substrate

Abstract

To provide a substrate using a heat conduction member which can alleviate stress upon heat loading and has high heat conductivity.SOLUTION: A substrate has a heat conduction member having a plurality of carbon nanotubes, a first resin layer provided on one end side of the plurality of carbon nanotubes and a second resin layer provided on the other end side of the plurality of carbon nanotubes, a first metal layer stacked on the first resin layer, and a second metal layer stacked on the second resin layer, wherein the first resin layer and the second resin layer do not contain a filler, one end side of the plurality of carbon nanotubes is impregnated with the resin constituting the first resin layer, and the other end side of the plurality of carbon nanotubes is impregnated with the resin constituting the second resin layer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a substrate.

Background Art

[0002] There is known a substrate having an insulating substrate such as a ceramic substrate, a metal layer having a circuit pattern formed on one surface of the insulating substrate, and a heat radiating metal layer formed on the other surface. A device that becomes a heat generating body during operation, such as a semiconductor chip for power control, is mounted on the metal layer having the circuit pattern (see, for example, Patent Document 1).

[0003] However, an insulating substrate such as a ceramic substrate is low in flexibility and hard, and there is a difference in the coefficient of thermal expansion between the insulating substrate and the metal layers arranged above and below, so stress is generated during heat load, and the insulating substrate and the metal layer are separated from each other. There was a case where peeling occurred between them. In recent years, the use of insulating resin layers has been spreading as an alternative to ceramic substrates and the like, but the thermal conductivity is about 10 W / m·K.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention has been made in view of the above points, and an object thereof is to provide a substrate using a heat conductive member that can relieve stress during heat load and has high thermal conductivity.

Means for Solving the Problems

[0006] The substrate comprises a thermal conductive member having a plurality of carbon nanotubes, a first resin layer provided on one end of the plurality of carbon nanotubes, and a second resin layer provided on the other end of the plurality of carbon nanotubes; a first metal layer laminated on the first resin layer; and a second metal layer laminated on the second resin layer. The first and second resin layers do not contain fillers, the resin constituting the first resin layer is impregnated on one end of the plurality of carbon nanotubes, and the resin constituting the second resin layer is impregnated on the other end of the plurality of carbon nanotubes. The heat conductive member has a first opening that penetrates the heat conductive member and exposes the first metal layer, and the second metal layer has a second opening that penetrates the second metal layer and communicates with the first opening. . [Effects of the Invention]

[0007] According to the disclosed technology, it is possible to provide a substrate that can alleviate stress under thermal load and uses a thermal conductive material with high thermal conductivity. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view illustrating a substrate according to the first embodiment. [Figure 2] This is a diagram (part 1) illustrating the manufacturing process of a heat-conducting member according to the first embodiment. [Figure 3] This is a diagram (part 2) illustrating the manufacturing process of a heat-conducting member according to the first embodiment. [Figure 4] This is a diagram (part 3) illustrating the manufacturing process of a heat-conducting member according to the first embodiment. [Figure 5] This figure illustrates the manufacturing process of a substrate according to the first embodiment. [Figure 6] This is a cross-sectional view illustrating a substrate according to Modification 1 of the First Embodiment. [Figure 7] This is a cross-sectional view illustrating a substrate according to a modified example 2 of the first embodiment. [Figure 8] This is a cross-sectional view (part 1) illustrating a substrate according to a modified example 3 of the first embodiment. [Figure 9] This figure illustrates a method for manufacturing a substrate according to a modified example 3 of the first embodiment. [Figure 10]This is a cross-sectional view (part 2) illustrating a substrate according to a modified example 3 of the first embodiment. [Figure 11] This is a cross-sectional view illustrating a substrate according to the second embodiment. [Modes for carrying out the invention]

[0009] The embodiments for carrying out the invention will be described below with reference to the drawings. In each drawing, the same reference numerals are used for identical components, and redundant explanations may be omitted.

[0010] <First Embodiment> [Substrate structure] Figure 1 is a cross-sectional view illustrating a substrate according to the first embodiment, where Figure 1(a) is an overall view, Figure 1(b) is a partially enlarged view of the heat conductive member 10 in Figure 1(a), and Figure 1(c) is an enlarged view of part A in Figure 1(a).

[0011] Referring to Figure 1(a), the substrate 1 according to the first embodiment has a heat conductive member 10, a first metal layer 20, and a second metal layer 30. Referring to Figure 1(b), the heat conductive member 10 has a plurality of carbon nanotubes 11, a first resin layer 12, and a second resin layer 13.

[0012] The first metal layer 20 and the second metal layer 30 are arranged one above the other with the heat conduction member 10 interposed therebetween. The heat conduction member 10 is a so-called TIM (Thermal Interface Material), which is a member that conducts heat between the first metal layer 20 and the second metal layer 30. The first metal layer 20 is laminated on the first resin layer 12 of the heat conduction member 10. The upper surface of the first metal layer 20 is in contact with the lower surface of the first resin layer 12 of the heat conduction member 10. As shown in Fig. 1(c), although there are irregularities on the upper surface of the first metal layer 20, the resin constituting the first resin layer 12 enters into the irregularities formed on the upper surface of the first metal layer 20. That is, the resin constituting the first resin layer 12 has a surface shape following the irregularities on the surface of the first metal layer 20 on the side of the first resin layer 12. Therefore, the upper surface of the first metal layer 20 and the lower surface of the first resin layer 12 are not in point contact but contact with each other over a wide area. As a result, the thermal resistance between the upper surface of the first metal layer 20 and the lower surface of the first resin layer 12 is reduced, and heat is easily transferred from the first resin layer 12 to the first metal layer 20.

[0013] The second metal layer 30 is laminated on the second resin layer 13 of the heat conduction member 10. The lower surface of the second metal layer 30 is in contact with the upper surface of the second resin layer 13 of the heat conduction member 10. Similar to the case of Fig. 1(c), although there are irregularities on the lower surface of the second metal layer 30, the resin constituting the second resin layer 13 enters into the irregularities formed on the lower surface of the second metal layer 30. That is, the resin constituting the second resin layer 13 has a surface shape following the irregularities on the surface of the second metal layer 30 on the side of the second resin layer 13. Therefore, the lower surface of the second metal layer 30 and the upper surface of the second resin layer 13 are not in point contact but contact with each other over a wide area. As a result, the thermal resistance between the lower surface of the second metal layer 30 and the upper surface of the second resin layer 13 is reduced, and heat is easily transferred from the second metal layer 30 to the second resin layer 13.

[0014] On the second metal layer 30, a device that serves as a heating element can be mounted. The second metal layer 30 is, for example, patterned according to the electrode structure of the device to be mounted. When the device mounted on the second metal layer 30 generates heat during operation, the heat is transmitted to the first metal layer 20 via the heat conduction member 10 and dissipated from the first metal layer 20. The first metal layer 20 and the second metal layer 30 can be formed of a material having excellent thermal conductivity, such as copper or aluminum. The thicknesses of the first metal layer 20 and the second metal layer 30 can be, for example, about 0.1 μm to 3.0 μm. Note that part or all of the second metal layer 30 may function as wiring, or may be a mere metal layer not electrically connected to the device to be mounted. Also, the second metal layer 30 may not be patterned. Further, the first metal layer 20 may be joined to a heat sink.

[0015] [Structure of Heat Conduction Member] As shown in FIG. 1(b), in the heat conduction member 10, a plurality of carbon nanotubes 11 are arranged between the first resin layer 12 and the second resin layer 13 with their longitudinal directions generally oriented in the heat conduction direction. Here, the heat conduction direction is a direction substantially perpendicular to the upper surface of the second resin layer 13 and the lower surface of the first resin layer 12. The interval between adjacent carbon nanotubes 11 may be constant or may not be constant. Adjacent carbon nanotubes 11 may be in contact, but it is preferable that there is a gap between adjacent carbon nanotubes 11. Thereby, the shrinkage property of the carbon nanotubes 11 is improved, and they are more likely to expand and contract.

[0016] The carbon nanotubes 11 are, for example, substantially cylindrical carbon crystals with a diameter of about 0.7 to 70 nm. The length of the carbon nanotubes 11 in the longitudinal direction is, for example, 50 μm or more and 300 μm or less. The carbon nanotubes 11 have high thermal conductivity, and their thermal conductivity is, for example, about 3000 W / m·K. In order to obtain good heat transfer performance, the areal density of the carbon nanotubes 11 is preferably 1×10 10 per cm 2 or more.

[0017] The first resin layer 12 is provided on one end of the multiple carbon nanotubes 11. The resin constituting the first resin layer 12 is impregnated into one end of the multiple carbon nanotubes 11. In other words, one end of the multiple carbon nanotubes 11 is embedded in the first resin layer 12.

[0018] The length of the portion embedded in the first resin layer 12 at one end of each of the multiple carbon nanotubes 11 is, for example, 0.1 μm or more and 10 μm or less. The position of the tip 11a at one end of each carbon nanotube 11 may vary.

[0019] The tips 11a at one end of each of the multiple carbon nanotubes 11 do not protrude from the lower surface of the first resin layer 12. That is, the side of the first resin layer 12 facing the first metal layer 20 is a region formed solely from resin, where the tips 11a at one end of each of the multiple carbon nanotubes 11 do not extend. However, the tips 11a at one end of some of the carbon nanotubes 11 may reach the lower surface of the first resin layer 12 or protrude from the lower surface.

[0020] The second resin layer 13 is provided on the other end side of the multiple carbon nanotubes 11. The resin constituting the second resin layer 13 is impregnated into the other end side of the multiple carbon nanotubes 11. In other words, the other end side of the multiple carbon nanotubes 11 is embedded in the second resin layer 13.

[0021] The length of the portion embedded in the second resin layer 13 at the other end of each carbon nanotube 11 is, for example, 0.1 μm or more and 10 μm or less. However, the position of the tip 11b at the other end of each carbon nanotube 11 may vary.

[0022] The tips 11b of the other ends of the multiple carbon nanotubes 11 do not protrude from the upper surface of the second resin layer 13. That is, the second side of the second resin layer 13 that faces the second metal layer 30 is a region formed only of resin, where the other ends of the multiple carbon nanotubes 11 do not extend. However, the tips 11b of the other ends of some of the carbon nanotubes 11 may reach the upper surface of the second resin layer 13 or protrude from the upper surface.

[0023] Each of the first resin layer 12 and the second resin layer 13 does not contain fillers. The thermal conductivity of each of the first resin layer 12 and the second resin layer 13 is, for example, about 0.1 W / m·K to 0.3 W / m·K. Each of the first resin layer 12 and the second resin layer 13 can be formed from, for example, a polyphenylene ether-based resin.

[0024] The thickness of the first resin layer 12 and the second resin layer 13 can be, for example, 1 μm or more and 30 μm or less. Preferably, the thickness of the first resin layer 12 and the second resin layer 13 is 1 μm or more and 10 μm or less, and more preferably 0.1 μm or more and 5 μm or less.

[0025] If the thickness of the first resin layer 12 and the second resin layer 13 is 1 μm or more and 30 μm or less, the thermal resistance of the first resin layer 12 and the second resin layer 13 can be kept low, and the decrease in the overall thermal conductivity of the heat conduction member 10 can be suppressed. If the thickness of the first resin layer 12 and the second resin layer 13 is 1 μm or more and 10 μm or less, the decrease in the overall thermal conductivity of the heat conduction member 10 can be further suppressed, and if it is 0.1 μm or more and 5 μm or less, the decrease in the overall thermal conductivity of the heat conduction member 10 can be further suppressed.

[0026] In the heat conductive member 10, a first resin layer 12 without filler is placed on one end of the carbon nanotube 11, and a second resin layer 13 without filler is placed on the other end of the carbon nanotube 11. Therefore, the resins constituting the first resin layer 12 and the second resin layer 13 can impregnate both ends of the carbon nanotube 11, making it possible to form a sheet. In addition, in the heat conductive member 10, the first resin layer 12 and the second resin layer 13 are thinned to an extent that does not affect the heat dissipation performance of the heat conductive member 10. As a result, the heat conductive member 10 can be formed into a sheet, has high thermal conductivity and excellent heat dissipation. The thermal conductivity of the heat conductive member 10 can be, for example, about 20 to 30 W / m·K.

[0027] [Method for manufacturing heat conductive material] Next, a method for manufacturing the heat conductive member will be described. Figures 2 to 4 illustrate the manufacturing process of the heat conductive member according to the first embodiment.

[0028] First, in the process shown in Figure 2(a), a substrate 200 is prepared, and multiple carbon nanotubes 11 are formed on the upper surface of the substrate 200. For the substrate 200, for example, a plate-shaped silicon (Si) or copper (Cu) can be used.

[0029] More specifically, a metal catalyst layer is formed on the upper surface of the substrate 200 by sputtering or the like. For example, Fe, Co, Al, and Ni can be used as the metal catalyst layer. The thickness of the metal catalyst layer can be, for example, several nanometers. Next, the substrate 200 with the metal catalyst layer is placed in a heating furnace, and carbon nanotubes 11 are formed on the metal catalyst layer by CVD (chemical vapor deposition) at a predetermined pressure and temperature and with a process gas. The pressure and temperature of the heating furnace can be, for example, 0.1 to 8.0 kPa and 500 to 800°C. Furthermore, for example, acetylene gas can be used as the process gas, and for example, argon gas or hydrogen gas can be used as the carrier gas.

[0030] Next, in the step shown in Figure 2(b), the transfer member 210 is brought into contact with the upper end of the carbon nanotube 11 grown on the substrate 200 and pressed towards the substrate 200. For example, a silicone rubber sheet can be used as the transfer member 210. Next, in the step shown in Figure 2(c), the substrate 200 shown in Figure 2(b) is peeled off. As a result, the carbon nanotube 11 is transferred to the transfer member 210.

[0031] Next, in the process shown in Figure 3(a), a laminate of the protective layer 16 and the first resin layer 12 is prepared, and the transfer member 210 on which the carbon nanotubes 11 have been transferred is placed on the first resin layer 12 with the carbon nanotubes 11 facing the first resin layer 12. For the first resin layer 12, for example, a film-like thermosetting polyphenylene ether resin can be used. The first resin layer 12 does not contain fillers. For the protective layer 16, for example, a polyethylene terephthalate film or the like can be used.

[0032] Next, in the process shown in Figure 3(b), the transfer member 210 is pressed toward the first resin layer 12 while the structure shown in Figure 3(a) is heated. As a result, the first resin layer 12 softens, and the resin constituting the first resin layer 12 impregnates one end of the multiple carbon nanotubes 11.

[0033] Next, in the step shown in Figure 4(a), the transfer member 210 shown in Figure 3(b) is removed from the carbon nanotube 11. The heat generated during the heating process in Figure 3(b) is also transferred to the transfer member 210, causing it to soften. As a result, the transfer member 210 can be easily removed from the carbon nanotube 11.

[0034] Next, in the process shown in Figure 4(b), a laminate of the protective layer 17 and the second resin layer 13 is prepared. The second resin layer 13 is then positioned toward the carbon nanotube 11 and pressed toward the first resin layer 12 while being heated. This softens the second resin layer 13, and the resin constituting the second resin layer 13 impregnates the other ends of the multiple carbon nanotubes 11. For example, a film-like thermosetting polyphenylene ether resin can be used as the second resin layer 13. The second resin layer 13 does not contain fillers. For example, a polyethylene terephthalate film can be used as the protective layer 17. Through the above steps, the heat conductive member 10 equipped with protective layers 16 and 17 is completed.

[0035] [Manufacturing method for circuit boards] Next, we will explain the method for manufacturing the substrate. Figure 5 is a diagram illustrating the manufacturing process of a substrate according to the first embodiment.

[0036] First, in the process shown in Figure 5(a), the protective layer 16 provided on the first resin layer 12 of the heat conductive member 10 shown in Figure 4(b) is peeled off. Then, the first metal layer 20 is prepared, and the heat conductive member 10 is placed on the first metal layer 20 so that the first metal layer 20 and the first resin layer 12 are in contact. Next, the first resin layer 12 and the first metal layer 20 are heated to temporarily bond the first resin layer 12 and the first metal layer 20. The heating is carried out, for example, at about 150 to 200°C for several minutes. At that time, it is preferable to roll a roller or the like over the protective layer 17 side to apply pressure.

[0037] Next, in the process shown in Figure 5(b), after cooling the first resin layer 12 and the first metal layer 20, the protective layer 17 provided on the second resin layer 13 of the heat conductive member 10 is peeled off. Then, the second metal layer 30 is prepared and placed on the second resin layer 13 so that the second metal layer 30 and the second resin layer 13 are in contact. Next, the second resin layer 13 and the second metal layer 30 are heated to temporarily bond the second resin layer 13 and the second metal layer 30. Heating is carried out, for example, at about 150 to 200°C for several minutes. At that time, it is preferable to roll a roller or the like over the second metal layer 30 to apply pressure.

[0038] After the process shown in Figure 5(b), the heat conductive member 10 is permanently bonded to the first metal layer 20 and the second metal layer 30. Specifically, for example, in an atmosphere at a temperature of about 200°C, pressure is continuously applied from the first metal layer 20 and the second metal layer 30 towards the heat conductive member 10 for about 10 to 20 minutes at a pressure of about 0.1 to 1.0 MPa. This completes the substrate 1.

[0039] As mentioned above, the upper surface of the first metal layer 20 has irregularities, but during temporary bonding and / or permanent bonding, the resin constituting the first resin layer 12, which has been softened by heating, penetrates into the irregularities formed on the upper surface of the first metal layer 20. As a result, the upper surface of the first metal layer 20 and the lower surface of the first resin layer 12 come into contact over a wide area, and the thermal resistance between them becomes low. Similarly, the lower surface of the second metal layer 30 has irregularities, but during temporary bonding and / or permanent bonding, the resin constituting the second resin layer 13, which has been softened by heating, penetrates into the irregularities formed on the lower surface of the second metal layer 30. As a result, the lower surface of the second metal layer 30 and the upper surface of the second resin layer 13 come into contact over a wide area, and the thermal resistance between them becomes low.

[0040] In conventional DBC (Direct Bonded Copper) and DBA (Direct Bonded Aluminum) substrates, a ceramic substrate is provided at the location of the heat conductive member 10 on the substrate 1. The ceramic substrate is strongly bonded to the metal layers located on the upper and lower surfaces by diffusion bonding. However, because the ceramic substrate is hard and has low flexibility, and there is a difference in the coefficient of thermal expansion between it and the metal layers positioned above and below it, stress is generated under thermal load, causing delamination due to warping between the ceramic substrate and the metal layers. As a result, voids are created at the interface between the upper and lower surfaces of the ceramic substrate and the metal layers, resulting in point contact between the upper and lower surfaces of the ceramic substrate and the metal layers, and increasing the thermal resistance between them.

[0041] Furthermore, in substrate structures using insulating resin layers, which are increasingly replacing conventional DBC and DBA substrates, efforts are being made to improve thermal conductivity by using high thermal conductivity fillers, but the thermal conductivity is still only around 10 W / m·K.

[0042] On the other hand, in the substrate 1 having the heat conductive member 10, a highly flexible carbon nanotube 11 is positioned in the center of the thickness direction of the heat conductive member 10. Therefore, the carbon nanotube 11 can alleviate the stress during thermal loading caused by the difference in thermal expansion coefficients of each member. As a result, the risk of delamination or warping occurring between the heat conductive member 10 and the first metal layer 20 and the second metal layer 30 during thermal loading can be reduced. The elastic modulus of the heat conductive member 10 having the carbon nanotube 11 is 5 GPa or less, which is sufficiently small compared to ceramic substrates and solder. Furthermore, the heat conductive member 10 having the carbon nanotube 11 has a thermal conductivity that is 2 to 3 times higher than that of the substrate structure using the insulating resin layer described above.

[0043] Furthermore, since the resins constituting the first resin layer 12 and the second resin layer 13 are insulating resins, insulation between the first metal layer 20 and the second metal layer 30 can be ensured. In addition, since these insulating resins are thermosetting resins, they have good heat resistance and can achieve a heat resistance temperature of approximately 370°C.

[0044] <Variations of the first embodiment> In the modified version of the first embodiment, an example of a substrate with a different structure from the substrate according to the first embodiment is shown. In the modified version of the first embodiment, the description of components that are the same as those described in the previously described embodiment may be omitted.

[0045] Figure 6 is a cross-sectional view illustrating a substrate according to Modification 1 of the First Embodiment. Referring to Figure 6, the substrate 1A according to Modification 1 of the First Embodiment has two heat conductive members 10, a first metal layer 20, a second metal layer 30, and a ceramic substrate 40.

[0046] The first metal layer 20 is laminated on the first resin layer 12 of one of the heat conductive members 10 (the lower heat conductive member 10 in Figure 6). The second metal layer 30 is laminated on the second resin layer 13 of the other heat conductive member 10 (the upper heat conductive member 10 in Figure 6). The ceramic substrate 40 is bonded between the second resin layer 13 of one of the heat conductive members 10 and the first resin layer 12 of the other heat conductive member 10. In other words, the first metal layer 20 and the ceramic substrate 40 are positioned above and below one of the heat conductive members 10. Similarly, the second metal layer 30 and the ceramic substrate 40 are positioned above and below the other heat conductive member 10.

[0047] Thus, in substrate 1A, a ceramic substrate 40 is sandwiched between two heat-conducting members 10. This allows the carbon nanotubes 11 of each heat-conducting member 10 to alleviate the stress caused by the difference in thermal expansion coefficients of each member during thermal load, while utilizing the heat dissipation, insulation, and durability of the ceramic substrate 40. As a result, good heat conduction from the second metal layer 30 to the first metal layer 20 can be achieved without warping or delamination of the heat-conducting members 10 during thermal load.

[0048] Figure 7 is a cross-sectional view illustrating a substrate according to Modification 2 of the First Embodiment. Referring to Figure 7, in the substrate 1B according to Modification 2 of the First Embodiment, the heat conductive member 10 has a first opening 10x that penetrates the heat conductive member 10 and exposes the upper surface of the first metal layer 20. The second metal layer 30 also has a second opening 30x that penetrates the second metal layer 30 and communicates with the first opening 10x. The first opening 10x and the second opening 30x may be circular or rectangular through holes in a plan view, or they may be slits that divide the heat conductive member 10 and the second metal layer 30 into multiple regions. With a structure like that of the substrate 1B, for example, wires can be placed in the first opening 10x and the second opening 30x to electrically connect the first metal layer 20 and the second metal layer 30.

[0049] Figure 8 is a cross-sectional view (part 1) illustrating a substrate according to modification 3 of the first embodiment. Referring to Figure 8, in the substrate 1C according to modification 3 of the first embodiment, the heat conductive member 10 has a first pad 10a that penetrates the first resin layer 12 and is joined to one end of the carbon nanotube 11. The heat conductive member 10 also has a second pad 10b that penetrates the second resin layer 13 and is joined to the other end of the carbon nanotube 11. The first pad 10a and the second pad 10b are electrically connected via the carbon nanotube 11.

[0050] The first pad 10a is formed within a via hole 10y that penetrates the first resin layer 12. The second pad 10b is formed within a via hole 10z that penetrates the second resin layer 13. A second opening 30x that penetrates the second metal layer 30 is formed at a position that overlaps with the via holes 10y and 10z in a plan view.

[0051] Figure 9 illustrates a method for manufacturing a substrate according to a third modification of the first embodiment. Note that Figures 9(a) and 9(b) are inverted vertically compared to Figure 4(b).

[0052] First, after performing the same steps as in Figures 2(a) to 4(b) of the first embodiment, in the step shown in Figure 9(a), via holes 10y that penetrate the first resin layer 12 of the heat conductive member 10 are formed. The via holes 10y can be formed, for example, by irradiating the first resin layer 12 with laser light through the protective layer 16. For example, a carbon dioxide laser or an ultraviolet laser can be used to form the via holes 10y.

[0053] Next, in the process shown in Figure 9(b), a first pad 10a is formed in the via hole 10y. The first pad 10a can be formed, for example, by placing a thermosetting conductive paste or conductive film in the via hole 10y and heating and curing it.

[0054] Next, in the process shown in Figure 9(c), the structure shown in Figure 9(b) is inverted, and via holes 10z penetrating the second resin layer 13 of the heat conductive member 10 are formed in the same manner as in Figure 9(a), and then a second pad 10b is formed inside the via holes 10z in the same manner as in Figure 9(b).

[0055] Next, in the process shown in Figure 9(d), a first metal layer 20 is formed in contact with the first resin layer 12, similar to Figures 5(a) and 5(b), and a second metal layer 30 having a second opening 30x is formed in contact with the second resin layer 13. This completes the substrate 1C.

[0056] A structure like substrate 1C allows, for example, a wire to be placed within the second opening 30x, thereby electrically connecting the second metal layer 30 and the second pad 10b. This electrically connects the second metal layer 30 with the first pad 10a and the second pad 10b.

[0057] Figure 10 is a cross-sectional view (part 2) illustrating a substrate according to modification 3 of the first embodiment. As shown in the substrate 1D in Figure 10, a first pad 10c may be formed in a via hole 10y, and a second pad 10f may be formed in a via hole 10z. The first pad 10c has a structure in which a thin film resin layer 10d and a solder layer 10e are laminated from the carbon nanotube 11 side. The second pad 10f has a structure in which a thin film resin layer 10g and a solder layer 10h are laminated from the carbon nanotube 11 side.

[0058] In substrate 1D, by making the thin-film resin layers 10d and 10g as thin as possible, the solder layer 10e and solder layer 10h can be electrically connected via the carbon nanotube 11, and improved electrical conductivity can be expected compared to the structure using conductive paste or conductive film shown in Figure 9. Instead of solder layers 10e and 10h, sintered material or indium may be used. In this case as well, improved electrical conductivity can be expected compared to the structure using conductive paste or conductive film shown in Figure 9. The thin-film resin layers 10d and 10g act as buffer layers because direct adhesion between the carbon nanotube 11 and the solder layer, sintered material, or indium is difficult.

[0059] <Second Embodiment> In the second embodiment, an example of a substrate having a heat-conducting member with a different structure from that of the first embodiment is shown. In the second embodiment, descriptions of components that are the same as those described in the previously described embodiments may be omitted.

[0060] Figure 11 is a cross-sectional view illustrating a substrate according to the second embodiment, where Figure 11(a) is an overall view, Figure 11(b) is a partially enlarged view of the heat conductive member 10A in Figure 11(a), and Figure 11(c) is an enlarged view of part B in Figure 11(a).

[0061] Referring to Figure 11(a), the substrate 2 according to the second embodiment differs from the substrate 1 (see Figure 1, etc.) in that the heat conductive member 10 is replaced with a heat conductive member 10A.

[0062] In addition to the configuration of the heat conductive member 10, the heat conductive member 10A further includes a third resin layer 14 laminated on the first metal layer 20 side of the first resin layer 12, and a fourth resin layer 15 laminated on the second metal layer 30 side of the second resin layer 13.

[0063] The first metal layer 20 is laminated on the third resin layer 14 of the heat conductive member 10A. The upper surface of the first metal layer 20 is in contact with the lower surface of the third resin layer 14 of the heat conductive member 10A. As shown in Figure 11(c), the upper surface of the first metal layer 20 has irregularities, but the resin constituting the third resin layer 14 fills in the irregularities formed on the upper surface of the first metal layer 20. That is, the resin constituting the third resin layer 14 has a surface shape that follows the irregularities of the surface of the first metal layer 20 on the third resin layer 14 side. Therefore, the upper surface of the first metal layer 20 and the lower surface of the third resin layer 14 do not make point contact, but rather contact over a wide area. As a result, the thermal resistance between the upper surface of the first metal layer 20 and the lower surface of the third resin layer 14 is reduced, and heat is easily transferred from the third resin layer 14 to the first metal layer 20.

[0064] The second metal layer 30 is laminated on the fourth resin layer 15 of the heat conductive member 10A. The lower surface of the second metal layer 30 is in contact with the upper surface of the fourth resin layer 15 of the heat conductive member 10A. Similar to the case in Figure 11(c), the lower surface of the second metal layer 30 has irregularities, but the resin constituting the fourth resin layer 15 fills in the irregularities formed on the lower surface of the second metal layer 30. That is, the resin constituting the fourth resin layer 15 has a surface shape that follows the irregularities of the surface of the second metal layer 30 on the fourth resin layer 15 side. Therefore, the lower surface of the second metal layer 30 and the upper surface of the fourth resin layer 15 do not make point contact, but rather contact over a wide area. As a result, the thermal resistance between the lower surface of the second metal layer 30 and the upper surface of the fourth resin layer 15 is reduced, and heat is easily transferred from the second metal layer 30 to the fourth resin layer 15.

[0065] Similar to the first embodiment, the first resin layer 12 and the second resin layer 13 do not contain fillers. On the other hand, the third resin layer 14 contains a filler 14f. The third resin layer 14 has a higher thermal conductivity than the first resin layer 12. The fourth resin layer 15 contains a filler 15f. The fourth resin layer 15 has a higher thermal conductivity than the second resin layer 13. For example, alumina or aluminum nitride can be used as the fillers 14f and 15f. The diameters of the fillers 14f and 15f can be, for example, about 0.1 μm to 10 μm. The thermal conductivity of the first resin layer 12 and the second resin layer 13 is, for example, about 0.1 W / m·K to 0.3 W / m·K. On the other hand, the thermal conductivity of the third resin layer 14 and the fourth resin layer 15 is, for example, about 1 W / m·K to 15 W / m·K.

[0066] The third resin layer 14 and the fourth resin layer 15 can be formed from, for example, a polyphenylene ether-based resin. The resin layers constituting the third resin layer 14 and the fourth resin layer 15 may be formed from resins different from those used for the first resin layer 12 and the second resin layer 13.

[0067] It is preferable that the first resin layer 12 is thinner than the third resin layer 14, and the second resin layer 13 is thinner than the fourth resin layer 15. The thickness of the first resin layer 12 and the third resin layer 14 can be, for example, 1 μm or more and 30 μm or less. The thickness of the first resin layer 12 and the second resin layer 13 can be, for example, 1 μm or more and 10 μm or less, and more preferably 0.1 μm or more and 5 μm or less. The thickness of the third resin layer 14 and the fourth resin layer 15 can be, for example, about 50 μm to 250 μm.

[0068] The first resin layer 12 has a lower thermal conductivity than the third resin layer 14, and the second resin layer 13 has a lower thermal conductivity than the fourth resin layer 15. However, if the thickness of the first resin layer 12 and the second resin layer 13 is between 1 μm and 30 μm, the thermal resistance of the first resin layer 12 and the second resin layer 13 can be kept low, thereby suppressing a decrease in the overall thermal conductivity of the heat conduction member 10A. If the thickness of the first resin layer 12 and the second resin layer 13 is between 1 μm and 10 μm, the decrease in the overall thermal conductivity of the heat conduction member 10A can be further suppressed, and if it is between 0.1 μm and 5 μm, the decrease in the overall thermal conductivity of the heat conduction member 10A can be further suppressed.

[0069] In the heat conductive member 10A, similar to the heat conductive member 10, a first resin layer 12 without filler is placed on one end of the carbon nanotube 11, and a second resin layer 13 without filler is placed on the other end of the carbon nanotube 11. As a result, the resins constituting the first resin layer 12 and the second resin layer 13 can impregnate both ends of the carbon nanotube 11, making it possible to form a sheet. Furthermore, the first resin layer 12 and the second resin layer 13 are thinned to an extent that does not affect the heat dissipation performance of the heat conductive member 10A, and a third resin layer 14 with good thermal conductivity is laminated onto the first resin layer 12, and a fourth resin layer 15 with good thermal conductivity is laminated onto the second resin layer 13. As a result, the heat conductive member 10A can be formed into a sheet, has high thermal conductivity, and has excellent heat dissipation properties. The thermal conductivity of the heat-conducting member 10A can be approximately 20-30 W / m·K when the carbon nanotube 11, the first metal layer 20, and the second metal layer 30 are in contact with the fillers 14f and 15f in the third resin layer 14 and the fourth resin layer 15.

[0070] As with substrate 2, the same effect as substrate 1 can be achieved by using a heat conductive member 10A instead of the heat conductive member 10 of substrate 1. The heat conductive member 10A can be manufactured in the same manner as the heat conductive member 10. However, in the process shown in Figure 3(a), a laminate of the protective layer 16, the third resin layer 14, and the first resin layer 12 is prepared. Also, in the process shown in Figure 4(b), a laminate of the protective layer 17, the fourth resin layer 15, and the second resin layer 13 is prepared.

[0071] Although preferred embodiments have been described in detail above, the invention is not limited to the embodiments described above, and various modifications and substitutions can be made to the embodiments described above without departing from the scope of the claims.

[0072] For example, modifications 1 to 3 of the first embodiment and the second embodiment can be combined within the limits of not causing technical inconsistencies.

[0073] For example, when the modified example 3 of the first embodiment is combined with the second embodiment, the heat conductive member comprises a first pad that penetrates the first and third resin layers and is joined to one end of the carbon nanotube, and a second pad that penetrates the second and fourth resin layers and is joined to the other end of the carbon nanotube, with the first pad and the second pad being electrically connected via the carbon nanotube. [Explanation of Symbols]

[0074] 1, 1A, 1B, 1C, 1D, 2 boards 10,10A heat conductive material 10a, 10c First pad 10b, 10f Second pad 10d,10g thin film resin layer 10e, 10h solder layer 10x 1st opening 10y, 10z Beer Hall 11 Carbon nanotubes 11a One end of a carbon nanotube 11b The other end of the carbon nanotube 12 1st resin layer 13 Second resin layer 14f, 15f filler 14 Third resin layer 15 4th resin layer 16,17 Protective layer 20 1st metal layer 30 Second metal layer 30x 2nd opening 40 Ceramic substrates 200 circuit boards 210 Transfer Member

Claims

1. A thermal conductive member having a plurality of carbon nanotubes, a first resin layer provided on one end of the plurality of carbon nanotubes, and a second resin layer provided on the other end of the plurality of carbon nanotubes, A first metal layer laminated on the first resin layer, The present invention comprises a second metal layer laminated on the second resin layer, The first resin layer and the second resin layer do not contain fillers. The resin constituting the first resin layer is impregnated into one end of a plurality of carbon nanotubes, The resin constituting the second resin layer is impregnated into the other end of the plurality of carbon nanotubes, The heat conductive member has a first opening that penetrates the heat conductive member and exposes the first metal layer, A substrate having a second metal layer that penetrates the second metal layer and communicates with the first opening.

2. Two heat-conducting members, each having a plurality of carbon nanotubes, a first resin layer provided on one end of the plurality of carbon nanotubes, and a second resin layer provided on the other end of the plurality of carbon nanotubes, A first metal layer laminated on the first resin layer of the heat conductive member, The other heat conductive member has a second metal layer laminated on the second resin layer, The system comprises a ceramic substrate bonded between the second resin layer of one of the heat conductive members and the first resin layer of the other heat conductive member, The first resin layer and the second resin layer of each of the heat conductive members do not contain fillers. The resin constituting the first resin layer of each of the heat conductive members is impregnated into one end of a plurality of carbon nanotubes. The resin constituting the second resin layer of each of the heat conductive members is impregnated into the other end of a plurality of carbon nanotubes, forming a substrate.

3. The aforementioned heat conductive member is A third resin layer laminated on the first metal layer side of the first resin layer, The second resin layer further comprises a fourth resin layer laminated on the second metal layer side of the second resin layer, The third resin layer has a higher thermal conductivity than the first resin layer. The fourth resin layer has a higher thermal conductivity than the second resin layer. The substrate according to claim 1 or 2, wherein the third resin layer and the fourth resin layer contain a filler.

4. The resin constituting the first resin layer has a surface shape that conforms to the irregularities on the surface of the first metal layer facing the first resin layer. The substrate according to claim 1 or 2, wherein the resin constituting the second resin layer has a surface shape that conforms to the irregularities on the second resin layer side of the second metal layer.

5. The resin constituting the third resin layer has a surface shape that conforms to the irregularities on the surface of the first metal layer facing the third resin layer. The substrate according to claim 3, wherein the resin constituting the fourth resin layer has a surface shape that conforms to the irregularities on the surface of the second metal layer facing the fourth resin layer.

6. The first metal layer side of the first resin layer is a region formed solely from resin, in which one end of the plurality of carbon nanotubes is not embedded. The substrate according to claim 1 or 2, wherein the second metal layer side of the second resin layer is a region formed solely from resin, in which the other ends of the plurality of carbon nanotubes are not embedded.

7. The substrate according to claim 3, wherein the first resin layer is thinner than the third resin layer, and the second resin layer is thinner than the fourth resin layer.

8. The substrate according to claim 1 or 2, wherein the first resin layer and the second resin layer are formed from a polyphenylene ether resin.

9. The substrate according to claim 3, wherein the third resin layer and the fourth resin layer are formed from a polyphenylene ether resin.

10. The aforementioned heat conductive member is A first pad that penetrates the first resin layer and is joined to one end of the carbon nanotube, The invention comprises a second pad that penetrates the second resin layer and is joined to the other end of the carbon nanotube, The substrate according to claim 1, wherein the first pad and the second pad are electrically connected via the carbon nanotube.

11. The aforementioned heat conductive member is A first pad that penetrates the first resin layer and the third resin layer and is joined to one end of the carbon nanotube, The invention comprises a second pad that penetrates the second resin layer and the fourth resin layer and is joined to the other end of the carbon nanotube, The substrate according to claim 3, wherein the first pad and the second pad are electrically connected via the carbon nanotube.

Images