Electronic circuit board and method of manufacturing the same

Abstract

To provide an electronic circuit substrate excellent in substantial heat conducting property in the thickness direction of the substrate and to provide a manufacturing method for the same that can be manufactured efficiently.SOLUTION: The electronic circuit substrate includes a substrate on which a through hole is formed and a flexible heat conductive body inserted into the through-hole. The heat conductive body is in contact with a different member on both sides of the through-hole in the depth direction. The heat conductive body preferably has anisotropic heat conducting properties. The heat conductive body is preferably composed of a material including scaled graphite.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electronic circuit board and a method for manufacturing an electronic circuit board. [Background technology]

[0002] In recent years, as electronic components (heat generating elements) have become smaller, heat generated in electronic components placed on a substrate is transferred locally to the substrate, and there is a demand for a heat dissipation structure that can more efficiently dissipate heat from the heat generating element from a heat dissipation member (see, for example, Patent Document 1).

[0003] 19, a conventional heat dissipation structure 220 includes a semiconductor device (heat generating element) 210, a substrate (support) 211, a solder layer 212a, a heat spreader 213, copper inlays (columnar bodies) 214, an insulating layer 215, and a heat sink 216. A plurality of cylindrical copper inlays 214 are disposed so as to be embedded from a first surface 211a to a second surface 211b of the substrate 211. The copper inlays 214 serve as a heat transfer path, allowing heat generated in the semiconductor device 210 to be efficiently transferred from the first surface 211a side to the second surface 211b side.

[0004] However, the contact between the copper inlay 214 and the heat spreader 213 and heat sink 216 is between hard surfaces, in other words, it is point contact due to minute irregularities on the surface, so sufficient adhesion cannot be ensured and the actual thermal conductivity in the thickness direction of the substrate 211 cannot be made sufficient.

[0005] Furthermore, grease is sometimes applied to the thermal interface between the heat dissipation member and the heat generating element to prevent the formation of an air layer that acts as a heat insulating layer. However, general grease does not have high thermal conductivity. For this reason, diamond grease, which contains dispersed diamonds with relatively high thermal conductivity, is also used (see, for example, Patent Document 2). However, diamond grease is expensive, and even when diamond grease is used, it is difficult to obtain sufficient thermal conductivity. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6551566 [Patent Document 2] Special Publication No. 2017-530220 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide an electronic circuit board having excellent substantial thermal conductivity in the thickness direction of the board, and a method for manufacturing an electronic circuit board that can efficiently manufacture an electronic circuit board having excellent substantial thermal conductivity in the thickness direction of the board. [Means for solving the problem]

[0008] The electronic circuit board of the present invention comprises: a substrate having a through hole formed therein; a flexible thermal conductor inserted into the through hole; the heat conductor includes a plurality of heat conductive portions and a joint portion made of a flexible material and joining the heat conductive portions together; The joint contains resin fibers, The thermal conductor is characterized in that it is in contact with different members on both sides of the through hole in the depth direction.

[0009] The method for manufacturing an electronic circuit board of the present invention comprises the steps of: providing a substrate having a through hole; a step of joining and soldering an electronic component to the portion of the substrate where the through hole is provided; inserting a flexible thermal conductor into the through hole; and fixing a cooling unit to the surface of the substrate opposite to the surface on which the electronic components are provided so as to be in contact with the heat conductor. death, the heat conductor includes a plurality of heat conductive portions and a joint portion made of a flexible material and joining the heat conductive portions together; The joint contains resin fibers. It is characterized by the following. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide an electronic circuit board having excellent substantial thermal conductivity in the thickness direction of the board, and a method for manufacturing an electronic circuit board that can efficiently manufacture an electronic circuit board having excellent substantial thermal conductivity in the thickness direction of the board. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view schematically showing an example of an electronic circuit board of the present invention. [Figure 2] FIG. 1 is a perspective view schematically illustrating an example of a thermal conductor. [Figure 3] FIG. 3 is an enlarged cross-sectional view schematically illustrating a portion of the laminated heat conductive portion and the bonding portion. [Figure 4] FIG. 2 is a plan view schematically illustrating an example of a heat conducting portion that constitutes a heat conductor. [Figure 5] FIG. 2 is a schematic partially exploded perspective view showing a plurality of stacked heat conductive parts in an exploded state. [Figure 6] FIG. 2 is a conceptual diagram of an example of a cured product of a curable resin material that constitutes a joint. [Figure 7] FIG. 2 is a cross-sectional view schematically showing a heat-conducting portion-forming sheet made of flake graphite. [Figure 8] FIG. 10 is a cross-sectional view schematically showing a state in which a composition for forming a joint is applied to a sheet for forming a heat-conducting part having recesses formed therein. [Figure 9] FIG. 2 is a diagram schematically illustrating an example of an apparatus used in a step of applying a composition for forming a joint and a step of winding. [Figure 10] FIG. 2 is a diagram schematically illustrating a cut body obtained in a cutting step. [Figure 11] FIG. 10 is a diagram schematically illustrating a state in which the incision body is pressed to further increase the flatness of the incision body. [Figure 12]FIG. 10 is a diagram schematically illustrating a cutting process. [Figure 13] FIG. 10 is a perspective view schematically showing another example of a thermal conductor. [Figure 14] FIG. 14 is a vertical cross-sectional view of the thermal conductor shown in FIG. [Figure 15] FIG. 2 is a cross-sectional view schematically showing another example of the electronic circuit board of the present invention. [Figure 16] FIG. 2 is a plan view schematically showing another example of the electronic circuit board of the present invention. [Figure 17] 1A and 1B are diagrams schematically showing another example of the electronic circuit board of the present invention, in which (A) is a cross-sectional view and (B) is a plan view. [Figure 18] 1A to 1C are cross-sectional views schematically illustrating an example of a method for manufacturing an electronic circuit board according to the present invention. [Figure 19] FIG. 1 is a cross-sectional view schematically showing an example of a heat dissipation structure of a conventional electronic component. DETAILED DESCRIPTION OF THE INVENTION

[0012] Preferred embodiments of the present invention will be described in detail below. [1] Electronic circuit board First, the electronic circuit board of the present invention will be described. FIG. 1 is a cross-sectional view schematically showing an example of an electronic circuit board of the present invention.

[0013] In the drawings referred to in this specification, some parts may be reduced or enlarged to clearly show the relationships between the components. The size ratios between the components shown in the drawings do not represent the actual size ratios between the components. In this specification, the term "natural state" refers to a state in which no external forces other than gravity are applied, and in particular, a state in which no external forces other than gravity have been applied within 24 hours. It is also preferable that the thermal conductor has not been subjected to a stress of 0.1 MPa or more since its manufacture. Unless otherwise specified, measurements and treatments described in this specification were performed at 20°C.

[0014] The electronic circuit board 100 includes a substrate 110 having a through-hole 111 formed therein, and a flexible thermal conductor 1 inserted into the through-hole 111. The thermal conductor 1 is in contact with different members on both sides of the through-hole 111 in the depth direction.

[0015] The flexibility of the thermal conductor 1 allows the thermal conductor 1 and a member in contact with each other to be in surface-to-surface contact. In other words, sufficient adhesion can be ensured, and the substantial thermal conductivity from the member to the thermal conductor 1 can be excellent. As a result, the electronic circuit board 100 has excellent substantial thermal conductivity in the thickness direction of the board 110 .

[0016] In the illustrated configuration, the substrate 110 has through-holes that penetrate in the thickness direction as the through-holes 111 to which the thermal conductor 1 is applied, but the substrate 110 may have non-through-holes that do not penetrate in the thickness direction of the substrate 110 instead of through-holes as the through-holes 111 to which the thermal conductor 1 is applied. Furthermore, the substrate 110 may have non-through-holes in addition to through-holes. The following explanation will mainly focus on the case where the substrate 110 has through-holes as the through-holes 111 to which the thermal conductor 1 is applied.

[0017] The thermal conductor 1 can be configured to be in contact with a high-temperature member on one surface 110a of the substrate 110 and in contact with a heat dissipation member on the other surface 110b of the substrate 110. This allows it to be used as a heat transfer member that transfers heat from the high-temperature member to the heat dissipation member and efficiently dissipates the heat from the heat dissipation member, or as a heat transfer member that contacts a heating object to be heated and a high-temperature member that is at a higher temperature than the heating object and transfers thermal energy from the high-temperature member to the heating object and efficiently heats the heating object, etc.

[0018] The following description will mainly focus on the case where the thermal conductor 1 is used in contact with at least a part of the surface of a high-temperature member, which is a heat generating member, and at least a part of the surface of a heat dissipating member.

[0019] The high-temperature component is not particularly limited as long as it reaches a temperature higher than the surrounding atmosphere, and examples thereof include various electronic components and electrical components, and more specifically, examples thereof include a computer central processing unit (CPU), a graphics processing unit (GPU), a power semiconductor element (power device), an FPGA, an ASIC, an SoC for a smartphone, a DSP or microcomputer for an embedded device, or semiconductor elements such as a transistor.

[0020] The maximum surface temperature of the high-temperature member is preferably 40°C or higher and 250°C or lower, more preferably 50°C or higher and 200°C or lower, and even more preferably 60°C or higher and 180°C or lower. When the thermal conductor 1 is applied to such high-temperature members, it can conduct and dissipate heat more effectively, and the effects of the present invention are more pronounced.

[0021] In the electronic circuit board 100 shown in FIG. 1, for example, a power semiconductor device 120 is arranged on one surface 110a of the board 110, and a cooling unit 130 is arranged on the other surface 110b of the board 110. The thermal conductor 1 is in contact with the power semiconductor device 120 on one surface 110a of the substrate 110, and is in contact with the cooling unit 130 on the other surface 110b of the substrate 110.

[0022] In the electronic circuit board 100, for example, a thermal conductor 1 is disposed between and thermally coupled to a power semiconductor element 120 as a high-temperature member that is a heat-generating body and a cooling unit 130 as a heat dissipation member. At this time, the flexible thermal conductor 1 is inserted into the through hole 111 while being pressed in the thickness direction of the board 110. In other words, the thermal conductor 1 is disposed between the power semiconductor element 120 and the cooling unit 130 while being pressed in the thickness direction of the board 110.

[0023] Among the electronic and electrical components described above, the power semiconductor element 120 tends to generate a particularly large amount of heat, and by applying the power semiconductor element 120, the effects of the present invention can be made even more pronounced.

[0024] As described above, the thermal conductor 1 is made of a material with excellent thermal conductivity, and is also highly flexible and conforms well to the surfaces of the high-temperature components and heat dissipation components. Therefore, even if the surfaces of the high-temperature components and heat dissipation components have relatively large irregularities, the thermal conductor 1 can adhere well to these components, reducing the interfacial thermal resistance and improving the effective thermal conductivity from the power semiconductor elements 120 to the thermal conductor 1 and from the thermal conductor 1 to the cooling unit 130. This allows heat from the power semiconductor element 120, which is a high-temperature component, to be effectively dissipated, preventing malfunctions such as breakdowns and erroneous operation of the power semiconductor element 120 due to heat, and extending the product life of the power semiconductor element 120.

[0025] The following description will mainly focus on the case where the thermal conductor 1 is in contact with the power semiconductor device 120 on one surface 110a of the substrate 110 and in contact with the cooling unit 130 on the other surface 110b of the substrate 110.

[0026] [1-1] Substrate The substrate 110 is a plate-like member that supports the power semiconductor elements 120 and the cooling unit 130. The substrate 110 is not particularly limited, but may be, for example, a printed wiring board that is commonly used in electronic circuit boards.

[0027] The substrate 110 is, for example, a laminated substrate, which allows the electronic circuit board 100 to be more highly integrated. The thickness of the substrate 110, that is, the length indicated by T1 in FIG. 1, is not particularly limited, but is preferably, for example, 1 mm or more and 6 mm or less, and more preferably 2 mm or more and 5 mm or less. This allows the effects of the present invention to be more pronounced. In this specification, the "thickness of substrate 110" refers to the thickness of substrate 110 at the portion where through-hole 111 is provided.

[0028] [1-1-1]Through hole The substrate 110 has a through hole 111 formed therein. The through-hole 111 is a recess provided in the thickness direction of the substrate 110. In particular, in the illustrated configuration, the through-hole 111 is a hole drilled through the substrate 110. By inserting the thermal conductor 1 into this through-hole 111, it is possible to improve the thermal conductivity between both surfaces of the substrate 110, in other words, in the thickness direction of the substrate 110.

[0029] The shape of the through-hole 111 is not particularly limited and is set appropriately depending on the shapes of the power semiconductor element 120 and the cooling unit 130 disposed on the substrate 110. The shape of the through-hole 111 can be set, for example, to be similar to that of the power semiconductor element 120 but smaller than that of the power semiconductor element 120. Examples of the shape of the through-hole 111 when viewed in plan, or the cross-sectional shape of the through-hole 111, include a circle, an ellipse, a polygon, and a combination of these. Furthermore, the longitudinal cross-sectional shape of the through-hole 111 may be, for example, one that has a constant width in the thickness direction of the substrate 110, or one that has a portion whose width changes depending on the thickness of the substrate 110.

[0030] When through-hole 111 has a polygonal shape in plan view, for example, a rectangular cross-sectional shape, the length of the longest side is preferably 5 mm or more and 15 mm or less, and more preferably 7 mm or more and 10 mm or less, thereby making the above-mentioned effects more pronounced.

[0031] When the shape of through hole 111 when viewed in a plane, or the cross-sectional shape of through hole 111, is approximately circular, it is preferable that the diameter of the circle be a value within the above range, and when the shape of through hole 111 when viewed in a plane, or the cross-sectional shape of through hole 111, is approximately elliptical, it is preferable that the length of the major axis of the ellipse be a value within the above range, thereby making the above-mentioned effects more pronounced.

[0032] The size of through hole 111 may or may not be constant in the thickness direction of substrate 110. When substrate 110 has portions where through hole 111 has different sizes in the thickness direction, it is preferable that the length of one side of through hole 111, the diameter, and the length of the long axis at the portion where they are maximum are values ​​within the above ranges.

[0033] For example, in the illustrated configuration, the shape and size of the through-holes 111 are constant in the thickness direction of the substrate 110. This allows the thermal conductivity of the thermal conductors 1 inserted in the through-holes 111 to be kept constant in the thickness direction of the substrate 110, making the effects of the present invention more pronounced. This is also advantageous from the standpoint of manufacturing, as it allows processes such as forming the through-holes 111 in the substrate 110 and inserting the thermal conductors 1 into the through-holes 111 to be carried out efficiently.

[0034] An insulating layer (not shown) may be formed on the inner wall surface of through-hole 111 . This makes it possible to more effectively prevent problems such as electrical short circuits in electronic circuits.

[0035] [1-2] Power semiconductor devices The power semiconductor element 120 is a semiconductor element (power device) for power control. Examples of such power semiconductor elements 120 include a rectifier diode, a power transistor (power MOSFET, insulated gate bipolar transistor (IGBT)), a thyristor, a gate turn-off thyristor (GTO), and a triac.

[0036] The power semiconductor element 120 is fixed onto one surface 110 a of the substrate 110 by, for example, solder 121 . This improves the bonding strength between the substrate 110 and the power semiconductor element 120, more reliably ensures conductivity, and more reliably prevents damage to the power semiconductor element 120 when it is fixed. Also, the productivity of the electronic circuit board 100 can be improved.

[0037] [1-3] Cooling unit The cooling unit 130 is a member for radiating heat from the power semiconductor elements 120. Examples of such a cooling unit 130 include a vapor chamber, a heat dissipation fin, a Peltier element, an air-cooled unit, and a water-cooled unit.

[0038] The cooling unit 130 is fixed onto the other surface 110b of the substrate 110 by, for example, screws 131. This allows for better adhesion between the substrate 110 and the cooling unit 130, and more reliably improves the cooling efficiency of the cooling unit 130. Furthermore, by using the screws 131 for fixation (bolt tightening), the surface pressure when the substrate 110 and the thermal conductor 1 are brought into close contact with each other can be more suitably adjusted.

[0039] In particular, by soldering the power semiconductor elements 120 to the substrate 110 and fixing the cooling unit 130 to the substrate 110 with screws, the above-mentioned effects can be obtained, and the power semiconductor elements 120 can be effectively prevented from being subjected to undesirable heat history during the manufacturing process of the electronic circuit board 100, thereby improving the reliability of the electronic circuit board 100. In addition, the productivity of the electronic circuit board 100 can be further improved.

[0040] [1-4] Thermal conductor FIG. 2 is a perspective view schematically showing an example of a thermal conductor. FIG. 3 is a cross-sectional view schematically showing an enlarged view of stacked thermal conductive portions and joint portions. FIG. 4 is a plan view schematically showing an example of a thermal conductive portion constituting the thermal conductor. FIG. 5 is a partially exploded perspective view schematically showing a plurality of stacked thermal conductive portions. FIG. 6 is a conceptual diagram of an example of a cured product of a curable resin material constituting the joint portions. Note that resin fibers 22 are not shown in FIG. 3.

[0041] The thermal conductor 1 is used by being inserted into the through-hole 111 in an electronic circuit board 100 having a substrate 110 in which the through-hole 111 is formed, and is flexible and in contact with different members on both sides of the depth direction of the through-hole 111.

[0042] In the configuration shown in FIG. 1, for example, the thermal conductor 1 is in contact with the power semiconductor element 120 on one side (i.e., on one side 110a of the substrate 110) and in contact with the cooling unit 130 on the other side (i.e., on the other side 110b of the substrate 110).

[0043] As will be described in detail later, the thermal conductor 1 has excellent thermal conductivity in a predetermined direction, i.e., in the thickness direction of the substrate 110, and is used so as to come into contact with different components arranged on both sides of the substrate 110.

[0044] The thermal conductor 1 has flexibility, which ensures sufficient adhesion between the thermal conductor 1 and members in contact with it, such as high-temperature members and heat-dissipating members, and reduces the interfacial thermal resistance, thereby increasing the effective thermal conductivity.

[0045] When thermal conductor 1 is compressed at 20°C with a stress of 0.25 MPa in a direction corresponding to the insertion direction into through hole 111, the compression ratio of thermal conductor 1 is preferably 4.0% or more and 10.0% or less, and more preferably 5.0% or more and 8.0% or less. This allows the effects of the present invention to be more pronounced.

[0046] When thermal conductor 1 is compressed at 20°C with a stress of 0.50 MPa in a direction corresponding to the insertion direction into through hole 111, the compression ratio of thermal conductor 1 is preferably 7.0% or more and 20.0% or less, and more preferably 9.0% or more and 15.0% or less. This allows the effects of the present invention to be more pronounced.

[0047] The thermal conductor 1 may be any material as long as it has flexibility and thermal conductivity as a whole, but is preferably made of a material containing resin. This allows for excellent adhesion between the thermal conductor 1 and the member in contact with the thermal conductor 1, and allows for excellent actual thermal conductivity between the member and the thermal conductor 1.

[0048] The thermal conductor 1 may be any material as long as it is flexible as a whole, but the thermal conductor 1 shown in Fig. 2 includes a plurality of thermally conductive portions 10 and joint portions 20 made of a flexible material that join the thermally conductive portions 10. In other words, the thermal conductor 1 shown in Fig. 2 is a composite laminate having a plurality of thermally conductive portions 10 and joint portions 20. The thermally conductive portions 10 and the joint portions 20 are arranged in such a manner that at least a portion of their surfaces can come into contact with a member to which the thermal conductor 1 is applied when the thermal conductor 1 is inserted into a through-hole 111 in a substrate 110. This allows for excellent adhesion between the thermal conductor 1 and the member in contact with the thermal conductor 1, and allows for excellent actual thermal conductivity between the member and the thermal conductor 1.

[0049] The following explanation will focus on the case where the thermal conductor 1 has multiple thermal conductive portions 10 and joining portions 20 made of a material including a flexible resin material 21, which joins each thermal conductive portion 10.

[0050] The thermal conductor 1 may have at least one joint 20, but in the example shown in Figure 2, it has multiple thermal conductive parts 10 and multiple joint parts 20, and thermal conductive parts 10 are arranged at both ends in the stacking direction.

[0051] As will be described in detail later, such a thermal conductor 1 can be suitably manufactured, for example, by winding a thermal conductive part forming sheet (thermal conductive part forming member) 10' used to form the thermal conductive part 10, which has a joint forming composition 20' used to form the joint 20 applied to at least one surface, around the circumferential surface of a winding roll R2, thereby forming an alternating layer of the thermal conductive parts 10 and the joints 20.

[0052] In this specification, the stacking direction of the heat-conducting portion 10 and the bonding portion 20 in the heat conductor 1 is defined as the stacking direction of the heat conductor 1, and the in-plane direction of the heat-conducting portion-forming sheet 10' is defined as the in-plane direction of the heat-conducting portion 10. For example, in the configuration shown in FIG. 2, the left-right direction is the stacking direction of the heat conductor 1, and the vertical depth direction is the in-plane direction of the heat-conducting portion 10. Furthermore, in FIGS. 7 and 8 described below, the horizontal depth direction is the in-plane direction of the heat-conducting portion-forming sheet 10' and the in-plane direction of the heat-conducting portion 10.

[0053] In this specification, the extending direction of the heat conducting portion 10 in the plane of the upper surface of the heat conductor 1 is defined as the extending direction of the heat conducting portion 10. For example, in the configuration shown in Fig. 2, the extending direction of the heat conducting portion 10 is the depth direction in the plane of the upper surface of the heat conductor 1.

[0054] The thermal conductor 1 preferably has anisotropic thermal conductivity. This allows the thermal conductor 1 to more efficiently transfer heat in a predetermined direction, and also prevents unwanted heat conduction, more effectively preventing adverse effects of heat on the substrate 110 (especially a laminated substrate) and components provided on the substrate 110.

[0055] In the thermal conductor 1 having the configuration shown in FIG. 2, the thermal conductivity of the thermal conductive portion 10 in the in-plane direction is higher than the thermal conductivity of the thermal conductive portion 10 and the bonding portion 20 in the stacking direction. This allows the thermal conductor 1 to transfer heat more efficiently in the in-plane direction of the thermal conductive portion 10 than in the stacking direction of the thermal conductive portion 10 and the bonding portion 20.

[0056] The thermal conductor 1 preferably has a higher thermal conductivity in the thickness direction of the substrate 110 than in a predetermined in-plane direction of the substrate 110.

[0057] This allows the thermal conductor 1 to more efficiently transfer heat in the thickness direction of the substrate 110, and the above-described effects of the present invention are more significantly exhibited.

[0058] The above conditions can be satisfied, for example, when the thermal conductor 1 is placed in the through hole 111 of the substrate 110, by aligning the in-plane direction of the thermal conductive portion 10 with the thickness direction of the substrate 110 and aligning the stacking direction of the thermal conductive portion 10 and the bonding portion 20 with the in-plane direction of the substrate 110.

[0059] The thermal conductor 1 also has anisotropy in thermal conductivity on the upper surface, in other words, the surface exposed on the surface of the substrate 110. That is, in the upper surface of the thermal conductor 1, the thermal conductivity in the stacking direction of the thermal conductive portion 10 and the bonding portion 20 is lower than the thermal conductivity in the extending direction of the thermal conductive portion 10.

[0060] As will be described later, by arranging the thermal conductor 1, for example, within the plane of the substrate 110, so that the extension direction of the thermal conductive section 10 and the bonding section 20 and the stacking direction of the thermal conductive section 10 and the bonding section 20 are controlled in the X-axis direction and the Y-axis direction within the plane of the substrate 110, it is possible to impart anisotropy to the thermal conductivity within the plane of the substrate 110 via the thermal conductor 1.

[0061] The shape of the thermal conductor 1 is not particularly limited, but is preferably set appropriately according to the shape of the through-hole 111 formed in the substrate 110. This allows the above-described effects of the present invention to be more pronounced.

[0062] The shape of the thermal conductor 1 when viewed from above, or the cross-sectional shape of the thermal conductor 1, may be, for example, a circle, an ellipse, a polygon, or a combination of these. The longitudinal cross-sectional shape of the thermal conductor 1 may be, for example, a shape having a constant width in the thickness direction of the substrate 110, or a shape having a portion whose width changes depending on the thickness of the substrate 110.

[0063] When the shape of the thermal conductor 1 when viewed in a plane, or the cross-sectional shape of the thermal conductor 1, is polygonal, for example, rectangular, the length of the longest side of the rectangle is preferably 5 mm or more and 15 mm or less, and more preferably 7 mm or more and 10 mm or less. This ensures a sufficient contact area between the thermal conductor 1 and the member in contact with the thermal conductor 1, and makes it possible to more reliably exhibit the above-mentioned effects more significantly.

[0064] Specifically, for example, the thermal conductor 1 preferably has a rectangular shape larger than 5 mm×5 mm when viewed from above. This makes it possible to more significantly exhibit the above-mentioned effects.

[0065] The size of the thermal conductor 1 may or may not be constant in the thickness direction of the substrate 110. When the thermal conductor 1 has portions with different sizes in the thickness direction of the substrate 110, it is preferable that the length of one side of the thermal conductor 1 at the portion where the length is greatest is within the above range.

[0066] For example, in the illustrated configuration, the shape and size of the thermal conductor 1 are constant in the thickness direction of the substrate 110. Specifically, the thermal conductor 1 is shaped like a square pillar. This allows the thermal conductivity of the thermal conductor 1 inserted into the through-hole 111 in the thickness direction of the substrate 110 to be kept constant, making the effects of the present invention more pronounced. This is also advantageous from the standpoint of manufacturing, as it allows processes such as cutting the thermal conductor 1 and inserting the thermal conductor 1 into the through-hole 111 to be carried out efficiently.

[0067] Even if the shape of the through-hole 111 is complex, the thermal conductor 1 can be cut to fit the shape of the through-hole 111, making it easier to accommodate than, for example, using a copper inlay.

[0068] The length of the thermal conductor 1 in its natural state in the thickness direction of the substrate 110, ie, the length indicated by T2 in FIG. 2, is preferably 1.0 mm or more and 6.0 mm or less, and more preferably 2.0 mm or more and 5.0 mm or less. This allows for more suitable adhesion between the thermal conductor 1 and a member in contact with the thermal conductor 1, thereby providing particularly excellent substantial thermal conductivity. Therefore, for example, when a member in contact with the thermal conductor 1 is a heat generating body, the heat dissipation can be improved.

[0069] In the following description, the case where the thermal conductor 1 has a square prism shape will be mainly described. In addition, although the figures referred to in this specification clearly show the interface between the heat conducting portion 10 and the joint portion 20, the interface between the heat conducting portion 10 and the joint portion 20 may be unclear, for example, because part of the heat conducting portion 10 penetrates into the joint portion 20.

[0070] [1-4-1] Heat conduction part The plurality of heat conducting portions 10 are portions that mainly contribute to the thermal conductivity of the entire heat conductor 1, particularly the thermal conductivity in the in-plane direction of the heat conducting portions 10.

[0071] It is preferable that at least some of the multiple heat conducting portions 10 are provided continuously inside the heat conductor 1, particularly in the thickness direction of the substrate 110, and are exposed on two different surfaces of the heat conductor 1, particularly on two different surfaces where the heat conductor 1 comes into contact with other components, in other words, on both sides in the depth direction of the through hole 111. This makes it possible to improve the substantial thermal conductivity of the substrate 110 in the thickness direction.

[0072] In particular, the heat conductor 1 of the illustrated configuration has at least one pair of parallel surfaces, and at least some of the multiple heat conducting portions 10 are penetrating heat conducting portions that are continuously provided inside the heat conductor 1 and exposed on two surfaces. This allows for more optimal adhesion between the thermal conductor 1 and the components in contact with the thermal conductor 1, thereby improving the effective thermal conductivity between the two parallel surfaces, in other words, between both surfaces of the substrate 110. In this specification, "parallel" does not mean "parallel" in the strict mathematical sense, but allows for a slight deviation.

[0073] The heat conductive portion 10 is not particularly limited as long as it has thermal conductivity, and examples of materials constituting the heat conductive portion 10 include ceramic materials such as aluminum nitride, boron nitride, silicon nitride, silicon carbide, and alumina, carbon materials such as graphite and carbon fiber, and metal materials such as copper and aluminum, but it is preferable that the heat conductive portion 10 be made of a material containing a carbon material, and it is more preferable that the heat conductive portion 10 be made of a material containing graphite. This makes it possible to improve the substantial thermal conductivity between the thermal conductor 1 and members in contact with the thermal conductor 1, while reducing the manufacturing costs of the thermal conductor 1.

[0074] [1-4-1-1] Carbon materials In particular, when the heat conductive part 10 is formed from a heat conductive part-forming sheet 10' containing a carbon material such as graphite or carbon fiber, the following effects can be obtained in addition to the effects described above. That is, the flexibility and flexibility of the heat conductor 1 can be improved, and, for example, the heat conductor 1 can have improved restoring force when bent, cushioning properties due to internal voids, and improved contactability due to appropriate deformation when contacting a member in contact with the heat conductor 1. In particular, these effects are more pronounced when graphite is used as the carbon material.

[0075] As the graphite constituting the heat conductive portion 10, it is preferable to use flake graphite. By using flake graphite, the flake graphite can be preferably oriented in the in-plane direction of the heat conductive portion 10 by a method described below, thereby making it possible to particularly improve the thermal conductivity in the in-plane direction of the heat conductive portion 10. Furthermore, by using flake graphite, it is possible to preferably provide void portions 12 as described below in portions of the heat conductive portion 10 other than the hole portions 11 described below, particularly in portions near the center of the heat conductive portion 10 in the thickness direction, which is the normal direction to the in-plane direction of the heat conductive portion 10, thereby obtaining the effects described below.

[0076] [1-4-1-2] Ceramic materials Furthermore, when the heat conducting portion 10 is made of a ceramic material, the substantial thermal conductivity between the heat conductor 1 and a member in contact with the heat conductor 1 can be improved while the dust generation of the heat conductor 1 can be reduced, and problems such as electrical short circuits in electronic circuits can be more effectively prevented. In particular, nitride ceramics such as aluminum nitride and oxide ceramics such as alumina are themselves highly insulating materials, so that even if a part of the heat conducting portion 10 falls off from the heat conductor 1 due to dust generation or the like, the above-mentioned problems can be effectively prevented.

[0077] [1-4-1-3] Metal material Furthermore, when the heat conductive part 10 is formed from a heat conductive part-forming sheet 10' made of a metal material, the following additional effects can be obtained in addition to the effects described above. That is, the dust generation of the heat conductor 1 can be reduced due to the strong bonding force inside the metal material. Furthermore, even when a relatively large load is applied to the heat conductor 1, irreversible deformation of the heat conductor 1, such as collapse of the heat conductor 1 due to buckling, can be more effectively prevented.

[0078] Examples of the metal material constituting the heat conductive part 10 include various simple metals and alloys, and one or more selected from these can be used in combination. More specifically, examples of the metal material constituting the heat conductive part 10 include those containing one or more selected from the group consisting of Al, Cu, Ag, Au, Mg, and Zn, and those containing Al are preferred. This makes it possible to further improve the thermal conductivity of the heat conducting portion 10. An example of an alloy containing the metal elements constituting the above group is duralumin, which is an aluminum alloy containing Al, Cu, and Mg.

[0079] The heat conducting portion 10 is preferably made of substantially a single component. This can further improve the thermal conductivity of the heat conducting portion 10. In addition, this is generally advantageous in terms of reducing the manufacturing cost of the heat conductor 1. The phrase "consisting essentially of a single component" means that the proportion of the main component in the target area is 95% by weight or more, preferably 97% by weight or more, and more preferably 99% by weight or more.

[0080] However, if the heat conductive part 10 contains a gas such as air, the content of that gas is ignored. Also, if the heat conductive part 10 is made of a metal material, an oxide film of the metal that makes up the heat conductive part 10, such as a passivation film, may be formed on the surface. Even when such an oxide film is formed, the heat conductive part is treated as being "composed essentially of a single component." The same applies to the heat conductive part-forming sheet 10', which will be described in detail later.

[0081] The thermal conductivity of the heat conducting portion 10 in the in-plane direction at 20°C is preferably 7 W / (m·K) or more and 2500 W / (m·K) or less, and more preferably 20 W / (m·K) or more and 1800 W / (m·K) or less. The thermal conductivity value can be determined by measurement using a transient hot wire method based on the laser flash method.

[0082] t in Figure 2 10 The thickness of the heat conducting portion 10 in the stacking direction indicated by is preferably 5 μm or more and 500 μm or less, and more preferably 20 μm or more and 150 μm or less. This makes it possible to ensure that the proportion of the thermal conductive portion 10 in the thermal conductor 1 is sufficiently high, while also making it easier to improve the flexibility of the thermal conductor 1 as a whole, thereby more reliably achieving the above-mentioned effects more significantly. Here, the thickness of the heat conducting portion 10 refers to the thickness at a portion where the hole portion 11 described below is not provided.

[0083] As shown in FIG. 2, each of the heat conducting portions 10 constituting the heat conductor 1 may be provided with a recess in the thickness direction. This makes it possible to improve the bonding strength between the heat conducting portion 10 and the bonding portion 20 .

[0084] In particular, in each heat conducting portion 10 shown in FIG. 3, the recess is a hole 11 that penetrates the heat conducting portion 10 in the thickness direction. This makes the above-mentioned effects more pronounced.

[0085] In the following description, the case where the recess is a hole will be mainly described. The number of holes (recesses) 11 provided in each heat conducting portion 10 may be only one depending on the size of the heat conducting portion 10 in the in-plane direction, but is preferably plural. This makes the above-mentioned effects even more pronounced.

[0086] When multiple holes 11 are provided in a single heat conductive portion 10, the spacing between adjacent holes 11 in the in-plane direction of the heat conductive portion 10 is preferably 300 μm or more and 1000 μm or less, and more preferably 400 μm or more and 800 μm or less. This makes it possible to make the above-mentioned effects more pronounced. In this specification, the "interval between holes 11" refers to the distance between the centers of adjacent holes 11.

[0087] In the configuration shown in FIG. 4, the multiple holes 11 provided in the single heat conducting portion 10 are arranged in a staggered pattern, but the arrangement pattern of the multiple holes 11 in the in-plane direction of the single heat conducting portion 10 is not limited to this and may be any pattern, for example, they may be arranged randomly.

[0088] The resin material 21 has entered at least a part of the hole 11. In other words, the cured product of the curable resin material has entered through the recess into the interior of the heat conductive part 10 where the recess is provided. As a result, in particular, by having the resin material 21 penetrate into the hole 11 provided in the heat conducting portion 10, the bond between the heat conducting portion 10 and the joint portion 20 can be made stronger, and the shape adaptability to the surface shape of the member that comes into contact with the heat conductor 1, such as a heat generating member or a heat dissipating member, and the durability of the heat conductor 1 can be improved.

[0089] As shown in FIG. 5, when the heat conductive portions 10 are observed from the stacking direction with the bonding portions 20, it is preferable that the plurality of heat conductive portions 10 have holes 11 that do not overlap each other.

[0090] When overlapping holes 11 exist in multiple heat conductive portions 10, the resin material 21 of the joint portion 20 that has entered the overlapping holes 11 forms a skewer shape that penetrates through the multiple heat conductive portions 10. In such a case, the resin material 21 may slip through the holes 11, resulting in insufficient bonding between the heat conductive portions 10.

[0091] In contrast, when the heat conductive portion 10 is observed from the stacking direction with the joint portion 20, the presence of non-overlapping hole portions 11 in the multiple heat conductive portions 10 prevents the resin material 21 of the joint portion 20 that has penetrated into the hole portions 11 from slipping through, making the joint between the heat conductive portions 10 stronger.

[0092] In FIG. 5, only the heat conducting portion 10 is shown, and the bonding portion 20 is omitted. The shape of the hole 11 is not particularly limited, and examples of the shape of the hole 11 when the heat conductive member 10 is viewed in plan and the cross-sectional shape of the hole 11 in the heat conductive member 10 include a circle, an ellipse, a polygon, etc. Furthermore, the longitudinal cross-sectional shape of the heat conductive member 10 may be, for example, a shape having a constant width in the depth direction of the hole 11, or a shape having a portion whose width changes in the depth direction of the hole 11.

[0093] When the shape of the hole 11 when the heat conductive portion 10 is viewed in a plane, that is, when the cross-sectional shape of the hole 11 in the heat conductive portion 10 is circular, the diameter of the hole 11 is preferably 30 μm or more and 500 μm or less, and more preferably 50 μm or more and 200 μm or less. This makes it possible to make the above-mentioned effects more pronounced.

[0094] The size (diameter) of the pores 11 may or may not be constant in the thickness direction of the heat conductive part 10. When the heat conductive part 10 has portions where the size (diameter) of the pores 11 varies in the thickness direction, it is preferable that the diameter value at the portion where the diameter of the pores 11 is maximum is within the above range.

[0095] The proportion of the thermal conductive portion 10 in the thermal conductor 1 is preferably 15% by volume or more and 80% by volume or less, and more preferably 20% by volume or more and 70% by volume or less. This makes the above-mentioned effects more pronounced.

[0096] The proportion of the thermal conductive portion 10 in the thermal conductor 1 (but the solid portion excluding the void portion 2) is preferably 30% or more and 90% or less, and more preferably 40% or more and 82% or less, in terms of area ratio in the cross section in the stacking direction of the thermal conductor 1. This makes the above-mentioned effects more pronounced.

[0097] [1-4-2]Joint part The joining portion 20 is disposed between two adjacent heat conducting portions 10 to join the heat conducting portions 10 together, and is configured to contain a flexible resin material 21. The resin material 21 is a cured product of a curable resin material 21′, which will be described later.

[0098] Since the joint 20 contains a flexible resin material 21, the thermal conductor 1 has excellent shape adaptability to the surface shapes of components that come into contact with the thermal conductor 1, such as heat-generating components and heat-dissipating components. Furthermore, since the joints 20 contain the flexible resin material 21, the thermal conductor 1 can be suitably prevented from being damaged when the thermal conductor 1 is deformed.

[0099] [1-4-2-1] Resin materials The resin material 21 constituting the joint 20 is not particularly limited as long as it is flexible, and examples thereof include flexible epoxy resin, rubber-based resin, urethane-based resin, silicone-based resin, fluorine-based resin, acrylic-based resin, and thermoplastic elastomer. However, as shown in FIG. 6, the resin material 21 preferably includes a polyrotaxane 50 having a cyclic molecule 51, a first polymer 52 having a linear molecular structure and encapsulating the cyclic molecule 51 in a skewered manner, and blocking groups 53 provided near both ends of the first polymer 52, and a second polymer 60, and the polyrotaxane 50 and the second polymer 60 are bonded via the cyclic molecule 51.

[0100] This can improve the bonding strength between the thermally conductive portions 10 and the bonding portions 20 in the thermal conductor 1, and can improve the durability of the thermal conductor 1. Furthermore, the flexibility, heat resistance, etc. of the thermal conductor 1 can be improved.

[0101] In particular, when stress in the direction of the arrow is applied to resin material 21 in the state shown in Fig. 6(A), resin material 21 can assume the form shown in Fig. 6(B). That is, in resin material 21, cyclic molecules 51 can move along first polymers 52, that is, first polymers 52 can move within cyclic molecules 51, so that deformation stress can be efficiently absorbed within resin material 21. Therefore, even when a large external force such as a twisting force is applied, destruction of joints 20 and destruction of the joints between heat conductive members 10 can be effectively prevented.

[0102] The resin material 21 containing the polyrotaxane 50 and the second polymer 60 will be described in detail below. The cyclic molecules 51 constituting the polyrotaxane 50 may be any molecules capable of moving along the first polymer 52, but are preferably optionally substituted cyclodextrin molecules, and it is particularly preferred that the cyclodextrin molecules be selected from the group consisting of α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, and derivatives thereof.

[0103] At least a portion of the cyclic molecules 51 in the polyrotaxane 50 is bonded to at least a portion of the second polymer 60 as described above. Examples of the functional group (functional group bonding to the second polymer 60) possessed by the cyclic molecule 51 include an -OH group, an -NH group, an -COOH group, an epoxy group, a vinyl group, a thiol group, and a photocrosslinking group. Examples of the photocrosslinking group include cinnamic acid, coumarin, chalcone, anthracene, styrylpyridine, styrylpyridinium salt, and styrylquinolium salt.

[0104] When the maximum amount of cyclic molecules 51 included when cyclic molecules 51 are skewered and included by first polymer 52 is set to 1, the amount of cyclic molecules 51 skewered and included by first polymer 52 is preferably 0.001 or more and 0.6 or less, and more preferably 0.05 or more and 0.4 or less. Two or more different types of cyclic molecules 51 may be used.

[0105] Examples of the first polymer 52 constituting the polyrotaxane 50 include cellulose-based resins such as polyvinyl alcohol, polyvinylpyrrolidone, poly(meth)acrylic acid, carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose; polyacrylamide, polyethylene oxide, polyethylene glycol, polypropylene glycol, polyvinyl acetal-based resins, polyvinyl methyl ether, polyamine, polyethyleneimine, casein, gelatin, starch, and / or copolymers thereof; polyolefin-based resins such as polyethylene, polypropylene, and copolymers with other olefin-based monomers; polyester resins; polyvinyl chloride resins; polystyrene-based resins such as polystyrene and acrylonitrile-styrene copolymer resins; polymethyl methacrylate resins; Examples of the polymerizable compound include acrylic resins such as acrylates, (meth)acrylic acid ester copolymers, and acrylonitrile-methyl acrylate copolymer resins, polycarbonate resins, polyurethane resins, vinyl chloride-vinyl acetate copolymer resins, and polyvinyl butyral resins; and derivatives or modified products thereof, polyisobutylene, polytetrahydrofuran, polyaniline, acrylonitrile-butadiene-styrene copolymers, polyamides such as nylon, polyimides, polyisoprene, polybutadiene, and other polysiloxanes, polydimethylsiloxane, polysulfones, polyimines, polyacetic anhydrides, polyureas, polysulfides, polyphosphazenes, polyketones, polyphenylenes, polyhaloolefins, and derivatives thereof, with polyethylene glycol being particularly preferred.

[0106] The weight average molecular weight of the first polymer 52 is preferably 10,000 or more, and more preferably 35,000 or more. Two or more different types of first polymers 52 may be used.

[0107] A preferred combination of the cyclic molecule 51 and the first polymer 52 is one in which the cyclic molecule 51 is an α-cyclodextrin which may be substituted, and the first polymer 52 is polyethylene glycol.

[0108] The blocking group 53 constituting the polyrotaxane 50 is not particularly limited as long as it is a group that has the function of preventing the cyclic molecule 51 from detaching from the first polymer 52, and examples thereof include dinitrophenyl groups, cyclodextrins, adamantane groups, trityl groups, fluoresceins, pyrenes, substituted benzenes (substituents include alkyl, alkyloxy, hydroxy, halogen, cyano, sulfonyl, carboxyl, amino, phenyl, etc.; one or more substituents may be present), optionally substituted polynuclear aromatics, steroids, etc.

[0109] Substituents constituting the substituted benzenes and substituted polynuclear aromatics include alkyl, alkyloxy, hydroxy, halogen, cyano, sulfonyl, carboxyl, amino, phenyl, etc. One or more substituents may be present. Two or more different blocking groups 53 may also be used.

[0110] In the resin material 21, at least a portion of the polyrotaxanes 50 are bonded to the second polymer 60 via the cyclic molecules 51, but the resin material 21 may contain polyrotaxanes 50 that are not bonded to the second polymer 60, or polyrotaxanes 50 may be bonded to each other.

[0111] The second polymer 60 is bonded to the polyrotaxane 50 via the cyclic molecule 51. Examples of functional groups that the second polymer 60 has and that bond to the cyclic molecule 51 include an -OH group, an -NH group, an -COOH group, an epoxy group, a vinyl group, a thiol group, and a photocrosslinking group. Examples of photocrosslinking groups include cinnamic acid, coumarin, chalcone, anthracene, styrylpyridine, styrylpyridinium salt, and styrylquinolium salt.

[0112] Examples of the second polymer 60 include cellulose-based resins such as polyvinyl alcohol, polyvinylpyrrolidone, poly(meth)acrylic acid, carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose; polyacrylamide, polyethylene oxide, polyethylene glycol, polypropylene glycol, polyvinyl acetal-based resins, polyvinyl methyl ether, polyamine, polyethyleneimine, casein, gelatin, starch, and / or copolymers thereof; polyolefin-based resins such as polyethylene, polypropylene, and copolymer resins with other olefin-based monomers; polyester resins; polyvinyl chloride resins; polystyrene-based resins such as polystyrene and acrylonitrile-styrene copolymer resins; polymethyl methacrylate; Examples of the resin include those having a skeleton of various resins such as acrylic resins such as (meth)acrylic acid ester copolymers and acrylonitrile-methyl acrylate copolymer resins, polycarbonate resins, polyurethane resins, vinyl chloride-vinyl acetate copolymer resins, polyvinyl butyral resins, and derivatives or modified products thereof, polyisobutylene, polytetrahydrofuran, polyaniline, acrylonitrile-butadiene-styrene copolymers, polyamides such as nylon, polyimides, polyisoprene, polybutadiene, polysiloxanes such as polydimethylsiloxane, polysulfones, polyimines, polyacetic anhydrides, polyureas, polysulfides, polyphosphazenes, polyketones, polyphenylenes, and polyhaloolefins, and having the functional groups described above.

[0113] The second polymer 60 and the cyclic molecule 51 may be chemically bonded to each other by a cross-linking agent. The molecular weight of the crosslinking agent is preferably less than 2000, more preferably less than 400.

[0114] Examples of crosslinking agents include cyanuric chloride, trimesoyl chloride, terephthaloyl chloride, epichlorohydrin, dibromobenzene, glutaraldehyde, phenylenediisocyanate, trilein diisocyanate, divinyl sulfone, 1,1'-carbonyldiimidazole, alkoxysilanes, etc. Two or more different crosslinking agents may be used.

[0115] The second polymer 60 may be a homopolymer or a copolymer. In the resin material 21, at least a portion of the second polymer 60 is bonded to the polyrotaxane 50 via the cyclic molecule 51, but the resin material 21 may contain second polymers 60 that are not bonded to the polyrotaxane 50, or the second polymers 60 may be bonded to each other. Two or more different types of second polymers 60 may be used. The ratio of the content of the polyrotaxane 50 to the content of the second polymer 60 in the resin material 21 is preferably 1 / 1000 or more in weight ratio.

[0116] The content of the resin material 21 in the joint 20 is preferably 5% by volume or more and 90% by volume or less, and more preferably 25% by volume or more and 75% by volume or less.

[0117] This improves the bonding strength of the heat conduction part 10 by the bonding part 20, and when the bonding part 20 contains resin fibers 22, the content of resin fibers 22 in the bonding part 20 can be sufficiently ensured, and the effect of containing the resin fibers 22 can be fully exerted.

[0118] [1-4-2-2] Resin fiber The joint 20 may contain resin fibers 22 in addition to the resin material 21 as described above.

[0119] This effectively prevents the thermal conductor 1 from sagging and deforming even when used under pressure for a long period of time, and effectively prevents the problem of the adhesion between the thermal conductor 1 and the member in contact decreasing over time due to the surface pressure on the member in contact with the thermal conductor 1 decreasing and the thermal resistance increasing.

[0120] The thickness of the resin fibers 22 contained in the joint 20 is preferably 1.0 μm or more and 30 μm or less, more preferably 2.0 μm or more and 25 μm or less, even more preferably 3.0 μm or more and 20 μm or less, and most preferably 4.0 μm or more and 15 μm or less. This makes the above-mentioned effects more pronounced.

[0121] The resin fibers 22 may be made primarily of a resin material, and examples of the resin materials that make up the resin fibers 22 include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides, ethylene vinyl acetate resins, polyvinyl alcohol, etc., but it is preferable that the resin fibers 22 be made of polyester, and it is more preferable that they be made of polyethylene terephthalate.

[0122] This makes it possible to improve the strength of the resin fiber 22 itself, more effectively exert the effect of including the resin fiber 22 in the joint 20 as described above, and improve the adhesion between the resin fiber 22 and the resin material 21, thereby improving the durability and reliability of the thermal conductor 1.

[0123] At least one resin fiber 22 may be contained in the joint 20, but it is preferable that a plurality of resin fibers 22 are contained. This makes the above-mentioned effects more pronounced.

[0124] Furthermore, each resin fiber 22 may be contained in an independent state in the joint 20, or a plurality of resin fibers 22 may be contained in an entangled state. More specifically, the resin fibers 22 may be made of, for example, a woven fabric or a nonwoven fabric.

[0125] In particular, since the resin fibers 22 are contained in the joint 20 as a nonwoven fabric, the resin fibers 22 can be distributed more uniformly in the joint 20, and undesired variations in composition can be effectively suppressed, thereby more significantly achieving the above-mentioned effects.

[0126] The content of resin fibers 22 in the joint 20 is preferably 2% by volume or more and 70% by volume or less, more preferably 4% by volume or more and 50% by volume or less, and even more preferably 6% by volume or more and 30% by volume or less.

[0127] This makes it possible to more significantly exert the effect of including the resin fibers 22 described above, and also ensures a sufficient content of the resin material 21 in the joint 20, thereby making the joint strength of the heat conduction part 10 by the joint 20 sufficiently excellent.

[0128] When the content of resin material 21 in joint 20 is X1 [volume %] and the content of resin fiber 22 in joint 20 is X2 [volume %], it is preferable to satisfy the relationship 0.04≦X2 / X1≦10.0, it is more preferable to satisfy the relationship 0.07≦X2 / X1≦5.0, and it is even more preferable to satisfy the relationship 0.10≦X2 / X1≦3.0. This makes the above-mentioned effects more pronounced.

[0129] [1-4-2-3] Metal particles The joint 20 may contain metal particles (not shown) in addition to the resin material 21 and the resin fibers 22 . As mentioned above, the part that mainly contributes to the thermal conductivity of the thermal conductive portion 10 in the in-plane direction is the thermal conductive portion 10, but since metal particles generally have higher thermal conductivity than the resin material 21 that constitutes the joint 20, the inclusion of metal particles in the joint 20 can improve the thermal conductivity of the joint 20, and can further improve the thermal conductivity of the thermal conductor 1 as a whole.

[0130] In particular, when adjacent heat conducting sections 10 are connected by one or more metal particles contained in the joint 20, the metal particles act as a "thermal path" that thermally connects the heat conducting sections 10, thereby further improving the overall thermal conductivity of the heat conductor 1.

[0131] Furthermore, by including metal particles made of a metal material having electromagnetic wave shielding properties, it is possible to impart an electromagnetic wave shielding function to the thermal conductor 1. In particular, it is possible to suitably impart a shielding function against high frequency electromagnetic waves such as those used in fifth generation mobile communications.

[0132] The metal particles preferably contain one or more types selected from the group consisting of Fe, Ag, Pt, Cu, Sn, Al and Ni, and iron particles are more preferred.

[0133] The average particle size of the metal particles is not particularly limited, but is preferably 0.01 μm or more and 10 μm or less, and more preferably 0.1 μm or more and 3.0 μm or less. In this specification, the average particle size refers to the particle size at which the cumulative 50% from the smallest diameter side is measured in a weight-based particle size distribution measured with a laser diffraction particle size distribution analyzer.

[0134] The content of metal particles in the joint 20 is preferably 1% by volume or more and 50% by volume or less, and more preferably 10% by volume or more and 30% by volume or less.

[0135] [1-4-2-4] Ceramic particles In addition to the above materials, the joint 20 may contain ceramic particles (not shown). This makes it possible to stabilize and uniform the structure of the joint 20, and also stabilize the proportion and size of voids in the joint 20. As a result, it is possible to more effectively prevent unintended variations in the properties of the thermal conductor 1 at each location.

[0136] Various ceramics can be used as constituent materials for the ceramic particles, but when ceramic materials such as nitride-based ceramics such as aluminum nitride, boron nitride, and silicon nitride, carbide-based ceramics such as silicon carbide, and oxide-based ceramics such as alumina are used, the thermal conductivity of the thermal conductor 1 as a whole can be further improved. In particular, when adjacent thermally conductive sections 10 are connected by one or more ceramic particles contained in the joint 20, the ceramic particles act as a "thermal path" that thermally connects the thermally conductive sections 10, and the thermal conductivity of the thermal conductor 1 as a whole can be further improved.

[0137] When the joint 20 contains the above-mentioned metal particles in addition to the ceramic particles, the heat path may be formed by the ceramic particles and the metal particles. The ceramic particles may be made of silica, which can reduce the production cost of the thermal conductor 1 and also provide the effects of stabilizing and uniforming the structure of the bonding portion 20 described above.

[0138] The average particle size of the ceramic particles is not particularly limited, but is preferably 5 μm or more and 200 μm or less, and more preferably 20 μm or more and 70 μm or less.

[0139] The content of ceramic particles in the joint 20 is preferably 1% by volume or more and 50% by volume or less, and more preferably 10% by volume or more and 30% by volume or less. This allows the effects of including the resin material 21 and the effects of including the ceramic particles to be exhibited in a well-balanced manner.

[0140] [1-4-2-5] Spacer The joint 20 may include a spacer. If the joint 20 includes a spacer, unintended variations in the thickness of the joint 20 can be suitably suppressed.

[0141] The shape of the spacer may be, for example, spheroidal, cylindrical, prismatic, needle-like, etc., but is preferably spherical, and more preferably spherical. This makes it possible to more effectively suppress undesired variations in the thickness of the joint 20. Furthermore, it is possible to more effectively form the gap 2 between the cured product of the curable resin material 21′ that constitutes the joint 20 and the spacer.

[0142] When the spacers are spherical, particularly true spheres, the average particle size of the spacers is not particularly limited, but is preferably 0.1 μm or more and 100 μm or less, and more preferably 1.0 μm or more and 50 μm or less.

[0143] The spacer may be made of any material, such as a metal material, a ceramic material, or glass, but is preferably made of a resin material.

[0144] Examples of resin materials constituting the spacer include polyester resins such as polyethylene terephthalate, acrylic resins, polyolefin resins such as polyvinyl chloride, polystyrene, polyethylene, and polypropylene, phenolic resins (including Bakelite), and fluorine-based resins, and one or more selected from these may be used in combination.

[0145] When the joint 20 contains a spacer, the content of the spacer in the joint 20 is preferably 0.1% by volume or more and 20% by volume or less, and more preferably 0.5% by volume or more and 10% by volume or less.

[0146] [1-4-2-6] Other ingredients The joint 20 may contain components other than those mentioned above. Examples of such components include plasticizers, colorants, antioxidants, ultraviolet absorbers, light stabilizers, softeners, modifiers, rust inhibitors, fillers, electromagnetic wave absorbers such as ferrite, surface lubricants, corrosion inhibitors, heat stabilizers, lubricants, primers, antistatic agents, polymerization inhibitors, crosslinking agents, catalysts, leveling agents, thickeners, dispersants, antioxidants, flame retardants, and hydrolysis inhibitors.

[0147] However, the content of these components in the joint 20 is preferably 5% by weight or less, and more preferably 1% by weight or less.

[0148] In Figure 2, t 20 The thickness of the joint 20 in the stacking direction of the heat conducting portion 10 and the joint 20 indicated by is preferably 0.1 μm or more and 1000 μm or less, and more preferably 5.0 μm or more and 100 μm or less. This makes the above-mentioned effects more pronounced. Here, the thickness of the joint portion 20 refers to the thickness of the portion of the heat conducting portion 10 that is in contact with the joint portion 20 where no hole 11 is provided.

[0149] The proportion of the joints 20 in the thermal conductor 1 is preferably 15% by volume or more and 70% by volume or less, more preferably 16% by volume or more and 60% by volume or less, and even more preferably 18% by volume or more and 50% by volume or less. This makes the above-mentioned effects more pronounced.

[0150] The proportion of the joints 20 in the thermal conductor 1 (but the solid part excluding the voids 2) is preferably 10% or more and 70% or less in area ratio in the cross section in the stacking direction of the thermal conductor 1, more preferably 15% or more and 60% or less, and even more preferably 18% or more and 50% or less. This makes the above-mentioned effects more pronounced.

[0151] [1-4-3]Void part In the illustrated configuration, the thermal conductor 1 has, in addition to the thermally conductive portions 10 and the joint portions 20, void portions 2 where the thermally conductive portions 10 and the joint portions 20 are not present. The voids 2 are portions of the thermal conductor 1 where the thermally conductive portions 10 and the bonding portions 20 are not present. The voids 2 usually contain air or gases such as gases generated when the resin material 21 that constitutes the bonding portions 20 hardens.

[0152] The presence of such voids 2 allows the voids 2 to act as cushions, absorbing deformation, particularly deformation of the joints 20, that occurs when the thermal conductor 1 is pressed, thereby preventing excessive deformation of the thermal conductor 1 as a whole. This also provides the thermal conductor 1 with appropriate flexibility, improving adhesion between the thermal conductor 1 and a member in contact with the thermal conductor 1, thereby improving the effective thermal conductivity between the member and the thermal conductor 1. In particular, the joints 20 contain the resin fibers 22 described above, along with the resin material 21 that functions as a binder, allowing relatively small voids 2 to be dispersed and formed. This improves adhesion between the thermal conductive members 10 and the joints 20, thereby improving the durability and reliability of the thermal conductor 1.

[0153] The void portion 2 normally contains air or a gas such as a gas generated when a curable resin material 21' (see FIG. 8 described later) used to form the resin material 21 is cured. In the thermal conductor 1, the gap 2 is provided at least in a portion adjacent to the joint 20.

[0154] The proportion of voids 2 in the thermal conductor 1 (proportion in the natural state; the same applies below) is preferably 5% by volume or more and 65% by volume or less, more preferably 5% by volume or more and 50% by volume or less, even more preferably 6% by volume or more and 40% by volume or less, and most preferably 7% by volume or more and 32% by volume or less. This makes the above-mentioned effects more pronounced.

[0155] When the proportion of thermally conductive portions 10 in the thermal conductor 1 is VC [volume %], the proportion of joint portions 20 in the thermal conductor 1 is VJ [volume %], and the proportion of void portions 2 in the thermal conductor 1 is VV [volume %], it is preferable to satisfy the relationship 25≦[(VJ+VV) / (VC+VJ+VV)]×100≦90, it is more preferable to satisfy the relationship 25≦[(VJ+VV) / (VC+VJ+VV)]×100≦70, it is even more preferable to satisfy the relationship 31≦[(VJ+VV) / (VC+VJ+VV)]×100≦65, and it is most preferable to satisfy the relationship 37≦[(VJ+VV) / (VC+VJ+VV)]×100≦62. This makes the above-mentioned effects more pronounced.

[0156] The density of the thermal conductor 1 in its natural state is 0.6 g / cm 3 More than 2.5g / cm 3 It is preferable that the concentration is 0.9 g / cm or less. 3 More than 2.0g / cm 3 More preferably, it is:

[0157] By using the above-mentioned materials for forming the heat conducting portions 10 and the joint portions 20 of the heat conductor 1, the overall density can be made lower than that of conventional copper inlays.

[0158] This allows the thermal conductor 1 to be particularly lightweight. When the electronic circuit board 100 having the thermal conductor 1 is mounted on an electronic device or the like, it does not prevent the weight of the electronic device or the like from being reduced. In other words, the electronic device or the like can be made even lighter. The density of copper used in conventional copper inlays is approximately 8.9 g / cm 3 is.

[0159] [1-5] Manufacturing method of thermal conductor Next, a method for manufacturing the thermal conductor will be described. FIG. 7 is a cross-sectional view schematically showing a heat-conducting part-forming sheet made of flake graphite. FIG. 8 is a cross-sectional view schematically showing a state in which a joint-forming composition has been applied to a heat-conducting part-forming sheet having recesses formed therein. FIG. 9 is a view schematically showing an example of an apparatus used in the joint-forming composition application step and the winding step. FIG. 10 is a view schematically showing a cut body obtained in the cutting step. FIG. 11 is a view schematically showing a state in which the cut body has been pressed to further increase its flatness. FIG. 12 is a view schematically showing the cutting step.

[0160] The method for manufacturing a thermal conductor includes, for example, a winding step in which a heat-conducting portion-forming sheet 10', which is used to form a heat-conducting portion 10 and has a recess (hole) 11 formed therein, is applied with a joint-forming composition 20', which is a composition containing a curable resin material 21', and is wound around the circumferential surface of a winding roll R2 to obtain a cylindrical wound body 30; a cutting step in which the wound body 30 is cut open in a direction non-perpendicular to the axial direction of the roll to obtain a cut body 40; and a curing step in which the curable resin material 21' contained in the cut body 40 is hardened to form the joint 20.

[0161] By winding the heat-conducting-part-forming sheet 10' to which the bond-forming composition 20' has been applied around the circumferential surface of a roll, the heat conductor 1 can be produced more efficiently than, for example, when using a sheet-like raw material. Furthermore, by curing the curable resin material 21' after cutting the wound body 30, the wound body 30 can be cut in a softer state than the bond 20 containing the resin material 21. This makes it possible to suitably correct distortions caused by winding, and effectively prevent peeling or reduced adhesion between the heat-conducting-part-forming sheet 10', which is the portion corresponding to the heat conductive part 10, and the bond-forming composition 20', which is the portion corresponding to the bond 20, when forming the cut body 40, which is flatter than the wound body 30. As a result, the final heat conductor 1 has distortion suitably removed, and peeling or reduced adhesion between the heat conductive portion 10 and the joint portion 20, destruction of the joint portion 20, destruction of the joint between the heat conductive portions 10, etc. are effectively prevented, and the heat conductive portion 10 and the joint portion 20 are firmly adhered to each other.

[0162] Furthermore, the method for manufacturing a thermal conductor may include, for example, a step of applying a composition for forming a joint 20' to a sheet for forming a thermal conductive part 10' having a recess (hole) 11 formed therein prior to the winding step.

[0163] [1-5-1] Heat conductive sheet The heat-conducting part-forming sheet 10 ′ used in the bond-forming composition application step is to become the heat-conducting part 10 in the heat conductor 1 . As the heat-conducting portion-forming sheet 10', a sheet material made of a material corresponding to the heat-conducting portion 10 to be formed is usually used.

[0164] The heat-conducting portion-forming sheet 10' is preferably composed substantially of a single component. This can further improve the thermal conductivity of the formed heat conducting portion 10. In addition, this is generally advantageous in terms of reducing the manufacturing cost of the heat conductor 1.

[0165] By using a sheet material containing graphite as the heat-conducting-part-forming sheet 10', it is possible to reduce the manufacturing cost of the heat conductor 1 while improving the substantial thermal conductivity between the heat conductor 1 and a member in contact with the heat conductor 1. In addition, it is possible to improve the flexibility and pliability of the heat conductor 1, for example, improving the restoring force when the heat conductor 1 is bent, the cushioning properties due to internal voids, and the contactability due to appropriate deformation when the heat conductor 1 comes into contact with an overheated part. Hereinafter, the sheet material containing graphite will also be referred to as a "graphite sheet material."

[0166] Furthermore, by using a sheet material made of a metal material as the heat-conducting portion-forming sheet 10', the manufacturing cost of the heat conductor 1 can be reduced while improving the substantial thermal conductivity between the heat conductor 1 and a member in contact with the heat conductor 1. Furthermore, the strong bonding force within the metal material can reduce the dust generation of the heat conductor 1. Furthermore, even when a relatively large load is applied to the heat conductor 1, irreversible deformation of the heat conductor 1, such as collapse of the heat conductor 1 due to buckling, is more effectively prevented. Hereinafter, a sheet material made of a metal material will also be referred to as a "metal sheet material."

[0167] [1-5-1-1] Graphite sheet material The graphite sheet material may contain, in addition to graphite, components other than graphite, such as binders or resin fibers, but is preferably composed essentially of graphite alone, i.e., composed essentially of a single component. Such graphite sheet material can be produced, for example, by compressing powdered graphite into a sheet.

[0168] The graphite is preferably flake graphite. This allows the flake graphite to be suitably oriented in the in-plane direction of the heat conducting portion 10, thereby making it possible to provide the heat conducting portion 10 with particularly excellent thermal conductivity in the in-plane direction.

[0169] More specifically, when flake graphite is compressed into a sheet, the flake graphite FG is oriented in the in-plane direction of the sheet, as shown in Fig. 7. That is, the thickness direction of the flake graphite FG is suitably oriented along the thickness direction of the sheet. When used as a thermal conductor 1, the thermal conductivity of the heat-conducting portion 10 in the in-plane direction can be made particularly excellent.

[0170] The graphite sheet material is preferably produced by a method including, for example, a pressurizing step of pressing flake graphite to form it into a sheet, a drying step of drying the graphite formed into a sheet, and a heating and pressing step of heating and pressing (hot pressing) the graphite formed into a sheet.

[0171] In the pressing step, the graphite is pressed to form it into a sheet. The pressing step can be suitably carried out at a temperature of, for example, 10° C. or higher and 35° C. or lower. The pressing pressure at this time can be, for example, 1 MPa or higher and 30 MPa or lower.

[0172] In the drying process, the graphite formed into a sheet is subjected to a drying treatment. This removes excess moisture and other volatile components, improving handling. It also improves the shape stability and strength of the graphite sheet material.

[0173] The drying step can be carried out by reducing pressure, heating, or natural drying. When the drying step is carried out by heating, the heating temperature can be 40°C or higher and 100°C or lower.

[0174] In the heating and pressing step, the graphite formed into a sheet is subjected to a heating and pressing treatment in the thickness direction of the sheet. This allows the flake graphite to be more suitably oriented. It also improves the shape stability and strength of the graphite sheet material.

[0175] The heating temperature in the heating and pressing step can be, for example, 100°C or higher and 400°C or lower. This more effectively prevents moisture, binder, and the like from unintentionally remaining in the finally obtained graphite sheet material. The pressing pressure in the heating and pressing step can be, for example, 10 MPa or higher and 40 MPa or lower.

[0176] 7, when flake graphite FG is compressed into a sheet, the flake graphite FG is densely packed and hard near the surface of the graphite sheet material, whereas the flake graphite FG is coarsely packed and relatively soft near the center in the thickness direction of the graphite sheet material, resulting in voids 12. When a graphite sheet material obtained by compressing flake graphite into a sheet shape is used as the heat-conducting-part-forming sheet 10' and holes 11 are provided in the graphite sheet material as the heat-conducting-part-forming sheet 10' and the heat-conducting part 10 formed by the heat-conducting-part-forming sheet 10', only the holes 11 penetrate from one side to the other, and no voids 12 penetrate from one side of the graphite sheet material or the heat-conducting part 10 to the other in other parts.

[0177] In this way, when the heat-conducting portion-forming sheet 10' has voids 12 inside, particularly near the center in the thickness direction, the curable resin material 21' can penetrate not only into the holes 11 but also into the voids 12 inside the heat-conducting portion-forming sheet 10', thereby further improving the adhesion between the heat-conducting portion 10 and the joint 20 in the manufactured heat conductor 1, the durability of the heat conductor 1, etc.

[0178] In addition, the density of the graphite sheet material is relatively high near the surface, and relatively low inside the graphite sheet material.

[0179] The density of the graphite sheet material as a whole is 0.3 g / cm 3 More than 2.1g / cm 3 It is preferable that the concentration is 0.7 g / cm or less. 3 More than 2.1g / cm 3 More preferably, it is: This allows the graphite sheet material alone to have particularly excellent thermal conductivity and strength in the surface direction, while also having more suitable voids 12 near the center of the graphite sheet material in the thickness direction, thereby more significantly demonstrating the effects described above.

[0180] [1-5-1-2] Metal sheet material As the metal sheet material, in addition to the metal material, it is possible to use one that contains components other than the metal material, such as binders and resin fibers, but it is preferable that the metal sheet material is composed essentially of only the metal material, i.e., is composed essentially of a single component. As the metal sheet material, for example, a metal foil obtained by rolling a metal material into a sheet shape can be preferably used.

[0181] The thickness of the heat-conducting portion-forming sheet 10' is preferably 5 μm or more and 500 μm or less, and more preferably 20 μm or more and 150 μm or less.

[0182] The heat-conducting part-forming sheet 10' to be subjected to the bond-forming composition application step is preferably one in which recesses (holes) 11 are provided in advance in the thickness direction. This allows the joint-forming composition 20' to penetrate more suitably into the recess (hole) 11 during the joint-forming composition application process, and makes it possible to more suitably achieve the penetration pattern of the resin material 21 into the recess (hole) 11 in the final thermal conductor 1.

[0183] The method for forming the recesses (holes) 11 in the heat-conducting part-forming sheet 10' is not particularly limited, but for example, the recesses (holes) 11 can be efficiently formed by rotating a roll body having a plurality of protrusions formed on its peripheral surface that correspond to the recesses (holes) 11 while pressing it against the surface of the heat-conducting part-forming sheet 10' with a predetermined force.

[0184] The recesses (holes) 11 in the heat-conducting-part-forming sheet 10' are not limited to those formed by the above-described method, and may be formed by other methods. For example, the recesses (holes) 11 may be formed using a member having a plurality of protrusions corresponding to the recesses (holes) 11 formed on a flat plate, an awl, or the like. Alternatively, the recesses (holes) 11 may be formed in the heat-conducting-part-forming sheet 10' by preparing a heat-conducting-part-forming sheet 10' that does not have the recesses (holes) 11 as described above, or may be formed simultaneously with the molding of the heat-conducting-part-forming sheet 10'.

[0185] The recesses (holes) 11 of the heat-conducting portion-forming sheet 10′ can satisfy the same conditions as those described above for the recesses (holes) 11 of the heat-conducting portion 10. This provides the same effects as those described above.

[0186] [1-5-2] Composition for forming joints The bond forming composition 20' used in the bond forming composition applying step is to become the bond 20 in the thermal conductor 1, and is a composition containing a curable resin material 21'.

[0187] The curable resin material 21' is not particularly limited as long as the resin material 21 obtained by curing the curable resin material 21' has flexibility, and a precursor of the resin material 21 described above, such as an uncured product or a semi-cured product, can be used. This provides the same effects as described above.

[0188] Furthermore, the curable resin material 21' preferably generates gas during the curing step described below. This allows the voids 2 to be suitably formed in the thermal conductor 1 .

[0189] The bond-forming composition 20' may contain resin fibers 22 in addition to the curable resin material 21'. As a result, when manufacturing the thermal conductor 1, there is no need to prepare the resin fiber 22 separately from the joint-forming composition 20', and the equipment used to manufacture the thermal conductor 1 (particularly the equipment used in the joint-forming composition application process and the winding process) can be relatively simple in configuration.

[0190] The bond forming composition 20' may contain metal particles, ceramic particles, spacers, and the like in addition to the above-mentioned components.

[0191] When the composition for forming a joint 20' contains the above-mentioned components, it is preferable to adjust the content in the composition for forming a joint 20' so that the content in the joint 20 of the final thermal conductor 1 is within the above-mentioned range.

[0192] The bond-forming composition 20' may contain components other than those described above. Examples of such components include plasticizers, colorants, antioxidants, ultraviolet absorbers, light stabilizers, softeners, modifiers, rust inhibitors, fillers, electromagnetic wave absorbers such as ferrite, surface lubricants, corrosion inhibitors, heat stabilizers, lubricants, primers, antistatic agents, polymerization inhibitors, crosslinking agents, catalysts, leveling agents, thickeners, dispersants, antioxidants, flame retardants, and hydrolysis inhibitors.

[0193] However, the content of these components in the bond-forming composition 20' is preferably 5% by weight or less, and more preferably 1% by weight or less.

[0194] Furthermore, it is preferable that the bond-forming composition 20′ does not contain a solvent component, which can prevent the solvent component from unintentionally remaining in the final thermal conductor 1, thereby improving the reliability of the thermal conductor 1.

[0195] [1-5-3] Bonding composition application process In the joint forming composition applying step, a joint forming composition 20' containing a curable resin material 21' is applied to at least one surface of the heat-conducting part forming sheet 10'.

[0196] Methods for applying the joint forming composition 20' to the surface of the heat conductive part forming sheet 10' include, for example, coating using a bar coater, roll coater, reverse roll coater, gravure coater, die coater, kiss coater, rod coater, dip coater, or spray coater.

[0197] This allows the joint forming composition 20' to be continuously and appropriately applied to the surface of the heat conduction part forming sheet 10', which is advantageous in improving the reliability of the heat conductor 1 to be manufactured and the productivity of the heat conductor 1.

[0198] The joint-forming composition 20' may be applied to only one side of the heat-conducting part-forming sheet 10' or to both sides thereof. However, when the heat-conducting part-forming sheet 10' has holes 11, it is preferable to apply the joint-forming composition 20' from one side of the heat-conducting part-forming sheet 10', as shown in FIG. 9.

[0199] This allows the curable resin material 21' to suitably penetrate into the holes 11. More specifically, by applying the bond-forming composition 20' from one surface of the heat-conductive-part-forming sheet 10', the air present in the holes 11 can be pushed out to the other surface of the heat-conductive-part-forming sheet 10', allowing the curable resin material 21' to more suitably penetrate into the holes 11. Furthermore, if the heat-conductive-part-forming sheet 10' has voids 12 in addition to the holes 11, the curable resin material 21' can also suitably penetrate into the voids 12 inside the heat-conductive-part-forming sheet 10' via the holes 11.

[0200] At this time, the bond forming composition 20' is preferably applied using a kiss coater.

[0201] In addition, in Figure 8, a graphite sheet material made of flake graphite FG is shown as the heat-conducting portion-forming sheet 10', but the above-mentioned effects can also be obtained with other heat-conducting portion-forming sheets 10'.

[0202] However, by using the above-described graphite sheet material as the heat-conducting-part-forming sheet 10', the following additional effect can be obtained. That is, when the heat-conducting-part-forming sheet 10' is the above-described graphite sheet material, the flake graphite FG is densely packed and hard near the surface of the graphite sheet material, whereas the flake graphite FG is coarsely packed and relatively soft near the center in the thickness direction of the graphite sheet material, resulting in voids 12. This allows the curable resin material 21' to suitably penetrate into the voids 12 inside the heat-conducting-part-forming sheet 10' through the pores 11. This further improves the adhesion between the heat-conducting parts 10 and the joints 20 in the manufactured heat conductor 1, the durability of the heat conductor 1, and the like.

[0203] This step can be performed using, for example, the apparatus shown in Fig. 9. More specifically, a raw roll R1 is prepared by winding up a pre-fabricated heat-conducting-part-forming sheet 10'. One end of the heat-conducting-part-forming sheet 10' is pulled out from the raw roll R1, and a kiss coater M10 is used to apply a bond-forming composition 20' to one side of the heat-conducting-part-forming sheet 10'.

[0204] The kiss coater M10 is a device that coats a sheet using one or more rolls, and is capable of coating only the area where the sheet is in contact with the coating roll M11.

[0205] The kiss coater M10 includes a coating roll M11 driven to rotate in the direction of the arrow by a motor (not shown), a liquid receiving pan M12 containing a joint-forming composition 20′, and a squeegee M13 that maintains a constant film thickness of the joint-forming composition 20′ on the surface of the coating roll M11 by contacting its tip with the surface of the coating roll M11. Approximately the lower half of the coating roll M11 is immersed in the joint-forming composition 20′ in the liquid receiving pan M12. The heat-conducting part-forming sheet 10′ is guided and transported by guide rolls M14, M14, and is transported in contact with the upper surface of the coating roll M11 during application of the joint-forming composition 20′. As a result, when the coating roll M11 rotates, the joint-forming composition 20′ in the liquid receiving pan M12 is drawn up by the coating roll M11, adjusted to a predetermined application amount by the squeegee M13, and then applied to the surface of the heat-conducting part-forming sheet 10′. The liquid receiving pan M12 is supplied with the joint forming composition 20' by a pump from a supply tank (not shown), and the height of the joint forming composition 20' in the liquid receiving pan M12 is controlled to be kept constant.

[0206] By using the kiss coater M10, the composition for forming a joint 20' can be applied to the sheet for forming a heat conduction part 10' without immersing it in the composition for forming a joint 20', making it possible to efficiently apply a constant amount of the composition for forming a joint 20' continuously during the application process.

[0207] In the step of applying the composition for forming a joint, it is preferable to include air bubbles between the heat-conducting portion-forming sheet 10' and the composition for forming a joint 20'. This allows the gap 2 to be suitably formed between the heat conductive portion 10 and the bonding portion 20 after the resin material 21 has hardened.

[0208] Methods for incorporating air bubbles between the heat-conducting part-forming sheet 10' and the joint-forming composition 20' include, for example, adjusting the surface shape of the heat-conducting part-forming sheet 10', the viscosity of the joint-forming composition 20', or the wettability of the heat-conducting part-forming sheet 10'.

[0209] Furthermore, after the bond-forming composition 20' is applied to the heat-conducting-part-forming sheet 10', the gas generated during the curing reaction can be used to form bubbles (form the voids 2).

[0210] This step is preferably carried out using a heated composition 20' for forming a joint so that the viscosity of the composition 20' for forming a joint becomes lower than the viscosity at room temperature (20° C.). As a result, after this step is completed, for example, in the winding step, the joint-forming composition 20' applied to the heat-conducting-part-forming sheet 10' is cooled, and the viscosity of the joint-forming composition 20' can be made lower than the viscosity in this step. As a result, in steps subsequent to the joint-forming composition application step, the joint-forming composition 20' applied to the heat-conducting-part-forming sheet 10' can be more effectively prevented from unintentionally flowing away.

[0211] The heating temperature of the joint forming composition 20' in this step is not particularly limited, but is preferably set so that the viscosity of the joint forming composition 20' satisfies the following condition.

[0212] The viscosity of the joint forming composition 20' when applied to the heat conduction part forming sheet 10' is preferably 500 mPa·s or more and 50,000 mPa·s or less, and more preferably 2,000 mPa·s or more and 40,000 mPa·s or less.

[0213] This allows the joint-forming composition 20' to be more suitably applied to the heat-conducting-part-forming sheet 10' at a predetermined thickness. Furthermore, when the heat-conducting-part-forming sheet 10' has recesses (holes) 11, the joint-forming composition 20' can be more suitably introduced into the recesses (holes) 11. The viscosity of the bond-forming composition 20' can be determined by measurement in accordance with JIS Z8803:2011.

[0214] Furthermore, for example, in this process, multiple types of joint-forming composition 20' may be used, or a material containing only some of the components of the aforementioned joint-forming composition 20' may be used in combination with a material containing other components.

[0215] [1-5-4] Winding process In the winding step, the heat-conducting part-forming sheet 10' to which the joint-forming composition 20' has been applied is wound around the circumferential surface of a winding roll R2 to obtain a cylindrical wound body 30.

[0216] The wound body 30 obtained in this manner has a structure in which, from its center toward the periphery, portions made up of the heat-conducting portion-forming sheet 10' and portions made up of the joint-forming composition 20' are arranged alternately.

[0217] Although Figure 9 shows the case where the heat-conducting portion-forming sheet 10' is guided and transported by guide rolls M14, M14, the heat-conducting portion-forming sheet 10' may also be transported by guide rolls (not shown) other than the guide rolls M14, M14, and the transport direction may be changed by the guide rolls as necessary.

[0218] In the illustrated configuration, the heat-conducting part-forming sheet 10' to which the joint-forming composition 20' has been applied is wound around the circumferential surface of a winding roll R2 having a circular cross section, but this is not limited to this, and the sheet may be wound around the circumferential surface of a roll having an elliptical, polygonal, track-shaped, or other cross section.

[0219] In the winding step, a resin fiber sheet (woven fabric, nonwoven fabric, etc.) containing resin fibers 22 may be wound around the winding roll R2 together with the heat-conducting portion-forming sheet 10' described above. In this case, the resin fiber sheet may be one to which the joint-forming composition 20' has been applied in the same manner as described above, or one to which the joint-forming composition 20' has not been applied.

[0220] When a resin fiber sheet to which the joint-forming composition 20' has been applied is used, the heat-conducting part-forming sheet 10' may be one to which the joint-forming composition 20' has been applied as described above, or one to which the joint-forming composition 20' has not been applied may be used. In other words, in the step of applying the joint-forming composition, the joint-forming composition 20' may be applied to the resin fiber sheet instead of the heat-conducting part-forming sheet 10'. When a resin fiber sheet is used, it may be used with an adhesive applied to at least a part of its surface.

[0221] By using a resin fiber sheet in the manufacture of the thermal conductor, the resin fibers 22 can be suitably oriented in the in-plane direction of the joint 20, which allows the resin fibers 22 to be more uniformly dispersed and the overlapping state of the resin fibers 22 to be made uniform. As a result, the tensile strength of the joint 20 is improved and the thickness of the joint 20 can be made more uniform.

[0222] When a resin fiber sheet is used, the thickness of the resin fiber sheet is preferably 3 μm or more and 300 μm or less, and more preferably 5 μm or more and 100 μm or less.

[0223] [1-5-5] Incision process In the cutting step, the wound body 30 is cut open in a direction non-perpendicular to the axial direction of the winding roll R2 to obtain a cut body 40.

[0224] By cutting open the wound body 30 before the curing process for hardening the curable resin material 21', it is possible to cut it in a softer state than the joint 20 containing the resin material 21 (the hardened product of the curable resin material 21').

[0225] In this process, an incision is made in the stacking direction of the wound body 30 in a direction non-perpendicular to the axial direction of the cylindrical winding roll R2, from one end of the winding roll R2 to the other end in the axial direction, and the wound body 30 is opened at the incision and removed from the winding roll R2 to form a cut body 40.

[0226] The direction in which the wound body 30 is cut open is not particularly limited as long as it is a direction non-perpendicular to the axial direction of the winding roll R2, and may be, for example, a direction substantially parallel to the axial direction of the winding roll R2 or a direction oblique to the axial direction of the roll. Also, the wound body 30 may have portions cut open in different directions. For example, the wound body 30 may have portions cut open in a direction substantially parallel to the axial direction of the winding roll R2 and portions cut open in a direction oblique to the axial direction of the roll.

[0227] The method for cutting the wound body 30 is not particularly limited, but examples thereof include methods using a band saw, a saw, a cutter, a trimming cutter, a laser, an ultrasonic cutter, a water cutter, and the like.

[0228] [1-5-6]Curing process In the curing step, the curable resin material 21' contained in the joint forming composition 20' is cured in the cut body 40. After the cutting step, a curing step may be performed to harden the hardenable resin material 21' contained in the cut body 40.

[0229] As shown in Figure 10, when the wound body 30 is cut open to form the cut body 40, the cut body 40 is usually in a curved state. If the curable resin material 21' is cured before the wound body 30 is cut open, an attempt to improve the flatness of the curved cut body 40 will result in distortion due to the difference in curvature between the inner and outer peripheries of the cut body 40, which is likely to cause peeling or reduced adhesion between the heat conductive portion 10 and the joint portion 20, damage to the joint portion 20, or damage to the joints between the heat conductive portions 10. In contrast, by performing a process of curing the curable resin material 21' on the cut body 40, which has been improved in flatness by cutting the wound body 30, the occurrence of the above-mentioned problems can be effectively prevented.

[0230] This step can be performed by, for example, curing the curable resin material 21' in a state where the inner and outer circumferential sides of the incision body 40 are in contact with a flat surface. More specifically, for example, as shown in FIG. 11, by sandwiching the cut body 40 between two flat plates 90 and applying pressure, the curable resin material 21' can be hardened to form the resin material 21 while increasing the flatness of the heat conduction portion 10 and the bonding portion 20.

[0231] The pressure at this time is not particularly limited, but is preferably more than 0 MPa and not more than 100 MPa, and more preferably 10 MPa or more and not more than 50 MPa.

[0232] If the pressure is less than the lower limit, it may be difficult to sufficiently improve the flatness of the heat conductive portion 10 and the joint portion 20. On the other hand, if the pressure exceeds the upper limit, the curable resin material 21′ may flow out significantly from between adjacent heat conductive portion-forming sheets 10′, which may make it difficult to form the joint portion 20 with the desired thickness.

[0233] Furthermore, by performing the curing process while pressing the cut body 40, it is possible to more effectively prevent peeling or a decrease in adhesion between the heat conducting part 10 and the joint part 20, destruction of the joint part 20, destruction of the joint between the heat conducting parts 10, etc., thereby improving the durability of the heat conductor 1.

[0234] When the curable resin material 21' is a thermosetting resin, the heating temperature differs depending on the conditions of the curable resin material 21', but is preferably 80°C or higher and 220°C or lower, and more preferably 100°C or higher and 190°C or lower. This allows the hardenable resin material 21' to be hardened appropriately.

[0235] After going through the above steps, the thermal conductor 1 is obtained by processing it into a predetermined shape as required.

[0236] [1-5-7] Cutting process If the thermal conductor 1 to be manufactured is in the form of a block, after the above-mentioned curing step, a cutting step is carried out in which the thermal conductor 1 is cut into a block shape with the thermal conductive portions 10 and the bonding portions 20 exposed on both sides. This makes it possible to obtain, for example, a block-shaped thermal conductor 1 having a desired thickness.

[0237] After the curing step, for example, cutting along the cutting lines AA' and BB' in FIG. 12 can provide a block-shaped thermal conductor 1 having a thickness T3. Here, even if the thickness T3 of the thermal conductor 1 to be manufactured is relatively small, the curable resin material 21' becomes a resin material 21 with higher shape stability after the curing process, so the thermal conductor 1 can be easily cut.

[0238] The cutting method is not particularly limited, but examples thereof include methods using a cutter, a trimming cutter, a laser, an ultrasonic cutter, a water cutter, and the like.

[0239] The cutting direction may be substantially parallel to the stacking direction (thickness direction of the incision body 40) or may be oblique to the stacking direction (thickness direction of the incision body 40). Fig. 12 shows how the incision body 40 is cut substantially parallel to the stacking direction.

[0240] The surface of the thermal conductor 1, particularly the surface where the thermal conductive portions 10 and the bonding portions 20 are exposed, may be polished. This allows the surface roughness of the thermal conductor 1 to be suitably adjusted.

[0241] The surface roughness Ra of the thermal conductor 1 in its natural state, ie, when no external force is applied, is preferably 0.1 μm or more and 80 μm or less, and more preferably 0.1 μm or more and 10 μm or less. This allows the thermal conductor 1 to more suitably follow the surface shape of the member that comes into contact with it, thereby improving the substantial thermal conductivity between the member and the thermal conductor 1. The surface roughness Ra of the thermal conductor 1 can be measured, for example, by a method in accordance with JIS B 0601-2013.

[0242] In an electronic circuit board 100 equipped with such a thermal conductor 1, when the thickness of the substrate 110 at the portion where the through hole 111 is provided is T1 [mm] and the length of the thermal conductor 1 in its natural state in the thickness direction of the substrate 110 is T2 [mm], it is preferable to satisfy the relationship 0.70≦T1 / T2≦0.99, it is more preferable to satisfy the relationship 0.75≦T1 / T2≦0.98, and it is even more preferable to satisfy the relationship 0.80≦T1 / T2≦0.97. This improves the adhesion of the thermal conductor 1 to the member that comes into contact with the thermal conductor 1, and reduces the interfacial thermal resistance, thereby increasing the effective thermal conductivity.

[0243] Furthermore, when one of the two surfaces of the through-hole 111 in the depth direction (the two surfaces that come into contact with different members) is the top surface and the other surface is the bottom surface, the sum of the areas of the top surface and the bottom surface of the thermal conductor 1 in its natural state is defined as S1 [mm 2 ], and the side surface area of ​​the thermal conductor 1 in its natural state is S2 [mm 2 ], it is preferable to satisfy the relationship 0.2≦S1 / S2≦10.0, it is more preferable to satisfy the relationship 0.4≦S1 / S2≦7.0, and it is even more preferable to satisfy the relationship 0.5≦S1 / S2≦5.0. This ensures a sufficient contact area between the thermal conductor 1 and the member in contact with the thermal conductor 1, and the above-described effects of the present invention are more significantly exhibited.

[0244] In this specification, the "area of ​​the side surface" refers to the area of ​​the entire side surface, and for example, when the thermal conductor 1 has a quadrangular prism shape, it refers to the sum of the areas of the four side surfaces.

[0245] [1-6] Other examples of thermal conductor configurations Next, other configuration examples of the thermal conductor will be described. Fig. 13 is a perspective view schematically showing another example of a thermal conductor. Fig. 14 is a longitudinal cross-sectional view of the thermal conductor shown in Fig. 13, Fig. 14(a) is a cross-sectional view taken along line CC', and Fig. 14(b) is a cross-sectional view taken along line DD'. In the thermal conductor 1 shown in FIGS. 13 and 14, a plurality of thermal conductive portions 10 are provided in an island shape when viewed in a plan view from a first direction.

[0246] This makes it possible to reduce the variation in thermal conductivity at each part of the surface of the thermal conductor 1 (in the xy plane direction shown in Figure 13) while also making it easier to improve the flexibility of the thermal conductor 1 as a whole, thereby more significantly achieving the effects of the present invention described above.

[0247] In this specification, the term "island-like" refers to a state in which a plurality of heat conductive portions 10 are not continuous but are scattered within the joint portion 20. In other words, the heat conductive portions 10 are independent of each other in both the x and y directions.

[0248] 13, the heat conductor 1 has a plurality of heat conductive portions 10 arranged in a staggered pattern when viewed from a first direction. In other words, first rows 10a and second rows 10b in which the heat conductive portions 10 are arranged in the x direction are alternately arranged in the y direction so that the heat conductive portions 10 are staggered. This makes it possible to more significantly exhibit the above-mentioned effects.

[0249] It is preferable that the heat conducting portions 10 in the first row 10a and the heat conducting portions 10 in the second row 10b at least partially overlap in the y direction. This makes it possible to more significantly exhibit the above-mentioned effects.

[0250] When viewed from the first direction, the w 10 The width of the heat conducting portion 10 indicated by is preferably 1 mm or more and 30 mm or less, more preferably 5 mm or more and 20 mm or less, and even more preferably 7 mm or more and 15 mm or less.

[0251] This makes it possible to ensure that the proportion of the thermal conductive portion 10 in the thermal conductor 1 is sufficiently high, while also making it easier to improve the flexibility of the thermal conductor 1 as a whole, thereby more reliably achieving the aforementioned effects more significantly.

[0252] When the thermal conductor 1 is viewed from above in the first direction, the heat transfer coefficient g in FIG. 10 The distance between adjacent heat conducting portions 10 indicated by is preferably 1 μm or more and 2000 μm or less, more preferably 2 μm or more and 1500 μm or less, and even more preferably 3 μm or more and 1000 μm or less.

[0253] This makes it possible to ensure that the proportion of the thermal conductive portion 10 in the thermal conductor 1 is sufficiently high, while also making it easier to improve the flexibility of the thermal conductor 1 as a whole, thereby making it possible to more significantly achieve the effects described above.

[0254] In this specification, the "distance between adjacent heat conducting portions 10" refers to the gap as the shortest distance between adjacent heat conducting portions 10.

[0255] 13 shows a case where the plurality of heat conducting parts 10 are arranged in a staggered pattern, the plurality of heat conducting parts 10 may be arranged in a pattern other than a staggered pattern. The plurality of heat conducting parts 10 may be arranged regularly or randomly.

[0256] As shown in FIG. 14, the inclination direction of the heat conducting portions 10 (through heat conducting portions 10c) with respect to the normal direction V1 of the surface is opposite between the first row 10a and the second row 10b of the heat conducting portions 10.

[0257] The inclination direction of the through-hole heat conduction portions 10c of the first row 10a relative to the normal direction V1 of the surface is defined as the positive (+) direction, and the inclination direction of the through-hole heat conduction portions 10c of the second row 10b relative to the normal direction of the surface is defined as the negative (-) direction.

[0258] That is, the through-hole heat conducting portions 10c of the first row 10a are inclined at an angle θ1 in the positive direction relative to the normal direction V1 of the surface, and the through-hole heat conducting portions 10c of the second row 10b are inclined at an angle θ2 in the negative direction relative to the normal direction V1 of the surface.

[0259] In this way, by providing the through-hole heat conductive portions 10c inclined in different directions, particularly by providing the through-hole heat conductive portions 10c inclined in a positive direction with respect to the surface normal direction V1 and the through-hole heat conductive portions 10c inclined in a negative direction with respect to the surface normal direction V1, irreversible deformation of the heat conductor 1, such as collapse of the heat conductor 1 due to buckling, can be more effectively suppressed even when a relatively large load is applied to the heat conductor 1, thereby improving the durability of the heat conductor 1. Furthermore, when the heat conductor 1 is compressed in the first direction, surface pressure is more easily applied to the heat conductor 1, further improving the adhesion between the heat conductor 1 and the member in contact with the heat conductor 1. Furthermore, when pressure is applied to the heat conductor 1 in the first direction, the pressure includes a force component in a direction pressing the heat conductive portions 10 and the joint portions 20 together, thereby further improving the adhesion between the heat conductive portions 10 and the joint portions 20.

[0260] In particular, by arranging the through-hole heat conductive portions 10c that are inclined in a positive direction relative to the normal direction V1 of the surface and the through-hole heat conductive portions 10c that are inclined in a negative direction relative to the normal direction V1 of the surface alternately, the above-mentioned effect can be more pronounced.

[0261] As shown in FIG. 14, the normal direction V1 of the surface and the extending direction e of the penetrating heat conducting portion 10c are 10 The absolute values ​​of the angles θ1 and θ2 formed with the above are preferably 3° or more and 45° or less, more preferably 5° or more and 40° or less, and even more preferably 8° or more and 35° or less.

[0262] This makes it easier for surface pressure to be applied to the thermal conductor 1 when the thermal conductor 1 is compressed in the first direction, thereby further improving the adhesion between the thermal conductor 1 and a member that comes into contact with the thermal conductor 1. Furthermore, when pressure is applied to the thermal conductor 1 in the first direction, the pressure includes a force component in a direction that presses the thermal conductive portion 10 and the joint portion 20 together, thereby further improving the adhesion between the thermal conductive portion 10 and the joint portion 20.

[0263] The angles θ1 and θ2 may have different sizes, but it is preferable that they are the same.

[0264] Furthermore, the angles are not exact numerical values ​​in the mathematical sense, but may include a normal error in the technical field of the present invention. For example, a difference of less than 1° is interpreted as the same angle.

[0265] The inclination direction of the heat conducting portion 10 is not particularly limited, but when the heat conducting portion 10 (heat conducting portion forming member 10') is strip-shaped, it is preferable that the surface direction of the heat conducting portion 10 is inclined with respect to the normal direction V1 of the surface.

[0266] As a result, even when a relatively large load is applied to the thermal conductor 1, irreversible deformation of the thermal conductor 1, such as collapse of the thermal conductor 1 due to buckling or the like, can be more effectively suppressed, and the durability of the thermal conductor 1 can be further improved. Furthermore, when the thermal conductor 1 is compressed from the first direction, surface pressure is more easily applied to the thermal conductor 1, and the adhesion between the thermal conductor 1 and a member in contact with the thermal conductor 1 can be further improved. Furthermore, when pressure is applied to the thermal conductor 1 in the first direction, the pressure includes a force component in a direction pressing the thermal conductive portion 10 and the joint portion 20 together, and this further improves the adhesion between the thermal conductive portion 10 and the joint portion 20.

[0267] [1-7] Other examples of electronic circuit board configurations Next, another example of the configuration of the electronic circuit board of the present invention will be described. Fig. 15 is a cross-sectional view schematically showing another example of an electronic circuit board of the present invention. Fig. 16 is a plan view schematically showing another example of an electronic circuit board of the present invention. Fig. 17 is a view schematically showing another example of an electronic circuit board of the present invention, where (A) is a cross-sectional view and (B) is a plan view.

[0268] As shown in FIG. 15, the electronic circuit board 100 may have at least one of an insulating layer 101 and an insulating layer 102 arranged inside the through hole 111, in other words, between components arranged on both sides of the board 110.

[0269] The insulating layer 101 is disposed as an intermediate layer of the thermal conductor 1, and the insulating layer 102 is disposed as a surface layer of the thermal conductor 1. This makes it possible to effectively prevent problems such as electrical short circuits in electronic circuits.

[0270] Examples of materials constituting the insulating layer 101 as the intermediate layer of the thermal conductor 1 include ceramics such as AlN, Si3N4, and BN.

[0271] The insulating layer (intermediate layer) 101 is formed, for example, by forming a two-stage structure of thermal conductors 1 arranged in the through-hole 111 and sandwiching a thin plate made of ceramic as described above between the two thermal conductors 1.

[0272] For example, PCM (Phase Change Material) can be used as a material for forming the insulating layer 102 as the surface layer of the thermal conductor 1. PCM softens when heated, improving adhesion and thereby exhibiting excellent heat dissipation performance.

[0273] The insulating layer (surface layer) 102 is formed by applying or depositing a PCM on the surface of the thermal conductor 1, for example.

[0274] It is preferable that a part of the PCM penetrates into the thermal conductor 1. This makes it possible to make the above-mentioned effects more pronounced.

[0275] As shown in Figure 16, when a predetermined in-plane direction of substrate 110 is defined as the Y-axis direction and a predetermined in-plane direction of substrate 110 that is perpendicular to the Y-axis direction is defined as the X-axis direction, it is preferable that the thermal conductivity of thermal conductor 1 in the Y-axis direction is lower than the thermal conductivity in the X-axis direction.

[0276] The thermal conductor 1 is arranged in the through hole 111, for example, so that on the surface of the substrate 110, in other words, on the surface that contacts the member, the extension direction of the thermal conductive portion 10 and the bonding portion 20 is the X-axis direction, and the stacking direction of the thermal conductive portion 10 and the bonding portion 20 is the Y-axis direction. In the configuration shown in FIG. 16, the up-down direction in the drawing is the X-axis direction, and the left-right direction in the drawing is the Y-axis direction.

[0277] This makes it possible to impart anisotropy to the thermal conductivity within the plane of the substrate 110 via the thermal conductor 1. Specifically, it is possible to suitably control the thermal conductivity in the Y-axis direction within the plane of the substrate 110 so that it is lower than the thermal conductivity in the X-axis direction.

[0278] As shown in FIG. 16, the electronic circuit board 100 may also include components other than the above-described members, such as the power semiconductor device 120 and the cooling unit 130.

[0279] In the electronic circuit board 100, it is preferable that a component 150 that is more susceptible to heat effects be arranged on the extension line in the Y-axis direction of the portion of the board 110 where the thermal conductor 1 is provided, than a component 140 that is arranged on the extension line in the X-axis direction of the portion of the board 110 where the thermal conductor 1 is provided.

[0280] This effectively prevents heat from the power semiconductor elements 120, which are heat-generating bodies, from being transmitted in the Y-axis direction via the substrate 110, and effectively reduces the influence of heat on the components 150.

[0281] Examples of components 150 that are relatively susceptible to heat include electrolytic capacitors, large-scale integrated circuits (SOC: System-on-a-chip), and aluminum electrolytic capacitors.

[0282] In addition, in the electronic circuit board 100 shown in FIG. 17, for example, a heat spreader 160 is disposed between the power semiconductor element 120 and the substrate 110. This allows the heat from the power semiconductor element 120 to be dissipated more efficiently. In this case, it is preferable to arrange the through holes 111 and the thermal conductor 1 in accordance with the shape of not only the power semiconductor element 120 but also the heat spreader 160 . This allows the heat from the power semiconductor device 120 to be dissipated more efficiently.

[0283] In this way, even if the thermal conductor 1 has a complex shape, it can be accommodated by cutting the thermal conductor 1 into a predetermined shape, which is easier to accommodate than, for example, using a copper inlay.

[0284] Furthermore, for example, in a case where a board 110 having power semiconductor elements 120 arranged on one surface 110a cannot have sufficient space on the other surface 110b side of the board 110, a cooling unit (not shown) may be arranged on the side of the board 110, for example, on the right side in the example shown in Fig. 17, rather than on the other surface 110b side of the board 110. In this case, heat from the power semiconductor elements 120 is conducted to the side of the board 110 via the heat spreader 160.

[0285] In this case, the direction connecting the thermal conductor 1 and the cooling unit is preferably set to the X-axis direction. In other words, the thermal conductor 1 is preferably arranged so that the extension direction of the thermal conductive portion 10 and the bonding portion 20 is set to the X-axis direction. In the configuration shown in FIG. 17(B), the left-right direction in the drawing is the X-axis direction, and the up-down direction in the drawing is the Y-axis direction. This allows the heat from the power semiconductor element 120 to be conducted and dissipated more efficiently to the side of the substrate 110.

[0286] Note that these conditions may be different when the electronic circuit board 100 has multiple thermal conductors 1. Furthermore, when the electronic circuit board 100 has multiple thermal conductors 1, it is preferable that at least one thermal conductor 1 satisfies the above conditions, more preferably that multiple thermal conductors 1 satisfy the above conditions, and even more preferably that all thermal conductors 1 satisfy the above conditions. This allows the effects of the present invention to be more pronounced.

[0287] Such an electronic circuit board 100 is provided with a thermal conductor 1 having excellent thermal conductivity, and therefore can more efficiently dissipate heat from electronic components that are heat-generating bodies, thereby more effectively reducing the risk of shortened life spans of devices and systems, malfunctions, etc.

[0288] In particular, when the power semiconductor element 120 is used as the electronic component, the amount of heat generated tends to be large, so the above-mentioned effect can be particularly pronounced.

[0289] [2] Manufacturing method for electronic circuit boards Next, a method for manufacturing an electronic circuit board according to the present invention will be described. FIG. 18 is a cross-sectional view schematically showing an example of a method for producing an electronic circuit board according to the present invention.

[0290] The manufacturing method for an electronic circuit board of this embodiment includes a substrate preparation process for preparing a substrate 110 having through holes 111, an electronic component joining process for joining and soldering electronic components to the portions of the substrate 110 where the through holes 111 are provided, a heat conductor insertion process for inserting a flexible heat conductor 1 into the through holes 111, and a cooling unit fixing process for fixing a cooling unit 130 to the side of the substrate 110 opposite the side where the electronic components are provided so as to come into contact with the heat conductor 1. This makes it possible to more suitably manufacture an electronic circuit board 100 that has excellent substantial thermal conductivity in the thickness direction of the substrate 110.

[0291] The following description will focus on the case where a power semiconductor element 120 is used as the electronic component.

[0292] [2-1] Substrate preparation process First, in the substrate preparation step, a substrate 110 having a through-hole 111 is prepared. As shown in FIG. 18(A), the substrate 110 may have through holes 111 formed in advance, or the substrate 110 may be prepared without through holes 111 formed therein, and then the through holes 111 may be formed in the substrate 110.

[0293] [2-2] Electronic component bonding process In the electronic component bonding step, the power semiconductor element 120 is fixed to the portion of the substrate 110 on the side of one surface 110a where the through hole 111 is provided. 18(B), the power semiconductor element 120 is fixed onto one surface 110a of the substrate 110 by soldering using solder 121. At this time, the power semiconductor element 120 is fixed onto the substrate 110 so as to cover the through-hole 111.

[0294] [2-3] Heat conductor insertion process In the thermal conductor inserting step, a flexible thermal conductor 1 is inserted into the through-hole 111 .

[0295] As shown in Figure 18(C), the thermal conductor 1 is inserted into the through hole 111 so that the in-plane direction of the thermal conductive portion 10 is the thickness direction of the substrate 110 and the stacking direction of the thermal conductive portion 10 and the bonding portion 20 is the in-plane direction of the substrate 110. This allows the substrate 110 to have excellent thermal conductivity in the thickness direction.

[0296] Furthermore, it is preferable that the length of the thermal conductor 1 in its natural state in the thickness direction of the substrate 110 is longer than that of the substrate 110. In other words, it is preferable that the thermal conductor 1 inserted into the through-hole 111 protrudes from the through-hole 111 on the other surface 110b side of the substrate 110.

[0297] [2-4] Cooling unit fixing process In the cooling unit fixing step, the cooling unit 130 is fixed to the surface of the substrate 110 opposite to the surface on which the power semiconductor elements 120 are provided so as to come into contact with the thermal conductor 1. As shown in FIG. 18(D), the cooling unit 130 is fixed onto the other surface 110b of the substrate 110 by screwing using screws 131.

[0298] At this time, the portion of the thermal conductor 1 that protrudes from the substrate 110 is pressed by the cooling unit 130, so that the thermal conductor 1 is pressed in the thickness direction of the substrate 110. This allows the thermal conductor 1 to be more suitably attached to the power semiconductor element 120 and the cooling unit 130, thereby achieving particularly excellent substantial thermal conductivity.

[0299] After going through the above steps, the electronic circuit board 100 is obtained by disposing the insulating layers and other members as described above as necessary.

[0300] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these.

[0301] For example, the above description has focused on the case where one thermal conductor is inserted into one through hole, but it is also possible to insert two or more thermal conductors into one through hole.

[0302] Furthermore, in the above description, the case where only a thermal conductor is inserted into a through-hole has been mainly described, but a combination of a thermal conductor and a copper inlay may also be inserted into a through-hole.

[0303] Furthermore, while the above explanation has focused on inserting a block-shaped thermal conductor cut to fit the shape of the through-hole, it is also possible to insert a plate-shaped thermal conductor that has been curved (elastically deformed). In this case, the curved thermal conductor is biased when it tries to return to its original shape. In other words, the elastic restoring force presses the thermal conductor against the inner wall surface of the through-hole. This effectively prevents the thermal conductor from accidentally falling out of the through-hole.

[0304] Furthermore, in the above-described embodiment, the substrate constituting the electronic circuit board has been mainly described as having through-holes that penetrate the substrate in the thickness direction as through-holes to which a thermal conductor is applied. However, the substrate may also have non-penetrating through-holes that do not penetrate the substrate in the thickness direction as through-holes to which a thermal conductor is applied. In such a case, the thermal conductor applied to the non-penetrating through-hole may contact a copper thin plate (thermal conductive layer) constituting the substrate, for example, on one surface in the depth direction of the non-penetrating through-hole (bottomed recess) (the surface on the bottom side of the non-penetrating through-hole). That is, in the present invention, one of the different components may be the substrate. In such a configuration, heat can be suitably conducted (heat diffused) in the surface direction of the substrate (thin copper plate) via the thin copper plate provided in the substrate.

[0305] Furthermore, the electronic circuit board is not limited to one manufactured by the method described above. For example, the method for manufacturing an electronic circuit board may further include other steps in addition to the steps described above.

[0306] Furthermore, in the above explanation, a method for manufacturing an electronic circuit board has been described that includes a substrate preparation process, an electronic component joining process, a thermal conductor insertion process, and a cooling unit fixing process in this order, but the electronic circuit board may also be manufactured using a method in which the order of these processes is reversed, for example.

[0307] The electronic circuit board according to the present invention may be manufactured using a method comprising the steps of: preparing a substrate having a through hole; inserting a flexible thermal conductor into the through hole; and soldering an electronic component to the substrate while the thermal conductor is in contact with another component on one side of the through hole in a depth direction and applying surface pressure to the electronic component on the other side opposite the one side. By employing such a method, the thermal conductor can be suitably attached to the different component without using screws, for example.

[0308] Furthermore, the above explanation has focused on the case where the heat conducting portions and joints that make up the heat conductor are planar, but at least some of the heat conducting portions and joints that make up the heat conductor may be non-planar, for example, curved or bent.

[0309] Furthermore, in the above explanation, a case where a hole is provided in each heat conducting portion constituting the heat conductor was described as a typical example, but some of the multiple heat conducting portions constituting the heat conductor may not have a hole provided therein.

[0310] Furthermore, the heat conductive portion may be provided with a recess that does not penetrate the heat conductive portion in the thickness direction, i.e., a recess with a bottom, instead of or in addition to the above-described hole. Also, the heat conductive portion does not necessarily have to be provided with a recess.

[0311] The heat conductor may have a configuration other than the heat conductive portion, joint portion, and gap portion described above.

[0312] Furthermore, the thermal conductor is not limited to those manufactured by the above-mentioned method. For example, the manufacturing method of the thermal conductor may further include other steps (pre-treatment step, intermediate treatment step, post-treatment step, etc.) in addition to the steps described above.

[0313] Furthermore, the formation of holes in the heat-conductive part-forming sheet may be carried out after the heat-conductive part-forming sheet is pulled out from the original roll. More specifically, for example, holes may be formed in the heat-conductive part-forming sheet after the heat-conductive part-forming sheet without holes is pulled out from the original roll and before the joint-forming composition is applied, or holes may be formed in the heat-conductive part-forming sheet at the same time as the joint-forming composition is applied to the heat-conductive part-forming sheet without holes.

[0314] Furthermore, in the above description, a method for producing a thermal conductor using a method having a winding step, a cutting step, and a curing step in this order has been described, but a thermal conductor may also be produced by, for example, a method in which the order of these steps is reversed, a method that does not have some of these steps, a method that replaces some of these steps with other steps, etc. More specifically, for example, instead of the method having the winding step and the cutting step, a thermal conductor may be produced using a method in which multiple heat-conducting part-forming sheets to which a bond-forming composition has been applied are stacked together, and then a curing step is performed.

[0315] Furthermore, in the above explanation, a method for manufacturing a thermal conductor is described in which a thermal conductive part forming sheet to which a joint forming composition has been applied is rolled into a rolled body and the rolled body is then cut open. However, the thermal conductor may also be manufactured, for example, by stacking individual thermal conductive part forming members to which a joint forming composition has been applied into a laminate.

[0316] In the method for manufacturing a thermal conductor, the order of the above-described steps may be at least partially reversed. [Explanation of symbols]

[0317] 1: Thermal conductor 2 :Void part 10: Heat conduction section 10a: First column 10b: Second column 10c: Heat conducting through part 10': Heat conductive part forming sheet (heat conductive part forming member) 11: Hole (recess) 12:Void part 20: Joint 20': Composition for forming joints 21: Resin materials 21': Curable resin material 22: Resin fiber 30: Rolled body 40: Incision body 50: Polyrotaxane 51: Cyclic molecules 52: First polymer 53: Blocking group 60: Second polymer 90: Flat plate 100: Electronic circuit board 101: Insulating layer (intermediate layer) 102: Insulating layer (surface layer) 110: Substrate 110a: One side 110b: The other side 111:Through hole 120: Power semiconductor element 121: Solder 130: Cooling unit 131: Screw 140: Parts 150: Parts 160: Heat spreader 210: Semiconductor devices 211: Substrate (support) 211a: 1st page 211b: 2nd side 212a: Solder layer 213: Heat spreader 214: Copper inlay (column) 215: Insulating layer 216: Heat sink 220: Heat dissipation structure A-A': Cutting line B-B': Cutting line C-C': Cutting line D-D': Cutting line FG: Flake graphite e 10 :Extending direction g 10 :interval M10: Kiss Coater M11: Coating roll M12: Liquid receiving pan M13: Squeegee M14: Guide roll R1: Raw material roll R2: Winding roll t 10 : Thickness t 20 : Thickness T1: Thickness T2: Length T3: Thickness V1: Normal direction w 10 :width θ1: angle θ2: angle

Claims

1. a substrate having a through hole formed therein; a flexible thermal conductor inserted into the through hole; the heat conductor includes a plurality of heat conductive portions and a joint portion made of a flexible material and joining the heat conductive portions together; The joint contains resin fibers, The electronic circuit board according to claim 1, wherein the thermal conductor is in contact with different members on both sides of the through hole in the depth direction.

2. 2. The electronic circuit board according to claim 1, wherein the thermal conductor has a compressibility of 4.0% or more and 10.0% or less when compressed at 20°C with a stress of 0.25 MPa in a direction corresponding to the insertion direction into the through hole.

3. 3. The electronic circuit board according to claim 1, wherein the thermal conductor has a compressibility of 7.0% or more and 20.0% or less when compressed at 20°C with a stress of 0.50 MPa in a direction corresponding to the insertion direction into the through hole.

4. 4. The electronic circuit board according to claim 1, wherein the thermal conductor has anisotropic thermal conductivity.

5. 5. The electronic circuit board according to claim 4, wherein the thermal conductor has a higher thermal conductivity in a thickness direction of the board than in a predetermined in-plane direction of the board.

6. 6. The electronic circuit board according to claim 4, wherein when a predetermined in-plane direction of the board is defined as a Y-axis direction and a direction perpendicular to the Y-axis direction is defined as an X-axis direction, the thermal conductivity of the thermal conductor in the Y-axis direction is lower than the thermal conductivity in the X-axis direction.

7. 7. The electronic circuit board according to claim 6, wherein components that are more susceptible to heat than components arranged on an extension line in the X-axis direction of the portion of the board where the thermal conductor is provided are arranged on an extension line in the Y-axis direction of the portion of the board where the thermal conductor is provided.

8. 8. The electronic circuit board according to claim 1, wherein the thermal conductor is made of a material containing resin.

9. 9. The electronic circuit board according to claim 8, wherein the resin comprises a polyrotaxane having a cyclic molecule, a first polymer having a linear molecular structure and encapsulating the cyclic molecule in a skewered manner, and blocking groups provided near both ends of the first polymer, and a second polymer, wherein the polyrotaxane and the second polymer are bonded via the cyclic molecule.

10. 10. The electronic circuit board according to claim 1, wherein the thermal conductor is made of a material containing a carbon material.

11. The electronic circuit board according to claim 10 , wherein the carbon material is graphite.

12. The electronic circuit board according to claim 11 , wherein the graphite is flake graphite.

13. 13. The electronic circuit board according to claim 1, wherein at least some of the plurality of heat conducting portions are provided continuously inside the heat conductor and exposed on both surfaces.

14. The electronic circuit board according to any one of claims 1 to 13, wherein the heat conductive portion is made of substantially a single component.

15. 15. The electronic circuit board according to claim 1, wherein the thermally conductive portion accounts for 15% by volume or more and 80% by volume or less of the thermal conductor.

16. 16. The electronic circuit board according to claim 1, wherein the proportion of the joints in the thermal conductor is 15% by volume or more and 70% by volume or less.

17. The electronic circuit board according to any one of claims 1 to 16, wherein the thermal conductor has, in addition to the thermal conductive portion and the joint portion, a void portion where the thermal conductive portion and the joint portion are not present.

18. 18. The electronic circuit board according to claim 1, wherein the thickness of the substrate at the portion where the through hole is provided is T1 [mm], and the length of the thermal conductor in its natural state in the thickness direction of the substrate is T2 [mm], satisfying the relationship of 0.70≦T1 / T2≦0.

99.

19. The electronic circuit board according to any one of claims 1 to 18, wherein the length of the thermal conductor in its natural state in the thickness direction of the board is 1.0 mm or more and 6.0 mm or less.

20. The electronic circuit board according to any one of claims 1 to 19, wherein the substrate is a laminated substrate.

21. 21. The electronic circuit board according to claim 1, wherein the heat conductor is in contact with a power semiconductor element on one side of the board and in contact with a cooling unit on the other side of the board.

22. the power semiconductor device is soldered to the substrate; 22. The electronic circuit board according to claim 21, wherein the cooling unit is fixed onto the board by screws.

23. The thermal conductor has a top surface and a bottom surface, and the sum of the areas of the top surface and the bottom surface of the thermal conductor in its natural state is S1 [mm ２ ], and the side surface area of ​​the thermal conductor in its natural state is S2 [mm ２ 23. The electronic circuit board according to claim 1, wherein when S1 / S2 is 0.2≦S1 / S2≦10.0, the relationship is satisfied.

24. providing a substrate having a through hole; a step of joining and soldering an electronic component to the portion of the substrate where the through hole is provided; inserting a flexible thermal conductor into the through hole; and fixing a cooling unit to a surface of the substrate opposite to a surface on which the electronic components are provided so as to be in contact with the thermal conductor, the heat conductor includes a plurality of heat conductive portions and a joint portion made of a flexible material and joining the heat conductive portions together; The method for manufacturing an electronic circuit board, wherein the joint portion contains resin fibers.

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