Heat dissipation structure

Abstract

To provide a heat dissipation structure which is excellent in heat cycle characteristics.SOLUTION: A heat dissipation structure has an electric circuit device including heating elements and heat dissipation plates provided on both main surfaces of the heating elements, a pair of coolers laminated on the heat dissipation plates through an insulation plate, and a fastening tool for holding the electric circuit device, the insulation plates, and the coolers in a state of pressed in a lamination direction, wherein the insulation plate contains a porous nitride sintered plate, and a resin filled into pores of the nitride sintered plate, and heat resistance in the lamination direction is 0.30°C / W or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a heat dissipation structure. [Background technology]

[0002] Power modules that control large currents are used in the fields of automobiles, electric railways, industrial equipment, power generation, and the like. Semiconductor elements and ceramic circuit boards are used in such power modules. Power modules are required to have high heat dissipation properties as their output becomes higher. In addition, in electronic devices such as personal computers and servers, there is a demand for high performance heat dissipation members incorporated in electronic devices as they become smaller, thinner, and lighter.

[0003] Patent Document 1 discloses a heat dissipation structure for an electric circuit device, which includes a heat sink exposed to the outside of the electric circuit device, a heat transfer member, and a cooler arranged to form a laminated structure, characterized in that the heat transfer member is a ceramic resin composite in which a resin composition is impregnated into a sintered body in which ceramic primary particles form a three-dimensional integral structure, and the heat transfer member is arranged to be laminated in direct contact with at least one of the heat sink and the cooler. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018 / 025933 Summary of the Invention [Problem to be solved by the invention]

[0005] The ceramic resin composite described above is a boron nitride sintered body and a semi-cured thermosetting resin composition containing an epoxy resin is used, and when forming a heat dissipation structure for an electric circuit device, the components are laminated and heat-treated to cure the semi-cured thermosetting resin composition and bond the components together. However, equipment is required to cure the thermosetting resin composition, and depending on the curing conditions, etc., there are cases where the expected performance is not achieved, so the curing conditions must be adjusted.

[0006] Therefore, a method may be considered in which the ceramic resin composite is used after the thermosetting resin composition containing the epoxy resin is completely cured. If such a solution is possible, the above-mentioned equipment would be unnecessary, and the performance of the ceramic resin composite that becomes the insulating layer would be specified at the time of shipment, so that adjustment of the curing conditions, etc. would also be unnecessary. However, according to the studies of the present inventors, a heat dissipation structure using a ceramic resin composite that has been completely cured in advance may have lower performance than a heat dissipation structure manufactured using a conventional semi-cured resin.

[0007] The heat dissipation structure described above is also required to have sufficiently excellent reliability depending on the application in which it is used, and is required to maintain sufficient reliability even when exposed to heat cycles under severe conditions, such as in power devices.

[0008] An object of the present disclosure is to provide a heat dissipation structure having excellent heat cycle characteristics. [Means for solving the problem]

[0009] According to the study by the present inventors, when a conventional thermosetting resin composition containing an epoxy resin is impregnated into a nitride sintered plate and completely cured to use the member as an insulating layer, the member is hard and lacks flexibility, and therefore has poor conformability to the surface of an electric circuit device and a cooler, and sufficient heat dissipation is not achieved due to the generation of voids at the interface, and the properties change before and after a heat cycle test due to the voids at the interface.Furthermore, when a member in which the epoxy resin is completely cured as described above is used as an insulating layer, increasing the clamping pressure in order to reduce the voids between the member and other members leads to damage of the member.The present disclosure is based on these findings.

[0010] One aspect of the present disclosure provides a heat dissipation structure having an electric circuit device including a heat generating element and a heat dissipation plate provided on both main surfaces of the heat generating element, a pair of coolers stacked on the heat dissipation plate via an insulating plate, and a fastener that holds the electric circuit device, the insulating plate, and the cooler in a pressurized state in the stacking direction, wherein the insulating plate includes a porous nitride sintered plate and a resin filled in the pores of the nitride sintered plate, and the heat dissipation structure has a thermal resistance in the stacking direction of 0.30°C / W or less.

[0011] The heat dissipation structure has a thermal resistance in the stacking direction within a predetermined range. The thermal resistance within the above range means that the insulating plate has high adhesion to the electric circuit device and the heat dissipation plate. With this configuration, the heat dissipation structure can suppress fluctuations in performance values ​​such as thermal resistance before and after a heat cycle test, and can exhibit excellent heat cycle characteristics.

[0012] The porosity of the nitride sintered plate may be 25 to 65% by volume.

[0013] The filling rate of the resin in the pores may be 90% by volume or more.

[0014] The insulating plate may have a thickness of 0.35 mm or less.

[0015] The pressure applied by the fastener in the stacking direction may be 10 MPa or more. Effect of the Invention

[0016] According to the present disclosure, a heat dissipation structure having excellent heat cycle characteristics can be provided. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of a heat dissipation structure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings as appropriate. However, the following embodiments are merely examples for explaining the present disclosure, and are not intended to limit the present disclosure to the following contents. In the description, the same reference numerals are used for the same elements or elements having the same functions, and redundant descriptions are omitted as the case may be. In addition, positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings, unless otherwise specified. Furthermore, the dimensional ratios of each element are not limited to those shown in the drawings.

[0019] Unless otherwise specified, the materials exemplified in this specification can be used alone or in combination of two or more. When a plurality of substances corresponding to each component are present in the composition, the content of each component in the composition means the total amount of the plurality of substances present in the composition, unless otherwise specified.

[0020] One embodiment of the heat dissipation structure includes an electric circuit device including a heat generating element and a heat dissipation plate provided on both main surfaces of the heat generating element, a pair of coolers stacked on the heat dissipation plate via an insulating plate, and a fastener for holding the circuit device, the insulating plate, and the cooler in a pressurized state in the stacking direction. In the heat dissipation structure, the insulating plate includes a porous nitride sintered plate and a resin filled in the pores of the nitride sintered plate. The heat dissipation structure has a thermal resistance of 0.30° C. / W or less in the stacking direction of the circuit device, the insulating plate, and the cooler.

[0021] FIG. 1 is a schematic cross-sectional view showing an example of a heat dissipation structure. The heat dissipation structure 100 shown in FIG. 1 includes a cooler 30 having a through hole at an end into which a fastener 40 is inserted, an insulating plate 20 provided so as to be in direct contact with the main surface of the cooler 30 in a region closer to the center than the through hole of the cooler 30, and an electric circuit device 10 arranged to be sandwiched between the pair of insulating plates 20, which are stacked. The electric circuit device 10, the insulating plate 20, and the cooler 30 are held in a state of being pressed in the stacking direction by the fastener 40 inserted into the through hole of the cooler 30. The electric circuit device 10 is composed of a heat generating element 2, a heat dissipation plate 4 provided on both main surfaces of the heat generating element 2, and a sealing material 6 provided so as to cover at least a part of the heat generating element 2 and the heat dissipation plate 4. Although the pair of coolers 30 in FIG. 1 are shown as having the same shape, they may have different shapes, and as long as pressure can be applied between the coolers 30 by the fastener 40, the through hole may be formed in only one of the coolers 30.

[0022] The heat generating element 2 incorporated in the electric circuit device 10 may be an element that generates heat as it is used. The heat generating element 2 may be, for example, an element that generates heat when used by passing a current through it. The heat generating element 2 may be, for example, a semiconductor element or a power semiconductor element. The power semiconductor element is, for example, an element that is responsible for driving control of motors, lighting devices, etc., and power-related control such as power conversion.

[0023] The heat sink 4 incorporated in the electric circuit device 10 dissipates heat generated from the heat generating element 2 to the outside. The heat sink 4 may be disposed in the vicinity of the heat generating element 2, but is preferably disposed so as to be in direct contact with the heat generating element 2. The heat sink 4 is also preferably disposed so as to be in direct contact with the insulating plate 20, and from this viewpoint, it is desirable for the heat sink 4 to have an exposed surface that is exposed to the outside of the electric circuit device 10. With this configuration, heat is transferred from the heat sink 4 to the cooler 30 via the insulating plate 20, thereby making it possible to obtain a heat dissipation structure 100 with superior heat dissipation properties.

[0024] The heat sink 4 may be, for example, a metal plate. Examples of metals constituting the heat sink 4 include copper, aluminum, titanium, and alloys thereof. From the viewpoint of improving heat dissipation, the metal constituting the heat sink 4 preferably contains copper, and more preferably is copper.

[0025] The upper limit of the thickness of the heat sink 4 may be, for example, 3.0 mm or less, 2.7 mm or less, 2.5 mm or less, or 2.0 mm or less. By setting the upper limit of the thickness of the heat sink 4 within the above range, the heat diffusion performance of the heat sink can be further improved while maintaining the weight reduction of the heat dissipation structure. The lower limit of the thickness of the heat sink 4 may be, for example, 0.3 mm or more, 0.5 mm or more, 0.7 mm or more, or 1.0 mm or more. By setting the lower limit of the thickness of the heat sink 4 within the above range, the thermal resistance of the heat dissipation structure can be further reduced while maintaining the diffusion performance of the heat sink of the heat generated from the heat generating element. The thickness of the heat sink 4 may be adjusted within the above range, and may be, for example, 0.3 to 3.0 mm.

[0026] The sealing material 6 protects the heat generating element 2 from light, heat, water, etc. The sealing material 6 may be a curable resin. Examples of the curable resin include an epoxy resin and a silicone resin.

[0027] The insulating plate 20 is a resin-filled plate having a nitride sintered plate and a resin filled in the pores of the nitride sintered plate. The nitride sintered plate contains nitride particles formed by sintering primary particles of nitride together and pores. The nitride constituting the nitride particles may contain at least one selected from the group consisting of boron nitride, aluminum nitride, and silicon nitride, for example. From the viewpoint of providing the insulating plate 20 with superior heat dissipation, the nitride may contain boron nitride, and is preferably boron nitride.

[0028] The average pore size of the nitride sintered plate may be, for example, 4.0 μm or less, 3.8 μm or less, 3.6 μm or less, or 3.5 μm or less. Since the size of the pores in such a nitride sintered plate is small, the contact area between the nitride particles can be kept sufficiently large, and the heat dissipation property of the insulating plate 20 can be further improved. The average pore size of the nitride sintered plate may be, for example, 0.8 μm or more, 1.0 μm or more, 1.2 μm or more, 1.4 μm or more, 1.6 μm or more, 1.7 μm or more, 1.8 μm or more, 2.0 μm or more, 2.5 μm or more, or 3.0 μm or more. Since such a nitride sintered plate can be sufficiently deformed by applying pressure during bonding, the followability of the interface can be further improved when laminated with the electric circuit device 10 and the cooler 30, and the heat cycle characteristics of the obtained heat dissipation structure can be further improved. The average pore size of the nitride sintered plate may be adjusted within the above-mentioned range, and may be, for example, 1.0 to 4.0 μm, or 3.0 to 3.5 μm.

[0029] The average pore diameter (median pore diameter) of the nitride sintered plate can be measured by the following procedure. First, the insulating plate 20 is heated to burn and remove the resin, thereby obtaining a nitride sintered plate. Then, using a mercury porosimeter, the pore diameter distribution is obtained when the nitride sintered plate is pressurized while increasing the pressure from 0.0042 MPa to 206.8 MPa. With the horizontal axis representing the pore diameter and the vertical axis representing the cumulative pore volume, the pore diameter at which the cumulative pore volume reaches 50% of the total pore volume is the average pore diameter. As the mercury porosimeter, for example, one manufactured by Shimadzu Corporation can be used.

[0030] The upper limit of the porosity of the nitride sintered plate, i.e., the ratio of the volume of the pores in the nitride sintered plate, may be, for example, 65% by volume or less, 60% by volume or less, or 58% by volume or less. When the upper limit of the porosity of the nitride sintered body is within the above range, the decrease in the mechanical strength of the nitride sintered plate can be more sufficiently suppressed, and the insulating plate 20 with better handleability can be provided. The lower limit of the porosity of the nitride sintered plate may be, for example, 25% by volume or more, 28% by volume or more, 30% by volume or more, 32% by volume or more, 34% by volume or more, 36% by volume or more, 38% by volume or more, 40% by volume or more, 42% by volume or more, 44% by volume or more, or 46% by volume or more. When the upper limit of the porosity of the nitride sintered body is within the above range, the resin content can be improved, the flexibility of the insulating plate 20 can be improved, and the followability of the interface when laminated with the electric circuit device 10 and the cooler 30 can be further improved, and the heat cycle characteristics of the obtained heat dissipation structure can be further improved. The porosity of the nitride sintered plate may be adjusted within the above-mentioned range, and may be, for example, 25 to 65 volume %, 30 to 65 volume %, or 40 to 60 volume %.

[0031] The upper limit of the bulk density of the nitride sintered plate is, for example, 1700 kg / m 3 Below 1600kg / m 3 Below 1500kg / m 3 Below 1400kg / m 3 or less than 1300kg / m 3 The lower limit of the bulk density of the nitride sintered plate is, for example, 1000 kg / m 3 More than 1100kg / m 3 or more than 1200kg / m 3 It may be more than that.

[0032] The porosity in this specification is calculated from the bulk density [Y (kg / m 3 )] was calculated, and the bulk density was compared with the theoretical density of the nitride [X(kg / m 3 )], the theoretical density X can be calculated by the following formula (1). When the nitride constituting the nitride sintered plate is boron nitride, the theoretical density X is 2280 kg / m 3When the nitride sintered plate is made of aluminum nitride, the theoretical density X is 3260 kg / m 3 When the nitride sintered plate is made of silicon nitride, the theoretical density X is 3170 kg / m 3 Since the insulating plate 20 is impregnated with resin, when the insulating plate 20 is used as the measurement object, it is possible to perform a heat treatment at 800°C or higher for 5 hours in advance to burn off and remove the resin, and then use the resulting nitride sintered plate as the measurement object. Porosity (volume%) = [1-(Y / X)] x 100 (1)

[0033] When the nitride sintered plate is a boron nitride sintered plate, the bulk density Y is 800 to 1500 kg / m 3 may be 1000 to 1400 kg / m 3 When the bulk density Y is within the above range, it is possible to achieve a higher level of both the strength of the nitride sintered plate and the improvement of the heat cycle characteristics of the heat dissipation structure by increasing the filling amount of the resin.

[0034] The resin filled in the pores of the nitride sintered plate may be, for example, a resin with relatively high flexibility. Examples of the resin include silicone resin and thermoplastic resin with a softening point of 80° C. or higher. Examples of the silicone resin include addition reaction type silicone. Examples of the addition reaction type silicone include one-liquid reaction type silicone resin containing an organopolysiloxane having both a vinyl group and a hydrosilyl group (H-Si group) in one molecule, and two-liquid reaction type silicone resin containing an organopolysiloxane having a vinyl group at the end or side chain and an organopolysiloxane having two or more hydrosilyl groups at the end or side chain. Specific examples of the addition reaction type silicone include "XE14-B8530A / B" (trade name) manufactured by MOMENTIVE and "YE5822" (trade name) manufactured by GE Toshiba Silicone. An example of a thermoplastic resin having a softening point of 80° C. or higher is a hydrocarbon-based cooligomer (manufactured by Henkel, product name: “PSX-Pm”). The softening point of the thermoplastic resin may be 100° C. or higher, 120° C. or higher, or 150° C. or higher.

[0035] In the insulating plate 20, the filling rate of the resin in the pores of the nitride sintered plate may be adjusted from the viewpoint of improving the conformability of the main surface of the insulating plate 20 to the main surfaces of the electric circuit device 10 and the cooler 30. The lower limit of the filling rate of the resin in the pores of the nitride sintered plate may be, for example, 90 volume % or more, 92 volume % or more, 94 volume % or more, or 96 volume % or more. The upper limit of the filling rate of the resin in the pores of the nitride sintered plate is not particularly limited and may be 100 volume % or more, 99 volume % or less, or 98 volume % or less. The filling rate of the resin in the pores of the nitride sintered plate may be adjusted within the above-mentioned range, and may be, for example, 90 to 99 volume %.

[0036] In this specification, the resin filling rate means the ratio of the volume of the pores filled with resin to the total volume of the pores in the nitride sintered plate. The resin filling rate in the insulating plate 20 is measured by the method described in the examples of this specification.

[0037] The lower limit of the elastic modulus of the insulating plate 20 may be, for example, 200 MPa or more, 250 MPa or more, 300 MPa or more, or 350 MPa or more. When the lower limit of the elastic modulus is within the above range, the handling property of the insulating plate 20 is improved, and the occurrence of damage to the heat dissipation structure due to pressure by the fastener 40 can be suppressed. The upper limit of the elastic modulus of the insulating plate 20 may be, for example, 2300 MPa or less, 2000 MPa or less, 1700 MPa or less, or 1500 MPa or less. When the upper limit of the elastic modulus is within the above range, the insulating plate 20 can be appropriately deformed by pressure by the fastener 40 when preparing the heat dissipation structure, and the conformability to the main surfaces of the electric circuit device 10 and the cooler 30 can be further improved, and the heat cycle characteristics of the obtained heat dissipation structure can be further improved. The elastic modulus of the insulating plate 20 may be adjusted within the above range, and may be, for example, 200 to 2300 MPa.

[0038] The elastic modulus in this specification means a value measured by the following method. First, a nitride sintered body (e.g., boron nitride sintered body) is processed to prepare a measurement sample having a prismatic shape (length x width x height = 10 mm x 10 mm x 0.4 mm). Then, the measurement sample is subjected to the compression modulus at 200°C using a compression tester in accordance with the description in JIS K 7181:2001 "Plastics - Determination of Compressive Properties". The measurement is performed under the following conditions. As the compression tester, for example, "Autograph AG-X (300kN)" (product name) manufactured by Shimadzu Corporation can be used. Compression speed: 0.1mm / min Load cell: 100kN Test temperature: 200℃

[0039] The upper limit of the thickness of the insulating plate 20 may be, for example, 0.35 mm or less, 0.32 mm or less, 0.30 mm or less, or 0.25 mm or less. When the upper limit of the thickness of the insulating plate 20 is within the above range, the conformability of the insulating plate to the unevenness on the surface of the electric circuit device and the cooler is further improved, and the thermal resistance of the heat dissipation structure can be further reduced. The lower limit of the thickness of the insulating plate 20 may be, for example, 0.10 mm or more, 0.15 mm or more, 0.17 mm or more, or 0.20 mm or more. When the lower limit of the thickness of the insulating plate 20 is within the above range, the insulating plate is further prevented from cracking, and the handleability can be improved. The thickness of the insulating plate 20 may be adjusted within the above range, and may be, for example, 0.10 to 0.35 mm.

[0040] The upper limit of the bulk density of the insulating plate 20 is, for example, 2000 kg / m 3 Below 1900kg / m 3 or less than 1800kg / m 3 If the upper limit of the bulk density of the insulating plate 20 is within the above range, the flexibility of the insulating plate can be improved, the conformability of the insulating plate to the surfaces of the electric circuit device and the cooler can be improved, and the thermal resistance of the heat dissipation structure can be reduced. The lower limit of the bulk density of the insulating plate 20 is, for example, 1500 kg / m 3 More than 1600kg / m 3 or more than 1700kg / m 3 If the lower limit of the bulk density of the insulating plate 20 is within the above range, the heat dissipation property of the insulating plate can be further improved, and the thermal resistance of the heat dissipation structure can be further reduced. The bulk density of the insulating plate 20 can be adjusted within the above range, for example, 1500 to 2000 kg / m 3 It may be.

[0041] The lower limit of the thermal conductivity of the insulating plate 20 may be, for example, 25 W / mK or more, or 30 W / mK or more. When the lower limit of the thermal conductivity is within the above range, the thermal resistance can be reduced more than that of a conventional insulating heat dissipation material obtained from a resin composition in which a resin and a filler are mixed. The upper limit of the thermal conductivity of the insulating plate 20 may be, for example, 90 W / mK or less, 85 W / mK or less, or 80 W / mK or less. The fact that the upper limit of the thermal conductivity is within the above range also corresponds to the low bulk density of the insulating plate, and the insulating plate can be flexibly deformed, so that the gap at the interface with the electric circuit device and the cooler can be further reduced. The thermal conductivity of the insulating plate 20 may be adjusted within the above range, and may be, for example, 25 to 90 W / mK.

[0042] The thermal conductivity in this specification means a value calculated by the following method. First, the thermal diffusivity A (unit: m 2 The thermal diffusivity A of the sample is measured by the laser flash method. The bulk density B of the sample (unit: kg / m 3) is determined from the volume and mass of the sample. Furthermore, the specific heat capacity C (unit: J / (kg·K)) of the sample is measured in accordance with the description of JIS K 7123-1987 "Method of measuring specific heat capacity of plastics". More specifically, 25 mg of the sample is taken, crushed, and molded into pellets to obtain a molded body. The molded body obtained is filled into a platinum pan, and the specific heat capacity is measured using a differential scanning calorimeter (manufactured by Netsch, product name: DSC214). The specific heat capacity is measured under the conditions of a heating rate of 10°C / min and a nitrogen atmosphere, heating from 25°C to 300°C, and a cooling rate of 20°C / min and a nitrogen atmosphere, cooling from 300°C to 25°C. Based on the values ​​of thermal diffusivity A, bulk density B, and specific heat capacity C (the result at 25°C is applied) obtained in this way, the thermal conductivity H in the thickness direction of the sample is calculated from the following formula (2). The thermal diffusivity A can be measured using a measuring device such as a xenon flash analyzer (manufactured by NETZSCH, product name: LFA467NanoFlash). H=A×B×C…Formula (2)

[0043] The upper limit of the compressive strength of the insulating plate 20 may be, for example, 20.0 MPa or less, 18.0 MPa or less, 16.0 MPa or less, 14.0 MPa or less, 12.0 MPa or less, 10.0 MPa or less, or 8.0 MPa or less. When the upper limit of the compressive strength is within the above range, deformation due to the tightening pressure when preparing the heat dissipation structure becomes easier, and the heat cycle characteristics of the heat dissipation structure can be further improved. The lower limit of the compressive strength of the insulating plate 20 may be, for example, 4.0 MPa or more, 4.5 MPa or more, 5.0 MPa or more, or 5.5 MPa or more. When the lower limit of the compressive strength is within the above range, damage to the insulating plate 20 during preparation of the heat dissipation structure can be more sufficiently suppressed. The compressive strength of the insulating plate 20 may be adjusted within the above range, and may be, for example, 2.0 to 20 MPa.

[0044] The compressive strength in this specification means a value measured by the following method. First, a nitride sintered body (e.g., a boron nitride sintered body) is processed to prepare a measurement sample (length x width x height = 10 mm x 10 mm x 0.4 mm) in the shape of a rectangular column. Then, the measurement sample is subjected to compression strength measurement at 200°C using a compression tester in accordance with the description of JIS K 7181:2001 "Plastics - Determination of Compressive Properties". The measurement is performed under the following conditions. As the compression tester, for example, "Autograph AG-X (300kN)" (product name) manufactured by Shimadzu Corporation can be used. Compression speed: 0.1mm / min Load cell: 100kN Test temperature: 200℃

[0045] The cooler 30 has a function of cooling the heat transferred from the heat generating element 2 via the insulating plate 20. The cooler 30 may be made of a metal. Examples of metals include aluminum, copper, and titanium. The cooler 30 is not particularly limited as long as it can secure a sufficient contact area with the insulating plate 20, and is not limited to being plate-shaped. The cooler 30 may have irregularities formed on the surface opposite to the insulating plate 20, may have cooling fins, and may be equipped with a pipe for flowing a cooling medium (e.g., cooling water) or the like.

[0046] The fastener 40 is not particularly limited as long as it can apply pressure between a pair of coolers 30. In Fig. 1, a jig composed of a bolt and a nut is shown as a specific example of the fastener 40. In this example, a nut is screwed onto a bolt that is screwed into a through hole of the cooler 30 arranged at the bottom of Fig. 1 and inserted into a through hole of the cooler 30 arranged at the top, and the bolt is tightened to apply a desired pressure between the coolers 30.

[0047] The lower limit of the pressure (clamping pressure) in the stacking direction by the fastener 40 may be, for example, 5 MPa or more, 7 MPa or more, 10 MPa or more, 15 MPa or more, or 20 MPa or more. When the lower limit of the clamping pressure is within the above range, the adhesion between the members constituting the heat dissipation structure can be further improved. The upper limit of the clamping pressure may be, for example, 35 MPa or less, 30 MPa or less, 27 MPa or less, or 25 MPa or less. When the upper limit of the clamping pressure is within the above range, cracking of the insulating plate can be further suppressed, and gaps at the interface with the electric circuit device and the cooler can be further reduced. The pressure in the stacking direction by the fastener 40 may be adjusted within the above range, and may be, for example, 5 to 35 MPa.

[0048] The insulating plate 20 according to the present disclosure has a suitable flexibility and is excellent in conformity with other members. The insulating plate 20 has excellent adhesion at the interface between the electric circuit device 10 and the cooler 30, and the heat dissipation structure 100 has a low thermal resistance in the stacking direction. The heat dissipation structure has a thermal resistance of 0.30° C. / W or less in the stacking direction of the circuit device, the insulating plate, and the cooler.

[0049] The upper limit of the thermal resistance in the stacking direction of the heat dissipation structure 100 may be, for example, 0.25°C / W or less, 0.20°C / W or less, or 0.15°C / W or less. The upper limit of the thermal resistance within the above range means that the adhesion between the insulating plate 20 and the electric circuit device 10 and the cooler 30 is better, and the heat cycle characteristics of the obtained heat dissipation structure 100 can be further improved. The lower limit of the thermal resistance in the stacking direction of the heat dissipation structure 100 is not particularly limited, and may be, for example, 0.01°C / W or more, 0.03°C / W or more, 0.04°C / W or more, 0.05°C / W or more, or 0.06°C / W or more. The thermal resistance in the stacking direction of the heat dissipation structure may be adjusted within the above range, and may be, for example, 0.01 to 0.30°C / W, or 0.04 to 0.30°C / W. For example, the thermal resistance in the stacking direction of heat dissipation structure 100 may be 0.30° C. / W or less when heat dissipation plate 4 is made of a copper plate having a thickness of 3.0 mm.

[0050] In this specification, the thermal resistance in the lamination direction of the heat dissipation structure refers to the thermal resistance of the path from the outer surface of the heat sink of the heat dissipation structure to the outer surface of the cooler. The thermal resistance is measured based on the following method. First, the heat generation amount of the electric circuit device is set to 310 W, the inlet temperature of the cooling water sent to the cooler is set to 65°C, and the flow rate of the cooling water is set to 5 L / min. Thermocouples are inserted into the outer surface of the heat sink and the outer surface of the cooler to measure the temperature. Based on the measured value, the value of the thermal resistance is determined from the following formula (3). Thermal resistance (℃ / W) = [Outer surface temperature of heat sink (℃) - Outer surface temperature of cooler (℃)] / 310 (W) ... Equation (3)

[0051] The lower limit of the breakdown voltage of the heat dissipation structure 100 may be, for example, 20 kV / mm or more, or 25 kV / mm or more. By setting the lower limit of the breakdown voltage within the above range, it becomes easier to control the switching of the current using the element.

[0052] The dielectric breakdown strength of the heat dissipation structure in this specification means a value measured based on the method described in JIS C 2110-1:2016 "Solid electrical insulating materials - Test methods for dielectric breakdown strength - Part 1: Tests using applied power frequency AC voltage."

[0053] The above-mentioned heat dissipation structure can be manufactured, for example, by the following manufacturing method. That is, one embodiment of the manufacturing method of the heat dissipation structure includes a step of stacking a first cooler, a first insulating plate, an electric circuit device, a second insulating plate, and a second cooler in this order, and applying pressure to the circuit device, the insulating plate, and the cooler in the stacking direction with a fastener. Here, the electric circuit device includes a heat generating element and heat dissipation plates provided on both main surfaces of the heat generating element.

[0054] The insulating plate may be a resin-filled plate including a porous nitride sintered plate and a resin filled in the pores of the nitride sintered plate. The insulating plate may be prepared by the manufacturing method described below.

[0055] The preparation method of the insulating board differs depending on the resin to be impregnated into the insulating board and cured or solidified. For example, when the resin contains a silicone resin, the preparation method of the insulating board includes a sintering step of sintering a molded board containing a nitride to obtain a nitride sintered board, a step of impregnating the nitride sintered board with a mixture containing at least one of a silane compound and a siloxane compound to obtain an impregnated body, and a curing step of heat-treating the impregnated body to polymerize the mixture to obtain a resin-filled board. The resin in the resin-filled board includes a silicone resin, which is a polymer of a siloxane compound. When the resin contains a thermoplastic resin having a softening point of 80°C or higher, the preparation method of the insulating board includes a sintering step of sintering a molded board containing a nitride to obtain a nitride sintered board, a resin impregnation step of melting and impregnating the thermoplastic resin into the nitride sintered board, and a solidification step of solidifying the resin after impregnation. Hereinafter, the case where the resin contained in the insulating board contains a silicone resin will be described.

[0056] The molded plate in the sintering step may be a product obtained by molding a raw material powder containing a nitride. The nitride contained in the raw material powder may contain at least one nitride selected from the group consisting of boron nitride, aluminum nitride, and silicon nitride. When containing boron nitride, the boron nitride may be amorphous boron nitride or hexagonal boron nitride. When preparing a boron nitride sintered plate as the nitride sintered plate, for example, amorphous boron nitride powder having an average particle size of 0.5 to 10.0 μm or hexagonal boron nitride powder having an average particle size of 3.0 to 40.0 μm can be used as the raw material powder.

[0057] The raw material powder may be molded to obtain a molded body by, for example, uniaxial pressing, cold isostatic pressing (CIP), or doctor blade pressing. A sintering aid may be added to the raw material powder before molding. Examples of the sintering aid include metal oxides such as yttrium oxide, aluminum oxide, and magnesium oxide, alkali metal carbonates such as lithium carbonate and sodium carbonate, and boric acid.

[0058] When a sintering aid is added, the amount of the sintering aid may be, for example, 0.01 parts by mass or more, or 0.10 parts by mass or more, relative to 100 parts by mass of the total of the nitride and the sintering aid. The amount of the sintering aid may be, for example, 20.00 parts by mass or less, 15.00 parts by mass or less, or 10.00 parts by mass or less, relative to 100 parts by mass of the total of the nitride and the sintering aid. By setting the amount of the sintering aid added within the above range, it becomes easier to adjust the average pore size of the nitride sintered plate.

[0059] The firing temperature in the sintering step may be, for example, 1600° C. or higher, or 1700° C. or higher. The firing temperature may be, for example, 2200° C. or lower, or 2000° C. or lower. The firing time may be, for example, 1 hour or longer, or 30 hours or shorter. The sintering step may be performed in an inert gas atmosphere such as nitrogen, helium, or argon.

[0060] For sintering, for example, a batch furnace or a continuous furnace can be used. Examples of the batch furnace include a muffle furnace, a tubular furnace, and an atmosphere furnace. Examples of the continuous furnace include a rotary kiln, a screw conveyor furnace, a tunnel furnace, a belt furnace, a pusher furnace, and a large continuous furnace. In this way, a nitride sintered plate can be obtained.

[0061] In the impregnation step, a mixture containing at least one of a silane compound and a siloxane compound is impregnated into the pores of the nitride sintered plate to obtain an impregnated body. By reducing the thickness of the nitride sintered body, the impregnation of the mixture can be made smooth.

[0062] The mixture may contain a polysiloxane compound. For example, an addition reaction type silicone can be suitably used as the mixture. Specific examples of the addition reaction type silicone include a one-liquid reaction type silicone resin containing an organopolysiloxane having both a vinyl group and a hydrosilyl group (H-Si group) in one molecule, and a two-liquid reaction type silicone resin containing an organopolysiloxane having a vinyl group at the end or side chain and an organopolysiloxane having two or more hydrosilyl groups at the end or side chain. An example of the addition reaction type silicone may be "XE14-B8530A / B" (trade name) manufactured by Momentive Performance Materials.

[0063] From the viewpoint of improving the impregnation into the pores of the nitride sintered plate during the production of the insulating plate and the insulating properties of the insulating plate, the weight average molecular weight of the organopolysiloxane having both a vinyl group and a hydrosilyl group in one molecule and the organopolysiloxane having a vinyl group at the end or side chain (both collectively referred to as "organopolysiloxane having a vinyl group") in the addition reaction type silicone may be adjusted. The weight average molecular weight of the organopolysiloxane having a vinyl group may be, for example, 10,000 to 30,000, or 15,000 to 25,000, or 400,000 to 600,000, or 450,000 to 550,000. From the above viewpoint, it is more preferable to use a mixture of the vinyl group-containing organopolysiloxanes having different weight average molecular weights. For example, a mixture of the vinyl group-containing organopolysiloxane having a weight average molecular weight of 10,000 to 30,000 and the vinyl group-containing organopolysiloxane having a weight average molecular weight of 400,000 to 600,000, or a mixture of the vinyl group-containing organopolysiloxane having a weight average molecular weight of 15,000 to 25,000 and the vinyl group-containing organopolysiloxane having a weight average molecular weight of 450,000 to 550,000 can be used.

[0064] The mixture may contain, for example, a curing agent in addition to at least one of the silane compound and the siloxane compound. The curing agent may be a catalyst that promotes the curing reaction of the polysiloxane compound. For example, "RD-1" (trade name) manufactured by DuPont-Toray Specialty Materials Co., Ltd., "XC-86-250" (trade name) manufactured by Momentive Performance Materials Japan, LLC, etc. may be used as the curing agent.

[0065] The amount of the curing agent added may be, for example, 0.01 to 5.00 parts by mass, 0.03 to 4.00 parts by mass, or 0.05 to 2.00 parts by mass with respect to 100 parts by mass in total of the silane compound and the siloxane compound.

[0066] In the curing step, the impregnated body is heat-treated to polymerize the mixture (at least one of the silane compound and the siloxane compound) to obtain a resin-filled board.

[0067] The temperature of the heat treatment in the curing step may be, for example, 50 to 250° C., 70 to 200° C., 90 to 150° C., or 100 to 130° C. The heating time in the curing step may be, for example, 3 to 24 hours, or 5 to 12 hours.

[0068] Although several embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments. In addition, the contents of the descriptions of the above-described embodiments can be mutually applied. EXAMPLES

[0069] The present disclosure will be described in more detail below using examples and comparative examples. Note that the present disclosure is not limited to the following examples.

[0070] Example 1 [Preparation of nitride sintered plates] 100 parts by mass of orthoboric acid manufactured by Nippon Denko Corporation and 35 parts by mass of acetylene black (product name: HS100) manufactured by Denka Co., Ltd. were mixed using a Henschel mixer. The obtained raw material mixture was filled into a graphite crucible and heated in an arc furnace in an argon atmosphere at 2200°C for 5 hours to obtain a lump of boron carbide (B 4 C) was obtained. The obtained lump was coarsely crushed by a jaw crusher to obtain a coarse powder. This coarse powder was further crushed by a ball mill having silicon carbide balls (φ10 mm) to obtain a crushed powder.

[0071] The prepared pulverized powder was filled into a crucible made of boron nitride. It was then heated in a resistance heating furnace under a nitrogen gas atmosphere at 2000°C and 0.85 MPa for 10 hours. In this way, boron carbonitride (B 4 CN 4 ) was obtained.

[0072] A sintering aid was prepared by blending powdered boric acid and calcium carbonate. In the preparation, 50.0 parts by mass of calcium carbonate was blended with 100 parts by mass of boric acid. The atomic ratio of boron to calcium at this time was 17.5 atomic % of calcium to 100 atomic % of boron. 20 parts by mass of sintering aid was blended with 100 parts by mass of the fired product, and mixed using a Henschel mixer to prepare a powdered blend.

[0073] The mixture was pressed at 150 MPa for 30 seconds using a powder press to obtain a sheet-shaped molded body (length x width x thickness = 50 mm x 50 mm x 0.35 mm). The molded body was placed in a boron nitride container and introduced into a batch-type high-frequency furnace. In the batch-type high-frequency furnace, it was heated for 5 hours under conditions of normal pressure, nitrogen flow rate of 5 L / min, and 2000°C. Thereafter, the boron nitride sintered plate was removed from the boron nitride container. In this way, a sheet-shaped boron nitride sintered plate was obtained. The thickness of the boron nitride sintered plate was 0.32 mm.

[0074] <Measurement of bulk density and porosity> The porosity of the obtained boron nitride sintered plate was determined. First, the bulk density [Y (kg / m 3 )] was calculated, and the bulk density was compared with the theoretical density of the nitride [X(kg / m 3 The theoretical density X of the boron nitride plate was calculated from the above formula (1). The results are shown in Table 1. 3 was used. Porosity (volume%) = [1-(Y / X)] x 100 (1)

[0075] <Measurement of average pore diameter> The pore volume distribution of the obtained boron nitride sintered plate was measured using a Shimadzu Corporation mercury porosimeter (device name: Autopore IV9500) while increasing the pressure from 0.0042 MPa to 206.8 MPa. The pore diameter at which the cumulative pore volume reached 50% of the total pore volume was defined as the "average pore diameter." The results are shown in Table 1.

[0076] [Preparation of insulating board] A liquid mixture was prepared by mixing 100 parts by mass of addition reaction type silicone (manufactured by MOMENTIVE, product name: XE14-B8530 2, heat resistance temperature: 200°C or higher) with 2 parts by mass of a curing agent (DuPont Toray Specialty Materials Co., Ltd., product name: RD-1). The prepared mixture was dropped onto the upper main surface of the boron nitride sintered plate using a dispenser, and impregnated into the pores of the boron nitride sintered plate. The amount of the mixture dropped was 1.5 times the total volume of the pores of the boron nitride sintered plate. A part of the dropped mixture did not impregnate the boron nitride sintered plate and remained on the main surface. The remaining part was removed by a squeegee.

[0077] The boron nitride sintered plate impregnated with the above mixture was heat-treated at 150°C for 24 hours to carry out a curing reaction, thereby curing the impregnated mixture into a resin, thereby preparing an insulating plate (resin-impregnated body).

[0078] <Resin filling rate in insulating board> The filling rate of the resin contained in the insulating plate was calculated using the following formula (4). The results are shown in Table 1. Filling rate of resin in insulating plate (volume %)={(bulk density of insulating plate-bulk density of boron nitride sintered plate) / (theoretical density of insulating plate-bulk density of boron nitride sintered plate)}×100 …Equation (4)

[0079] <Bulk density of insulating board> The bulk density of the insulating board was calculated based on the volume calculated from the length of each side of the insulating board (measured with a vernier caliper) and the mass of the insulating board measured with an electronic balance in accordance with JIS Z 8807:2012 "Method of measurement of density and specific gravity by geometrical measurement" (see JIS Z 8807:2012, item 9). The theoretical density of the insulating board was calculated using the following formula (5). Theoretical density of insulating plate = bulk density of boron nitride sintered plate + true density of resin × (1 - bulk density of boron nitride sintered plate / true density of boron nitride) ... formula (5)

[0080] The true densities of the boron nitride sintered plate and the resin were calculated from the volumes and masses of the boron nitride sintered plate and the resin measured using a dry automatic density meter in accordance with JIS Z 8807:2012 "Method of measurement of density and specific gravity by gas displacement method" (see formulas (14) to (17) in JIS Z 8807:2012, section 11).

[0081] <Thermal conductivity of insulating plate> The thermal conductivity H of the insulating plate was determined according to the following method. A sample was prepared from the insulating plate by processing it to a size of length x width x thickness = 10 mm x 10 mm x 0.40 mm. The thermal diffusivity A of the obtained sample was measured by the laser flash method using a xenon flash analyzer (manufactured by NETZSCH, product name: LFA467NanoFlash). The bulk density B (unit: kg / m 3) was determined from the volume and mass of the sample. Furthermore, the specific heat capacity C (unit: J / (kg·K)) of the sample was measured in accordance with the description of JIS K 7123-1987 "Method of measuring specific heat capacity of plastics". More specifically, 25 mg of the sample was taken, crushed, and molded into pellets to obtain a molded body. The molded body obtained was filled into a platinum pan, and the specific heat capacity was measured using a differential scanning calorimeter (manufactured by Netsch, product name: DSC214). The specific heat capacity was measured under the following conditions: heating from 25°C to 300°C at a heating rate of 10°C / min under nitrogen atmosphere, and cooling from 300°C to 25°C at a heating rate of 20°C / min under nitrogen atmosphere. Based on the values ​​of thermal diffusivity A, bulk density B, and specific heat capacity C obtained in this way, the thermal conductivity H in the thickness direction of the sample was calculated from the following formula (2). H=A×B×C…Formula (2)

[0082] <Compressive strength of insulating plate> The same mixture as that described in the above "Preparation of nitride sintered plate" was used, and a powder press was used to press the mixture at 150 MPa for 30 seconds to prepare a sheet-shaped insulating plate (length x width x thickness = 50 mm x 50 mm x 0.4 mm). The compressive strength of the obtained insulating plate was measured by the method described below.

[0083] First, the insulating plate was processed to obtain a measurement sample having a rectangular column shape (length x width x height = 10 mm x 10 mm x 0.4 mm). The compression strength of the obtained measurement sample was measured at 200°C using a compression tester (Shimadzu Corporation, Autograph AG-X (300 kN)) in accordance with the description of JIS K 7181:2001 "Plastics - Determination of compression characteristics". The measurement was performed under the following conditions. Compression speed: 0.1mm / min Load cell: 100kN Test temperature: 200℃

[0084] [Manufacturing of heat dissipation structures] As an electric circuit device, a copper plate having a thickness of 3.0 mm, a semiconductor element, and a copper plate having a thickness of 3.0 mm were laminated in this order and sealed with a sealing material. Also, an aluminum plate was prepared as a cooler. A pipe for flowing cold water was arranged on one main surface of the aluminum plate (the surface located on the outermost surface of the heat dissipation structure), and cooling was performed by circulating cold water through the pipe. Using the insulating plate described above as an insulating plate, an aluminum plate, an insulating plate, an electric circuit device, an insulating plate, and an aluminum plate were laminated in this order, and a tightening pressure of 10 MPa was applied between the aluminum plates by adjusting the bolts and nuts, thereby manufacturing a heat dissipation structure.

[0085] <Measurement of thermal resistance of heat dissipation structure> The thermal resistance of the path from the outer surface of the heat sink of the heat dissipation structure to the outer surface of the cooler was measured based on the following method. First, the heat generation amount of the electric circuit device was set to 310 W, the inlet temperature of the cooling water sent to the cooler was set to 65°C, and the flow rate of the cooling water was set to 5 L / min. Thermocouples were inserted into the outer surface of the heat sink and the outer surface of the cooler to measure the temperature. Based on the measured values, the following formula ( 3) The thermal resistance value was determined. Thermal resistance (℃ / W) = [Outer surface temperature of heat sink (℃) - Outer surface temperature of cooler (℃)] / 310 (W) ... Equation (3)

[0086] <Evaluation of heat cycle characteristics of heat dissipation structures> The heat cycle characteristics of the heat dissipation structure were evaluated by the following method. First, an ultrasonic inspection image of the joint was obtained for the obtained heat dissipation structure using an ultrasonic inspection device. The initial bonded area ratio was determined by utilizing the fact that the areas where the insulating plate, the heat sink, and the cooler were not bonded (where peeling occurred) are represented by black areas in the obtained ultrasonic inspection image. The initial bonded area ratio means the ratio (area %) of the area that is actually bonded (area obtained by subtracting the area of ​​the black areas from the area of ​​the insulating plate in the ultrasonic inspection image: initial bonded area) to the area to be bonded (i.e., area of ​​the insulating plate).

[0087] Next, a heat cycle test was performed on the heat dissipation structure to be measured, in which one cycle consisted of holding at -40°C for 30 minutes and holding at 175°C for 30 minutes, and this cycle was repeated 1000 times. After that, the bonding state was confirmed using an ultrasonic flaw detector. The bonding rate was determined as the ratio of the bonding area to the initial bonding area in the ultrasonic flaw detector image obtained after the heat cycle test (the value of {[bonding area after heat cycle test] / [initial bonding area]}×100). From the obtained initial bonding area rate and bonding rate, the heat cycle characteristics of the heat dissipation structure were evaluated according to the following criteria. A: The initial bonding area ratio is 90% or more, and the bonding rate is 95% or more. B: The initial bonding area ratio is 90% or more, and the bonding ratio is 80% or more and less than 95%. C: The initial bonding area ratio is 90% or more, and the bonding ratio is 60% or more and less than 80%. D: The initial bonding area ratio is 90% or more, and the bonding ratio is 50% or more and less than 60%. E: The initial bonding area ratio is 90% or more, and the bonding ratio is less than 50%. F: The initial bonding area ratio is less than 90%.

[0088] <Dielectric breakdown strength of heat dissipation structure> The dielectric breakdown strength of the heat dissipation structure was measured based on the method described in JIS C 2110-1:2016 "Solid electrical insulating materials - Test methods for dielectric breakdown strength - Part 1: Tests using power frequency AC voltage application." The results are shown in Table 2.

[0089] Example 2 An insulating plate was prepared in the same manner as in Example 1, except that a boron nitride sintered plate having the average pore size, porosity, and bulk density shown in Table 1 was used as the nitride sintered plate when preparing the insulating plate. A heat dissipation structure was manufactured in the same manner as in Example 1, except that the insulating plate prepared in this manner was used. Various properties of the obtained insulating plate and heat dissipation structure were evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0090] Example 3 An insulating plate was prepared in the same manner as in Example 1, except that a boron nitride sintered plate having the average pore size, porosity, and bulk density shown in Table 1 was used as the nitride sintered plate when preparing the insulating plate. A heat dissipation structure was manufactured in the same manner as in Example 1, using the insulating plate prepared in this manner and the clamping pressure being 20 MPa. Various properties of the obtained insulating plate and heat dissipation structure were evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0091] Comparative Example 1 [Preparation of insulating board] First, a boron nitride sintered plate having the average pore size, porosity and bulk density shown in Table 1 was prepared as a nitride sintered plate for preparing an insulating plate.

[0092] Next, 10 parts by mass of a commercially available curing agent (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., product name: Acmex H-8) was mixed with 100 parts by mass of a commercially available epoxy resin (manufactured by Mitsubishi Chemical Corporation, product name: Epicoat 807) to prepare a thermosetting resin composition. The prepared thermosetting resin composition was heated at 120°C for 15 minutes, and then, while maintaining the temperature, was dropped onto the upper main surface of the boron nitride sintered plate using a dispenser to impregnate the plate with the thermosetting resin composition. The amount of the thermosetting resin composition dropped was 1.5 times the total volume of the pores of the boron nitride sintered plate. A part of the dropped thermosetting resin composition did not impregnate the boron nitride sintered plate and remained on the main surface.

[0093] The thermosetting resin composition remaining on the upper main surface of the boron nitride sintered plate was smoothed using a stainless steel scraper (manufactured by Narby Co., Ltd.) under atmospheric pressure. The excess thermosetting resin composition was removed to obtain an impregnated body with a smooth main surface. The impregnated body was heated at 120°C for 180 minutes under atmospheric pressure to semi-cure the thermosetting resin composition. In this manner, a rectangular prism-shaped resin-impregnated plate (length x width x thickness = 50 mm x 50 mm x 0.32 mm) was produced. The boron nitride sintered body was exposed on a part of the main surface of the resin-impregnated plate. The obtained resin-impregnated plate was further heated at 200°C for 24 hours to cure the semi-cured resin, thereby preparing a resin-filled plate. The obtained resin-filled plate (insulating plate) was evaluated in the same manner as the insulating plate of Example 1. The results are shown in Table 1.

[0094] [Manufacturing of heat dissipation structures] Using the resin-filled plate prepared as described above, a resin-filled plate, an electric circuit device, and a resin-filled plate were laminated in this order to prepare a laminate including an insulating plate, an electric circuit device, and an insulating plate in this order. Coolers were laminated on both sides of the obtained laminate so as to be in contact with the insulating plate, and a heat dissipation structure was manufactured by adjusting the clamping pressure between the aluminum plates to 10 MPa using bolts and nuts.

[0095] The obtained heat dissipation structure was evaluated for various properties in the same manner as in Example 1. The results are shown in Table 2.

[0096] Comparative Example 2 Instead of an insulating plate, a heat dissipation sheet (thickness: 0.2 mm, bulk density: 1.6 g / cm) was prepared by mixing and molding 100 parts by mass of a polyorganosiloxane-based polymer (manufactured by Toray Dow Corning Silicone Co., Ltd., product name: CF3110), 1 part by mass of a crosslinking agent (manufactured by Toray Dow Corning Silicone Co., Ltd., product name: RC-4), and 48 parts by mass of aggregate-type boron nitride powder (Denka Co., Ltd., SGPS grade). 3 A heat dissipation structure was prepared in the same manner as in Example 1, except that a 100% Cr-based SiO2 (copper alloy, thermal conductivity: 8 W / mK) was used.

[0097] Comparative Example 3 Instead of insulating plates, we used sintered silicon nitride plates (thickness: 0.32 mm, bulk density: 3.2 g / cm 3 A heat dissipation structure was prepared in the same manner as in Example 1, except that a 100% Cr-based SiO2 (copper alloy, thermal conductivity: 80 W / mK) was used.

[0098] Comparative Example 4 Instead of insulating plates, we used sintered silicon nitride plates (thickness: 0.32 mm, bulk density: 3.2 g / cm 3 A heat dissipation structure was prepared in the same manner as in Example 1, except that a member having a grease layer made of heat dissipation grease (manufactured by Shin-Etsu Chemical Co., Ltd., product name: G-747) on both main surfaces of a heat dissipation material (heat conductivity: 80 W / mK) was used.

[0099] [Table 1]

[0100] [Table 2] [Industrial Applicability]

[0101] According to the present disclosure, a heat dissipation structure having excellent heat cycle characteristics can be provided. [Explanation of symbols]

[0102] 2...heat generating element, 4...heat sink, 6...sealant, 10...electrical circuit device, 20...insulating plate, 30...cooler, 40...fastener, 100...heat dissipation structure.

Claims

1. an electric circuit device including a heat generating element and heat sinks provided on both main surfaces of the heat generating element; a pair of coolers stacked on the heat sink via an insulating plate; a fastener that holds the electric circuit device, the insulating plate, and the cooler in a pressurized state in a stacking direction, The insulating plate includes a porous nitride sintered plate and a resin filled in pores of the nitride sintered plate, A heat dissipation structure having a thermal resistance of 0.30° C. / W or less in a stacking direction.

2. The heat dissipation structure according to claim 1, wherein the porosity of the nitride sintered plate is 25 to 65 volume %.

3. The heat dissipation structure according to claim 1 , wherein a filling rate of the resin in the pores is 90% by volume or more.

4. The heat dissipation structure according to any one of claims 1 to 3, wherein the insulating plate has a thickness of 0.35 mm or less.

5. The heat dissipation structure according to any one of claims 1 to 4, wherein a pressure in a stacking direction applied by the fastener is 10 MPa or more.

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