Mounting boards and electrical devices equipped with mounting boards

Abstract

To provide a mounting board capable of preventing damage to an electronic component caused by a short circuit between a bonding material and an electronic component, or between a printed circuit board on which electronic components are mounted and an electronic component, or contact between the printed circuit board and the electronic component when screwing the printed circuit board to a heat sink, and an electric device mounted with the mounting board.SOLUTION: A mounting board includes an electronic component, a printed circuit board, a heat spreader, and a heat dissipation component, and a first insulating member and a second insulating member, which are insulators, are arranged between the electronic component and the heat spreader and between the heat spreader and the heat dissipation component, respectively, and the hardness of the first insulating member and the second insulating member is lower than the hardness of the heat spreader.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a mounting board and an electrical device equipped with the mounting board. [Background technology]

[0002] A semiconductor device capable of significantly improving the heat dissipation of electronic components has been known. The semiconductor device includes electronic components, a substrate on which the electronic components are mounted, a lower housing on which the substrate is mounted, and a heat spreader to which the electronic components are metal-bonded via a bonding material on a first surface. The lower housing has an opening for engaging the heat spreader, and the heat spreader is bonded to the opening via the bonding material. The heat spreader has a second surface, opposite to the first surface, exposed from the lower housing (see, for example, Patent Document 1).

[0003] Also known is a heat dissipation structure for a semiconductor device in which heat generated in the semiconductor device is transferred from its heat dissipation surface through a non-insulating member to a highly conductive, thermally conductive member for diffusion, and then transferred to a heat dissipation component through a first insulating member. The semiconductor device has an electrical connection surface electrically connected to a substrate and a heat dissipation surface on the opposite side, and the heat dissipation structure is characterized in that the heat dissipation surface is joined to or in contact with the highly conductive, thermally conductive member through the non-insulating member, and the highly conductive, thermally conductive member is joined to or in contact with the heat dissipation component through the first insulating member (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-003258 [Patent Document 2] Japanese Patent Application Publication No. 2017-191904 Summary of the Invention [Problem to be solved by the invention]

[0005] In a semiconductor device such as that disclosed in Patent Document 1, in order to significantly improve the heat dissipation of electronic components that generate a large amount of heat when current is passed through them, the electronic components are bonded to a heat spreader, which has the property of dissipating heat into the atmosphere, via a bonding material. To more closely bond the electronic components to the heat spreader via the bonding material, a configuration is conceivable in which a substrate on which the electronic components are mounted is fixed to the heat spreader by screwing. However, because the bonding material is non-insulating, the thermal pad and the heat spreader are electrically connected, which may make it difficult to ensure a sufficient insulation distance between the terminals of the electronic components and the heat spreader. Furthermore, in a heat dissipation structure such as that disclosed in Patent Document 2, a non-insulating component is disposed between the semiconductor device and the heat spreader, and an insulating component is disposed between the heat spreader and the heat sink. However, if the non-insulating component or insulating component is highly hard, a large distortion occurs in the substrate when the substrate on which the semiconductor device is mounted is fixed to the heat sink by screwing. This distortion may cause damage to components such as ceramic capacitors mounted on the substrate.

[0006] The present invention has been made in view of the above-mentioned problems, and an ultimate object of the present invention is to provide a mounting board that can prevent a short circuit from occurring between a heat spreader and terminals of an electronic component (corresponding to the above-mentioned semiconductor device) when the printed circuit board (corresponding to the above-mentioned board) on which the electronic component is mounted is screwed to a heat sink, or can prevent distortion of the printed circuit board from occurring and damaging the electronic component due to this distortion, and an electrical device equipped with the mounting board. [Means for solving the problem]

[0007] To solve the above problems, the present invention provides: an electronic component including an electronic element, a package formed to surround the electronic element, and a heat dissipation pad having heat dissipation properties; a printed circuit board on which the electronic components are mounted via terminals connected to an external circuit; a heat spreader containing metal as a main component and through which heat generated from the electronic component is transferred; a heat dissipation component that is mainly made of metal and that further transfers heat from the heat spreader to dissipate the heat into the air, a first insulating member and a second insulating member, which are insulators, are disposed between the electronic component and the heat spreader, and between the heat spreader and the heat dissipation component, respectively; The mounting board is characterized in that the hardness of the first insulating member and the second insulating member is lower than the hardness of the heat spreader.

[0008] According to the present invention, because the first insulating member for heat dissipation is an insulator, short circuits can be prevented even if the terminals approach the heat spreader due to force applied to the mounting board. Furthermore, because the first and second insulating members have low hardness and high deformability, the first and second insulating members can be deformed preferentially when force is applied to the mounting board. This suppresses deformation of the board. Furthermore, when electronic components are mounted on the printed circuit board at a certain distance via leads, the reduction in the distance between the electronic components and the printed circuit board is suppressed. Furthermore, by disposing the first insulating member between the thermal pad of the electronic component and the heat spreader, short circuits between the terminals of the electronic component and the heat spreader can be suppressed.

[0009] Furthermore, in the present invention, the mounting board may be characterized in that the hardness of the first insulating member is between Asker C5 and Asker C50, using Asker C, a standard for expressing hardness. This can prevent distortion of the printed circuit board when the printed circuit board is attached to the heat dissipation component. From the viewpoint of preventing distortion, it is more preferable that the hardness of the first insulating member is between Asker C5 and Asker C20.

[0010] The present invention may also provide a mounting board characterized in that the thickness of the first insulating member is 0.2 mm or more and 0.8 mm or less. As described above, this can prevent distortion of the printed circuit board when the printed circuit board is attached to the heat dissipation component. From the viewpoint of preventing distortion, it is more desirable that the thickness of the first insulating member be 0.2 mm or more and 0.3 mm or less.

[0011] The present invention may also provide a mounting board in which the area of ​​the heat spreader is between two and seven times the area of ​​the thermal pad. This facilitates close contact of the electronic component with the heat spreader via the first insulating member, thereby preventing distortion of the printed circuit board when the printed circuit board is attached to the thermal component. Furthermore, heat generated by the electronic component is easily transferred to the heat spreader via the thermal pad and the first insulating member, and further to the second insulating member. From the perspective of improving heat dissipation, the area of ​​the heat spreader is preferably between two and four times the area of ​​the thermal pad. From the perspective of preventing distortion, the area of ​​the heat spreader is preferably between four and six times the area of ​​the thermal pad.

[0012] Furthermore, in the present invention, the mounting board may be characterized in that the thermal conductivity of the first insulating member is higher than that of the second insulating member, thereby improving the efficiency of heat transfer when heat generated by the electronic component is transferred to the heat spreader.

[0013] In the present invention, the thermal conductivity of the first insulating member is 3 W / mK or more and 20 W / mK or less. The mounting substrate may be characterized in that the thermal conductivity of the first insulating member is 3 W / mK or more and 8 W / mK or less. This improves the efficiency of heat transfer from the heat generated by the electronic components to the heat spreader, as described above. From the viewpoint of improving heat dissipation, the thermal conductivity of the first insulating member is preferably 3 W / mK or more and 8 W / mK or less.

[0014] Furthermore, in the present invention, the mounting board may be characterized in that the thickness of the heat spreader is 0.3 mm or more and 1.0 mm or less, which is desirable from the viewpoint of improving heat dissipation because the heat spreader can easily transfer heat to the heat dissipation component via the second insulating member.

[0015] In addition, the present invention may provide a mounting board characterized in that the first insulating member is connected to the heat dissipation pads of each of the plurality of electronic components. This allows heat dissipation from the plurality of electronic components on the printed circuit board with a simple structure, and enables miniaturization and cost reduction of the mounting board.

[0016] The present invention may also be directed to an electrical device that performs power conversion of power supplied from a power supply device and that includes the above-described mounting board. This allows heat generated from the cooling structure to be diffused into the air outside the electrical device, or the electrical device to be cooled by the outside air. Furthermore, a circuit pattern of a printed circuit board can be mounted on the electrical device.

[0017] The above means for solving the problems can be used in combination with each other whenever possible. [Effects of the Invention]

[0018] According to the present invention, when assembling a printed circuit board on which electronic components are mounted, it is possible to prevent a short circuit from occurring between the heat dissipation pads and terminals of the electronic components, or to prevent distortion of the printed circuit board, which would cause damage to the electronic components. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of a mounting board according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view schematically illustrating how a printed circuit board on which electronic components are mounted is screwed to a heat sink in the mounting board according to the first embodiment of the present invention. [Figure 3] FIG. 3 is a table showing the results of a comparative evaluation of the thermal resistance of the mounting board according to Example 1 of the present invention, which was evaluated based on differences in the characteristic values ​​of the first insulating member and the heat spreader. [Figure 4] FIG. 4 is a table showing the results of a comparative evaluation of the mounting board according to Example 1 of the present invention, in which distortion of the printed circuit board due to differences in the characteristic values ​​of the first insulating member and the heat spreader was evaluated. [Figure 5] FIG. 5 is a cross-sectional view showing an example of a power conditioner equipped with the mounting board according to the first embodiment of the present invention. [Figure 6] FIG. 6 is a cross-sectional view schematically illustrating how a printed circuit board on which electronic components are mounted is screwed to a heat sink in a mounting board according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] [Application example] An outline of an application example of the present invention will be described below with reference to some of the drawings. The present invention can be applied to a mounting board 1 as shown in Fig. 1. Furthermore, by mounting a mounting board 1 as shown in Fig. 1, the present invention can also be applied to a power conditioner 8 (corresponding to the electrical device in the present invention) as shown in Fig. 5.

[0021] FIG. 1 is a cross-sectional view showing an example of a mounting board 1 to which the present invention is applied. The mounting board 1 in this application example is configured to include an electronic component 2, a printed circuit board 3, a heat spreader 4, a heat sink 5, and the like. The electronic component 2 is, for example, a semiconductor component such as an ASIC (Application Specific Integrated Circuit) or a power semiconductor such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), and is configured to include an electronic element (not shown), a package 21 formed to surround the electronic element, and a heat dissipation pad 22 with heat dissipation properties. The heat dissipation pad 22 is formed integrally with leads 23 on which a semiconductor chip using, for example, gallium nitride (GaN) is mounted. When a current is passed through the electronic element, the electronic component 2 generates heat. The mounting board 1 also includes other electronic components (e.g., capacitors) in addition to the electronic component 2, but the electronic component 2 generates a larger amount of heat than the other electronic components.

[0022] Leads 23, which serve as terminals and are connected to an external circuit, extend from the inside to the outside of package 21 of electronic component 2, with some of them formed in a gull-wing shape. One end of lead 23 is electrically connected to printed circuit board 3 (more precisely, to electrodes formed on the surface of printed circuit board 3) via, for example, solder paste (not shown). In the case shown in FIG. 1, electronic component 2 is mounted so as to be in contact with printed circuit board 3. Printed circuit board 3 may be, for example, a build-up printed wiring board having a multilayer structure and a base material made of thermosetting epoxy resin.

[0023] The heat spreader 4 is primarily made of a metal such as aluminum and has a thermal conductivity of approximately 190 W / mK. As described above, heat generated by the electronic component 2 is transferred to the heat spreader 4 via the thermal pad 22 and the first insulating member 6 (described later). The area of ​​the heat spreader 4 is larger than that of the thermal pad 22. The heat sink 5 is also primarily made of a metal such as aluminum. Heat absorbed by the heat spreader 4 is further transferred to the heat sink 5 via the second insulating member 61 (described later), which then diffuses the transferred heat to the surroundings, e.g., the outside air. The thermal conductivity of the heat spreader 4 is much greater than that of the first insulating member 6 and the second insulating member 61, which facilitates heat transfer from the first insulating member 6 to the second insulating member 61. Here, the heat sink 5 corresponds to the heat dissipation component of the present invention.

[0024] The first insulating member 6 and the second insulating member 61 are insulators made of, for example, sheet-like silicone. The first insulating member 6 is disposed between the electronic component 2 and the heat spreader 4, and the second insulating member 61 is disposed between the heat spreader 4 and the heat sink 5. To bond the electronic component 2, the heat spreader 4, and the heat sink 5 more closely, adhesive materials may be used as the first insulating member 6 and the second insulating member 61.

[0025] In this application example, the characteristic values ​​of the first insulating member 6 and the second insulating member 61 are as follows. The first insulating member 6 has a thickness of 0.3 mm, a thermal conductivity of 8 W / mK, and a hardness of Asker C20. Asker C is a type of standard that indicates hardness. The second insulating member 61 has a thickness of 1.0 mm, a thermal conductivity of 1 W / mK, and a hardness of Asker C20. The hardness of the first insulating member 6 and the second insulating member 61 is lower than that of the heat spreader 4. The thermal conductivity of the first insulating member 6 is higher than that of the second insulating member 61. The above characteristic values ​​are merely examples, and are not limited to these values ​​as long as the conditions are met.

[0026] Example 1 Hereinafter, a mounting board 1 according to a first embodiment of the present invention and a power conditioner 8 as an example of an electrical device will be described in more detail with reference to the drawings. Note that the mounting board 1 and the power conditioner 8 according to the present invention are not intended to be limited to the following configurations.

[0027] <Configuration of mounting board> FIG. 2 is a cross-sectional view of a mounting board 1 according to a first embodiment of the present invention, illustrating how a printed circuit board 3 mounted with an electronic component 2 is screwed to a heat sink 5. The printed circuit board 3 has a plurality of screw holes 31, and the printed circuit board 3 can be fixed to the heat sink 5 by passing screws 7 through the screw holes 31 and tightening them. The leads 23 are positioned away from the first insulating member 6 by a vertical distance D and a horizontal distance D′ (hereinafter, the distances D and D′ are collectively referred to as the “insulation distance”) in the orientation of FIG. 2. Although the insulation distance provides a certain distance between the leads 23 and the first insulating member 6, the force generated when the screws are tightened can deform the leads 23 or the first insulating member 6, potentially causing contact between the leads 23 and the first insulating member 6. Therefore, if a non-insulating heat dissipation member were used instead of the first insulating member 6, the leads 23 and the heat dissipation member could be short-circuited. Furthermore, if the metal heat spreader 4 is joined to the heat dissipation pad 22 via a non-insulating heat dissipation member, the heat spreader 4 will have the same potential as the heat dissipation pad 22, shortening the insulation distance between the lead 23 and the first insulating member 6, which could cause a short circuit due to surface discharge, space discharge, etc.

[0028] In contrast, in this embodiment, as described in the application example above, the first insulating member 6 is an insulator, so even if the lead 23 and the first insulating member 6 come into contact with each other due to the force generated during screw tightening, a short circuit can be prevented. Furthermore, the hardness of the first insulating member 6 and the second insulating member 61 is lower than that of the heat spreader 4. Therefore, the second insulating member 61 is highly deformable and easily absorbs the force generated during screw tightening (the arrows in FIG. 2 indicate this force), including the force generated by the heat spreader 4, which has a relatively high hardness. In other words, the deformation of the second insulating member 61 suppresses the deformation of the first insulating member 6 and the printed circuit board 3, and also suppresses a reduction in the insulation distance. As a result, contact between the lead 23 and the first insulating member 6 during screw tightening can also be suppressed. Furthermore, the relatively large thickness of the second insulating member 61 also contributes to absorbing the force generated during screw tightening.

[0029] Furthermore, while the heat sink 5 is poorly deformable under force, the second insulating member 61 is highly deformable under force. Therefore, compared to when the heat spreader 4 is pressed directly against the heat sink 5, pressing the heat spreader 4 against the second insulating member 61 makes it easier for the heat spreader 4 to adhere to the heat sink 5, and heat is more easily transferred from the heat spreader 4. As a result, the amount of heat that the heat sink 5 dissipates to the surroundings increases. Furthermore, because the first insulating member 6, which is disposed in contact with the heat dissipation pad 22, is relatively thin and has a relatively high thermal conductivity, heat generated by the electronic component 2 is easily transferred to the heat spreader 4.

[0030] <Example of effectiveness verification> Fig. 3 is a table showing the results of a comparative evaluation of the mounting board 1 according to Example 1 of the present invention, evaluating the thermal resistance due to differences in the characteristic values ​​of the first insulating member 6 and the heat spreader 4. Fig. 4 is a table showing the results of a comparative evaluation of the mounting board 1 according to Example 1 of the present invention, evaluating the distortion of the printed circuit board 3 due to differences in the characteristic values ​​of the first insulating member 6 and the heat spreader 4. Here, the thermal resistance is evaluated as follows: if the thermal resistance is 5.0 K / W or more and 10.6 K / W or less, it is considered to be a good value (denoted as "effective" in Figs. 3 and 4); if the thermal resistance is less than 5.0 K / W, it is considered to be a better value (denoted as "significantly effective" in Figs. 3 and 4); and if the thermal resistance exceeds 10.6 K / W, it is considered to be a value in which no significant effect is obtained (denoted as "no effect" in Figs. 3 and 4). Similarly, in evaluating the distortion of the printed circuit board 3 (hereinafter simply referred to as "distortion"), if the distortion is between 939 μST and 1101 μST, it is considered a good value, if the distortion is less than 939 μST, it is considered a better value, and if the distortion is 1101 μST, it is considered a value that does not produce any significant effect.

[0031] In FIG. 3, the mounting substrate 1 under condition #1 is a standard configuration. Compared to condition #1, the distortion is small but the thermal resistance is high, and the thermal resistance is close to the upper limit of the range of good values ​​(10.6 K / W). Here, the mounting board 1 under condition #2 can be considered to have a configuration that improves heat dissipation. Under conditions #3 to #5, the thermal resistance is large, and the heat dissipation performance is worse than under condition #1. Compared to the other conditions, under condition #3, the thermal conductivity of the first insulating member 6 is the lowest at 2 W / mK, under condition #4 the area ratio of the heat spreader 4 to the thermal pad 22 is the smallest at 1.8 times, and under condition #5 the thickness of the heat spreader 4 is the thinnest at 0.1 mm. Note that under all conditions, the distortion is more favorable.

[0032] In FIG. 4, the mounting board 1 under condition #1 is a standard configuration. Under condition #2, the thermal resistance is lower than under condition #1, but the distortion is larger, with the distortion being close to the upper limit (939 μST) of the range of more favorable values. Here, the mounting board 1 under condition #2 can be considered to have a configuration that improves distortion. Under conditions #3 to #5, the distortion is larger than under condition #2, but the value ranges from more favorable to more favorable. Compared to condition #2, under condition #3, the hardness of the first insulating member 6 is higher; under condition #4, the thickness of the first insulating member 6 is thinner; and under condition #5, the area ratio of the heat spreader 4 to the thermal pad 22 is larger. Under condition #6, the hardness of the first insulating member 6 is even higher than under condition #3, resulting in a larger distortion. Compared to the other conditions, under condition #7, the hardness of the first insulating member 6 is Asker C60, the highest, and the distortion value is such that no significant effect is obtained.

[0033] From the results of the comparative evaluation in FIG. 3 , which evaluated thermal resistance, it is preferable that the thermal conductivity of the first insulating member 6 of the mounting board 1 according to Example 1 of the present invention is 3 W / mK or more and 8 W / mK or less. The thermal conductivity of the first insulating member 6 may be 3 W / mK or more and 20 W / mK or less. The thickness of the heat spreader 4 is preferable to be 0.3 mm or more and 1.0 mm or less. From the results of the comparative evaluation in FIG. 4 , which evaluated strain, it is preferable that the hardness of the first insulating member 6 of the mounting board 1 according to Example 1 of the present invention is Asker C20 or more and Asker C50 or less. The hardness of the first insulating member 6 is more preferable to be Asker C5 or more and Asker C20 or less. The thickness of the first insulating member 6 is preferable to be 0.2 mm or more and 0.3 mm or less. The thickness of the first insulating member 6 may be 0.2 mm or more and 0.8 mm or less. Furthermore, according to the results of the comparative evaluation in FIG. 3, the area ratio of the heat spreader 4 to the heat dissipation pad 22 is preferably 2 to 4 times, whereas according to the results of the comparative evaluation in FIG. 4, it is preferably 4 to 7 times, and more preferably 4 to 6 times.

[0034] <Power conditioner configuration> 5 is a cross-sectional schematic diagram showing an example of a power conditioner 8 equipped with the mounting board 1 according to the first embodiment of the present invention. The mounting board 1 may be mounted on an electric device, and the electric device may be, for example, a power conversion device such as the power conditioner 8, a motor drive device, a power supply device, or the like. The power conditioner 8 is connected to a power supply device (not shown) such as a solar cell, and boosts the voltage of the power supplied from the power supply device, converts it to AC, removes noise, and adjusts the waveform, and then supplies the AC power to a load (not shown) or an interconnected power system (not shown).

[0035] A thermally conductive metal base 82 is installed on one side of a housing 81 of the power conditioner 8. The heat sink 5 to which the printed circuit board 3 is connected is screwed to the metal base 82 with second screws 71. As a portion of the heat sink 5 is exposed to the outside of the housing 81 in this way, heat generated by the electronic components 2 is easily transferred to the outside air.

[0036] The printed circuit board 3 is fastened to the heat sink 5 using screws 7. The printed circuit board 3, the metal base 82, and the heat sink 5 are also fastened to each other with spacers 83-85 interposed therebetween. Other functional components such as a terminal block 87 are fixedly attached to the base 86. Furthermore, another circuit board such as a control board (not shown) may be attached to the printed circuit board 3 via a connector (not shown).

[0037] Example 2 Next, a mounting board 10 according to a second embodiment of the present invention will be described with reference to Fig. 6. The mounting board 10 has many components in common with the mounting board 1 of the first embodiment, and therefore, the same components are denoted by the same reference numerals and will not be described again. The components shown in the mounting board 10 can also be mounted on the power conditioner 8 of the first embodiment.

[0038] <Configuration of mounting board> FIG. 6 is a cross-sectional view showing a state in which the printed circuit board 3 on which the electronic component 2 is mounted is screwed to the heat sink 50 in the mounting board 10 according to the second embodiment of the present invention. Compared to the leads 23 shown in FIG. 2, the leads 230 are longer in the thickness direction of the electronic component 2, and the electronic component 2 is mounted on the printed circuit board 3 with a distance D2 between them. The force generated when the printed circuit board 3 is screwed (the arrows in FIG. 6 indicate this force) is preferentially absorbed by the second insulating member 61, as in the mounting board 1 shown in FIG. 2, thereby suppressing deformation of the leads 230. This suppresses the reduction of the distance D2 due to deformation of the leads 230. As a result, it is possible to prevent strain from occurring in the printed circuit board 3 or the leads 230 due to contact between the printed circuit board 3 and the electronic component 2, and prevent damage to the electronic component due to this strain. The suppression of the reduction of the insulation distance is similar to the mounting board 1 shown in FIG. 2.

[0039] Regarding the mounting board 10 according to Example 2 of the present invention, the results of the comparative evaluation in which the thermal resistance was evaluated and the distortion of the printed circuit board 3 were evaluated due to differences in the characteristic values ​​of the first insulating member 6 and the heat spreader 4 showed the same trends as those shown in FIGS. 3 and 4.

[0040] <Appendix 1> an electronic component including an electronic element, a package (21) formed to surround the electronic element, and a heat dissipation pad (22) having heat dissipation properties; a printed circuit board (3) on which the electronic components are mounted via terminals (23, 230) connected to an external circuit; a heat spreader (4) made mainly of metal to transfer heat generated from the electronic component; a heat dissipation component (5, 50) mainly composed of metal, through which heat in the heat spreader is further transferred and dissipated into the air; a first insulating member (6) and a second insulating member (61), which are insulators, are disposed between the electronic component and the heat spreader, and between the heat spreader and the heat dissipation component, respectively; A mounting board (1, 10) characterized in that the hardness of the first insulating member and the second insulating member is lower than the hardness of the heat spreader. [Explanation of symbols]

[0041] 1, 10: Mounting board 2: Electronic components 21: Package 22: Heat dissipation pad 23, 230: Lead 3: Printed circuit board 31: Screw hole 4: Heat spreader 5, 50: Heat sink 6: First insulating member 61: Second insulating member 7: Screws 71: Second screw 8: Power conditioner 81: Housing 82: Metal base 83-85: Spacer 86: Bass 87:Terminal block

Claims

1. an electronic component including an electronic element, a package formed to surround the electronic element, and a heat dissipation pad having heat dissipation properties; a printed circuit board on which the electronic components are mounted via terminals connected to an external circuit; a heat spreader containing metal as a main component and through which heat generated from the electronic component is transferred; a heat dissipation component that is mainly made of metal and that further transfers heat from the heat spreader to dissipate the heat into the air, a first insulating member and a second insulating member, which are insulators, are disposed between the electronic component and the heat spreader, and between the heat spreader and the heat dissipation component, respectively; the hardness of the first insulating member and the second insulating member is lower than the hardness of the heat spreader; A mounting board, characterized in that the thermal conductivity of the first insulating member is higher than the thermal conductivity of the second insulating member.

2. 2. The mounting board according to claim 1, wherein the hardness of the first insulating member is Asker C5 or more and Asker C50 or less, using Asker C, which is a standard that indicates hardness.

3. 3. The mounting board according to claim 1, wherein the first insulating member has a thickness of 0.2 mm or more and 0.8 mm or less.

4. 4. The mounting board according to claim 1, wherein the area of ​​the heat spreader is between two and seven times the area of ​​the heat dissipation pad.

5. The mounting board according to claim 1 , wherein the thermal conductivity of the first insulating member is equal to or greater than 3 W / mK and equal to or less than 20 W / mK.

6. The mounting board according to claim 1 , wherein the heat spreader has a thickness of 0.3 mm or more and 1.0 mm or less.

7. The mounting board according to claim 1 , wherein the first insulating member is connected to the heat dissipation pad of each of the plurality of electronic components.

8. An electrical device that performs power conversion of power supplied from a power supply device, An electrical device equipped with the mounting board according to any one of claims 1 to 7.

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