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

Abstract

To provide a thermal conductive sheet that can relieve stress while achieving both reliability and high thermal conductivity. [Solution] 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.

Description

[Technical Field]

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

[0002] With the miniaturization of electronic devices such as power modules, image sensors, and high-performance computing (HPC), and the increase in information processing load, heat generation problems are becoming more pronounced, and the importance of heat dissipation from heat sources is increasing. In various electronic devices, LSIs and other components can malfunction or fail if they are exposed to high temperatures for extended periods due to heat generated by the elements used. For this reason, thermal conductive materials are widely used to prevent LSIs and other components from overheating. These thermal conductive materials can prevent the device from overheating by diffusing the heat generated by the elements or by transferring it to a heat dissipation component that releases it to the atmosphere or other external environment.

[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. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-038748 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, the conventional thermal conductive sheet described in Patent Document 1 has a problem in 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 a problem in that it cannot relieve stress in response to the applied pressure, resulting in poor reliability.

[0006] The present invention aims to solve the aforementioned conventional problems and achieve the following objectives. Specifically, the present invention aims to provide a thermal conductive sheet that can relieve stress and achieve both reliability and high thermal conductivity. <1> Metal layer, A plurality of metal protrusions are provided on at least the first surface of the metal layer, The metal protrusion has a low-temperature sintered material on it, The thermal conductive sheet is characterized in that the area ratio of the plurality of metal protrusions to the first surface is 20% or more and 80% or less. <2> The metal layer further comprises a plurality of metal protrusions on a second surface opposite to the first surface, and a low-temperature sintered material on the metal protrusions. The area ratio of the plurality of metal protrusions to the second surface is 20% or more and 80% or less. <1> This is the thermal conductive sheet described in [reference]. <3> The low-temperature sintered material is at least one of gold, silver, and nickel. <1> or <2> This is the thermal conductive sheet described in [reference]. <4> The average thickness (T) of the aforementioned metal layer M The average thickness (T) of the metal protrusion relative to ) m ) ratio (T m / T M ) is 0.2 or more and 4 or less. <1> from <3> It is a thermal conductive sheet as described in one of the following. <5> The thermal conductivity of the metal layer is 50 W / (m·K) or more. <1> from <4> It is a thermal conductive sheet as described in one of the following. <6> The metal layer comprises at least one of gold, silver, copper, and aluminum. <1> from <5> It is a thermal conductive sheet as described in one of the following. <7> Let Ac be the contact area of ​​the metal protrusion, which has half the area of ​​the first surface and is located at the center of the centroid of the planar shape of the first surface. When Ap is the contact area of ​​the metal protrusions arranged in the peripheral portion of the first surface, which is the portion other than the central portion, The value obtained by dividing Ac by Ap (Ac / Ap) is between 1.2 and 10. <1> from <6> It is a thermal conductive sheet as described in one of the following. <8> The aforementioned <1> from <7> A method for manufacturing a heat conductive sheet as described in any of the following: The method for manufacturing a thermal conductive sheet is characterized by including 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> The aforementioned <1> from <7> A method for manufacturing a heat conductive sheet as described in any of the following: A step of applying the low-temperature sintered material to at least a first surface of a metal plate, A method for manufacturing a thermal conductive sheet, characterized by including the step of etching the exposed surface of the metal plate to which the low-temperature sintering material has not been applied to form the metal layer and the plurality of metal protrusions. <10> The aforementioned <1> from <7> A method for manufacturing a heat conductive sheet as described in any of the following: A step 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, The process of forming the plurality of metal protrusions by plating the low-temperature sintered material as a plating seed, A method for manufacturing a heat conductive sheet, characterized by including a step of sintering and joining the plurality of metal protrusions and the metal layer. [Effects of the Invention]

[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 achieves both reliability and high thermal conductivity. [Brief explanation of the drawing]

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

[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 is a thermal conductive sheet having 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 of the AA' section of 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 AA' 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 the first surface (only one side). The thermal conductive sheet 10 shown in Figure 4 has a metal portion 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 the plan view in 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 between 20% and 80%.

[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 aforementioned metals, and gold, silver, copper, and aluminum are more preferred.

[0015] There are no particular restrictions on the thermal conductivity of the metal layer, and it can be appropriately selected according to the purpose. However, from the viewpoint of thermal conductivity, a value of 50 W / (m·K) or higher is preferred, and 100 W / (m·K) or higher is more preferred. There are no particular restrictions on the thermal conductivity of the aforementioned metal, and it can be appropriately selected according to the purpose. However, from the viewpoint of thermal conductivity, a thermal conductivity of 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 limitations on the aforementioned metal protrusions, and they can be appropriately selected according to the purpose. Examples include metal formed by plating such as electrolytic plating or non-electrolytic plating; a metal material filled with a filler material if necessary; or a metal layer 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 metal formed by the electroplating, and it can be appropriately selected from the metals mentioned above depending on the purpose.

[0017] The aforementioned metal protrusion may be filled with a metal material, or it 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. However, 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 types.

[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> There are no particular limitations on the low-temperature sintered material, and it 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. Furthermore, gold and nickel are preferred as low-temperature sintered materials that have plating seed function and can be used in the manufacturing method of the heat conductive sheet of the third embodiment described later. There are no particular restrictions on the shape of the low-temperature sintered material, and it can be appropriately selected according to the purpose. Examples include spherical, plate-shaped, rod-shaped, and wire-shaped materials. To apply the low-temperature sintering material to the metal protrusions, a paste-like low-temperature sintering material may be used, or a composition containing, for example, a low-temperature sintering material and an optional 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 aforementioned low-temperature sintered material 50 The particle size 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, a network of sintered bodies made of the low-temperature sintered material can be formed when a thermal conductive sheet is sandwiched between the substrate and the opposing substrate and heated, thereby achieving high thermal conductivity and low thermal resistance in a laminate having a substrate, a thermal conductive sheet, and an opposing substrate. The volume average particle diameter (D 50 This can be measured, for example, by 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 greater than 40% by volume and 98% by volume or less, and more preferably 50% by volume or more and 95% by volume or less.

[0024] -resin- The aforementioned resin is not particularly limited and 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 limitations 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, 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] -Hardening agent- The curing agent is a curing agent corresponding to the curable material, and examples include polyaddition curing agents such as polyfunctional carboxylic acids, acid anhydride curing agents, aliphatic amine curing agents, aromatic amine curing agents (e.g., imidazole curing agents), phenol curing agents, and mercaptan curing agents, as well as catalytic curing agents such as imidazole. These can be used individually or in combination of two or more. Among these, aromatic amine-based curing agents are preferred, and imidazole-based 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 curing agent, a solvent, etc. The aforementioned composition may be a commercially available product, for example, a metal paste containing a low-temperature sintering material such as H 9890-6A (manufactured by Namics Corporation, thermosetting conductive adhesive, silver paste).

[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 order to reduce lifting and peeling from the substrate, provide excellent adhesion to the substrate, and offer superior reliability. In an embodiment in which the second surface of the heat conductive sheet has a plurality of metal protrusions and a low-temperature sintered material, the area ratio of the plurality of metal protrusions to the second surface when the second surface of the heat conductive sheet is viewed in plan view is preferably 20% to 80%, and more preferably 30% to 70%, in terms of reducing lifting and peeling from the substrate, having excellent adhesion to the substrate, and having excellent reliability.

[0031] [pattern] The patterns of the metal protrusions 12 and the low-temperature sintered material 13 are not particularly limited as long as they satisfy the aforementioned area ratio, and can be appropriately selected according to the purpose. For example, a pattern in which multiple shapes are arranged can be used. Among these, a pattern in which multiple geometric shapes are arranged regularly is preferred from the viewpoint of uniformity of thermal conductivity. Examples of the aforementioned 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 shape 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] Another configuration of the patterns of the metal protrusions 12 and the low-temperature sintered material 13 is preferable in that, when the heat conductive sheet is viewed in plan, the contact area Ac of the metal protrusions located in the center is larger than the contact area Ap of the metal protrusions located in the periphery, as this can further relieve stress when the heat conductive sheets are joined. Here, as shown by the dashed line in Figure 5, the first surface of the metal layer 11 is divided into two equal-area parts, the central part c and the peripheral part p. The central part c has half the area of ​​the first surface and is the part centered on the centroid of the planar shape of the first surface (inside the rectangle shown by the dashed line in Figure 5), and the peripheral part p is the part of the first surface other than the central part c (outside the rectangle shown by the dashed line in Figure 5). Figure 5 is a plan view illustrating the central part c and the peripheral part p of the heat conductive sheet of this embodiment, and the dashed line in Figure 5 is the boundary line dividing the central part c and the peripheral part p into equal areas. When the contact area of ​​the metal protrusion 12 located in the central part c is Ac, and the contact area of ​​the metal protrusion 12 located in the peripheral part p is Ap, it is preferable that the value obtained by dividing Ac by Ap (Ac / Ap) is 1.2 or more and 10 or less. For example, in the thermal conductive sheet shown in Figure 5, the area in contact with the multiple protrusions is 75% of the central part c of the first surface, and the area in contact with the multiple protrusions is 25% of the peripheral part p of the first surface, so Ac / Ap = 75 / 25 = 3.

[0034] There are no particular restrictions on the thermal conductivity of the thermal conductive sheet, and it can be appropriately selected according to the purpose. However, from the viewpoint of thermal conductivity, a thermal conductivity of 50 W / (m·K) or higher is preferred, 60 W / (m·K) or higher is more preferred, 70 W / (m·K) or higher is even more preferred, and 80 W / (m·K) or higher is particularly preferred.

[0035] There are no particular restrictions on the average thickness of the thermal conductive sheet, and it can be appropriately selected according to the purpose, but it is preferably 10 μm to 200 μm, and more preferably 30 μm to 150 μm.

[0036] The average thickness of the metal layer is not particularly limited and can be appropriately selected according to the purpose, but 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 ratio (T M ) of the average thickness (T m ) of the metal protrusions to the average thickness of the metal layer is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoint 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] In the case of the aspect having metal protrusions on both the first surface and the second surface of the heat conduction sheet, for the metal protrusions 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 adhering to a base material such as a heating element or a heat radiating member and an opposing base material, it is excellent in adhesive strength and mechanical strength after heat treatment (accelerated life test), and therefore, it is excellent in reliability. Since the heat conduction sheet has a metal layer and metal protrusions communicating in the thickness direction and the plane direction of the heat conduction sheet, stress can be relaxed. In addition, the problem that the film itself becomes brittle as in 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 preferably prevented.

[0040] (Method for manufacturing a heat conduction sheet) ​​​​Examples of methods for manufacturing the thermal conductive sheet of this embodiment include: applying a composition containing a low-temperature sintered material onto the metal protrusions in a metal layer having metal protrusions (first embodiment); 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 to a metal plate and etching it (second embodiment); and forming multiple metal protrusions by plating with the low-temperature sintered material as a plating seed, and joining the multiple 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 the 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 5 and 6 show schematic cross-sectional views illustrating an example of the process for manufacturing a thermal conductive sheet according to the first embodiment. First, a metal layer 11 having multiple metal protrusions 12 on a first surface and a second surface (both sides) is prepared (Figure 5). Next, a composition containing a low-temperature sintered material 13 is applied to each metal protrusion 12 (Figure 6). This allows for the manufacture of a heat conductive 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 contain the low-temperature sintered material and, if necessary, also contain a resin, a curing material, 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 8-10 show schematic cross-sectional views illustrating an example of the process for manufacturing a heat 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 with etching resistance is applied to the metal plate 11' in a desired pattern (Figures 8-9). For example, the low-temperature sintered material 13 with 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 (embodiments 1-3).

[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 11-14 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 multiple recesses corresponding to multiple metal protrusions 12 is prepared. As shown in Figures 11-14, in the case of manufacturing a heat conductive sheet 10 having multiple metal protrusions 12 and low-temperature sintered material 13 on both a first surface and a 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 of the recess mold 22 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 used for filling by the aforementioned plating, and it can be appropriately selected depending on the purpose, but it is preferable that it be at least one of nickel, gold, silver, and copper.

[0054] <Polishing process> Other steps may include a polishing step for polishing the surface of the low-temperature sintered material in the heat conductive sheet. There are no particular limitations on the method for polishing the surface of the low-temperature sintered material, and known methods can be appropriately selected depending on the purpose. The polishing process exposes metal protrusions and low-temperature sintered material on the surface of the resulting thermal conductive sheet, resulting in excellent adhesion to the substrate and / or opposing substrate, as well as superior reliability and conductivity of the thermal conductive sheet.

[0055] (Laminated structure) 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 terms of further improving adhesion, it is preferable that the laminate further comprises a cured product of a filler that is filled between the plurality of metal protrusions.

[0056] -Base material- There are no particular restrictions on the shape, structure, size, material, etc., of the aforementioned substrate, and they can be appropriately selected according to the purpose. Examples of the substrate shape include plates and sheets. Examples of the substrate structure include single-layer structures and laminated structures. The size of the substrate can be appropriately selected depending on the application.

[0057] Suitable materials for the substrate include, for example, silicon, aluminum, tungsten, molybdenum, glass, molded resin, stainless steel, and ceramics. Examples of the aforementioned ceramics include aluminum nitride, silicon carbide, alumina, and gallium nitride. Examples of the aforementioned 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 aforementioned substrate is not particularly limited and can be appropriately selected depending on the purpose. The aforementioned substrate may be the heat-generating element (electronic component) itself in the heat dissipation structure.

[0059] -Opposite 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 and laminated structures. The size of the opposing substrate can be appropriately selected depending on the application. 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. The average thickness of the opposing substrate is not particularly limited and can be appropriately selected depending on the purpose. The opposing substrate may be the heat spreader itself in the heat dissipation structure.

[0060] -Filler- The aforementioned 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 may contain a curing agent, filler, or other components.

[0061] --Curable material-- There are no particular limitations 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.

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

[0064] --Filler-- The filler may further contain a filler. Examples of the fillers 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 depending on the purpose. Examples include spherical, flattened, granular, and needle-shaped fillers.

[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-- Other ingredients are not particularly limited and can be selected as appropriate depending on the purpose, such as antioxidants.

[0068] (Method of manufacturing a laminate) The manufacturing method of the laminate according to 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 aforementioned heating step involves sandwiching the heat-conducting sheet of this embodiment between a base material and an opposing base material and heating it. This allows for bonding while relieving stress between the heat-conducting sheet and the base material, and between the heat-conducting sheet and the opposing base material.

[0070] The method of heating by sandwiching a thermal 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 thermal conductive sheet to form a thermal conductive network, and can be appropriately selected according to the purpose. However, it is preferable to carry out the process at 350°C or below and under a pressure of 20 MPa or below.

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

[0072] -Heat dissipation structure- The laminate in 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, if necessary, other members. The heat dissipation structure has the heat conductive sheet between the heat-generating element and the heat dissipation member. The heat dissipation structure may further have adhesive layers between its constituent members, if necessary.

[0073] There are no particular restrictions on the heat-generating element, and it can be appropriately selected according to 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 electronic components (heat-generating elements), 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 component for efficiently transferring heat from the electronic component to other components. There are no particular restrictions on the material of the heat spreader, and it can be appropriately selected according to the purpose, for example, copper, aluminum, etc. The heat spreader is usually in the shape of a flat plate. The heat sink is a component for releasing heat from the electronic component into the air. There are no particular restrictions on the material of the heat sink, and it can be appropriately selected depending on the purpose, for example, copper, aluminum, etc. 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 direction non-parallel to one surface of the base portion (for example, in a direction perpendicular to it). The heat spreader and the heat sink generally have a solid structure 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 hollow structure that is cylindrical, substantially cylindrical, or flattened. 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 thermal 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 thermal 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 electronic components 3 such as semiconductor elements. 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. Furthermore, by providing the heat conductive sheet 7 of this embodiment on the main surface 2a of the heat spreader 2, a heat dissipation member is formed that absorbs the heat emitted by the electronic component 3 and dissipates heat from the heat sink 5. [Examples]

[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 sheets> According to the manufacturing method shown in Figures 6-7 and 10-11, the thermal conductive sheet of Example 1 having the metal protrusions and low-temperature sintered material patterns shown in Figures 1-2 was manufactured by following the procedure below.

[0080] <<Manufacturing of a metal layer having 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 in the area corresponding to the negative pattern of the metal protrusions 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 up 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 thermal 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 with metal protrusions on both sides of the metal layer (see Figure 6).

[0082] <<Preparation of compositions containing low-temperature sintered materials>> A composition containing a low-temperature sintered material was prepared by adding 20 parts by mass of silver nanowire particles (T-YP808, manufactured by Seikoh PMC Co., Ltd., solid content 0.5% by mass) to 20 parts by mass of a partially hydrolyzed methyl silicate (Colcoat N-103X, manufactured by Colcoat Co., Ltd.) and mixing them uniformly using a stirring device (Awatori Rentaro Automatic Revolving Mixer, manufactured by Shinky Co., Ltd.).

[0083] <<Manufacturing of thermal conductive sheets>> Using an inkjet coating machine equipped with the obtained composition, the composition was directly applied to each metal protrusion of the fabricated structure. The composition was then heat-treated at 150°C for 5 minutes in an N2 atmosphere saturated with 5% by mass formic acid to produce a thermal conductive sheet of Example 1 having a low-temperature sintered material on the metal protrusions (see Figures 1-2, 7).

[0084] <Manufacturing of laminates> As the base material, a silicon chip (size: 20mm x 20mm, average thickness 0.6mm) with a copper layer on the contact surface with the thermal conductive sheet was used. The copper layer of the base material was pre-treated at 150°C for 10 minutes in an N2 atmosphere saturated with formic acid. As the opposing base material, a copper plate (size: 30mm x 30mm, average thickness 0.1mm) was used, which had also been treated at 150°C for 10 minutes in an N2 atmosphere saturated with formic acid. The fabricated thermal conductive sheet was sandwiched between the base material and the opposing base material, treated at 150°C for 10 minutes in an N2 atmosphere saturated with formic acid, and then lightly pressed with tweezers. The resulting laminate was placed in a vacuum high-pressure press (manufactured by Meisho Kiko Co., Ltd.), and a heating process was carried out at 350°C for 5 minutes under an N2 atmosphere saturated with formic acid and 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 the 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 filler in the laminate of Example 1 by the following filler filling step (see Figure 16).

[0086] <<Preparation of Filler>> 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, along with Ricacid 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 resulting bond 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 bond was then left to stand in a vacuum desiccator and degassed for 1 minute to fill the filler. After that, the degassed bond was cured at 100°C for 3 hours, followed by 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) The thermal conductive sheet and laminate of Comparative Example 1 were manufactured in the same manner as in Example 1, except that the low-temperature sintered material was not applied to the metal protrusions on 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) For 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. 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] <Rating> 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. 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. ○: The thermal conductivity is 60 W / m·K or higher and less than 80 W / m·K. △: Thermal conductivity is between 10 W / m·K and less than 60 W / m·K. ×: The thermal conductivity is less than 10 W / m·K.

[0096] <Adhesiveness> The resulting laminate was sandwiched between a copper plate (size: 25mm x 25mm) and a silicon plate (size: 20mm x 20mm). 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 50MHz, 7mm probe was used on the copper plate side, and a 25MHz 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), and after a temperature cycling test in which -40°C for 30 minutes and 120°C for 30 minutes were repeated 250 times, the adhesion of the laminate after the temperature cycling test was observed. Adhesion was evaluated based on a comparison of 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 amount of change in void space is small, with a change rate of more than 5% but less than or equal to 20% compared to the initial state. △: There is a change in the void space, but the rate of change is between 20% and 50% compared to the initial state, which is within the practical range. ×: There is a change in the void space, and the rate of change is 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). Die shear strength was measured by pressing the silicon plate 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 fractured was measured. The shear tool's movement speed 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] ○: The die shear strength is 1000N / silicon plate or higher. △: The die shear strength is between 500N / silicon plate and 1000N / silicon plate, which is within the practical range. ×: The die shear strength is less than 500N / silicon sheet, which is outside the practical range.

[0101] [Table 1] [Explanation of symbols]

[0102] 1. Thermal conductive sheet 2 Heat spreader 2a Main surface 3. Heat-generating element (electronic component) 3a Top side 5 Heatsink 6 Wiring board 7. Thermal conductive sheet 10 Thermal conductive sheets 11 Metal layer 11' Metal plate before etching 12 Metal protrusions 13 Low-temperature sintered materials 14 Fillers 15 Base material 16 Opposing substrate 21 masks 22 Recessed type 100-layer structure c center p Peripheral area

Claims

1. Metal layer, A plurality of metal protrusions are provided on at least the first surface of the metal layer, The metal protrusion has a low-temperature sintered material on it, A thermal conductive sheet characterized in that the area ratio of the plurality of metal protrusions to the first surface is 20% or more and 80% or less.

2. The metal layer further has a plurality of metal protrusions on a second surface opposite to the first surface, and a low-temperature sintered material on the metal protrusions. The thermal conductive sheet according to claim 1, 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, 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 The thermal conductive sheet according to claim 1, wherein the ratio is 0.2 or more and 4 or less.

5. The thermal conductive sheet according to claim 1, wherein the thermal conductivity is 50 W / (m·K) or more.

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

7. Let Ac be the contact area of ​​the metal protrusion, which has half the area of ​​the first surface and is located at the center of the centroid of the planar shape of the first surface. When Ap is the contact area of ​​the metal protrusions arranged in the peripheral portion of the first surface, which is the portion other than the central portion, The thermal conductive sheet according to claim 1, wherein 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 claims 1 to 7, A method for manufacturing a thermal conductive sheet, characterized by including 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 claims 1 to 7, A step of applying the low-temperature sintered material to at least a first surface of a metal plate, A method for manufacturing a thermal conductive sheet, characterized by comprising the step of etching the exposed surface of the metal plate to which the low-temperature sintering 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 claims 1 to 7, A step 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, The process of forming the plurality of metal protrusions by plating the low-temperature sintered material as a plating seed, A method for manufacturing a thermal conductive sheet, characterized by including a step of sintering and joining the plurality of metal protrusions and the metal layer.

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