Heat conductive sheet and manufacturing method of heat conductive sheet

Abstract

To provide a heat conductive sheet capable of achieving both of high heat conductivity and reliability.SOLUTION: A heat conductive sheet 10 has: a metal part 11 having a metal layer 11a, and metal convex parts 11b on at least a first surface of the metal layer; and a bonding part 12 on the first surface. An area ratio of the metal convex parts exposed to the first surface of the heat conductive sheet to the first surface is 20% or more and 80% or less, and a ratio (Tm / TM) of an average thickness (Tm) of the metal convex parts to an average thickness (TM) of the metal layer is 0.125 or more and 8 or less.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] With the miniaturization of electronic devices such as power modules, image sensors, and high-performance computing (HPC), and the increase in the amount of information processing, the problem of heat generation has become more prominent, and the importance of heat diffusion from the heat source has increased. In LSIs and the like in various electronic devices, if the LSI itself is exposed to high temperatures for a long time due to the heat generation of the elements used, there is a risk of malfunction or failure. For this reason, heat conduction materials are widely used to prevent the temperature rise of LSIs and the like. The heat conduction material can prevent the temperature rise of the device by diffusing the heat generated by the element or transmitting it to a heat dissipation member for discharging it to the outside of the system such as the atmosphere.

[0003] So far, a heat conduction sheet in which graphite layers containing anisotropic graphite particles are laminated and each graphite layer is bonded by a resin layer has been reported (see, for example, Patent Document 1). Also, a thermally conductive insulating sheet containing a thermally conductive insulating filler and an uncured and / or semi-cured product of a binder resin that is a thermosetting resin and having a thickness of 25 μm or more has been reported (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the thermal conductive sheet described in the conventional Patent Document 1, since the graphite layer has anisotropy and further includes a resin layer, the heat conduction path is limited, resulting in insufficient thermal conductivity and poor adhesion between the graphite and the metal. In addition, the thermal conductive insulating sheet described in the conventional Patent Document 2 has a problem that it has insulating properties and insufficient thermal conductivity.

[0006] An object of the present invention is to solve the above-described conventional problems and achieve the following objects. That is, an object of the present invention is to provide a thermal conductive sheet capable of achieving both high thermal conductivity and reliability.

Means for Solving the Problems

[0007] Means for solving the above problems are as follows. That is, <1> A thermal conductive sheet having a metal layer, and a metal portion having metal protrusions on at least a first surface of the metal layer, and an adhesive portion on the first surface, wherein the area ratio of the metal protrusions exposed on the first surface of the thermal conductive sheet to the first surface is 20% or more and 80% or less, the ratio (T M / T m ) of the average thickness (T m ) of the metal protrusions to the average thickness (T M ) of the metal layer is 0.125 or more and 8 or less. <2> The thermal conductive sheet according to <1>, further having metal protrusions and an adhesive portion on a second surface opposite to the first surface of the metal layer, wherein the area ratio of the metal protrusions exposed on the second surface of the thermal conductive sheet to the second surface is 20% or more and 80% or less. <3> The thermal conductive sheet according to <1> or <2>, wherein the area ratio of the metal portion exposed on the first surface of the thermal conductive sheet to the first surface is 30% or more and 70% or less. <4> The ratio (T M ) of the average thickness (T m ) of the metal protrusions to the average thickness (Tm / T M The thermal conductive sheet according to any one of <1> to <3> above, wherein () is 0.2 or more and 4 or less. <5> The 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> The thermal conductive sheet according to any one of <1> to <5> above, wherein the metal layer contains at least one of gold, silver, copper, aluminum, and nickel. <7> The thermal conductive sheet according to any one of <1> to <6> above, wherein the metal convex portion is a metal formed by electrolytic plating. <8> The thermal conductive sheet according to any one of <1> to <7> above, wherein the adhesive portion contains at least one of a modified acrylate compound, an epoxy resin, an unsaturated polyester resin, a polyurethane resin, a bismaleimide resin, an alkyd resin, a phenol resin, and a melamine resin. <9> A step of providing a protective portion on at least a first surface of the metal layer; A method for manufacturing a thermal conductive sheet, comprising: a step of forming metal convex portions on an exposed surface of the metal layer where the protective portion is not provided. <10> A step of removing the protective portion; The method for manufacturing a thermal conductive sheet according to claim 9, further comprising: a step of filling an adhesive portion on an exposed surface of the metal layer from which the protective portion has been removed. <11> The method for manufacturing a thermal conductive sheet according to <9> or <10> above, wherein the step of providing the protective portion is a step of providing a protective portion on the first surface of the metal layer and a second surface opposite to the first surface.

Advantages of the Invention

[0008] According to the present invention, the above-mentioned various problems in the prior art can be solved, the above-mentioned object can be achieved, and a thermal conductive sheet capable of achieving both high thermal conductivity and reliability can be provided.

Brief Description of the Drawings

[0009]

Figure 1

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Figure 8

Mode for Carrying Out the Invention

[0010] (Heat Conduction Sheet) The heat conduction sheet of the present invention is a heat conduction sheet having a metal layer, a metal part having metal convex portions on at least a first surface of the metal layer, and an adhesive part on the first surface. The area ratio of the metal convex portions exposed on the first surface of the heat conduction sheet to the first surface is 20% or more and 80% or less, and the average thickness (T M ) of the metal convex portions with respect to the average thickness (T m ) of the metal layer, the ratio (T m / T M ) is 0.125 or more and 8 or less. Preferably, the heat conduction sheet further has metal convex portions and an adhesive part on a second surface opposite to the first surface of the metal layer. Here, the area ratio of the metal convex portions exposed on the second surface of the heat conduction sheet to the second surface is 20% or more and 80% or less.

[0011] In the heat conduction sheet of the present embodiment, the metal part communicates in the thickness direction and the plane direction of the heat conduction sheet, and the ratio (T M ) of the average thickness (T m ) of the metal convex portions to the average thickness (T m / T M ) of the metal layer is 8 or less, so that the heat conduction sheet has heat conductivity not only in the thickness direction but also in the plane direction, and has excellent heat conductivity. Further, it has an adhesive part on at least the first surface, the area ratio of the metal convex portions exposed on the first surface of the heat conduction sheet to the first surface is 20% or more and 80% or less, and the ratio (T M ) of the average thickness (T m ) of the metal convex portions to the average thickness (T m / T M ) of the metal layer is 0.125 or more, so that in a laminate in which a heat conduction sheet is provided between base materials such as a heating element and a heat dissipation member, floating, peeling, and void generation from the base material can be reduced, the adhesion to the base material is excellent, and the reliability is excellent. Therefore, by providing a heat conduction sheet between the heating element and the heat dissipation member, heat generated from the heating element can be efficiently dissipated through the heat conduction sheet, and a heat conduction sheet capable of achieving both high heat conductivity and reliability can be provided.

[0012] FIG. 1 and FIG. 2A are a schematic cross-sectional view showing an example of the heat conduction sheet of the present embodiment and a schematic cross-sectional view in the A-A' cross-section thereof. Note that FIG. 1 is a schematic cross-sectional view in the B-B' cross-section of FIG. 2A. The heat conduction sheet 10 shown in FIGS. 1 and 2A has a metal part 11 and an adhesive part 12, and has a mode in which metal convex parts 11b and an adhesive part 12 are provided on both surfaces of the heat conduction sheet 10. The metal part 11 has a metal layer 11a and a plurality of metal convex parts 11b on the first surface of the metal layer 11a and the second surface opposite to the first surface, respectively. The heat conduction sheet 10 has an adhesive part 12 filled in the metal layer 11 except for the portions where the metal convex parts 11b are provided on the first surface and the second surface. As shown in the cross-sectional view of FIG. 1, patterns of the metal convex parts 11b and the adhesive part 12 are formed. The heat conduction sheet 10 has patterns of the metal convex parts 11b and the adhesive part 12 on the first surface and the second surface (each exposed surface) in the same pattern as the cross-sectional view of FIG. 1. The area ratio of the first surface of the metal convex part 11b exposed on the first surface of the heat conduction sheet 10 to the first surface is 20% or more and 80% or less, and the area ratio of the first surface of the metal convex part 11b exposed on the second surface of the heat conduction sheet 10 to the second surface is 20% or more and 80% or less. In each of the first surface and the second surface of the heat conduction sheet 10, the ratio (T M ) of the average thickness (T m ) of the metal convex part 11b to the average thickness (T m / T M ) of the metal layer 11a is 0.125 or more and 8 or less.

[0013] As shown in FIG. 2B, which shows an A-A' cross-sectional view of another example of the heat conduction sheet of the present embodiment, the heat conduction sheet 10 may have a mode in which the metal convex part 11b and the adhesive part 12 are provided on the first surface (only one side). The thermally conductive sheet 10 shown in FIG. 2B has a metal portion 11 and an adhesive portion 12. The metal portion 11 has a metal layer 11a and a plurality of metal protrusions 11b on the first surface of the metal layer 11a. The thermally conductive sheet 10 has adhesive portions 12 that are filled on the first surface of the metal layer 11a except for the portions where the metal protrusions 11b are provided. The pattern of the metal protrusions 11b and the adhesive portions 12 on the cross section in the planar direction of the thermally conductive sheet 10 in FIG. 2B and on the exposed surface is the same as the cross section in FIG. 1. The area ratio of the metal protrusions 11b exposed on the first surface of the thermally conductive sheet 10 to the first surface is 20% or more and 80% or less. In addition, the average thickness (T M ) the average thickness (T m ) ratio (T m / T M ) is greater than or equal to 0.125 and less than or equal to 8.

[0014] <Metal parts> The metal portion has a metal layer and a metal protrusion on at least a first surface of the metal layer. It is preferable that the metal portion has a metal protrusion on each of the first surface and the second surface of the metal layer. The metal portion may be a metal layer having metal protrusions formed by plating or the like, as described in the manufacturing method of the thermal conductive sheet described below, or may be a metal portion cut out by processing a metal plate by edging or the like.

[0015] <<Metal layer>> The material of the metal layer preferably contains a metal with high thermal conductivity, and more preferably consists of the metal. As the metal, from the viewpoints of thermal conductivity and safety, aluminum, nickel, iron, gold, silver, copper, zinc and tin are preferred, and gold, silver, copper, aluminum and nickel are more preferred.

[0016] The thermal conductivity of the metal layer is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoint of thermal conductivity, however, it is preferably 50 W / (m·K) or more, and more preferably 100 W / (m·K) or more. The thermal conductivity of the metal is not particularly limited and can be appropriately selected according to the purpose. From the perspective of thermal conductivity, 50 W / (m·K) or more is preferable, 100 W / (m·K) or more is more preferable, and 200 W / (m·K) or more is even more preferable.

[0017] <<Metal convex portion>> The metal convex portion is not particularly limited and can be appropriately selected according to the purpose. For example, metals formed by plating such as electrolytic plating and electroless plating; those filled with a metal material and a filler as necessary; those made of the same material as the metal layer cut out from a metal plate, etc. can be mentioned. Among these, metals formed by electrolytic plating are preferable. The metal formed by the electrolytic plating is not particularly limited and can be appropriately selected from the above metals according to the purpose.

[0018] The metal convex portion may be filled with a metal material, or may be filled with a mixture of a metal material and a filler which is an optional component. The type of the metal material is not particularly limited and can be appropriately selected according to the purpose. From the perspectives of thermal conductivity and safety, aluminum, aluminum oxide, aluminum nitride, boron nitride, carbon resin, nickel, iron, gold, silver, copper, zinc, tin are preferable, and gold, silver, copper, nickel are more preferable. These may be used alone or in combination of two or more.

[0019] The shape of the metal material is not particularly limited and can be appropriately selected according to the purpose. For example, particles, plate shape, rod shape, wire shape, etc. can be mentioned.

[0020] From the perspective of thermal conductivity, the content of the metal material in the metal convex portion is preferably 50% by mass or more, more preferably any one of 60% by mass or more, 70% by mass or more, and 80% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 99% by mass or more.

[0021] The filling material is not particularly limited and can be appropriately selected according to the purpose. Examples thereof include a dispersant, a surfactant, a binder resin, and the like.

[0022] <<Adhesive part>> The adhesive part is not particularly limited as long as it has adhesiveness and can be appropriately selected according to the purpose. However, it is preferably a resin having adhesiveness. The resin is preferably a polymerized product of a composition containing a curing component, a curing agent, and further containing other components such as a metal filler as required.

[0023] -Resin- The resin is not particularly limited and can be appropriately selected according to the purpose. However, a modified acrylate compound, an epoxy resin, an unsaturated polyester resin, a polyurethane resin, a bismaleimide resin, an alkyd resin, a phenol resin, or a melamine resin is preferable. These may be used alone or in combination of two or more.

[0024] -Curing component- As the curing component, it is preferable to use at least one of an oxirane ring compound and an oxetane compound. The oxirane ring compound is a compound having an oxirane ring, and examples thereof include an epoxy resin. The epoxy resin is not particularly limited and can be appropriately selected according to the purpose. Examples thereof include a glycidyl ether type epoxy resin, a phenol novolac type epoxy resin, a cresol novolac type epoxy resin, a bisphenol A type epoxy resin, a trisphenol type epoxy resin, a tetraphenol type epoxy resin, a phenol-xylylene type epoxy resin, a naphthol-xylylene type epoxy resin, a phenol-naphthol type epoxy resin, a phenol-dicyclopentadiene type epoxy resin, an alicyclic epoxy resin, and an aliphatic epoxy resin. These may be used alone or in combination of two or more.

[0025] - Hardening agent - As the hardening agent, a hardening agent corresponding to the hardening component is used. For example, polyfunctional carboxylic acids, acid anhydride-based hardening agents, aliphatic amine-based hardening agents, aromatic amine-based hardening agents (for example, imidazole-based hardening agents), phenolic hardening agents, mercaptan-based hardening agents, etc., such as polyaddition-type hardening agents, and catalyst-type hardening agents such as imidazole can be mentioned. These may be used alone or in combination of two or more. Among these, aromatic amine-based hardening agents are preferred, and imidazole-based hardening agents are more preferred.

[0026] - Metal filler - The bonding part may further contain a metal filler. As the metal filler, at least one of copper particles, silver-coated particles, and silver particles is preferred, and silver particles are more preferred. Examples of the silver-coated particles include silver-coated copper particles, silver-coated nickel particles, silver-coated aluminum particles, etc. The shape of the metal filler is not particularly limited and can be appropriately selected according to the purpose. For example, spherical, flat, granular, needle-shaped, etc. can be mentioned.

[0027] When the bonding part contains the metal filler, the content of the metal filler in the bonding part is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoint of enhancing the thermal conductivity without impairing the adhesiveness of the bonding part, it is preferably more than 0% by volume and 90% by volume or less, more preferably 40% by volume or more and 80% by volume or less, and still more preferably 50% by volume or more and 70% by volume or less.

[0028] The volume average particle diameter of the metal 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 diameter can be measured, for example, by a laser diffraction / scattering particle size distribution measuring device (Microtrac MT3300EXII).

[0029] [Area ratio] As the area ratio of the metal convex portions exposed on the first surface (exposed surface) of the heat conduction sheet with respect to the first surface of the heat conduction sheet, in terms of being able to reduce floating, peeling, and void generation from the base material, having excellent adhesion to the base material, and having excellent reliability, it is 20% or more and 80% or less, and preferably 30% or more and 70% or less.

[0030] [Pattern] As the pattern of the metal convex portions 11b and the adhesive portions 12, there is no particular limitation as long as the area ratio is satisfied, and it can be appropriately selected according to the purpose. For example, a pattern in which a plurality of figures are arranged can be mentioned. Among these, from the viewpoint of the uniformity of thermal conductivity, a pattern in which a plurality of figures are regularly arranged is preferable. Also, from the viewpoint of improving adhesion, a pattern in which the adhesive portions communicate in the planar direction is more preferable. From the viewpoint of improving thermal conductivity, a pattern in which the metal convex portions communicate in the planar direction is more preferable. Or, a pattern in which both the metal convex portions and the adhesive portions communicate in the planar direction, such as a comb-shaped electrode, may be used. In any case, it can be appropriately selected according to the intended aspect. Examples of the pattern include patterns such as 45° staggered (Figs. 3A - C, Fig. 5F), 60° staggered (Figs. 4A, Fig. 5A), square parallel (Figs. 4B, Fig. 5B), regular hexagon 60° staggered (Figs. 4C, Fig. 5C), equilateral triangle arrangement (Figs. 4D, Fig. 5D), rectangular alternate (Figs. 4E, Fig. 5E), etc., which will be described later.

[0031] With reference to Figs. 3A - E, the pattern and the area ratio of the metal convex portions 11b and the adhesive portions 12 will be described. Figs. 3A - C are schematic cross-sectional views showing another example of the heat conduction sheet of the present embodiment. Figs. 3D - E are schematic cross-sectional views showing an example of the heat conduction sheet of the comparative embodiment. Although it is a cross-sectional view in the planar direction of the heat conduction sheet, the pattern of the exposed surface of the heat conduction sheet is the same. The patterns shown in FIGS. 3A to 3E are patterns in which a plurality of circular metal convex portions 11b are arranged in a 45° direction with respect to each other (a so-called 45° staggered pattern, referred to as "45° staggered"). By appropriately adjusting the distance between the plurality of circles (for example, the distance between the centers of adjacent circles), the area ratio can be adjusted. The patterns shown in FIGS. 3A to 3E are, respectively, metal convex portion:adhesive portion (area ratio) of 80:20, 50:50, 20:80, 90:10, and 10:90, and the area ratio of the metal convex portion is 80%, 50%, 20%, 90%, and 10%. The embodiments of FIGS. 3A to 3C in which the area ratio is in the range of 20% or more and 80% or less respectively correspond to Examples 1 to 3 (and Examples 4 to 6) of the examples described later. Further, the comparative embodiments of FIGS. 3D to 3E in which the area ratio is outside the range of 20% or more and 80% or less respectively correspond to Comparative Examples 1 to 2 of the examples described later.

[0032] With reference to FIGS. 4A to 4E, variations of the patterns of the metal convex portion 11b and the adhesive portion 12 will be described. FIGS. 4A to 4E are schematic cross-sectional views showing another example of the heat conductive sheet of the present embodiment. The pattern shown in FIG. 4A is a pattern in which a plurality of circular metal convex portions 11b are arranged in a 60° direction with respect to each other (referred to as "60° staggered"). The pattern shown in FIG. 4B is a pattern in which a plurality of square metal convex portions 11b are arranged in parallel with each other (arranged in a 90° direction) (referred to as "square parallel"). The pattern shown in FIG. 4C is a pattern in which a plurality of regular hexagonal metal convex portions 11b are arranged in a 60° direction with respect to each other (referred to as "regular hexagon 60° staggered"). The pattern shown in FIG. 4D is a pattern in which a plurality of equilateral triangular metal convex portions 11b are arranged in a 60° direction with respect to each other (referred to as "equilateral triangle arrangement"). The pattern shown in FIG. 4E is a pattern in which a plurality of rectangular metal convex portions 11b are alternately arranged, that is, arranged by shifting by a length of 1 / 2 of the long side in the long side direction of the rectangle (referred to as "rectangle alternate"). The area ratio of the metal protrusions can be adjusted in the same manner as the 45° staggered pattern (Figs. 3A to 3C). Specifically, the area ratio can be adjusted by appropriately adjusting the distance between a plurality of figures (for example, the distance between the centers of adjacent figures).

[0033] As described above, the pattern in which the metal protrusions 11b are arranged as a plurality of figures has been explained. However, the arrangements of the metal protrusions 11b and the adhesive portions 12 are interchanged, and a pattern in which the adhesive portions 12 are arranged as a plurality of figures can be similarly preferably employed. Figs. 5A to 5E and Fig. 5F are schematic cross-sectional views showing another example of the heat conduction sheet of the present embodiment, and are the same as Figs. 4A to 4E and Fig. 3B, respectively, except that the arrangements of the metal protrusions 11b and the adhesive portions 12 are interchanged.

[0034] The size of the figure of the metal protrusion 11b in the pattern is not particularly limited and can be appropriately selected according to the purpose. However, the length of the long 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.

[0035] The thermal conductivity of the heat conduction sheet is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoint of thermal conductivity, it is preferably 20 W / (m·K) or more, more preferably 30 W / (m·K) or more, and still more preferably 50 W / (m·K) or more.

[0036] The average thickness of the heat conduction sheet is not particularly limited and can be appropriately selected according to the purpose. However, it is preferably 0.2 μm or more and 100 μm or less, more preferably 1 μm or more and 50 μm or less, and still more preferably 5 μm or more and 30 μm or less.

[0037] The average thickness of the metal layer is not particularly limited and can be appropriately selected according to the purpose. However, it is preferably 0.1 μm or more and 50 μm or less, more preferably 0.5 μm or more and 25 μm or less, and still more preferably 2.5 μm or more and 20 μm or less.

[0038] The ratio (T M / T m ) of the average thickness (T m ) of the metal protrusions to the average thickness (T M ) of the metal layer is not particularly limited and can be appropriately selected according to the purpose, but it is 0.125 or more and 8 or less. From the viewpoint of further improving thermal conductivity and reliability, 0.2 or more and 4 or less is preferable, and 0.5 or more and 2 or less is more preferable.

[0039] When it is a mode 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.

[0040] By manufacturing the heat conduction sheet by the manufacturing method of the heat conduction sheet described later, a heat conduction sheet having the desired area ratio and the ratio (T m / T M ) can be preferably manufactured. Further, the adhesive portion can be filled in the voids of the metal protrusions without gaps.

[0041] On the other hand, if voids remain in the heat conduction sheet and voids (also referred to as bubbles) are generated, the heat conduction sheet is heated by heat conduction from the heating element, and the voids (bubbles) expand and burst, or cracks occur, which may impair the reliability of the heat conduction sheet. In addition, since the voids (bubbles) have high heat insulation properties, the thermal conductivity of the obtained heat conduction sheet may decrease. Further, in a laminate in which a heat conduction sheet is provided between substrates such as a heating element and a heat radiating member, if floating, peeling from the substrate, or voids occur, the adhesion to the substrate decreases, which may impair the reliability of the heat conduction sheet.

[0042] As a method for confirming that the heat conduction sheet has reliability, there are: a method of evaluating the presence or absence of voids in the heat conduction sheet using an ultrasonic imaging device (SAT) for the laminate after pressure bonding; a method of evaluating the adhesion to the base material and the presence or absence of voids using an ultrasonic imaging device (SAT) for the laminate after pressure bonding after an accelerated life test (for example, at 130 °C and 85% humidity for 192 hours); a method of indirectly estimating the adhesion to the base material and the presence or absence of voids by comparing the ratio (%) of the thermal conductivity of the manufactured heat conduction sheet to the thermal conductivity of the used metal layer; combinations of these methods, etc.

[0043] Since the adhesion part is exposed on the surface of the heat conduction sheet, for example, when adhering to other members such as a heating element or a heat radiating member, it has excellent adhesion and can suppress the generation of voids. Therefore, it also has excellent reliability after heat treatment (accelerated life test). Since the heat conduction sheet has metal parts 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 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 preferably prevented.

[0044] (Method for manufacturing a heat conduction sheet) The method for manufacturing the heat conduction sheet of the present invention is not particularly limited and can be appropriately selected according to the purpose. For example, a method of forming metal convex parts and an adhesion part on a metal layer (first embodiment); a method of cutting out a metal part in which a metal layer and metal convex parts are integrated by edging a metal plate (second embodiment); a method of laminating a layer having previously formed metal convex parts and an adhesion part with a metal layer (third embodiment), etc.

[0045] [First Embodiment] The method for manufacturing the heat conduction sheet in the first embodiment includes a protection part imparting step and a metal convex part forming step, preferably has a protection part removing step and an adhesion part filling step, and further includes other steps such as a polishing step as necessary. The manufacturing method of the heat conduction sheet according to the first embodiment can preferably manufacture the heat conduction sheet of the present invention described above.

[0046] Figs. 6A to 6F show schematic cross-sectional views showing an example of the process of the manufacturing method of the heat conduction sheet according to the first embodiment. This aspect is an aspect in which metal convex portions are formed on the first surface and the second surface (both surfaces) of the metal layer. First, a metal layer 11a is prepared (Fig. 6A), a protective portion 13 is formed on the first surface of the metal layer 11a (Fig. 6B, protective portion applying step), and optionally, a protective portion 13 is also formed on the second surface of the metal layer 11a (Fig. 6C). Next, metal convex portions 11b are formed on the exposed surface of the metal layer 11a where the protective portion 13 is not provided (Fig. 6D, metal convex portion forming step). When the protective portion 13 is the adhesive portion 12, the heat conduction sheet 10 can be manufactured thereby.

[0047] When the protective portion 13 is not the adhesive portion 12, the protective portion 13 is removed (Fig. 6E, protective portion removing step), and a metal layer 11a and a metal portion 11 having metal convex portions 11b on the first surface and the second surface of the metal layer 11a are obtained. Next, the adhesive portion 12 is filled on the exposed surface of the metal layer 11a from which the protective portion 13 has been removed (Fig. 6F, adhesive portion filling step). Thereby, the heat conduction sheet 10 having the metal layer 11a, the metal portion 11 having metal convex portions 11b on the first surface and the second surface of the metal layer 11a, and the adhesive portion 12 on the first surface and the second surface of the metal layer 11a can be manufactured. Hereinafter, each step will be described in detail.

[0048] <Protective portion applying step> The protective portion applying step is a step of applying a protective portion on at least the first surface of the metal layer, and can be preferably carried out by a protective portion applying means. When manufacturing a heat conduction sheet having metal convex portions and an adhesive portion on both surfaces thereof, the protective portion applying step is a step of applying a protective portion on the first surface and the second surface of the metal layer.

[0049] As the pattern of the protective part applied by the protective part application step, it can be the same as the pattern of the adhesive part in the target heat conduction sheet. The protective part may be an adhesive part or a member different from the adhesive part, and can be suitably selected according to the target mode.

[0050] There is no particular limitation on the method of applying the protective part, and it can be appropriately selected according to the purpose. For example, a method of applying a protective part having a desired pattern by imprinting; a method of applying a protective part having a desired pattern by inkjet, screen printing, etc.; a method of forming a protective part having a desired pattern by resist, etc. can be mentioned. As a method of forming a protective part having a desired pattern by the resist, for example, a method of forming a protective part by applying a resist on at least the first surface of a metal layer, exposing and developing it into a desired pattern, and heating it after exposure and / or after development as necessary can be mentioned. The resist may be a negative type in which the exposed part remains after development or a positive type in which the unexposed part remains after development.

[0051] <Metal convex part forming step> The metal convex part forming step is a step of forming metal convex parts on the exposed surface of the metal layer on which the protective part is not applied, and can be suitably carried out by metal convex part forming means. There is no particular limitation on the method of forming metal convex parts, and it can be appropriately selected according to the purpose. For example, a method of forming metal convex parts by plating such as electrolytic plating and electroless plating; a method of forming metal convex parts by filling a composition containing a metal material; a method of forming metal convex parts by sputtering or vapor deposition, etc. can be mentioned. These methods may be carried out once, may be carried out a plurality of times, or may be carried out in combination of a plurality of processes. Regarding matters such as the metal, metal material, filler, etc. in the metal convex part, the matters described in the metal convex part of the heat conduction sheet of the present invention described above can be appropriately selected.

[0052] As the plating, either electrolytic plating or electroless plating (chemical plating) may be used, but from the viewpoint of throughput, electrolytic plating is preferred. The metal to be filled by the plating is not particularly limited and can be appropriately selected according to the purpose, but it preferably contains at least one of nickel, gold, silver, and copper, and more preferably is at least one of nickel, gold, silver, and copper.

[0053] The composition containing the metal material contains the metal material and further contains a filler and a solvent as required. As the content of the metal material in the composition, 50% by mass or more is preferable with respect to the solid content of the composition, more preferably any one of 60% by mass or more, 70% by mass or more, and 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more.

[0054] The solvent is not particularly limited and can be appropriately selected according to the purpose, and examples thereof include terpineol, butyl carbitol, butyl carbitol acetate, and texanol.

[0055] The composition can be prepared by mixing and dispersing the metal material, and further a filler and a solvent as required. As the composition, a commercially available product may be used, and examples thereof include H 9890-6A (manufactured by Namics Corporation, thermosetting conductive adhesive, silver paste) as a metal paste containing metal particles.

[0056] The method for filling the composition into the voids of the metal protrusions in the metal part is not particularly limited and can be appropriately selected according to the purpose, and examples thereof include a dipping method, an inkjet method, a dispensing method, a spray coating method, a slit coating method, and a spin coating method.

[0057] When the protective part is an adhesive part, the heat conduction sheet can be preferably manufactured by the protective part applying step and the metal convex part forming step. Further, if necessary, other steps such as a polishing step may be included. When the protective part is not an adhesive part, it is preferable to further include a protective part removing step and an adhesive part filling step in addition to the protective part applying step and the metal convex part forming step. Further, if necessary, other steps such as a polishing step may be included.

[0058] <Protective part removing step> The protective part removing step is a step of removing the protective part, and can be preferably carried out by protective part removing means. The method for removing the protective part is not particularly limited and can be appropriately selected according to the purpose. For example, methods such as removing the adhesive site by treatment with high-temperature heating, strong alkali, organic solvent, etc. can be mentioned.

[0059] <Adhesive part filling step> The adhesive part filling step is a step of filling an adhesive part on the exposed surface of the metal layer from which the protective part has been removed, and can be preferably carried out by adhesive part filling means. The method for filling the adhesive part is not particularly limited and can be appropriately selected according to the purpose. For example, methods such as dipping method, inkjet method, dispensing method, spray coating method, slit coating method, spin coating method, etc. can be mentioned.

[0060] <Polishing step> The polishing step may be a step of polishing the surface of the metal layer on which the metal convex part is formed following the metal convex part forming step or the protective part removing step, or may be a step of polishing the surface of the metal layer on which the metal convex part and the adhesive part are formed following the metal convex part forming step or the adhesive part filling step. The method for polishing the surface of the metal layer is not particularly limited, and known methods can be appropriately selected according to the purpose.

[0061] Through the polishing process, the metal protrusions and the adhesive parts are exposed on the surface of the obtained heat conduction sheet, so that the heat conduction sheet has excellent adhesion to other members, excellent reliability, and excellent electrical conductivity.

[0062] [Second Embodiment] The manufacturing method of the heat conduction sheet in the second embodiment includes a metal part forming process and an adhesive part filling process, and further includes other processes such as the polishing process as required. The metal part forming process is a process of edging a metal plate to form a metal part having a metal layer and metal protrusions on at least a first surface of the metal layer. The adhesive part filling process is a process of filling an adhesive part on the exposed surface of the metal layer.

[0063] FIGS. 7A to 7C show schematic cross-sectional views illustrating an example of the process of the manufacturing method of the heat conduction sheet according to the second embodiment. This aspect is an aspect of forming metal protrusions on the first surface and the second surface (both surfaces) of the metal layer. First, a metal plate 11' serving as a precursor of the metal part 11 is prepared (FIG. 7A), and a region corresponding to the pattern of the adhesive part 12 is removed from the metal plate 11' by edging to obtain a metal part 11 integrally having a metal layer 11a and metal protrusions 11b on the first surface and the second surface of the metal layer 11a (FIG. 7B, metal part forming process). Next, the adhesive part 12 is filled on the exposed surface of the metal layer 11a (FIG. 7C, adhesive part filling process). Thereby, a heat conduction sheet 10 having a metal layer 11a, a metal part 11 having metal protrusions 11b on the first surface and the second surface of the metal layer 11a, and adhesive parts 12 on the first surface and the second surface of the metal layer 11a can be manufactured.

[0064] [Third Embodiment] The manufacturing method of the heat conduction sheet in the third embodiment preferably includes a process of forming a layer having metal protrusions and an adhesive part, and a process of laminating the obtained layer having metal protrusions and an adhesive part on a metal layer, and further includes other processes such as the polishing process as required.

[0065] (Heat Dissipation Structure) The heat dissipation structure of the present invention includes a heat generating body, the heat conduction sheet of the present invention described above, and a heat dissipation member, and further includes other members as required. The heat dissipation structure has the heat conduction sheet between the heat generating body and the heat dissipation member. The heat dissipation structure may further have an adhesive layer between each component as required.

[0066] There is no particular limitation on the heat generating body, and it can be appropriately selected according to the purpose. For example, electronic components such as a CPU (Central Processing Unit), an MPU (Micro Processing Unit), and a GPU (Graphics Processing Unit) can be mentioned.

[0067] There is no particular limitation on the heat dissipation member as long as it is a structure that dissipates the heat generated by the electronic component (heat generating body), and it can be appropriately selected according to the purpose. For example, a heat spreader, a heat sink, a vapor chamber, a heat pipe, etc. can be mentioned. The heat spreader is a member for efficiently transferring the heat of the electronic component to other components. There is no particular limitation on the material of the heat spreader, and it can be appropriately selected according to the purpose. For example, copper, aluminum, etc. can be mentioned. The heat spreader is usually in a flat plate shape. The heat sink is a member for releasing the heat of the electronic component into the air. There is no particular limitation on the material of the heat sink, and it can be appropriately selected according to the purpose. For example, copper, aluminum, etc. can be mentioned. 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, an orthogonal direction) with respect to one surface of the base portion. The heat spreader and the heat sink generally have a solid structure without a space inside. The vapor chamber is a hollow structure. A volatile liquid is enclosed in the internal space of the hollow structure. Examples of the vapor chamber include those in which the heat spreader has a hollow structure, and plate-shaped hollow structures such as those in which the heat sink has a hollow structure. The heat pipe is a hollow structure in a cylindrical shape, a substantially cylindrical shape, or a flat cylindrical shape. A volatile liquid is enclosed in the internal space of the hollow structure.

[0068] Here, FIG. 8 is a schematic cross-sectional view showing an example of a semiconductor device as a heat dissipation structure. The heat conduction sheet 7 of the present invention dissipates heat generated by an electronic component 3 such as a semiconductor element. As shown in FIG. 5, it is fixed to the main surface 2a of the heat spreader 2 facing the electronic component 3 and is sandwiched between the electronic component 3 and the heat spreader 2. Further, the heat conduction sheet 1 is sandwiched between the heat spreader 2 and the heat sink 5. The heat conduction sheet 1 may be the heat conduction sheet of the present invention or another heat conduction sheet.

[0069] The heat spreader 2 is formed, for example, in a rectangular plate shape and has a main surface 2a facing the electronic component 3 and side walls 2b erected along the outer periphery of the main surface 2a. The heat conduction sheet 1 is provided on the main surface 2a surrounded by the side walls 2b of the heat spreader 2, and the heat sink 5 is provided on the other surface 2c on the side opposite to the main surface 2a via the heat conduction sheet 1. Since the heat spreader 2 has a higher thermal conductivity, the thermal resistance decreases and it can efficiently absorb the heat of the electronic component 3 such as a semiconductor element, so it can be formed using, for example, copper or aluminum with good thermal conductivity.

[0070] The electronic component 3 is, for example, a semiconductor element such as a BGA and is mounted on the wiring board 6. Also, the heat spreader 2 has the tip surface of the side wall 2b mounted on the wiring board 6, and thereby the side wall 2b surrounds the electronic component 3 at a predetermined distance. Then, by providing the heat conduction sheet 7 of the present invention on the main surface 2a of the heat spreader 2, a heat dissipation member is formed that absorbs the heat generated by the electronic component 3 and dissipates heat from the heat sink 5.

Example

[0071] Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to the following examples.

[0072] (Example 1) <Manufacture of heat conduction sheet> According to the manufacturing method shown in FIGS. 6A to 6F, the heat conduction sheet of Example 1 having the patterns of the metal protrusions and the adhesive portions shown in FIG. 3A was manufactured by the following procedure.

[0073] <<Fabrication of metal part>> On both surfaces of a copper plate (size: 20 mm × 20 mm, average thickness 18 μm, FIG. 6A) as a metal layer, in the regions corresponding to the adhesive portions 12 shown in FIG. 3A, an etching resist X-87 (manufactured by Taiyo Ink Manufacturing Co., Ltd.) was screen-printed as a coating liquid for forming a protective portion so as to have an average thickness of 9 μm, and heated at 100° C. for 5 minutes to form a protective portion (FIGS. 6B to 6C). In the pattern (45° staggered) shown in FIG. 3A, the metal protrusions were circular with a diameter of 100 μm, and the area ratio of the metal protrusions, that is, the area ratio of the metal protrusions exposed on each surface of the heat conduction sheet to each surface of the heat conduction sheet was set to 80%.

[0074] On the metal layer with the protective portion formed, nickel sulfamate bath was used for plating conditions: 50° C., pH 4.5, 10 mA / cm 2 to perform plating to form metal protrusions with an average thickness of 9 μm (FIG. 6D). Next, the protective portion was removed by immersion in 3% NaOH at 40° C. for 15 seconds to fabricate a metal part having metal protrusions on both surfaces of the metal layer (FIG. 6E).

[0075] <<Filling of adhesive portion and manufacture of heat conduction sheet>> On each surface of the metal layer in the obtained metal part, between a plurality of metal convex portions, as a coating liquid for forming an adhesive part, 25% by mass of bisphenol F type epoxy resin (EPICRON 830 (registered trademark), manufactured by DIC Corporation), 5% by mass of 2-phenyl-4-methyl-5-hydroxymethylimidazole (2P4MHZ-PW, manufactured by Shikoku Kasei Kogyo Co., Ltd.), and 70% by mass of phenoxy resin (Phenotote YP-50 (registered trademark), manufactured by Nippon Steel Chemical & Material Co., Ltd.) were filled by a comma knife bar coater (FJ-TADK104, manufactured by Fuji Seiki Co., Ltd.) so as to have the same thickness as the metal convex portions, and sandwiched between a nickel-plated copper plate (25 mm × 25 mm, average thickness 1.00 mm) and a silicon plate (20 mm × 20 mm, average thickness 0.76 mm). After performing a heat press for 2 minutes under the conditions of an upper plate temperature of 170°C on the copper plate side, a lower plate temperature of 170°C on the silicon plate side, and a set air pressure of 0.11 MPa (40 psi in pressure conversion), and then naturally cooling and releasing, the heat conduction sheet of Example 1 was manufactured.

[0076] (Example 2) In Example 1, except that the pattern shown in Fig. 3A was changed to the pattern shown in Fig. 3B and the area ratio of the metal convex portions was changed to 50%, the heat conduction sheet of Example 2 was obtained in the same manner as in Example 1.

[0077] (Example 3) In Example 1, except that the pattern shown in Fig. 3A was changed to the pattern shown in Fig. 3C and the area ratio of the metal convex portions was changed to 20%, the heat conduction sheet of Example 3 was obtained in the same manner as in Example 1.

[0078] (Examples 4 to 6) In Examples 1 to 3, except that the diameter of the metal convex portions in the patterns (45° staggered) shown in Figs. 3A to 3C was changed from 100 μm to 500 μm respectively, the heat conduction sheets of Examples 4 to 6 were obtained in the same manner as in Examples 1 to 3 respectively.

[0079] (Example 7) In Example 1, a heat conduction sheet of Example 7 was obtained in the same manner as in Example 1, except that the pattern shown in FIG. 3A (45° staggered) was changed to the pattern shown in FIG. 4A (60° staggered).

[0080] (Example 8) In Example 1, a heat conduction sheet of Example 8 was obtained in the same manner as in Example 1, except that the pattern shown in FIG. 3A (45° staggered) was changed to the pattern shown in FIG. 4B (square parallel).

[0081] (Example 9) In Example 1, a heat conduction sheet of Example 9 was obtained in the same manner as in Example 1, except that the pattern shown in FIG. 3A (45° staggered) was changed to the pattern shown in FIG. 4C (regular hexagon 60° staggered).

[0082] (Example 10) In Example 2, a heat conduction sheet of Example 10 was obtained in the same manner as in Example 1, except that the diameter of the metal protrusions shown in FIG. 3B was changed from 100 μm to 1000 μm.

[0083] (Example 11) In Example 2, the average thickness T of the metal layer M 18 μm was changed to 36 μm, the average thickness T of the metal protrusions m 9 μm was changed to 4.5 μm, and the ratio of the average thickness T of the metal protrusions to the average thickness T of the metal layer M m (T m / T M ) was changed from 1 to 1 / 8. A heat conduction sheet of Example 11 was obtained in the same manner as in Example 1.

[0084] (Example 12) In Example 2, the average thickness T of the metal layer M 18 μm was changed to 6 μm, the average thickness T of the metal protrusions m 9 μm was changed to 48 μm, and the ratio of the average thickness T of the metal protrusions to the average thickness T of the metal layer M m (T m / T M ​​A heat conduction sheet of Example 12 was obtained in the same manner as in Example 1, except that [[ID=]] was changed from 1 to 8.

[0085] (Comparative Example 1) In Example 1, a heat conduction sheet of Comparative Example 1 was obtained in the same manner as in Example 1, except that the pattern shown in Fig. 3A was changed to the pattern shown in Fig. 3D and the area ratio of the metal convex portions was changed to 90%.

[0086] (Comparative Example 2) In Example 1, a heat conduction sheet of Comparative Example 2 was obtained in the same manner as in Example 1, except that the pattern shown in Fig. 3A was changed to the pattern shown in Fig. 3E and the area ratio of the metal convex portions was changed to 10%.

[0087] (Comparative Examples 3 - 4) In Example 4, heat conduction sheets of Comparative Examples 3 - 4 were obtained in the same manner as in Example 4, except that the pattern shown in Fig. 3A was changed to the pattern shown in Fig. 3D or Fig. 3E and the area ratio of the metal convex portions was changed to 90% or 10%.

[0088] (Comparative Example 5) In Example 1, except that the average thickness T of the metal layer M 18μm was changed to 36μm, the average thickness T of the metal convex portions m 9μm was changed to 4μm, and the ratio of the average thickness T of the metal convex portions M to the average thickness T of the metal layer m (T m / T M ) was changed from 1 to 1 / 9, heat conduction sheets of Comparative Examples 5 - 6 were obtained in the same manner as in Example 1.

[0089] (Comparative Example 6) In Example 1, except that the average thickness T of the metal layer M 18μm was changed to 6μm, the average thickness T of the metal convex portions m 9μm was changed to 54μm, and the ratio of the average thickness T of the metal convex portions M to the average thickness T of the metal layer m (T m / T MA heat conduction sheet of Comparative Example 6 was obtained in the same manner as in Example 1, except that [[ID=]] was changed from 1 to 9.

[0090] (Comparative Example 7) Instead of the heat conduction sheet of Example 1, indium (Pure Indium Heat-Spring Kit (2.00 inches × 2.00 inches, thickness 0.004 inches), manufactured by Indium Corporation) was used. Indium was provided between a nickel-plated copper plate (25 mm × 25 mm, average thickness 1.00 mm) and a silicon plate (20 mm × 20 mm, average thickness 0.76 mm), and a shim tape (manufactured by Misumi Group Inc., average thickness 50 μm) was sandwiched around it. After heating and pressing for 2 minutes under the conditions of an upper plate temperature of 170°C on the copper plate side, a lower plate temperature of 170°C on the silicon plate side, and a set air pressure of 0.11 MPa (40 psi in pressure conversion), natural cooling was carried out, then it was opened and the shim tape was removed to form an indium layer with an average thickness of 100 μm, which was used as the heat conduction sheet of Comparative Example 7.

[0091] (Comparative Example 8) Instead of the heat conduction sheet of Example 1, a commercially available conductive adhesive (heat-conductive RTV rubber (room temperature curing type) KE3467, manufactured by Shin-Etsu Chemical Co., Ltd.) was used. The conductive adhesive was provided between a nickel-plated copper plate (25 mm × 25 mm, average thickness 1.00 mm) and a silicon plate (20 mm × 20 mm, average thickness 0.76 mm), and a shim tape (manufactured by Misumi Group Inc., average thickness 50 μm) was sandwiched around it. After leaving it at room temperature for one day, the shim tape was removed to form a conductive adhesive layer with an average thickness of 50 μm, which was used as the heat conduction sheet of Comparative Example 8.

[0092] <Evaluation> Next, for Examples 1 to 9 and Comparative Examples 1 to 8, "thermal conductivity" and "reliability" were evaluated as follows. The results are shown in Table 1.

[0093] <Thermal Conductivity> In accordance with JIS R 1611, the thermal resistance of each thermal conductive sheet was measured under the condition of a pulse width of 20 μsec using a flash method thermal diffusivity / thermal conductivity measuring device (LFA467, manufactured by Netzsch Gerätebau GmbH). Subsequently, the thermal resistance of the copper plate (25 mm × 25 mm, average thickness 1.00 mm) and silicon plate (20 mm × 20 mm, average thickness 0.76 mm) plated with nickel, which were the base materials used in the measurement, was subtracted from the measured value to calculate the thermal resistance of the thermal conductive sheet. 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 Tables 1 to 3. [Evaluation Criteria] ◎: The thermal conductivity is 20 W / m·K or more. 〇: The thermal conductivity is 10 W / m·K or more and less than 20 W / m·K. ×: The thermal conductivity is less than 10 W / m·K.

[0094] [Reliability] [<<Fabrication of Laminated Body after Crimping>>] Each thermal conductive sheet was sandwiched between a copper plate (25 mm × 25 mm, average thickness 1.00 mm) plated with nickel and a silicon plate (20 mm × 20 mm, average thickness 0.76 mm), and heat press was performed for 5 minutes under the conditions of an upper plate temperature of 150°C on the copper plate side, a lower plate temperature of 150°C on the silicon plate side, and a set air pressure of 0.11 MPa (40 psi in pressure conversion) using a mini press machine. Then, heating was performed at 150°C for 1 hour in an oven (Perfect Oven PHH-202, manufactured by Espec Corporation). [<<Accelerated Life Test and Evaluation of Reliability>>] The laminated body after crimping was put into a highly accelerated life test device (EHS-212MD, manufactured by Espec Corporation) at 130°C and 85% humidity for 192 hours. After the accelerated life test, each thermal conductive sheet was observed using an ultrasonic imaging device (SAT, FS300IIIHR, manufactured by Hitachi Power Solutions Co., Ltd.) to inspect the adhesion to the base material and the presence or absence of voids. 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 results are shown in Tables 1 to 3. [Evaluation Criteria] ◎: There is no lifting, peeling, or voids from the base material of the heat conduction sheet. 〇: The lifting, peeling, or voids from the base material of the heat conduction sheet are less than 0.1% of the observation field of view and are within the practical range. ×: The lifting, peeling, or voids from the base material of the heat conduction sheet are 0.1% or more of the observation field of view and are outside the practical range.

[0095]

Table 1

[0096]

Table 2

[0097]

Table 3

Explanation of Symbols

[0098] 1 Heat conduction sheet 2 Heat spreader 2a Main surface 3 Heat generating body (electronic component) 3a Upper surface 5 Heat sink 6 Wiring board 7 Heat conduction sheet 10 Heat conduction sheet 11 Metal part 11a Metal layer 11’ Metal plate before etching 11b Metal convex part 12 Adhesive part 13 Protection part

Claims

1. A metal layer, and a metal part having metal protrusions on at least a first surface of the metal layer, And an adhesive part on the first surface, a heat conduction sheet, wherein The area ratio of the metal protrusions exposed on the first surface of the heat conduction sheet to the first surface is 20% or more and 80% or less, The average thickness (T Ｍ ) of the metal layer, with respect to the average thickness (T ｍ ) of the metal protrusions, the ratio (T ｍ / T Ｍ ) is 0.125 or more and 8 or less. A heat conduction sheet characterized by this.

2. Further having metal protrusions and an adhesive part on a second surface opposite to the first surface of the metal layer, The heat conduction sheet according to claim 1, wherein the area ratio of the metal protrusions exposed on the second surface of the heat conduction sheet to the second surface is 20% or more and 80% or less.

3. The heat conduction sheet according to claim 1 or 2, wherein the area ratio of the metal protrusions exposed on the first surface of the heat conduction sheet to the first surface is 30% or more and 70% or less.

4. The average thickness (T Ｍ ) of the metal layer, with respect to the average thickness (T ｍ ) of the metal protrusions, the ratio (T ｍ / T Ｍ ) is 0.2 or more and 4 or less. The heat conduction sheet according to claim 1 or 2.

5. The heat conduction sheet according to claim 1 or 2, wherein the thermal conductivity of the metal layer is 50 W / (m·K) or more.

6. The heat conduction sheet according to claim 1 or 2, wherein the metal layer contains at least one of gold, silver, copper, aluminum, and nickel.

7. The heat conduction sheet according to claim 1 or 2, wherein the metal protrusions are formed of a metal by electrolytic plating.

8. The heat conduction sheet according to claim 1 or 2, wherein the bonding portion contains at least one of a modified acrylate compound, an epoxy resin, an unsaturated polyester resin, a polyurethane resin, a bismaleimide resin, an alkyd resin, a phenol resin, and a melamine resin.

9. A step of providing a protective portion on at least a first surface of the metal layer, A method for manufacturing a heat conduction sheet, comprising: a step of forming metal protrusions on an exposed surface of the metal layer where the protective portion is not provided.

10. A step of removing the protective portion, The method for manufacturing a heat conduction sheet according to claim 9, further comprising a step of filling an adhesive portion on an exposed surface of the metal layer from which the protective portion has been removed.

11. The method for manufacturing a heat conduction sheet according to claim 9 or 10, wherein the step of providing the protective portion is a step of providing a protective portion on the first surface of the metal layer and a second surface opposite to the first surface.

Images