cooling jacket 52 shows a cross section, and the other members show side surfaces.

  The composite heat sink 1 is used as a heat sink for IGBTs (electronic parts) 2b and diodes (electronic parts) 2c, which are heating elements. The composite heat sink 1 has a two-layer structure and includes a first metal plate (metal heat sink) 4 and an insulating substrate (insulating heat sink) 3. In the composite heat sink 1, the first metal plate 4 and the insulating substrate 3 are joined by soldering.

  An IGBT (Insulated Gate BipolarTransistor) 2b is a power semiconductor element (power device), and is used as a current control element for driving an electric device of a hybrid vehicle or an electric vehicle. A current exceeding 100 A flows through the IGBT 2b, and the amount of heat generated in the IGBT 2b is large.

  The IGBT 2b and the diode 2c are fixed to the surface of the first metal plate 4 by soldering. In addition, the insulating substrate 3 of the composite heat sink 1 is fixed to the second metal plate 51 by soldering. The second metal plate 51 is a copper plate member.

  The second metal plate 51 is fixed to the upper part of the water cooling jacket 52 by soldering. The water cooling jacket 52 is an aluminum heat sink, and has a water channel (water cooling channel) 52r formed therein. The water channel 52r is a cooling water channel (see arrow W in FIG. 1).

  The composite heat radiating plate 1, the second metal plate 51, and the water cooling jacket 52 constitute a cooling structure 7. In the cooling structure 7, the components are arranged in the order of two electronic components, the first metal plate 4, the insulating substrate 3, the second metal plate 51, and the water cooling jacket 52 from the top.

  The heat generated in the IBGT 2 b and the diode 2 c is sent to the water cooling jacket 52 via the composite heat radiating plate 1 and the second metal plate 51. The electronic components are cooled by heat exchange between the two electronic components (IGBT 2b and diode 2c) and water passing through the water channel 52r.

The IGBT 2b is connected to another control circuit (not shown) using a bonding wire (not shown).
Hereinafter, the configuration of each unit will be described.

(First metal plate)
The 1st metal plate 4 is demonstrated using FIG.2 and FIG.3. 2 and 3, the broken line indicates the shape of the hidden portion, and the two-dot chain line indicates the imaginary line. The first metal plate (metal heat radiating plate) 4 is a copper plate-like member. The shape of the first metal plate 4 is a square in the plan view. The first metal plate 4 is used for heat dissipation of the electronic components (IGBT 2b and diode 2c). The first metal plate 4 is bonded to the insulating substrate 3 and has a thermal expansion coefficient larger than that of the insulating substrate 3. Specifically, the thermal expansion coefficient of the insulating substrate 3 (described later) is 2.2 × 10 ⁻⁶ [1 / K], and the thermal expansion coefficient of the first metal plate 4 is 16.8 × 10 ^−6. [1 / K].

  The first metal plate 4 has a first surface 4s and a second surface 4t that are parallel to each other. The first surface 4s is an upper surface, and the second surface 4t is a lower surface. Eight first grooves 41 are linearly formed on the first surface 4s. In addition, eight second grooves 42 are formed in a linear shape on the second surface 4t. Here, “linear” indicates not a planar shape but a thin continuous state.

  Each groove shape of the first groove 41 and the second groove 42 is U-shaped and squared in a cross section (a cross section perpendicular to the direction in which the groove extends). Further, each of the eight first grooves 41 is different from the other grooves only in the arrangement direction, and the length and shape are all the same. Similarly, each of the eight second grooves 42 differs from the other grooves only in the arrangement direction, and the length and shape are all the same.

Here, each 1st groove | channel 41 is divided into three parts, ie, the centerline part 41c, and the two edge parts 41f (refer the part enclosed with the circle of FIG.2 and FIG.3). The two end portions 41f are located at both ends of the center line portion 41c.
Similarly, each of the second grooves 42 is divided into three parts, that is, a center line part 42c and two end parts 42f (see the part circled in FIG. 3). The two end portions 42f are located at both ends of the center line portion 42c.

The length ratio of the center line portion 41c and the two end portions 41f (the length ratio with respect to the total length of the first groove 41) [%] is as follows.
(A) Length ratio of center line portion 41c = 80%
(B) Length ratio of two end portions 41f (total) = 20%
Note that the lengths of the two end portions 41f are the same. That is, the length ratio of each end 41f is 10%.

  Similarly, the length ratio between the center line portion 42c and the two end portions 42f (the length ratio with respect to the entire length of the second groove 42) is 80% and 20%. The lengths of the two end portions 42f are the same.

  A direction perpendicular to the first surface 4s is defined as a vertical direction D (see arrow D direction in the figure). The center line portion 41 c of each first groove 41 and the center line portion 42 c of each second groove 42 are not located on the same straight line along the vertical direction D. That is, in the perspective plan view of the first metal plate 4 (a plan view including a hidden line; FIG. 3), the grooves that become folds during heat generation do not intersect with the cross.

  Further, the first grooves 41 and the second grooves 42 are arranged so as not to be positioned on the same straight line along the vertical direction D. That is, the plurality of first grooves 41 and the plurality of second grooves 42 are arranged so as not to overlap at all (no overlapping portions) in the perspective plan view (FIG. 3) of the first metal plate 4.

  In the center of the first surface 4s, a planar region 43 to which the electronic component is bonded is formed. The plurality of first grooves 41 are formed around the planar region 43. A groove is not formed in the planar region 43.

A circular region 44 having a radius R1 is formed at the center of the first surface 4s. In the present embodiment, the planar area 43 and the circular area 44 are the same area. The area of the planar region 43 is larger than the area of the installation surface (bottom surface) of the electronic components (IGBT 2b and diode 2c).
The plurality of first grooves 41 are formed in a swirling radial shape around the circular region 44.

  A circular region 47 is also formed in a flat shape at the center of the second surface 4t. The plurality of second grooves 42 are formed in a swirling radial pattern around the circular region 47.

  The arrangement of the plurality of lines in FIG. 6B is a “turning radial” arrangement. And the some line segment of FIG.6 (b) is equivalent to the turning radial groove | channel in a metal heat sink. FIG. 6B shows a state after the end point 4D has moved on the circumference of the circle 4C. In this state, a line 41V connects the end point 4D and the end point 4F. The angle formed by the line 41V and the line 41P is α [degree]. The turning of the end point 4D is referred to as “turning of the angle α”. In the first metal plate 4, the turning angle α is 20 degrees for both the first groove 41 and the second groove 42.

Each first groove 41 and the circular region 44 intersect at a point (see P _{i + 1 in} FIG. 7) closer to the end point (see Q _{i in} FIG. 7) than the contact position.

(About deformation during heat generation)
Next, the deformation state of the first metal plate 4 when the electronic component generates heat will be described with reference to FIG. FIG. 4 shows the state of the first metal plate 4 when the electronic component generates heat. In FIG. 4, components other than the first metal plate 4 (electronic component, insulating substrate 3, second metal plate). 51 and the water cooling jacket 52) are omitted.

  During the heat generation of the electronic component, the second surface 4t of the first metal plate 4 facing the insulating substrate 3 is contracted by the compression force, and the first surface 4s facing the electronic component is compressed. Is stretched by a pulling force. At this time, the first metal plate 4 is bent with the plurality of first grooves 41 and the plurality of second grooves 42 as folds, and has a corrugated shape (see FIG. 4). Further, during this heat generation, bending deformation in all the folds occurs simultaneously.

  FIG. 5 shows the paper 4M folded at the same fold as the first metal plate 4.

(Insulated substrate)
The insulating substrate (insulating heat sink) 3 is a diamond plate member. The insulating substrate 3 is formed as a thin film layer on the surface of the first metal plate 4 by the CVD method. As described above, the thermal expansion coefficient of the insulating substrate 3 is 2.2 × 10 ⁻⁶ [1 / K], which is the thermal expansion coefficient of the first metal plate 4 (16.8 × 10 ⁻⁶ [ 1 / K]).

(Production method of composite heat sink)
Next, the manufacturing method of the composite heat sink 1 is demonstrated. First, the arrangement of the plurality of first grooves 41 and the plurality of second grooves 42 of the first metal plate 4 is determined (groove arrangement design process). In this step, as shown above, a plurality of first grooves 41 are arranged in a swirling radial pattern on the first surface 4s, a plurality of second grooves 42 are arranged in a swirling radial pattern on the second surface 4t, and In the perspective plan view of the first metal plate 4, the plurality of first grooves 41 and the plurality of second grooves 42 are not overlapped.

  Then, according to said determined arrangement | positioning, the some 1st groove | channel 41 and the some 2nd groove | channel 42 are formed in a copper plate (groove formation process). This step is performed using an end mill or a rotary saw. The groove forming step may be performed manually.

  Next, the insulating substrate 3 is formed on the second surface 4t of the first metal plate 4 by a CVD method (insulating layer forming step). The composite heat sink 1 is formed as described above.

(effect)
Next, the effect obtained by the composite heat sink 1 will be described. The composite heat sink 1 is used for heat dissipation of two electronic components (IGBT 2b and diode 2c), and is joined to the insulating substrate 3 and the insulating substrate (insulating heat sink) 3, and the insulation And a first metal plate (metal heat radiating plate) 4 having a thermal expansion coefficient larger than that of the substrate 3.
The first metal plate 4 has a first surface 4s and a second surface 4t that are parallel to each other, and a plurality of first grooves 41 are linearly formed on the first surface 4s. A plurality of second grooves 42 are linearly formed on the second surface 4t, and each of the first grooves 41 has a center line portion 41c and two ends formed at both ends of the center line portion 41c. Each of the second grooves 42 includes a center line portion 42c and two end portions 42f formed at both ends of the center line portion 42c. The line portions 41c and the center line portions 42c of the second grooves 42 are not positioned on the same straight line along the direction perpendicular to the first surface 4s (vertical direction D). One groove 41 and a plurality of second grooves 42 are arranged.

In this configuration, a plurality of first grooves 41 and a plurality of second grooves 42 are formed on both surfaces of the first metal plate (metal heat radiating plate) 4, and a perspective plan view of the first metal plate 4 (a plan view including a hidden line; In the see through plan view), they are arranged so as not to overlap in most parts. Further, in this perspective plan view (FIG. 3), the grooves that become folds during heat generation do not cross. Therefore, when the 1st metal plate 4 is heated, it will bend with a groove part as a crease | fold and will become the shape which wavy in the shape of a bellows.
When the insulating substrate 3 and the first metal plate 4 are heated with the heat generation of the electronic component, the first metal plate is caused by the difference in thermal expansion coefficient between the insulating substrate 3 and the first metal plate 4. 4, not only the vicinity of the electronic component but also the entire first metal plate 4 is deformed, and the first metal plate 4 is deformed in a direction parallel to the surface of the first metal plate 4 when viewed as a whole. To do. Therefore, the first metal plate 4 is not warped in a mountain shape.
As described above, this configuration suppresses the mountain-shaped distortion of the metal heat sink (first metal plate 4) joined to the insulating heat sink (insulating substrate 3).

  In addition, when grooves are formed on both sides of a metal heat sink, if the grooves overlap in a perspective plan view, the thickness of the overlapped portion will become thin, which will become a heat dam and cooling efficiency will decrease. Resulting in. In this configuration, the plurality of first grooves 41 and the plurality of second grooves 42 are arranged so as not to overlap most of the first metal plate 4 in the perspective plan view, so that grooves are formed. A decrease in cooling efficiency due to the above can be suppressed.

  Moreover, in the composite heat sink 1, each 1st groove | channel 41 and each 2nd groove | channel 42 may be located on the same straight line along the direction (vertical direction D) perpendicular | vertical to a 1st surface. Is arranged so that there is no.

  In this configuration, the plurality of first grooves 41 and the plurality of second grooves 42 are arranged so as not to overlap at all in the perspective plan view of the first metal plate 4. For this reason, a decrease in cooling efficiency due to the formation of the grooves can be more reliably suppressed.

  Further, in the composite heat sink 1, a planar region 43 to which electronic components are joined is formed on the first surface 4 s, and the plurality of first grooves 41 are formed around the planar region 43. .

  In this configuration, since the groove is not formed in the planar region, the heat radiation effect by the metal heat radiating plate can be obtained without being obstructed by the groove.

Moreover, in the composite heat sink 1, the material of the insulating substrate 3 is diamond.
Since the thermal conductivity of diamond is high (thermal conductivity: 500 to 1000 W / (m · K)), the composite heat radiating plate 1 with higher heat dissipation performance can be obtained.
On the other hand, since the thermal expansion coefficient of diamond is small (thermal expansion coefficient: 2.2 × 10 ⁻⁶ [1 / K]), when diamond is used as the insulating substrate 3, metal heat dissipation accompanying heat generation of electronic components is performed. The problem of warping deformation of the plate becomes significant.
By using diamond as the material of the insulating substrate 3 in the composite heat radiating plate 1, high heat radiating performance is obtained, and distortion of the first metal plate 4 is suppressed.

  Further, in the composite heat sink 1, the plurality of first grooves 41 are formed in a swirling radial pattern around the central circular region 44 of the first surface 4s, and the plurality of second grooves 42 are formed in the second shape. Around the circular region 47 in the center of the surface 4t, the surface 4t is formed in a swirling radial shape.

  In this configuration, since the first groove 41 and the second groove 42 are formed in a swirling radial shape on both surfaces of the first metal plate 4, when the electronic component is arranged at the center of the first metal plate 4, the circular shape is obtained. The peripheral region of the region is deformed in a direction parallel to the surface of the first metal plate 4, and warpage deformation in the circular region is suppressed. Therefore, the mountain-shaped distortion of the first metal plate 4 is reliably suppressed.

(First embodiment)
Next, an example of the composite heat sink will be described with reference to FIGS. The cross-sectional position AA ′ in FIGS. 8 to 10 corresponds to the cross-sectional position AA ′ in FIG.
Here, a heat transfer test (simulation using a calculation code) was performed using a composite heat sink.

  There are three types of first metal plates used in this test: the first metal plate 104 </ b> A, the first metal plate 104 </ b> B, and the first metal plate 4. What joined the same insulated substrate 3 with respect to these three types of heat sinks was used as a test body.

The first metal plate 104A, the first metal plate 104B, and the first metal plate 4 have different groove depths. Specifically, the first metal plate 104A in FIG. 8 has a groove depth d of 0.6 mm, and the first metal plate 104B in FIG. 9 has a groove depth d of 1.0 mm, as shown in FIG. The first metal plate 4 has a groove depth d of 1.6 mm.
Further, in the first metal plate 104A, the first groove 141A and the second groove 142A correspond to the first groove 41 and the second groove 42, and in the first metal plate 104B, the first groove 141B and the second groove 142A. The two grooves 142B correspond to the first groove 41 and the second groove 42 described above.

(Test conditions)
The test conditions (simulation conditions) are shown below.
-Material of the first metal plate (first metal plate 104A, first metal plate 104B, first metal plate 4): copper-Width of the first metal plate (a in Fig. 2): 40 [mm]
-Length (b) of the first metal plate: 40 [mm]
-Thickness (t) of the first metal plate: 2.0 [mm]
・ Width (g) of groove (first groove and second groove): 0.2 [mm]
Groove depth (d): 0.6, 1.0, and 1.6 [mm]
-Radius (R1) of the circular area 44 and the circular area 47: 10 [mm]
-Power per unit area of electronic components (IGBT 2b and diode 2c) (total): 175 [W / cm ² ]
・ Average temperature on the bottom of electronic components: 65 [℃]
-Number of first grooves: 8-Number of second grooves: 8-Calculation software used: ABAQUS (manufactured by SIMULIA)
・ Junction part: Only one place (center part of the board)
-Deformation magnification of the figure: 1000 times (actual deformation amount is shown enlarged to 1000 times)
・ Temperature of the second surface excluding the central portion (20 mm diameter circular region): 65 degrees

Note that θ _i , P _i , and Q _i in FIG. 7 were obtained according to the following formula 1, formula 2, and formula 3. N in Equation 1 is the total number of grooves (first groove 41 and second groove 42), and here N = 16.

(Comparative example)
As a comparative example, a similar heat transfer test was performed using a conventional metal heat radiating plate 904 shown in FIG. Specifically, a heat transfer test was performed using the composite heat sink shown in FIG. 1 in which the first metal plate 4 was replaced with a conventional metal heat sink 904. The metal heat radiating plate 904 according to the comparative example is different from the first metal plate according to the present embodiment only in that no groove is formed on the surface. Other test conditions (test conditions not related to the groove shape) are the same as those in the above example. FIG. 11 is a view showing a conventional metal heat radiating plate as a comparative example, in which (a) is a perspective view and (b) is an AA ′ sectional view.

(Test results)
8 to 11, the numerical value in the upper right indicates the amount of deformation caused by thermal stress (stress acting on the metal heat sink due to the difference in thermal expansion coefficient between the insulating substrate and the metal heat sink). Is the meter [m].
As a result of the heat transfer test, compared to the comparative example, in the present example, the mountain-shaped distortion of the metal heat radiating plate was suppressed (see (b) of each figure).
Moreover, it turned out that the mountain-shaped distortion of a metal heat sink is suppressed more and it becomes close to a flat plate state, so that the depth of a groove | channel becomes deep.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. In addition, about the part similar to said embodiment, the same code | symbol is attached | subjected to a figure and the description is abbreviate | omitted. FIG. 12 is a perspective view showing a metal heat radiating plate according to the second embodiment. FIG. 13 is a perspective plan view of a metal heat sink according to the second embodiment. FIG. 14 is a perspective view for explaining a deformed state of the metal heat sink. The following description will focus on the parts different from the first embodiment, and the description of the same matters as in the first embodiment will be omitted. In addition, the broken line of FIG. 13 has shown the shape in the hidden part (back side).

The first metal plate (metal heat radiating plate) 204 is different from the above embodiment in the shape of the groove. The first metal plate 204 is disposed in place of the first metal plate 4 in the cooling structure 7 of FIG. 1, and the first metal plate 204 has two electrons, like the first metal plate 4. Arranged between the components (IGBT 2 b and diode 2 c) and the insulating substrate 3.
Further, the composite heat dissipation plate according to the present embodiment includes the first metal plate 204 and the insulating substrate 3.

  The first metal plate (metal heat radiating plate) 204 is a copper plate-like member. Similarly to the first metal plate 4, the shape of the first metal plate 204 is a square in the plan view. The first metal plate 204 has a larger coefficient of thermal expansion than the insulating substrate 3.

  The first metal plate 204 has a first surface 204s and a second surface 204t that are parallel to each other. A plurality of first grooves 241 are linearly formed on the first surface 204s. A plurality of second grooves 242 are linearly formed on the second surface 204t.

  Each groove shape of the first groove 241 and the second groove 242 is U-shaped and squared in a cross section (cross section orthogonal to the direction in which the groove extends).

Here, each first groove 241 is divided into three parts, that is, a center line part (see the M part in FIG. 13) and two end parts (see the N part in FIG. 13). The two end portions N are located at both ends of the center line portion M.
Similarly, each of the second grooves 242 is divided into three parts, that is, a center line part M and two end parts N (see the M part in FIG. 13 and the two N parts at both ends).

(1st groove)
The plurality of first grooves 241 include a plurality of first central grooves 245c, a plurality of first inclined grooves 245f, and a plurality of second inclined grooves 245s. Each first central groove 245c is formed along a first direction E (see the direction of arrow E in the figure). The first direction E is a direction along the first surface 204s.

  Each first inclined groove 245f is formed along the second direction F (see the direction of arrow F in the figure). The second direction F is a direction inclined with respect to the first direction E and is a direction along the first surface 204s. Each first inclined groove 245f extends to one side with respect to the first central groove 245c. For example, on the basis of the first central groove 245c surrounded by the ellipse H in FIG. 12, the first inclined groove 245f extends to the left side of the drawing.

  Each of the second inclined grooves 245s is formed along the third direction G (see the arrow G direction in the figure). The third direction G is a direction inclined with respect to both the first direction E and the second direction F, and is a direction along the first surface 204s. The angle formed by the first direction E and the second direction F is equal to the angle formed by the first direction E and the third direction G.

  Each second inclined groove 245s extends to the other side opposite to the first inclined groove 245f with the first central groove 245c as a reference. For example, on the basis of the first central groove 245c surrounded by the ellipse H in FIG. 12, the second inclined groove 245s extends to the right side of the drawing.

  The first central groove 245c, the first inclined groove 245f, and the second inclined groove 245s are different from each other only in the arrangement direction, and the length and shape are the same in all these grooves.

  The plurality of first central grooves 245c include two types of grooves (see grooves J and K in FIGS. 12 and 13). The groove J extends from one end side of the second inclined groove 245s and from one end side of the first inclined groove 245f. The groove K extends from the other end side of the second inclined groove 245s and from the other end side of the first inclined groove 245f. The first central groove 245c surrounded by the ellipse H corresponds to the groove J.

  The first inclined groove 245f and the second inclined groove 245s are taken as a set, and the row direction Y (see the arrow Y direction in the figure; the direction perpendicular to the first direction E and on the first surface 204s) (Direction along)). That is, the first inclined groove 245f, the second inclined groove 245s, the first inclined groove 245f, and the second inclined groove 245s (hereinafter the same) are arranged in this order, and these end portions N are coupled to each other. This is referred to as a “row arrangement groove”.

  Further, the end N of the first central groove 245c is coupled to the coupling point (vertex) of the first inclined groove 245f and the second inclined groove 245s. The end portions N of the three types of grooves (the first central groove 245c, the first inclined groove 245f, and the second inclined groove 245s) are continuous with each other. Thus, the first central groove 245c, the first inclined groove 245f, and the second inclined groove 245s are formed continuously.

  A row arrangement groove and a plurality of first central grooves 245c (groove J and groove K) extending therefrom are collectively referred to as a “row element”. The row elements are arranged side by side along the column direction X (see the arrow X direction in the figure; parallel to the E direction) at a certain interval.

  In addition, each of the grooves J and K of the plurality of first central grooves 245c is arranged side by side along the column direction X (see the arrow X direction in the figure; parallel to the E direction) at a certain interval. Yes. That is, each of the groove J and the groove K is intermittently arranged along the column direction X.

  In addition, the grooves J and the grooves K of the plurality of first central grooves 245c are arranged along the row direction Y at regular intervals. That is, each of the groove J and the groove K is intermittently arranged along the row direction Y.

  Further, the first inclined groove 245f and the second inclined groove 245s are arranged so as to extend from a position on one end side of the first central groove 245c.

  In the present embodiment, the angle formed by the second direction F and the first direction E is 120 degrees, but the inclination angle of the second direction with respect to the first direction E is not limited to 120 degrees. In the present embodiment, the angle formed by the third direction G and the first direction E is 120 degrees, but the inclination angle of the third direction with respect to the first direction E is not limited to 120 degrees.

(Second groove)
The plurality of second grooves 242 include a plurality of second central grooves 246c, a plurality of third inclined grooves 246f, and a plurality of fourth inclined grooves 246s. Each of the second central grooves 246 c is formed along the first direction E. Each of the third inclined grooves 246 f is formed along the second direction F. Each of the third inclined grooves 246f extends to one side with respect to the second central groove 246c.

  Each of the fourth inclined grooves 246 s is formed along the third direction G. Each fourth inclined groove 246s extends to the other side opposite to the third inclined groove 246f with the second central groove 246c as a reference.

  The second central groove 246c, the third inclined groove 246f, and the fourth inclined groove 246s are different from each other only in the arrangement direction, and the length and shape are the same in all these grooves.

  Similarly to the plurality of first central grooves 245c, the plurality of second central grooves 246c includes two types of grooves (see the grooves Q and R in FIG. 13). The groove Q extends from one end side of the fourth inclined groove 246s and from one end side of the third inclined groove 246f. The groove K extends from the other end side of the fourth inclined groove 246s and from the other end side of the third inclined groove 246f.

  The third inclined groove 246f and the fourth inclined groove 246s are continuously formed along the row direction Y as a set. In other words, the third inclined groove 246f, the fourth inclined groove 246s, the third inclined groove 246f, and the fourth inclined groove 246s (hereinafter the same) are arranged in this order, and these end portions N are joined together. This is referred to as a “row arrangement groove”.

  Further, the end N of the second central groove 246c is coupled to the coupling point (vertex) of the third inclined groove 246f and the fourth inclined groove 246s. The end portions N of the three types of grooves (second central groove 246c, third inclined groove 246f, and fourth inclined groove 246s) are continuous. As described above, the second central groove 246c, the third inclined groove 246f, and the fourth inclined groove 246s are formed continuously.

  The row arrangement grooves and the plurality of second central grooves 246c (grooves Q and R) extending therefrom are referred to as “row elements”. The row elements are arranged side by side along the column direction X at regular intervals.

  In addition, each of the groove Q and the groove R of the plurality of second central grooves 246c is arranged side by side along the column direction X with a constant interval. That is, each of the groove Q and the groove R is intermittently arranged along the column direction X.

  In addition, each of the grooves Q and the grooves R of the plurality of second central grooves 246c is arranged along the row direction Y at a predetermined interval. That is, each of the groove Q and the groove R is intermittently arranged along the row direction Y.

  The third inclined groove 246f and the fourth inclined groove 246s are arranged so as to extend from a position on one end side of the second central groove 246c.

  The relative arrangement of the three types of grooves (second central groove 246c, third inclined groove 246f, and fourth inclined groove 246s) included in the plurality of second grooves 242 is the three types of grooves included in the first groove 241. This is the same as the relative arrangement of the grooves.

(About the first metal plate)
In the first metal plate 204, the center line portion M of each first groove 241 and the center line portion M of each second groove 242 do not lie on the same straight line along the vertical direction D. (See FIG. 13).

  In addition, the first grooves 241 and the second grooves 242 are arranged so as not to be positioned on the same straight line along the vertical direction D. That is, the plurality of first grooves 241 and the plurality of second grooves 242 are arranged so as not to overlap at all in the perspective plan view of the first metal plate 204 (FIG. 13).

In the perspective plan view of the first metal plate 204 (FIG. 13), the first central grooves 245c and the second central grooves 246c are alternately arranged along the row direction Y at a constant interval. In the perspective plan view, the first central grooves 245 c and the second central grooves 246 c are alternately arranged along the row direction Y.
Note that the column direction X and the row direction Y coincide with the two side directions of the first metal plate 204 and are orthogonal to each other. Further, the column direction X and the row direction Y do not have to coincide with the two side directions of the first metal plate 204.

  In the perspective plan view of the first metal plate 204, a plurality of first grooves 241 (a first central groove 245c, a first inclined groove 245f, and a second inclined groove 245s) and a plurality of second grooves 242 ( A plurality of parallelograms are formed by the second central groove 246c, the third inclined groove 246f, and the fourth inclined groove 246s). All of the plurality of parallelograms have the same shape. Further, in the plurality of parallelograms, the opposite side of one set (A set) of the two sets of opposite sides is all along the column direction X (first direction E), and the other set (B set) The opposite side is along the second direction F or the third direction G. Further, in two parallelograms adjacent to each other in the row direction Y, the opposite side of the other set (B set) is the second direction F and the third direction G. The parallelogram groups arranged in a wavy shape along the row direction Y are continuously arranged along the column direction X.

  A plurality of first grooves 241 and a plurality of second grooves 242 are arranged along the folds of the Miura fold. Specifically, the first groove 241 in FIG. 13 corresponds to a mountain fold fold, and the second groove 242 corresponds to a valley fold fold. When the electronic component generates heat, the first metal plate 204 is deformed along the crease (see FIG. 14).

  In the present embodiment, the first groove 241 and the second groove 242 do not overlap in the region surrounded by the broken-line circle B in FIG. However, for example, in the portion surrounded by the broken-line circle B, the end N of the first groove and the end N of the second groove may overlap in the perspective plan view.

  In this configuration, the center line portion M of the first groove and the center line portion M of the second groove do not overlap in the perspective plan view of the metal heat sink, but the end N of the first groove and the second line The center line portion M of the groove may overlap. Further, in the perspective plan view of the metal heat sink, the center line portion M of the first groove and the end portion N of the second groove may overlap.

(About deformation during heat generation)
Next, the deformation state of the first metal plate 204 when the electronic component generates heat will be described with reference to FIG. FIG. 14 shows the state of the first metal plate 204 when the electronic component generates heat. In FIG. 14, components other than the first metal plate 204 (electronic component, insulating substrate 3, second metal plate). 51 and the water cooling jacket 52) are omitted.

  During the heat generation of the electronic component, the second surface 204t of the first metal plate 204 facing the insulating substrate 3 is contracted by the compression force and the first surface 204s facing the electronic component. Is stretched by a pulling force. At this time, the first metal plate 204 is bent with the plurality of first grooves 241 and the plurality of second grooves 242 as folds, and has a corrugated shape (see FIG. 14). Further, during this heat generation, bending deformation in all the folds occurs simultaneously.

(Production method of composite heat sink)
Next, the manufacturing method of the composite heat sink including the first metal plate 204 will be described. First, the arrangement of the plurality of first grooves 241 and the plurality of second grooves 242 of the first metal plate 204 is determined (groove arrangement design process). In this step, the first groove 241 and the second groove 242 are set along the fold of the Miura fold as described above.

  Then, according to the determined arrangement | positioning, the some 1st groove | channel 241 and the some 2nd groove | channel 242 are formed in a copper plate (groove formation process).

  Next, the insulating substrate 3 is formed on the second surface 204t of the first metal plate 204 (insulating layer forming step). A composite heat sink is formed as described above.

(effect)
The effect obtained by the composite heat sink according to the present embodiment will be described. In the composite heat dissipation plate according to the present embodiment, the plurality of first grooves 241 include a first central groove 245c, a first inclined groove 245f, and a second inclined groove 245s, and the plurality of second grooves 242 include Includes a second central groove 246c, a third inclined groove 246f, and a fourth inclined groove 246s.
Each of the first central groove 245c and the second central groove 246c is formed along the first direction E along the first surface 204s, and each of the first inclined groove 245f and the third inclined groove 246f is the second Each of the second inclined groove 245s and the fourth inclined groove 246s is formed along the direction F (the direction inclined with respect to the first direction E and along the first surface 204s). The first direction E and the second direction are formed along the third direction G (the direction inclined with respect to the first direction E and the second direction F and along the first surface 204s). The angle formed by F is equal to the angle formed by the first direction E and the third direction G. In the perspective plan view (FIG. 13), a plurality of first grooves 241 and a plurality of second grooves 242 are used. The parallelogram is formed.

  In this configuration, a plurality of first grooves 241 and a plurality of second grooves 242 are arranged on both surfaces of the first metal plate 204 so as not to overlap in the perspective plan view of the first metal plate 204. Therefore, a fold similar to Miura fold (see Japanese Utility Model Publication No. 56-25023) is formed on the first metal plate 204, and the fold becomes a plurality of parallelogram-shaped dividing lines. When the first metal plate 204 is heated, the first metal plate 204 is bent with the groove portion as a crease, and has a corrugated shape in a cross section perpendicular to the first metal plate 204. Therefore, the mountain-shaped distortion of the first metal plate 204 is reliably suppressed.

  Further, in this configuration, a fold according to the Miura fold is formed on the first metal plate 204. Therefore, the deformation of the first metal plate 204 is limited to a direction parallel to the surface of the first metal plate 204 with respect to the force acting on the surface of the first metal plate 204.

  Further, in this configuration, since the folds follow the Miura fold, bending deformations in all the folds occur simultaneously.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIGS. In addition, about the part similar to said embodiment, the same code | symbol is attached | subjected to a figure and the description is abbreviate | omitted. FIG. 15 is a perspective view showing a metal heat radiating plate according to the third embodiment. FIG. 16 is a perspective plan view of a metal heat sink according to the third embodiment. The following description will focus on the parts different from the second embodiment, and the description of the same matters as in the second embodiment will be omitted. In addition, the part which attached | subjected the code | symbol 304,304s, 341,342,343,344 corresponds to the part which attached | subjected the code | symbol 204,204s, 241,242,43,44 in said embodiment, respectively. In FIG.15 and FIG.16, the shape in the part (back side) where the broken line was hidden is shown, and a dashed-two dotted line shows an imaginary line.

  The first metal plate (metal heat radiating plate) 304 differs from the first metal plate 204 only in that a planar region 343 (circular region 344) is formed on the first surface 304s. An electronic component is joined to 434. The plurality of first grooves 341 are formed around the planar area 343.

  The second surface 204t is the same as in the second embodiment, and no circular region is formed on the second surface 204t. That is, the second groove 242 is also formed in the central portion of the second surface 204t. The metal heat sink may be configured in this way.

  In the present embodiment, a circular region (planar region) is not formed on the second surface 204t, but a circular region may be formed on the first surface and the second surface.

(Fourth embodiment)
Next, 4th Embodiment of this invention is described using FIG.17 and FIG.18. In addition, about the part similar to said embodiment, the same code | symbol is attached | subjected to a figure and the description is abbreviate | omitted. FIG. 17 is a perspective view showing a radiator plate assembly according to the fourth embodiment. FIG. 18 is a perspective plan view showing second and fourth layers of metal heat sinks according to the fourth embodiment. The following description will focus on the parts different from the above embodiment, and the description of the same matters as in the above embodiment will be omitted. In FIG. 18, the broken line indicates the shape of the hidden portion (back side).

The radiator plate assembly 6 is arranged in place of the first metal plate 4 in the cooling structure 7 of FIG. 1, and the radiator plate assembly 6 is an electronic component (like the first metal plate 4). The IGBT 2b and the diode 2c) are disposed between the insulating substrate 3 and the IGBT 2b.
Further, the composite heat sink according to the present embodiment includes a heat sink combination 6 and an insulating substrate 3.

  The radiator plate assembly 6 according to this embodiment includes five metal radiator plates. Specifically, the radiator plate assembly 6 includes a first metal plate 304, two first metal plates (metal radiator plates) 304 </ b> A, and two first metal plates 204. The first layer (uppermost layer) of the radiator plate assembly 6 is the first metal plate 304, the second and fourth layers are the first metal plate 304A, and the third and fifth layers (lowermost layer). Is the first metal plate 204.

  The five metal heat radiating plates are stacked and joined to each other. In addition, each of the five metal heat sinks is partially joined to the adjacent metal heat sink at a plurality of joint locations. “Partially” joined means that a joining portion of two adjacent metal heat radiation plates is partially formed in the entire surface. Moreover, the joining location of the five metal heat radiating plates is a position corresponding to the top in the bellows shape after heat deformation. Thereby, the bellows-shaped deformation | transformation of a metal heat sink is not inhibited.

  In addition, although the several metal heat sink is couple | bonded by diffusion bonding here, as a joining method, other methods, such as brazing (soldering, brazing), may be sufficient.

  The configuration of the first and second metal plates 304A of the second and fourth layers will be described with reference to FIG. The first metal plate 304A and the first metal plate 204 have a plane-symmetric configuration with respect to these contact surfaces. A first surface 304v and a second surface 304w are formed on the first metal plate 304A.

  A portion surrounded by a circle in FIG. 17 and a shaded portion in FIG. 18 indicate a joint portion 304y. 17 and 18 show only a part of the joint 304y (in FIG. 18, only the joint 304y in the upper left region of the figure and only the joint 304y in the first surface 304v. Shown). The joint location 304y is arranged at the “top equivalent position”. Further, the joining portion 304y is formed in a groove vicinity region (a region around the groove across the groove).

The top equivalent position is a region near the first groove (the first groove 341 and the first groove 241) for the first surface (the first surface 304v and the first surface 204s), For the second surface (second surface 304w and second surface 204t), the second groove (
This is the vicinity of the second groove 342 and the second groove 242).

  In these five metal heat sinks, the grooves on the respective surfaces face the grooves on the opposing surfaces. The grooves facing each other are mirror images of each other.

  The effect obtained by the composite heat sink according to the present embodiment will be described. The composite heat radiation plate according to the present embodiment includes a plurality of metal heat radiation plates (a first metal plate 304, two first metal plates 304A, and two first metal plates 204). The metal heat sinks are stacked and joined to each other, and each metal heat sink is partially joined to the adjacent metal heat sink at a plurality of joint locations.

In this configuration, a plurality of metal heat sinks are stacked, and each metal heat sink deforms in a direction parallel to the plate surface when the electronic component generates heat. As a result, in the entire heated radiator plate assembly 6, the mountain-like distortion of the metal radiator plate is efficiently suppressed.
Moreover, since metal heat sinks are partially joined, the bending deformation of a metal heat sink is not inhibited.
Moreover, the high heat dissipation effect is acquired by the several metal heat sink being stacked.

  In the radiator plate assembly 6, a plurality of five metal radiator plates that perform the same deformation as the Miura folding are stacked so as not to inhibit the bellows-like deformation. Thereby, the thermal deformation is three-dimensionally dispersed and the entire warpage deformation is suppressed.

  In the radiator plate assembly 6, a planar region 343 (circular region 344) is formed at the center of the upper surface of the first layer, and no groove is formed in this portion, but the upper surface of the first layer is not formed. Grooves may be formed throughout. That is, the first metal plate 204 in FIG. 12 may be the first layer of the heat sink combination.

  Moreover, in the heat sink combined body 6, although three types of metal heat sinks are stacked, the same kind of metal heat sink may be stacked and the heat sink combined body may be comprised. For example, five first metal plates 204 of FIG. 12 may be stacked to constitute a heat sink combination. Also, all the metal heat sinks included in the heat sink combination may be of different types.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described with reference to FIGS. In addition, about the part similar to said embodiment, the same code | symbol is attached | subjected to a figure and the description is abbreviate | omitted. FIG. 19 is a perspective view showing a metal heat radiating plate according to the fifth embodiment. FIG. 20 is a perspective plan view of a metal heat sink according to the fifth embodiment. The following description will focus on the parts different from the second embodiment, and the description of the same matters as in the second embodiment will be omitted. In addition, the part which attached | subjected the code | symbol 404, 404s, 404t, 441, 442 is corresponded to the part which attached | subjected the code | symbol 204, 204s, 204t, 241, 242 in said embodiment, respectively. 19 and 20, the broken line indicates the shape of the hidden portion (back side).

  The first metal plate (metal heat radiating plate) 404 according to this embodiment is different from the above embodiments in the shapes of the plurality of first grooves 441 and the plurality of second grooves 442. Specifically, in the present embodiment, the first central groove 245c is continuously formed from one end of the plate to the other end in the column direction X. The second central groove 246c is also formed continuously from one end of the plate to the other end in the column direction X. Further, in the perspective plan view (FIG. 20), the columns of the first central grooves 245c and the columns of the second central grooves 246c are alternately arranged along the row direction Y and arranged at regular intervals.

  Further, on the first surface 404s, the first inclined grooves 245f and the second inclined grooves 245s are alternately arranged along the row direction Y and continuously arranged. On the second surface 404t, the third inclined grooves 246f and the fourth inclined grooves 246s are arranged alternately and continuously along the row direction Y.

  In the perspective plan view, the first inclined grooves 245f and the third inclined grooves 246f are alternately arranged along the column direction X and arranged at a constant interval, and the second inclined grooves 245s and the fourth inclined grooves 245s are arranged. The inclined grooves 246 s are alternately arranged along the column direction X and are arranged at regular intervals.

  In the perspective plan view, a plurality of parallelograms are formed by the first central groove 245c, the first inclined groove 245f, the second inclined groove 245s, the second central groove 246c, the third inclined groove 246f, and the fourth inclined groove 246s. Is formed. The metal heat sink may be configured in this way.

(Sixth embodiment)
Next, a sixth embodiment of the present invention will be described with reference to FIGS. In addition, about the part similar to said embodiment, the same code | symbol is attached | subjected to a figure and the description is abbreviate | omitted. FIG. 21 is a perspective view showing a metal heat radiating plate according to the sixth embodiment. FIG. 22 is a perspective plan view of a metal heat sink according to the sixth embodiment. The following description will focus on the parts different from the second embodiment, and the description of the same matters as in the second embodiment will be omitted. In addition, the part which attached | subjected the code | symbol 504,504s, 504t, 541,542 corresponds to the part which attached | subjected the code | symbol 204,204s, 204t, 241,242 in said embodiment, respectively. In FIG. 22, the broken line indicates the shape of the hidden portion (back side).

  The first metal plate (metal heat radiating plate) 504 according to this embodiment is different from the above embodiments in the shapes of the plurality of first grooves 541 and the plurality of second grooves 542. Specifically, in the present embodiment, the first central groove 245c is formed continuously from one end of the plate to the other end in the column direction X. The second central groove 246c is also formed continuously from one end of the plate to the other end in the column direction X. In the perspective plan view, the first central grooves 245c and the second central grooves 246c are alternately arranged along the row direction Y at regular intervals.

  Further, on the first surface 504s, the first inclined groove 245f and the second inclined groove 245s are not continuous. The first inclined groove 245f and the second inclined groove 245s are disposed so as to extend from both end positions of the first central groove 245c.

  In the perspective plan view, the first inclined grooves 245f and the third inclined grooves 246f are alternately arranged along the column direction X and arranged at a constant interval, and the second inclined grooves 245s and the fourth inclined grooves 245s are arranged. The inclined grooves 246 s are alternately arranged along the column direction X and are arranged at regular intervals.

  In the perspective plan view, the first inclined grooves 245f and the fourth inclined grooves 246s are alternately arranged along the row direction Y, and are joined at the ends. Further, in the perspective plan view, the third inclined grooves 246f and the second inclined grooves 245s are alternately arranged along the row direction Y, and are joined at respective end portions.

  In the perspective plan view, a plurality of parallelograms are formed by the first central groove 245c, the first inclined groove 245f, the second inclined groove 245s, the second central groove 246c, the third inclined groove 246f, and the fourth inclined groove 246s. Is formed. The metal heat sink may be configured in this way.

(Seventh embodiment)
Next, a modification of the seventh embodiment of the present invention will be described with reference to FIG. In addition, about the part similar to said embodiment, the same code | symbol is attached | subjected to a figure and the description is abbreviate | omitted. 23A and 23B are views showing a metal heat dissipation plate according to the seventh embodiment, wherein FIG. 23A is a perspective plan view, and FIG. 23B is a CC ′ cross-sectional view. The following description will focus on the parts different from the first embodiment, and the description of the same matters as in the first embodiment will be omitted. In addition, the part which attached | subjected the code | symbol 604, 604s, 604t, 641, 642, 643, 644, 647 is attached | subjected the code | symbol 4, 4s, 4t, 41, 42, 43, 44, 47 in said embodiment, respectively. It corresponds to the part. In FIG. 22, the broken line indicates the shape of the hidden portion (back side).

The first metal plate (metal heat radiating plate) 604 has a groove shape different from that of the above embodiment. The first metal plate 604 is arranged instead of the first metal plate 4 in the cooling structure 7 of FIG. 1, and the first metal plate 604 is an electronic component (like the first metal plate 4). The IGBT 2b and the diode 2c) are disposed between the insulating substrate 3 and the IGBT 2b.
In addition, the composite heat dissipation plate according to this embodiment includes a first metal plate 604 and an insulating substrate 3.

  The first metal plate (metal heat radiating plate) 604 is a copper plate-like member. Similarly to the first metal plate 4, the shape of the first metal plate 604 is a square in the plan view. The first metal plate 604 has a larger coefficient of thermal expansion than the insulating substrate 3.

  The first metal plate 604 has a first surface 604s and a second surface 604t that are parallel to each other. Three first annular grooves (a first annular groove 641a, a first annular groove 641b, and a first annular groove 641c) are formed concentrically on the first surface 604s.

  Two second annular grooves (second annular groove 642a and second annular groove 642b) are formed concentrically on the second surface 604t. Further, the three first annular grooves on the first surface 604s and the two second annular grooves 604t on the second surface share the same center (center point O in FIG. 23) and are concentric. Is arranged.

  In addition, the first annular grooves and the second annular grooves are arranged so as not to be positioned on the same straight line along the vertical direction D. In other words, the plurality of first grooves 541 and the plurality of second grooves 542 are arranged so as not to overlap at all in the perspective plan view of the first metal plate 604 (FIG. 23A).

  Further, the five annular grooves have a diameter increasing in the order of the first annular groove 641a, the second annular groove 642a, the first annular groove 641b, the second annular groove 642b, and the first annular groove 641c. That is, in the perspective plan view, the five annular grooves are arranged in the order of the first annular groove 641a, the second annular groove 642a, the first annular groove 641b, the second annular groove 642b, and the first annular groove 641c from the inside. (From the inside, the first annular groove and the second annular groove are alternately arranged).

  Note that a circular region 644 (a planar region 643) is formed at the center of the first surface 604s. The circular region 644 is an inner region of the first annular groove 641a that is the innermost annular groove. The area of the circular region 644 is larger than the area of the installation surface (bottom surface) of the electronic components (IGBT 2b and diode 2c). A circular region is also formed in a flat shape at the center of the second surface 604t.

(effect)
The effect obtained by the composite heat sink according to the present embodiment will be described. The composite heat sink according to the present embodiment is used for heat dissipation of two electronic components (IGBT 2b and diode 2c), and is joined to the insulating substrate 3 and the insulating substrate (insulating heat sink) 3. And a first metal plate (metal heat radiating plate) 604 having a thermal expansion coefficient larger than that of the insulating substrate 3. The first metal plate 604 has a first surface 604s and a second surface 604t that are parallel to each other. The first surface 604s includes three first annular grooves (first annular groove 641a, first annular groove). The groove 641b and the first annular groove 641c) are formed concentrically, and two second annular grooves (the second annular groove 642a and the second annular groove 642b) are concentric on the second surface 604t. The plurality of first annular grooves and the plurality of second annular grooves are arranged concentrically and alternately from the inside, and each of the first annular grooves, each of the second annular grooves, Are arranged on the same straight line along the direction perpendicular to the first surface 604s.

In this configuration, the plurality of first annular grooves and the plurality of second annular grooves are not overlapped on both surfaces of the first metal plate 604 in the perspective plan view of the first metal plate 604 (FIG. 23A). Are arranged concentrically. That is, all the annular grooves have different diameters. Therefore, when the first metal plate 604 is heated, the first metal plate 604 is bent with the groove portion as a crease, and has a corrugated shape in a cross section perpendicular to the heat radiating plate.
When the insulating substrate 3 and the first metal plate 604 are heated with the heat generation of the electronic component, the difference between the thermal expansion coefficients of the insulating substrate 3 and the first metal plate 604 causes the first metal plate. In addition to the vicinity of the electronic component 604, the entire first metal plate 604 is deformed, and the first metal plate 604 is deformed in a direction parallel to the surface of the first metal plate 604 when viewed as a whole. To do. Therefore, a mountain-shaped warp deformation does not occur in the first metal plate 604.
As described above, this configuration suppresses the mountain-shaped distortion of the metal heat sink (first metal plate 4) joined to the insulating heat sink (insulating substrate 3).

  Further, in this configuration, the plurality of first annular grooves and the plurality of second annular grooves are arranged so as not to overlap at all in the perspective plan view of the first metal plate 604, so that the grooves are formed. The resulting decrease in cooling efficiency can be suppressed.

(Second embodiment)
Next, an example of the first metal plate 604 will be described with reference to FIG. FIG. 24 is a view showing an example of a metal heat radiating plate according to the seventh embodiment, wherein (a) is a perspective view and (b) is an AA ′ sectional view. Note that the cross-sectional position AA ′ in FIG. 24 corresponds to the cross-sectional position CC ′ in FIG.

  Here, a heat transfer test (simulation) was performed using a composite heat sink including the first metal plate 604 (the first metal plate 604 and the insulating substrate 3 joined). The test was performed in the form of the cooling structure described above.

(Test conditions)
The test conditions are shown below. The test conditions are the same as those in the first embodiment.
-Material of the first metal plate: Copper-Width of the first metal plate: 40 [mm]
-Length of the first metal plate: 40 [mm]
-Thickness of the first metal plate: 2.0 [mm]
・ Width of groove (first groove and second groove): 0.2 [mm]
-Groove depth: 1.0 [mm]
-Radius of the first annular groove 641a: 11 [mm]
-Radius of the first annular groove 641c: 19 [mm]
-Power per unit area of electronic components (IGBT 2b and diode 2c) (total): 175 [W / cm ² ]
・ Average temperature on the bottom of electronic components: 65 [℃]
-Number of first annular grooves: 3-Number of second annular grooves: 2-Calculation software used: ABAQUS (manufactured by SIMULIA)
・ Junction part: Only one place (center part of the board)
-Deformation magnification of the figure: 1000 times (actual deformation amount is shown enlarged to 1000 times)
-Temperature of the portion of the second surface 604t excluding the central portion (20 mm diameter circular region): 65 degrees

(Comparative example)
As a comparative example, a similar heat transfer test was performed using a conventional metal heat radiating plate 904 shown in FIG. Specifically, a heat transfer test was performed using the cooling structure of FIG. 1 in which the first metal plate 4 was replaced with a conventional metal heat radiating plate 904. The metal heat radiating plate 904 according to the comparative example is different from the first metal plate 604 according to the present embodiment only in that no groove is formed on the surface. Other implementation conditions (test conditions not related to the groove shape) are the same as those in the second embodiment.

(Test results)
The numerical value of the index in the upper right in FIG. 24 indicates the amount of deformation caused by thermal stress, and the unit is meter [m].
As a result of the heat transfer test, compared to the comparative example, in the present example, the mountain-shaped distortion of the metal heat radiating plate was suppressed, and it was close to a flat plate state.

(About other embodiments)
The embodiment of the present invention is not limited to the above embodiment. For example, the number of repetitions of the shape pattern of the first groove and the second groove with respect to the column direction X and the row direction Y is not limited to the above number, and may be larger or smaller.

  Further, the second metal plate 51 may not be provided. Further, the second metal plate 51 has the structure of the metal heat radiating plate of the present invention (the first metal plate 204, the first metal plate 304, the first metal plate 404, the first metal plate 504, the first metal plate 604, etc.). You may have. That is, the insulating heat sink may be sandwiched between the two metal heat sinks of the present invention. In addition, the number of electronic components to be radiated is not limited to two.

  In the above, the electronic component, the metal heat radiating plate, the insulating substrate 3, the second metal plate 51, and the water cooling jacket 52 are joined by soldering, while maintaining thermal conductivity between them. As long as they are bonded, these “bonding” methods may be diffusion bonding, brazing, or the like.

  In the above embodiment, the shape of the metal heat sink is a square in the plan view, but the shape of the metal heat sink may be a rectangle in the plan view, or other polygonal shape. There may be.

  The present invention can be used as a metal heat sink for heat dissipation of electronic components.

1 Composite heat sink 2b IGBT (electronic component)
2c Diode (electronic component)
3 Insulating substrate (insulating heat sink)
4 1st metal plate (metal heat sink)
4s 1st surface 4t 2nd surface 41 1st groove | channel 41c Center line part 41f End part 42 2nd groove | channel 42c Center line part 42f End part 43 Plane area | region 44 Circular area | region 47 Circular area | region 245c 1st center groove | channel 245f 1st inclination Groove 245s Second inclined groove 246c Second central groove 246f Third inclined groove 246s Fourth inclined groove 51 Second metal plate 52 Water cooling jacket 52r Water channel 7 Cooling structure

Claims (8)

A composite heat sink (1) used for heat dissipation of electronic components (2b, 2c),
An insulating heat sink (3);
A metal heat radiating plate (4) joined to the insulating heat radiating plate and having a larger coefficient of thermal expansion than the insulating heat radiating plate,
The metal heat sink has a first surface (4s) and a second surface (4t) parallel to each other,
A plurality of first grooves (41) are linearly formed on the first surface,
A plurality of second grooves (42) are formed in a linear shape on the second surface,
Each of the first grooves includes a center line portion (41c) and two end portions (41f) formed at both ends of the center line portion,
Each of the second grooves includes a center line portion (42c) and two end portions (42f) formed at both ends of the center line portion,
The center line portion of each of the first grooves and the center line portion of each of the second grooves are not located on the same straight line along a direction perpendicular to the first surface. The composite heat sink, wherein the plurality of first grooves and the plurality of second grooves are arranged.   Each of the first grooves and each of the second grooves are arranged so as not to be located on the same straight line along a direction perpendicular to the first surface. The composite heat sink according to claim 1. A planar region (43) to which the electronic component is joined is formed on the first surface,
The composite heat sink according to claim 1, wherein the plurality of first grooves are formed around the planar region.   The composite heat sink according to any one of claims 1 to 3, wherein a material of the insulating heat sink is diamond. The plurality of first grooves are formed in a swirling radial shape around a circular region (44) in the center of the first surface,
5. The plurality of second grooves are formed in a swirling radial shape around a central circular region (47) of the second surface. 6. Composite heatsink. The plurality of first grooves include a first central groove (245c), a first inclined groove (245f), and a second inclined groove (245s),
The plurality of second grooves include a second central groove (246c), a third inclined groove (246f), and a fourth inclined groove (246s),
Each of the first central groove and the second central groove is formed along a first direction along the first surface;
Each of the first inclined groove and the third inclined groove is a direction inclined with respect to the first direction, and is formed along a second direction along the first surface,
Each of the second inclined groove and the fourth inclined groove is a direction inclined with respect to the first direction and the second direction, and is formed along a third direction along the first surface. And
The angle formed by the first direction and the second direction is equal to the angle formed by the first direction and the third direction,
In the perspective plan view, a plurality of parallelograms are formed by a plurality of the first grooves and the plurality of second grooves, according to any one of claims 1 to 5. The composite heat sink described. A composite heat sink used for heat dissipation of electronic components (2b, 2c),
An insulating heat sink (3);
A metal heat radiating plate (604) joined to the insulating heat radiating plate and having a larger coefficient of thermal expansion than the insulating heat radiating plate,
The metal heat sink has a first surface and a second surface parallel to each other,
A plurality of first annular grooves (641a, 641b, 641c) are formed concentrically on the first surface,
A plurality of second annular grooves (642a, 642b) are formed concentrically on the second surface,
The plurality of first annular grooves and the plurality of second annular grooves are arranged concentrically,
Each said 1st annular groove and each said 2nd annular groove are arrange | positioned so that it may not be located on the same straight line along the direction perpendicular | vertical to a said 1st surface, It is characterized by the above-mentioned. A composite heat sink. Further comprising at least one said metal heat sink,
The plurality of metal heat sinks are stacked and joined together,
8. The composite according to claim 1, wherein each of the metal heat sinks is partially joined to the adjacent metal heat sink at a plurality of joint locations. 9. Heat sink.

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