Thermally-conductive sheet and thermally-conductive sheet production method

Abstract

This thermally-conductive sheet includes a metal layer, a plurality of metal protrusions on at least a first surface of the metal layer, and a low-temperature sintering material on the metal protrusions. The area ratio of the plurality of metal protrusions to the first surface is 20%-80%.

Description

Thermal conductive sheet, and method for manufacturing a thermal conductive sheet

[0001] The present invention relates to a heat conductive sheet and a method for manufacturing a heat conductive sheet.

[0002] With the miniaturization of electronic devices such as power modules, image sensors, and high-performance computing (HPC), and the increase in information processing capacity, heat generation has become more pronounced, and the importance of heat dissipation from heat sources is increasing. In LSIs and other components of various electronic devices, prolonged exposure to high temperatures due to heat generated by the components used can lead to malfunctions or failures. For this reason, thermal conductive materials are widely used to prevent the temperature of LSIs and other components from rising. These thermal conductive materials can prevent the temperature of the equipment from rising by dissipating the heat generated by the components or by transferring it to a heat dissipation component that releases it to the outside of the system, such as the atmosphere.

[0003] To date, sheet-like heat-bonding materials have been reported in which a support made of plate-shaped metal and a bonding agent containing metal nanoparticles and metal fine particles and a solvent are attached to both sides of the support, with the organic material mainly composed of an alcohol having 18 or fewer carbon atoms or a derivative thereof, or a compound containing a carboxyl group, or a mixture thereof.

[0004] Japanese Patent Publication No. 2023-038748

[0005] However, the conventional thermal conductive sheet described in Patent Document 1 has the problem that, because the bonding agent adheres uniformly to the support, cracks occur in the bonding agent area during reliability tests, making practical application difficult. In addition, it requires a high-pressure press, which places a heavy load on the equipment, and it has the problem of poor reliability because it cannot relieve stress in response to the applied pressure.

[0006] The present invention aims to solve the aforementioned conventional problems and achieve the following objectives. That is, the present invention aims to provide a thermal conductive sheet that can relieve stress and achieve both reliability and high thermal conductivity. <1> A thermal conductive sheet having a metal layer, a plurality of metal protrusions on at least a first surface of the metal layer, and a low-temperature sintered material on the metal protrusions, wherein the area ratio of the plurality of metal protrusions to the first surface is 20% or more and 80% or less. <2> The thermal conductive sheet according to <1>, further having a plurality of metal protrusions on a second surface of the metal layer opposite to the first surface, and a low-temperature sintered material on the metal protrusions, wherein the area ratio of the plurality of metal protrusions to the second surface is 20% or more and 80% or less. <3> The thermal conductive sheet according to <1> or <2>, wherein the low-temperature sintered material is at least one of gold, silver, and nickel. <4> The average thickness (T) of the metal layer Ｍ The average thickness (T) of the metal protrusion relative to ) ｍ ) ratio (T ｍ / T Ｍ) is a thermal conductive sheet according to any one of <1> to <3> above, wherein the thermal conductivity of the metal layer is 0.2 or more and 4 or less. <5> A thermal conductive sheet according to any one of <1> to <4> above, wherein the thermal conductivity of the metal layer is 50 W / (m·K) or more. <6> A thermal conductive sheet according to any one of <1> to <5> above, wherein the metal layer contains at least one of gold, silver, copper, and aluminum. <7> A thermal conductive sheet according to any one of <1> to <6> above, wherein when the contact area of ​​the metal protrusion that has half the area of ​​the first surface and is located in the center centered on the centroid of the planar shape of the first surface is Ac, and the contact area of ​​the metal protrusion located in the peripheral part of the first surface other than the central part is Ap, the value obtained by dividing Ac by Ap (Ac / Ap) is 1.2 or more and 10 or less. <8> A method for manufacturing a heat conductive sheet according to any one of <1> to <7> above, characterized in that it includes the step of applying a composition containing the low-temperature sintered material onto the metal protrusions in the metal layer having the metal protrusions. <9> A method for manufacturing a heat conductive sheet according to any one of <1> to <7> above, characterized in that it includes the steps of applying the low-temperature sintered material onto at least a first surface of a metal plate, and etching the exposed surface of the metal plate to which the low-temperature sintered material has not been applied to form the metal layer and the plurality of metal protrusions. <10> A method for manufacturing a heat conductive sheet according to any one of <1> to <7> above, characterized in that it includes the steps of preparing a mold having a plurality of recesses corresponding to the plurality of metal protrusions, applying the low-temperature sintered material to the bottom surface of each recess, plating the low-temperature sintered material as a plating seed to form the plurality of metal protrusions, and sintering and joining the plurality of metal protrusions and the metal layer.

[0007] According to the present invention, it is possible to solve the aforementioned problems in the conventional era, achieve the aforementioned objectives, relieve stress, and provide a thermal conductive sheet that can achieve both reliability and high thermal conductivity.

[0008] Figure 1 is a plan view showing an example of the heat conductive sheet of this embodiment. Figure 2 is a cross-sectional view of the heat conductive sheet of Figure 1 along line A-A'. Figure 3 is a cross-sectional view of another example of the heat conductive sheet of this embodiment along line A-A'. Figure 4 is a cross-sectional view of another example of the heat conductive sheet of this embodiment along line A-A'. Figure 5 is a plan view illustrating the central part c and peripheral part p of the heat conductive sheet of this embodiment. Figure 6 is a schematic cross-sectional view (part 1) showing an example of the process for manufacturing the heat conductive sheet of the first embodiment. Figure 7 is a schematic cross-sectional view (part 2) showing an example of the process for manufacturing the heat conductive sheet of the first embodiment. Figure 8 is a schematic cross-sectional view (part 1) showing an example of the process for manufacturing the heat conductive sheet of the second embodiment. Figure 9 is a schematic cross-sectional view (part 2) showing an example of the process for manufacturing the heat conductive sheet of the second embodiment. Figure 10 is a schematic cross-sectional view (part 3) showing an example of the process for manufacturing the heat conductive sheet of the second embodiment. Figure 11 is a schematic cross-sectional view (part 1) showing an example of the process for manufacturing the heat conductive sheet of the third embodiment. Figure 12 is a schematic cross-sectional view (part 2) showing an example of the process for manufacturing the heat conductive sheet of the third embodiment. Figure 13 is a schematic cross-sectional view showing an example of the process for manufacturing a heat conductive sheet according to the third embodiment (part 3). Figure 14 is a schematic cross-sectional view showing an example of the process for manufacturing a heat conductive sheet according to the third embodiment (part 4). Figure 15 is a schematic cross-sectional view showing an example of a laminate according to this embodiment. Figure 16 is a schematic cross-sectional view showing another example of a laminate according to this embodiment. Figure 17 is a schematic cross-sectional view showing an example of a heat dissipation structure according to this embodiment.

[0009] (Thermal Conductive Sheet) The thermal conductive sheet of this embodiment is a thermal conductive sheet having a metal layer, a plurality of metal protrusions on at least a first surface of the metal layer, and a low-temperature sintered material on the metal protrusions. The area ratio of the plurality of metal protrusions to the first surface is 20% or more and 80% or less. Preferably, the thermal conductive sheet further has a plurality of metal protrusions on a second surface opposite to the first surface of the metal layer, and a low-temperature sintered material on the metal protrusions. Here, the area ratio of the plurality of metal protrusions to the second surface is 20% or more and 80% or less.

[0010] The thermal conductive sheet of this embodiment has a metal layer, a plurality of metal protrusions on at least a first surface of the metal layer, and a low-temperature sintered material on the metal protrusions. The area ratio of the plurality of metal protrusions to the first surface is 20% to 80%, so the thermal conductive sheet has thermal conductivity not only in the thickness direction but also in the planar direction, resulting in excellent thermal conductivity. Furthermore, having a low-temperature sintered material on the metal protrusions, and the area ratio of the metal protrusions exposed on the first surface of the thermal conductive sheet to the first surface is 20% to 80%, allows for stress relief in a laminate in which the thermal conductive sheet is provided between substrates such as a heating element and a heat dissipation member, reducing lifting and peeling from the substrate, resulting in excellent adhesion to the substrate and superior reliability. Therefore, by providing a thermal conductive sheet between a heating element and a heat dissipation member, heat generated from the heating element can be efficiently dissipated through the thermal conductive sheet, stress can be relieved, and a thermal conductive sheet that achieves both reliability and high thermal conductivity can be provided.

[0011] Figures 1 and 2 are a plan view and a cross-sectional view along the A-A' section, respectively, showing an example of a thermal conductive sheet according to this embodiment. The thermal conductive sheet 10 shown in Figures 1 and 2 comprises a metal layer 11, a plurality of metal protrusions 12 on both sides of the metal layer 11, and a low-temperature sintered material 13 on the metal protrusions 12. As shown in the plan view of Figure 1, a pattern of metal protrusions 12 and low-temperature sintered material 13 is formed. The area ratio of the plurality of metal protrusions 12 to the first surface is 20% to 80%, and the area ratio of the plurality of metal protrusions 12 to the second surface is 20% to 80%.

[0012] Furthermore, the thermal conductive sheet may have a pattern of multiple metal protrusions 12 and low-temperature sintered material 13 on the first surface and a pattern of multiple metal protrusions 12 and low-temperature sintered material 13 on the second surface that are not identical or symmetrical across the metal layer. For example, as shown in Figure 3, which illustrates a cross-sectional view A-A' of another example of the thermal conductive sheet of this embodiment, the pattern on the first surface and the pattern on the second surface may be offset.

[0013] As shown in Figure 4, which illustrates another example of the thermal conductive sheet of this embodiment, the thermal conductive sheet 10 may have a plurality of metal protrusions 12 and a low-temperature sintered material 13 on a first surface (only one side). The thermal conductive sheet 10 shown in Figure 4 has a metal part 11, a plurality of metal protrusions 12 on the first surface of the metal layer 11, and a low-temperature sintered material 13 on the metal protrusions 12. The pattern of the metal protrusions 12 and the low-temperature sintered material 13 on the first surface of the thermal conductive sheet 10 in Figure 3 is the same as in the plan view of Figure 1. The area ratio of the metal protrusions 12 exposed on the first surface of the thermal conductive sheet 10 to the first surface is 20% or more and 80% or less.

[0014] <Metal Layer> The material of the metal layer preferably contains a metal with high thermal conductivity, and more preferably consists of such a metal. From the viewpoint of thermal conductivity and safety, aluminum, nickel, iron, gold, silver, copper, zinc, and tin are preferred as the metal, and gold, silver, copper, and aluminum are more preferred.

[0015] The thermal conductivity of the metal layer is not particularly limited and can be appropriately selected depending on the purpose, but from the viewpoint of thermal conductivity, 50 W / (m·K) or higher is preferred, and 100 W / (m·K) or higher is more preferred. The thermal conductivity of the metal is not particularly limited and can be appropriately selected depending on the purpose, but from the viewpoint of thermal conductivity, 50 W / (m·K) or higher is preferred, 100 W / (m·K) or higher is more preferred, and 200 W / (m·K) or higher is even more preferred.

[0016] <Metal protrusions> There are no particular restrictions on the metal protrusions, and they can be appropriately selected according to the purpose. Examples include metals formed by electroplating, non-electroplating, etc.; metals filled with a metal material and, if necessary, a filler; and metals made of the same material as the metal layer cut from a metal plate. Among these, metals formed by electroplating are preferred. There are no particular restrictions on the metals formed by electroplating, and they can be appropriately selected from the metals mentioned above according to the purpose.

[0017] The metal protrusions may be filled with a metal material, or they may be filled with a mixture of a metal material and a filler of any component. There are no particular restrictions on the type of metal material, and it can be appropriately selected according to the purpose, but from the viewpoint of thermal conductivity and safety, aluminum, aluminum oxide, aluminum nitride, boron nitride, carbon resin, nickel, iron, gold, silver, copper, zinc, and tin are preferred, and gold, silver, and nickel are more preferred. These may be used individually or in combination of two or more.

[0018] There are no particular restrictions on the shape of the metal material, and it can be appropriately selected according to the purpose. Examples include spherical, plate-shaped, rod-shaped, and wire-shaped materials.

[0019] As for the content of the metal material in the metal protrusions, from the viewpoint of thermal conductivity, 50% by mass or more is preferred, any of 60% by mass or more, 70% by mass or more, and 80% by mass or more is preferred, 90% by mass or more is even more preferred, 95% by mass or more is particularly preferred, and 99% by mass or more is most preferred.

[0020] The aforementioned filler is not particularly limited and can be appropriately selected according to the purpose, and examples include dispersants, surfactants, and binder resins.

[0021] <Low-Temperature Sintered Material> The low-temperature sintered material is not particularly limited and can be appropriately selected depending on the purpose. Examples include gold, silver, and nickel. Among these, gold and nickel are preferred as low-temperature sintered materials that have etching resistance and can be used in the manufacturing method of the heat conductive sheet of the second embodiment described later. Gold and nickel are also preferred as low-temperature sintered materials that have a plating seed function and can be used in the manufacturing method of the heat conductive sheet of the third embodiment described later. The shape of the low-temperature sintered material is not particularly limited and can be appropriately selected depending on the purpose. Examples include spherical, plate-shaped, rod-shaped, and wire-shaped materials. A paste-like low-temperature sintered material may be used to apply the low-temperature sintered material to the metal protrusions. For example, a composition containing the low-temperature sintered material and any component such as a resin, a curable material, a curing agent, or a solvent may be used.

[0022] The volume-average particle size (D) of the low-temperature sintered material ５０ The volume average particle size (D) is preferably 0.3 μm or more and 30 μm or less, and more preferably 0.5 μm or more and 10 μm or less. When the volume average particle size of the low-temperature sintered material is 0.3 μm or more and 30 μm or less, when the heat conductive sheet is sandwiched between the base material and the opposing base material and heated, a network of sintered bodies made of sintered low-temperature sintered material can be formed, and high thermal conductivity and low thermal resistance can be achieved in a laminate having a base material, a heat conductive sheet and an opposing base material. ５０ This can be measured, for example, using a laser diffraction / scattering particle size distribution analyzer (product name: Microtrac MT3300EXII).

[0023] When a low-temperature sintered material is part of the composition, there are no particular restrictions on the content of the low-temperature sintered material in the composition, and it can be appropriately selected according to the purpose. However, from the viewpoint of improving thermal conductivity, it is preferable that the content is more than 40% by volume and 98% by volume or less, and more preferably 50% by volume and 95% by volume or less.

[0024] - Resin - There are no particular restrictions on the resin, and it can be appropriately selected depending on the purpose, but modified acrylate compounds, epoxy resins, unsaturated polyester resins, polyurethane resins, bismaleimide resins, alkyd resins, phenolic resins, and melamine resins are preferred. These may be used individually or in combination of two or more.

[0025] -Curable Material- There are no particular restrictions on the curable material, and it can be appropriately selected depending on the purpose, but curable silicone, curable epoxy resin, curable polyurethane resin, and curable polyester resin are preferred examples. These may be used individually or in combination of two or more.

[0026] Examples of curable silicones include silicones having alkoxy groups, silicones having epoxy groups (glycidoxy groups), silicones having acryloyl groups (methacryloyl groups), and silicones having hydrosilyl groups and vinyl groups. Examples of curable epoxy resins include glycidyl ether type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, trisphenol type epoxy resins, tetraphenol type epoxy resins, phenol-xylylene type epoxy resins, naphthol-xylylene type epoxy resins, phenol-naphthol type epoxy resins, phenol-dicyclopentadiene type epoxy resins, alicyclic epoxy resins, and aliphatic epoxy resins. Examples of curable polyurethane resins include polyurethanes having acryloyl groups, polyurethanes having methacryloyl groups, urethane prepolymers containing terminal isocyanate groups, and epoxy-modified polyurethanes. Examples of curable polyester resins include polyesters having acryloyl groups, polyesters having methacryloyl groups, and epoxy-modified polyesters.

[0027] -Curing Agent- The curing agent is a curing agent corresponding to the curable material, and examples include polyfunctional carboxylic acids, acid anhydride curing agents, aliphatic amine curing agents, aromatic amine curing agents (e.g., imidazole curing agents), phenol curing agents, mercaptan curing agents, and other polyaddition curing agents, as well as catalytic curing agents such as imidazole. These may be used individually or in combination of two or more. Among these, aromatic amine curing agents are preferred, and imidazole curing agents are more preferred.

[0028] -Solvent- The solvent is not particularly limited and can be appropriately selected depending on the purpose. Examples include terpineol, butyl carbitol, butyl carbitol acetate, and texanol.

[0029] The above composition can be prepared by mixing and dispersing the low-temperature sintered material, and optionally a resin, a curable material, a curing agent, a solvent, etc. Commercially available products may be used as the above composition, for example, H 9890-6A (manufactured by Namics Corporation, a thermosetting conductive adhesive, silver paste) can be used as a metal paste containing the low-temperature sintered material.

[0030] [Area Ratio] When the first surface of the thermal conductive sheet is viewed in plan view, the area ratio of the plurality of metal protrusions to the first surface is preferably 20% to 80%, and more preferably 30% to 70%, in terms of reducing lifting and peeling from the substrate, providing excellent adhesion to the substrate, and offering superior reliability. In an embodiment in which the second surface of the thermal conductive sheet has a plurality of metal protrusions and a low-temperature sintered material, when the second surface of the thermal conductive sheet is viewed in plan view, the area ratio of the plurality of metal protrusions to the second surface is preferably 20% to 80%, and more preferably 30% to 70%, in terms of reducing lifting and peeling from the substrate, providing excellent adhesion to the substrate, and offering superior reliability.

[0031] [Pattern] The pattern of the metal protrusions 12 and the low-temperature sintered material 13 is not particularly limited as long as it satisfies the area ratio, and can be appropriately selected according to the purpose. For example, a pattern in which multiple figures are arranged can be given. Among these, a pattern in which multiple figures are arranged regularly is preferred from the viewpoint of uniformity of thermal conductivity. Examples of such patterns include 45° staggered (see Figure 1), 60° staggered, parallel squares, 60° staggered regular hexagons, equilateral triangle arrangement, and alternating rectangles.

[0032] There are no particular restrictions on the size of the metal protrusions 12 in the pattern, and they can be appropriately selected according to the purpose. However, the length of the longest side of the figure is preferably 10 μm or more and 1,000 μm or less, and more preferably 50 μm or more and 500 μm or less.

[0033] As another aspect of the patterns of the metal protrusions 12 and the low-temperature sintered material 13, it is preferable that the contact area Ac of the metal protrusions arranged at the center portion when the heat conduction sheet is viewed in plan is larger than the contact area Ap of the metal protrusions arranged at the peripheral portion, in terms of being able to more effectively relieve the stress when the heat conduction sheet is joined. Here, as shown by the broken line in FIG. 5, the first surface of the metal layer 11 is divided into two equal-area portions, a center portion c and a peripheral portion p. The center portion c has an area of 1 / 2 of the first surface and is a portion centered on the centroid of the planar shape of the first surface (inside the square shown by the broken line in FIG. 5), and the peripheral portion p is the portion other than the center portion c of the first surface (outside the square shown by the broken line in FIG. 5). Note that FIG. 5 is a plan view for explaining the center portion c and the peripheral portion p of the heat conduction sheet of the present embodiment, and the broken line in FIG. 5 is a boundary line that divides the center portion c and the peripheral portion p into equal areas. When the contact area of the metal protrusions 12 arranged at the center portion c is Ac and the contact area of the metal protrusions 12 arranged at the peripheral portion p is Ap, the value (Ac / Ap) obtained by dividing Ac by Ap is preferably 1.2 or more and 10 or less. For example, in the heat conduction sheet shown in FIG. 5, the ratio of the area where a plurality of protrusions contact with respect to the center portion c of the first surface is 75%, and the ratio of the area where a plurality of protrusions contact with respect to the peripheral portion p of the first surface is 25%, and Ac / Ap = 75 / 25 = 3.

[0034] The thermal conductivity of the heat conduction sheet is not particularly limited and can be appropriately selected according to the purpose. From the perspective of thermal conductivity, it is preferably 50 W / (m·K) or more, more preferably 60 W / (m·K) or more, still more preferably 70 W / (m·K) or more, and particularly preferably 80 W / (m·K) or more.

[0035] The average thickness of the heat conduction sheet is not particularly limited and can be appropriately selected according to the purpose. It is preferably 10 μm or more and 200 μm or less, and more preferably 30 μm or more and 150 μm or less.

[0036] The average thickness of the metal layer is not particularly limited and can be appropriately selected according to the purpose. It is preferably 10 μm or more and 100 μm or less, and more preferably 15 μm or more and 50 μm or less.

[0037] The average thickness (T of the metal layerＭ ), the ratio (T ｍ of the average thickness (T ｍ of the metal convex portion to Ｍ ) is not particularly limited and can be appropriately selected according to the purpose. From the viewpoints of further improving thermal conductivity and reliability, it is preferably 0.2 or more and 4 or less, and more preferably 0.5 or more and 2 or less.

[0038] When it is an aspect having metal convex portions on both the first surface and the second surface of the heat conduction sheet, for the metal convex portions on each surface, the ratio (T ｍ / T Ｍ ) can be set independently, and the ratio (T ｍ / T Ｍ ) of the first surface and the ratio (T ｍ / T Ｍ ) of the second surface may be different or the same.

[0039] Since the low-temperature sintering material is exposed on the surface of the heat conduction sheet, for example, when bonding to a base material such as a heating element or a heat radiating member and a counter base material, it is excellent in adhesive force and mechanical strength after heat treatment (accelerated life test), and therefore, it is excellent in reliability. The heat conduction sheet has a metal layer and metal convex portions communicating in the thickness direction and the plane direction of the heat conduction sheet, so that stress can be relaxed. Also, the problem that the film itself becomes brittle as in the case of a heat conduction sheet in which a heat conduction material is bound with a binder resin and the film collapses in a high-temperature test or the like is solved, and the collapse of the heat conduction sheet can be well prevented.

[0040] (Method for manufacturing a thermal conductive sheet) Examples of methods for manufacturing the thermal conductive sheet of this embodiment include, for example, a method of applying a composition containing a low-temperature sintered material onto the metal protrusions in a metal layer having metal protrusions (first embodiment); a method of cutting out a metal part in which the metal layer and metal protrusions are integrated by applying a low-temperature sintered material as a protective agent onto a metal plate and etching it (second embodiment); and a method of forming a plurality of metal protrusions by plating with a low-temperature sintered material as a plating seed, and joining the plurality of metal protrusions and the metal layer by sintering (third embodiment). In the first to third embodiments, embodiments for manufacturing a thermal conductive sheet having metal protrusions and a low-temperature sintered material on the first and second surfaces (both sides) of the metal layer are described, but a thermal conductive sheet having metal protrusions and a low-temperature sintered material on the first surface (one side) of the metal layer may also be used.

[0041] [First Embodiment] The method for manufacturing a heat conductive sheet in the first embodiment includes the step of applying a composition containing the low-temperature sintered material onto the metal protrusions in the metal layer having the metal protrusions, and further includes other steps as necessary.

[0042] Figures 6 and 7 show schematic cross-sectional views illustrating an example of the process for manufacturing a heat-conducting sheet according to the first embodiment. First, a metal layer 11 having a plurality of metal protrusions 12 on a first surface and a second surface (both sides) is prepared (Figure 6). Next, a composition containing a low-temperature sintered material 13 is applied to each metal protrusion 12 (Figure 7). This allows for the manufacture of a heat-conducting sheet 10.

[0043] There are no particular limitations on the method for forming a metal layer having metal protrusions, and a suitable method can be selected depending on the purpose. Examples include a method for forming metal protrusions containing a metal material on a metal layer (Embodiment 1-1); a method for forming metal protrusions on a metal layer by plating (Embodiment 1-2); and a method for cutting out a metal layer integrally having metal protrusions by etching a metal plate (Embodiment 1-3).

[0044] The composition containing the low-temperature sintered material may further contain a low-temperature sintered material and, if necessary, a resin, a curing agent, a solvent, etc. Each component can be appropriately selected from those described as low-temperature sintered materials for thermal conductive sheets.

[0045] There are no particular limitations on the method for imparting a composition containing a low-temperature sintered material, and a suitable method can be selected depending on the purpose. Examples include methods for imparting a composition having a desired pattern by imprinting; methods for imparting a composition having a desired pattern by inkjet, screen printing, etc.; and methods for imparting a composition having a desired pattern by resist.

[0046] After applying a composition containing a low-temperature sintered material, if the composition contains a solvent, a solvent removal treatment may be performed, and if the composition contains a curable material and a curing agent, a curing treatment may be performed. Alternatively, these treatments may be performed simultaneously with the sintering treatment of the low-temperature sintered material.

[0047] [Second Embodiment] The method for manufacturing a heat conductive sheet in the second embodiment includes the steps of applying the low-temperature sintered material to at least a first surface of a metal plate, and etching the exposed surface of the metal plate to which the low-temperature sintered material is not applied to form the metal layer and the plurality of metal protrusions, and further including other steps as necessary.

[0048] Figures 8 to 10 show schematic cross-sectional views illustrating an example of the process for manufacturing a thermal conductive sheet according to the second embodiment. First, a metal plate 11', which will serve as a precursor for the metal portion 11, is prepared, and a low-temperature sintered material 13 having etching resistance is applied to the metal plate 11' in a desired pattern (Figures 8 to 9). For example, the low-temperature sintered material 13 having the desired pattern can be applied by physical vapor deposition (PVD), such as sputtering or vapor deposition, via a mask 21 having the desired pattern. Next, areas where the low-temperature sintered material 13 has not been applied to the metal plate 11' are removed by etching. This makes it possible to manufacture a thermal conductive sheet 10 that integrally has a metal layer 11 and metal protrusions 12 on the first and second surfaces of the metal layer 11, and further has the low-temperature sintered material 13 on each metal protrusion 12 (Figure 10).

[0049] Alternatively, instead of the etching-resistant low-temperature sintered material 13, a protective part such as a resist may be provided to form a metal layer integrally with metal protrusions, and this can be used in the manufacturing process of the first embodiment (the first to third embodiments).

[0050] [Third Embodiment] The method for manufacturing a heat conductive sheet in the third embodiment includes the steps of: preparing a mold having a plurality of recesses corresponding to the plurality of metal protrusions; applying the low-temperature sintered material to the bottom surface of each recess; plating the low-temperature sintered material as a plating seed to form the plurality of metal protrusions; and sintering and joining the plurality of metal protrusions and the metal layer, and further including other steps as necessary.

[0051] Figures 11 to 14 show schematic cross-sectional views illustrating an example of the process for manufacturing a heat conductive sheet according to the third embodiment. First, a recess mold 22 having a plurality of recesses corresponding to a plurality of metal protrusions 12 is prepared. As shown in Figures 11 to 14, in the case of manufacturing a heat conductive sheet 10 having a plurality of metal protrusions 12 and a low-temperature sintered material 13 on both the first surface and the second surface, a pair of recess molds 22 are prepared, one for the first surface and one for the second surface. For the recess mold 22, a material with plating resistance, such as plastic, can be used. Next, the low-temperature sintered material 13 is applied to the bottom surface of each recess of the recess mold 22 (Figure 11). For example, the low-temperature sintered material 13 can be applied to the bottom surface of each recess by physical vapor deposition (PVD), such as sputtering or vapor deposition, via a mask 21 having a pattern corresponding to the bottom surface of each recess of the recess mold 22.

[0052] The low-temperature sintered material 13 applied to the bottom surface of each recess is used as a plating seed, and electroless plating (chemical plating), electrolytic plating, or other plating methods are performed to form multiple metal protrusions 12 (Figure 12). The multiple formed metal protrusions 12 are then arranged on the first and second surfaces of the metal layer 11, respectively, and stacked (Figure 13). The multiple metal protrusions 12 and the metal layer 11 are then joined by sintering at a high temperature. This makes it possible to manufacture a heat-conductive sheet 10 having a metal layer 11, metal protrusions 12 on the first and second surfaces of the metal layer 11, and low-temperature sintered material 13 on the metal protrusions 12 (Figure 14).

[0053] The aforementioned plating can be either electrolytic plating or electroless plating (chemical plating), but electrolytic plating is preferred from the viewpoint of throughput. There are no particular restrictions on the metal to be filled by the plating and it can be appropriately selected according to the purpose, but it is preferable that it be at least one of nickel, gold, silver, and copper.

[0054] <Polishing Process> The process may also include a polishing process to polish the surface of the low-temperature sintered material in the thermal conductive sheet. There are no particular restrictions on the method of polishing the surface of the low-temperature sintered material, and known methods can be appropriately selected according to the purpose. By polishing the surface, the metal protrusions and the low-temperature sintered material are exposed on the surface of the obtained thermal conductive sheet, resulting in excellent adhesion to the substrate and / or opposing substrate, as well as excellent reliability and conductivity of the thermal conductive sheet.

[0055] (Laminate) The laminate of this embodiment comprises a base material and an opposing base material, and a thermal conductive sheet of this embodiment sandwiched between the base material and the opposing base material. In one embodiment, in order to further improve adhesion, it is preferable that the laminate further comprises a cured product of a filler filled between the plurality of metal protrusions.

[0056] - Substrate - There are no particular restrictions on the shape, structure, size, material, etc., of the substrate, and it can be appropriately selected according to the purpose. Examples of the substrate shape include plate-like and sheet-like shapes. Examples of the substrate structure include single-layer structure and laminated structure. The size of the substrate can be appropriately selected according to the application, etc.

[0057] Suitable materials for the substrate include, for example, silicon, aluminum, tungsten, molybdenum, glass, molding resin, stainless steel, and ceramics. Examples of ceramics include aluminum nitride, silicon carbide, alumina, and gallium nitride. Examples of molding resins include epoxy resin, silicone resin, urethane resin, and acrylic resin. The substrate is preferably a silicon substrate.

[0058] The average thickness of the substrate is not particularly limited and can be appropriately selected depending on the purpose. The substrate may also be the heat-generating element (electronic component) itself in the heat dissipation structure.

[0059] - Opposing Substrate - The opposing substrate is positioned opposite the substrate, and there are no particular restrictions on its shape, structure, size, material, etc., and it can be appropriately selected according to the purpose. Examples of the shape of the opposing substrate include plate-like and sheet-like shapes. Examples of the structure of the opposing substrate include single-layer structures and laminated structures. The size of the opposing substrate can be appropriately selected according to the application, etc. The material of the opposing substrate is a material that is easily wetted by solder, and includes at least one selected from copper, gold, platinum, palladium, silver, zinc, iron, tin, nickel, magnesium, indium, and alloys thereof. There are no particular restrictions on the average thickness of the opposing substrate and it can be appropriately selected according to the purpose. The opposing substrate may be the heat spreader itself in the heat dissipation structure.

[0060] - Filler - The filler is not particularly limited as long as it has curability and adhesive properties, and can be appropriately selected according to the purpose, but it is preferable that it contains a curable material, and further, if necessary, it contains a curing agent, filler, and other components.

[0061] --Curable Material-- There are no particular restrictions on the curable material, and it can be appropriately selected according to the purpose, but curable silicone, curable epoxy resin, curable polyurethane resin, and curable polyester resin are preferred examples. These may be used individually or in combination of two or more.

[0062] Examples of curable silicones include silicones having epoxy groups (glycidoxy groups), silicones having acryloyl groups (methacryloyl groups), and silicones having hydrosilyl groups and vinyl groups. Examples of curable epoxy resins include glycidyl ether type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, trisphenol type epoxy resins, tetraphenol type epoxy resins, phenol-xylylene type epoxy resins, naphthol-xylylene type epoxy resins, phenol-naphthol type epoxy resins, phenol-dicyclopentadiene type epoxy resins, alicyclic epoxy resins, and aliphatic epoxy resins. Examples of curable polyurethane resins include polyurethanes having acryloyl groups, polyurethanes having methacryloyl groups, urethane prepolymers containing terminal isocyanate groups, and epoxy-modified polyurethanes. Examples of curable polyester resins include polyesters having acryloyl groups, polyesters having methacryloyl groups, and epoxy-modified polyesters.

[0063] --Curing Agent-- The curing agent is a curing agent corresponding to the curable material, and examples include polyfunctional carboxylic acids, acid anhydride curing agents, aliphatic amine curing agents, aromatic amine curing agents (e.g., imidazole curing agents), phenol curing agents, mercaptan curing agents, and other polyaddition curing agents, as well as catalytic curing agents such as imidazole. These may be used individually or in combination of two or more.

[0064] --Filler-- The filler may further contain a filler. Examples of the filler include metal powder, alloy powder, metal oxide, ceramic powder, and carbon powder. These may be used individually or in combination of two or more. There are no particular restrictions on the shape of the filler, and it can be appropriately selected according to the purpose, for example, spherical, flattened, granular, needle-shaped, etc.

[0065] When the filler contains the filler, there are no particular restrictions on the filler content in the filler, and it can be appropriately selected according to the purpose. However, from the viewpoint of improving mechanical strength, heat resistance, and thermal conductivity without impairing the adhesiveness of the filler, it is preferable that the content is greater than 0 vol% and 90 vol% or less, more preferably 40 vol% to 80 vol% or less, and even more preferably 50 vol% to 70 vol% or less.

[0066] The volume-average particle size of the filler is preferably 0.3 μm or more and 30 μm or less, and more preferably 0.5 μm or more and 10 μm or less. The volume-average particle size can be measured, for example, by a laser diffraction / scattering particle size distribution analyzer (Microtrac MT3300EXII).

[0067] --Other Ingredients-- There are no particular restrictions on other ingredients, and they can be selected as appropriate depending on the purpose. Examples include antioxidants.

[0068] (Method for manufacturing the laminate) The method for manufacturing the laminate of this embodiment preferably includes a step of heating the heat conductive sheet of this embodiment described above by sandwiching it between a base material and an opposing base material, and a step of filling a filler between the plurality of metal protrusions and curing it (filler curing step).

[0069] <Heating Process> The heating process involves sandwiching the heat-conducting sheet of this embodiment between the base material and the opposing base material and heating it. This allows the heat-conducting sheet and the base material, and the heat-conducting sheet and the opposing base material, to be joined in a state where the stress is relieved.

[0070] The method of heating by sandwiching a heat conductive sheet between a substrate and an opposing substrate is not particularly limited as long as the substrate and the opposing substrate can be joined via the heat conductive sheet to form a heat conduction network, and can be appropriately selected according to the purpose. However, it is preferable to carry out the method at 350°C or below and under a pressure of 20 MPa or below.

[0071] <Filler curing process> The filler curing process is a process of filling and curing a filler between at least one of the substrate and the opposing substrate and the plurality of metal protrusions. This makes it possible to further improve the adhesion between the heat conductive sheet and the substrate, and / or between the heat conductive sheet and the opposing substrate, which are joined in a state where stress has been relieved in the heating process.

[0072] - Heat Dissipation Structure - The laminate of this embodiment is preferably a heat dissipation structure. The heat dissipation structure preferably comprises a heating element as a base material, a heat dissipation member as an opposing base material, a heat conductive sheet sandwiched between the base material and the opposing base material and having a metal layer and a plurality of metal protrusions on at least a first surface of the metal layer, and a cured product of a filler filled between the plurality of metal protrusions, and further optionally having other members. The heat dissipation structure has the heat conductive sheet between the heating element and the heat dissipation member. The heat dissipation structure may further have adhesive layers between each component as needed.

[0073] There are no particular restrictions on the heat-generating element, and it can be appropriately selected depending on the purpose. Examples include electronic components such as CPUs (Central Processing Units), MPUs (Micro Processing Units), and GPUs (Graphics Processing Units).

[0074] The heat dissipation member is not particularly limited as long as it is a structure that dissipates the heat generated by the electronic component (heat-generating element), and can be appropriately selected according to the purpose. Examples include heat spreaders, heat sinks, vapor chambers, and heat pipes. The heat spreader is a member for efficiently transferring the heat of the electronic component to other components. The material of the heat spreader is not particularly limited and can be appropriately selected according to the purpose. Examples include copper and aluminum. The heat spreader is usually in the shape of a flat plate. The heat sink is a member for releasing the heat of the electronic component into the air. The material of the heat sink is not particularly limited and can be appropriately selected according to the purpose. Examples include copper and aluminum. The heat sink has, for example, a plurality of fins. The heat sink has, for example, a base portion and a plurality of fins provided so as to extend in a non-parallel direction (for example, a perpendicular direction) with respect to one surface of the base portion. The heat spreader and the heat sink are generally solid structures with no internal space. The vapor chamber is a hollow structure. A volatile liquid is sealed inside the hollow structure. Examples of the vapor chamber include a hollow heat spreader, a hollow heat sink, or a plate-shaped hollow structure. The heat pipe is a cylindrical, substantially cylindrical, or flattened cylindrical hollow structure. A volatile liquid is sealed inside the hollow structure.

[0075] Here, Figure 17 is a schematic cross-sectional view showing an example of a semiconductor device as a heat dissipation structure. The thermal conductive sheet 7 in this embodiment dissipates heat generated by electronic components 3 such as semiconductor elements, and as shown in Figure 17, it is fixed to the main surface 2a of the heat spreader 2 that faces the electronic components 3, and is sandwiched between the electronic components 3 and the heat spreader 2. The thermal conductive sheet 1 is sandwiched between the heat spreader 2 and the heat sink 5. The thermal conductive sheet 1 may be the thermal conductive sheet of this embodiment, or it may be any other thermal conductive sheet.

[0076] The heat spreader 2 is formed, for example, in the shape of a rectangular plate and has a main surface 2a facing the electronic component 3 and side walls 2b erected along the outer circumference of the main surface 2a. The heat spreader 2 has a heat conductive sheet 1 provided on the main surface 2a surrounded by the side walls 2b, and a heat sink 5 is provided on the other surface 2c opposite to the main surface 2a via the heat conductive sheet 1. The higher the thermal conductivity of the heat spreader 2, the lower the thermal resistance and the more efficiently it absorbs heat from the electronic component 3 such as a semiconductor element. For example, it can be formed using copper or aluminum, which have good thermal conductivity.

[0077] The electronic component 3 is, for example, a semiconductor element such as a BGA, and is mounted on the wiring board 6. The heat spreader 2 also has the leading edge of its side wall 2b mounted on the wiring board 6, thereby surrounding the electronic component 3 at a predetermined distance by the side wall 2b. The heat conductive sheet 7 of this embodiment is provided on the main surface 2a of the heat spreader 2, forming a heat dissipation member that absorbs the heat emitted by the electronic component 3 and dissipates the heat from the heat sink 5.

[0078] The present invention will be described more specifically below based on examples, but the present invention is not limited to the following examples.

[0079] (Example 1) <Manufacturing of Thermal Conductive Sheet> A thermal conductive sheet of Example 1 having the metal protrusions and low-temperature sintered material patterns shown in Figures 1-2 was manufactured according to the manufacturing method shown in Figures 6-7 and 10-11, by following the procedure below.

[0080] <<Manufacturing of a metal layer with a pattern of metal protrusions>> On both sides of a copper plate (size: 20 mm x 20 mm, average thickness 40 μm, see Figure 6) used as a metal layer, etching resist X-87 (manufactured by Taiyo Ink Manufacturing Co., Ltd.) was screen printed to an average thickness of 9 μm as a coating liquid for forming a protective layer in the area corresponding to the negative pattern of the metal protrusion pattern shown in Figure 3, and the protective layer was formed by heating at 100°C for 5 minutes. In the metal protrusion pattern (45° staggered) shown in Figure 3, the metal protrusions were made into a pattern of multiple circles with a diameter of 100 μm, and by adjusting the pitch (distance between centers) of adjacent metal protrusions, the area ratio of the metal protrusions, i.e., the area ratio of multiple metal protrusions to each surface of the heat conductive sheet, was set to 80%.

[0081] The metal plate with the protective layer formed was plated using a nickel sulfamate bath under the following conditions: 50°C, pH 4.5, 10 mA / cm². ２ Plating was performed to form metal protrusions with an average thickness of 30 μm. Next, the protective layer was removed by immersion in 3% NaOH at 40°C for 15 seconds to fabricate a structure having metal protrusions on both sides of the metal layer (see Figure 6).

[0082] <<Preparation of Composition Containing Low-Temperature Sintered Material>> 20 parts by mass of partially hydrolyzed methyl silicate (Colcoat N-103X, manufactured by Colcoat Co., Ltd.) were added to 20 parts by mass of silver nanowire particles (T-YP808, manufactured by Seikoh PMC Co., Ltd., solid content 0.5% by mass), and the mixture was uniformly mixed using a stirring device (Awatori Rentaro Automatic Revolving Mixer, manufactured by Thinky Co., Ltd.) to prepare a composition containing low-temperature sintered material.

[0083] <<Manufacturing of Thermal Conductive Sheet>> Using an inkjet coating machine equipped with the obtained composition, the composition is directly applied to each metal protrusion of the fabricated structure, and N2 is saturated with 5% by mass formic acid. ２ A heat-conductive sheet of Example 1, having a low-temperature sintered material on a metal protrusion, was fabricated by heat treatment at 150°C for 5 minutes under atmospheric conditions (see Figures 1-2 and 7).

[0084] <Manufacturing of Laminate> As the base material, a silicon chip (size: 20 mm x 20 mm, average thickness 0.6 mm) having a copper layer on the contact surface side with the thermal conductive sheet was used. In addition, the copper layer of the base material was pre-saturated with formic acid. ２ The treatment was carried out at 150°C for 10 minutes under atmospheric conditions. In addition, N saturated with formic acid was used as the counter substrate. ２ A copper plate (size: 30 mm x 30 mm, average thickness 0.1 mm) treated at 150°C for 10 minutes under atmospheric conditions was used. The fabricated heat conductive sheet was sandwiched between the base material and the opposing base material, and N2 saturated with formic acid was used. ２ After processing at 150°C for 10 minutes under atmospheric conditions, it was lightly pressed with tweezers. The resulting laminate was set in a vacuum high-pressure press (manufactured by Meisho Kiko Co., Ltd.) and saturated with formic acid. ２ A heating process was carried out at 350°C for 5 minutes under atmospheric conditions and under a pressure of 20 MPa. This produced the laminate of Example 1 in which the copper plate and silicon chip were joined by sintering via a thermal conductive sheet (see Figure 15).

[0085] (Example 2) The laminate of Example 2 was manufactured in the same manner as in Example 1, except that the space between the metal protrusions was filled with a filler in the laminate of Example 1 by the following filler filling step (see Figure 16).

[0086] <<Preparation of Filling Material>> Dimethyldimethoxysilane (500 g) and 3-glycidoxypropylmethyldimethoxysilane (100 g) were placed in a separable flask equipped with a 1000 mL thermometer and dropping funnel, and stirred at 50°C. An aqueous solution of potassium hydroxide (1.3 g) dissolved in water (165 g) was slowly added dropwise, and after the addition was complete, the mixture was stirred at 50°C for 6 hours. Acetic acid (1.4 g) was added, and volatile components were removed under reduced pressure. The potassium acetate was filtered to obtain the polymer. The obtained polymer was washed with hexane and water, and volatile components were removed under reduced pressure to obtain polymer A.

[0087] The polymer A (100g) obtained above, Ricasid MH-700G (acid anhydride, manufactured by Shin Nippon Rika Co., Ltd., 25g), U-CAT SA 102 (curing accelerator, manufactured by Sunapro Co., Ltd., 0.5g), HOSTANOX O16 (phenolic antioxidant, manufactured by Clariant, 0.5g), and Adeka Stab 3010 (phosphorus antioxidant, manufactured by ADEKA Corporation, 0.5g) were added, mixed, and degassed to obtain a filler.

[0088] <<Filler Filling Process>> The obtained joint was fixed in a cup with a sample clip, and the filler obtained above was poured in until the space formed between the base material and the metal protrusions of the thermal conductive sheet, and the space formed between the opposing base material and the metal protrusions of the thermal conductive sheet were filled. The joint was then left to stand in a vacuum desiccator and degassed for 1 minute to fill the filler. After that, the degassed joint was cured at 100°C for 3 hours, followed by curing at 130°C for 3 hours to produce the laminate of Example 2.

[0089] (Example 3) The thermal conductive sheet and laminate of Example 3 were manufactured in the same manner as in Example 2, except that the area ratio of the metal protrusions in the thermal conductive sheet was changed from 80% to 50%.

[0090] (Example 4) The thermal conductive sheet and laminate of Example 4 were manufactured in the same manner as in Example 2, except that the area ratio of the metal protrusions in the thermal conductive sheet was changed from 80% to 20%.

[0091] (Comparative Example 1) A thermal conductive sheet and a laminate of Comparative Example 1 were manufactured in the same manner as in Example 1, except that a low-temperature sintering material was not applied to the metal protrusions of the thermal conductive sheet.

[0092] (Comparative Example 2) The thermal conductive sheet and laminate of Comparative Example 2 were manufactured in the same manner as in Example 2, except that the area ratio of the metal protrusions in the thermal conductive sheet was changed to 10%.

[0093] (Comparative Example 3) A copper plate with an average thickness of 100 μm (size: 20 mm x 20 mm) was used as the thermal conductive sheet in Comparative Example 3. That is, the thermal conductive sheet and laminate of Comparative Example 3 were manufactured in the same manner as in Example 1, except that the area ratio of the metal protrusions on the thermal conductive sheet was set to 100%, and the low-temperature sintered material was not applied to the metal protrusions.

[0094] <Evaluation> The obtained thermal conductive sheets and laminates were evaluated for "thermal conductivity," "adhesion," and "mechanical strength" as follows. The results are shown in Table 1.

[0095] <Thermal Conductivity> In accordance with JIS R 1611, the thermal resistance of each laminate was measured using a Netsch flash method thermal diffusivity / thermal conductivity measuring device (LFA467, manufactured by Netsch-Gereitebau) under conditions of a pulse width of 20 μsec. Next, the thermal resistance of the thermal conductive sheet was calculated by subtracting the thermal resistance of the silicon chip with a copper layer (the base material) and the copper plate with titanium plating and nickel plating applied in that order (the opposing base material) from the measured values. Then, the thermal conductivity W / (m·K) of the thermal conductive sheet was calculated by dividing the average thickness of the thermal conductive sheet measured in advance by the thermal resistance. The thermal conductivity was evaluated according to the following criteria. The results are shown in Table 1. [Evaluation Criteria] ◎: Thermal conductivity is 80 W / m·K or higher. ○: Thermal conductivity is 60 W / m·K or higher and less than 80 W / m·K. △: Thermal conductivity is 10 W / m·K or higher and less than 60 W / m·K. ×: The thermal conductivity is less than 10 W / m·K.

[0096] <Adhesion> The obtained laminate was sandwiched between a copper plate (size: 25 mm x 25 mm) and a silicon plate (size: 20 mm x 20 mm). A mini press was used to heat and press the laminate for 5 minutes under the conditions of an upper plate temperature of 160°C, a lower plate temperature of 160°C, and a pressure of 10 psi to obtain the initial state laminate. A 50 MHz, 7 mm probe was used on the copper plate side, and a 25 MHz probe was used on the silicon plate side. The adhesion of the initial state laminate was observed using an ultrasonic imaging device (FineSAT III, manufactured by Hitachi High-Tech Corporation).

[0097] <<Temperature Cycling Test and Evaluation>> Next, the laminate in its initial state was placed in a thermal shock test apparatus (apparatus name: TSA-73EL-A, manufactured by ESPEC Corporation), and a temperature cycling test was performed by repeating -40°C for 30 minutes and 120°C for 30 minutes for 250 cycles. After the temperature cycling test, the adhesion of the laminate was observed. The adhesion was evaluated based on a comparison of the observation results and the following evaluation criteria. The results are shown in Table 1.

[0098] [Evaluation Criteria] ◎: The change in void space is extremely small, with a change rate of 5% or less compared to the initial state. ○: The change in void space is small, with a change rate of more than 5% but 20% or less compared to the initial state. △: There is a change in void space, with a change rate of more than 20% but 50% or less compared to the initial state, which is within the practical range. ×: There is a change in void space, with a change rate of 50% or more compared to the initial state, which is outside the practical range.

[0099] <Mechanical Strength> The adhesive strength of each laminate was measured using a measuring device (Die Shear Tester 4000, Nordson DAGE). As die shear strength, the silicon plate was pressed horizontally from the side with a shear tool, and the adhesive strength at which the joint surface between the silicon plate and the copper plate broke was measured. The movement speed of the shear tool was set to 100 μm / second. Mechanical strength was evaluated based on the following evaluation criteria. The results are shown in Table 1.

[0100] [Evaluation Criteria] ○: Die shear strength is 1000 N / silicon plate or higher. △: Die shear strength is 500 N / silicon plate or higher but less than 1000 N / silicon plate, which is within the practical range. ×: Die shear strength is less than 500 N / silicon plate, which is outside the practical range.

[0101]

[0102] This application claims priority based on Japanese Patent Application No. 2024-172494, filed on 1 October 2024, and incorporates into this International Application by reference to the entire contents of Japanese Patent Application No. 2024-172494.

[0103] 1 Thermal conductive sheet 2 Heat spreader 2a Main surface 3 Heating element (electronic component) 3a Top surface 5 Heat sink 6 Wiring board 7 Thermal conductive sheet 10 Thermal conductive sheet 11 Metal layer 11' Metal plate before etching 12 Metal protrusion 13 Low-temperature sintered material 14 Filler 15 Substrate 16 Opposing substrate 21 Mask 22 Recessed mold 100 Laminate c Center p Periphery

Claims

1. A thermal conductive sheet comprising a metal layer, a plurality of metal protrusions on at least a first surface of the metal layer, and a low-temperature sintered material on the metal protrusions, wherein the area ratio of the plurality of metal protrusions to the first surface is 20% or more and 80% or less.

2. The thermal conductive sheet according to claim 1, further comprising a plurality of metal protrusions on a second surface opposite to the first surface of the metal layer, and a low-temperature sintered material on the metal protrusions, wherein the area ratio of the plurality of metal protrusions to the second surface is 20% or more and 80% or less.

3. The thermal conductive sheet according to claim 1 or 2, wherein the low-temperature sintered material is at least one of gold, silver, and nickel.

4. Average thickness of the metal layer (T Ｍ The average thickness (T) of the metal protrusion relative to ) ｍ ) ratio (T ｍ / T Ｍ A thermal conductive sheet according to any one of claims 1 to 3, wherein the ratio is 0.2 or more and 4 or less.

5. A thermal conductive sheet according to any one of claims 1 to 4, wherein the thermal conductivity is 50 W / (m·K) or higher.

6. The thermal conductive sheet according to any one of claims 1 to 5, wherein the metal layer comprises at least one of gold, silver, copper, and aluminum.

7. A thermal conductive sheet according to any one of claims 1 to 6, wherein the contact area of ​​the metal protrusion having half the area of ​​the first surface and positioned at the center of the centroid of the planar shape of the first surface is Ac, and the contact area of ​​the metal protrusion positioned at the peripheral part of the first surface other than the central part is Ap, and the value obtained by dividing Ac by Ap (Ac / Ap) is 1.2 or more and 10 or less.

8. A method for manufacturing a thermal conductive sheet according to any one of claims 1 to 7, characterized by comprising the step of applying a composition containing the low-temperature sintered material onto the metal protrusions in the metal layer having the metal protrusions.

9. A method for manufacturing a thermal conductive sheet according to any one of claims 1 to 7, comprising the steps of: applying the low-temperature sintered material to at least a first surface of a metal plate; and etching the exposed surface of the metal plate to which the low-temperature sintered material is not applied to form the metal layer and the plurality of metal protrusions.

10. A method for manufacturing a heat conductive sheet according to any one of claims 1 to 7, comprising the steps of: preparing a mold having a plurality of recesses corresponding to the plurality of metal protrusions, and applying the low-temperature sintered material to the bottom surface of each recess; plating the low-temperature sintered material as a plating seed to form the plurality of metal protrusions; and sintering and joining the plurality of metal protrusions and the metal layer.

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