Thermosetting resin composition, resin sheet, heat dissipation plate, method for producing resin sheet, and method for producing heat dissipation plate

Abstract

To provide a resin sheet having excellent thermal conductivity and high tensile shear adhesive strength, a heat sink having excellent thermal conductivity, a thermosetting resin composition constituting a resin layer of the heat sink and the resin sheet, a method for producing the resin sheet, and a method for producing the heat sink.SOLUTION: At least one of bifunctional epoxy resins having two epoxy groups in molecules and polyfunctional epoxy resins having three or more epoxy groups in molecules, a curing agent that cures the epoxy resins, and a spherical filler having a coefficient of thermal conductivity of 200W / (m·K) or more and a mean particle size (D50) of 5 μm or more and 35 μm or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a thermosetting resin composition, a resin sheet, a heat sink, a method for producing a resin sheet, and a method for producing a heat sink. [Background technology]

[0002] When a device equipped with many electronic components such as IC chips and transistors is operated, the components generate a large amount of heat. If this generated heat cannot be efficiently dissipated, the performance of the electronic components will be impaired due to the heat, causing the device to malfunction. To prevent this malfunction, the substrate on which the electronic components are mounted is provided with a metal plate with high thermal conductivity attached via a thermally conductive adhesive on the side opposite the surface on which the electronic components are mounted. This metal plate allows the heat generated by the electronic components to be efficiently dissipated via the adhesive.

[0003] Patent Document 1 discloses a resin composition that can be used as an adhesive to bond a metal plate to a substrate. This resin composition contains metal powder with a thermal conductivity of 200 W / (m·K) or more and an average particle size of 5 μm to 20 μm, and a thermosetting resin that is liquid at room temperature. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5375067 Summary of the Invention [Problem to be solved by the invention]

[0005] When this resin composition is used as an adhesive for bonding a metal plate and a substrate, the resin contained in the resin composition is easily leaked out without being retained between the first metal powder and the second metal powder. In other words, voids are easily formed between the first metal powder and the second metal powder, and the amount of resin present between the metal plate and the substrate is small. This results in a decrease in the tensile shear adhesive strength of the adhesive between the substrate and the metal plate. Furthermore, the voids formed between the metal plate and the substrate make it difficult to efficiently dissipate heat generated by electronic components.

[0006] The present invention has been made in view of the above circumstances, and aims to provide a resin sheet having excellent thermal conductivity and high tensile shear adhesive strength, a heat sink plate having excellent thermal conductivity, a thermosetting resin composition constituting the resin layer and resin sheet of the heat sink plate, a method for manufacturing the resin sheet, and a method for manufacturing the heat sink plate. [Means for solving the problem]

[0007] The present invention is as follows. [1] The thermosetting resin composition according to the present invention comprises: an ethylene acrylic copolymer having a glass transition temperature of −20° C. or lower and having a carboxy group in a side chain; at least one epoxy resin selected from the group consisting of a bifunctional epoxy resin having two epoxy groups in one molecule and a multifunctional epoxy resin having three or more epoxy groups in one molecule; a curing agent for curing the epoxy resin; A spherical filler having a thermal conductivity of 200 W / (m·K) or more and an average particle diameter (D50) of 5 μm or more and 35 μm or less, the content of the ethylene acrylic copolymer is 40 parts by weight or more and 1000 parts by weight or less relative to 100 parts by weight of the epoxy resin, The weight ratio of the spherical filler is 75% by weight or more and 90% by weight or less with respect to 100% by weight of the total solid content.

[0008] [2] The content of the curing agent may be 1 part by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the epoxy resin.

[0009] [3] The thermosetting resin composition may contain a curing accelerator that accelerates the curing of the epoxy resin and the curing agent.

[0010] [4] The content of the curing accelerator may be 0.1 parts by weight or more and 2 parts by weight or less relative to 100 parts by weight of the epoxy resin.

[0011] [5] The material of the spherical filler may be at least one selected from the group consisting of aluminum, silver, and copper.

[0012] [6] A resin sheet according to the present invention is made of the thermosetting resin composition according to any one of [1] to [5].

[0013] [7] The resin sheet may have a thickness of 30 μm or more and 100 μm or less.

[0014] [8] The resin sheet may be in a semi-cured state.

[0015] [9] The heat sink according to the present invention is The device comprises a metal plate and a resin layer made of the thermosetting resin composition according to any one of [1] to [5], the resin layer being formed on at least one surface of the metal plate.

[0016]

[10] The cured state of the resin layer may be semi-cured.

[0017]

[11] The method for producing a resin sheet according to the present invention comprises: a sheet forming step of forming a sheet composed of the thermosetting resin composition according to any one of [1] to [5]; and a heating step of heating the sheet.

[0018]

[12] The method for manufacturing a heat sink according to the present invention comprises: [6] to [8], and a placement step of placing the resin sheet according to any one of the above items on a metal plate; and a heating and pressing step of heating and pressing the metal plate on which the resin sheet is disposed.

[0019]

[13] The method for manufacturing a heat sink according to the present invention comprises: A preparation step of preparing the thermosetting resin composition according to any one of [1] to [5]; a forming step of forming a resin layer composed of the thermosetting resin composition on at least one surface of a metal plate; and a heating step of heating the metal plate on which the resin layer has been formed. [Effects of the Invention]

[0020] The present invention can provide a resin sheet having excellent thermal conductivity and high tensile shear adhesive strength, a heat sink plate having excellent thermal conductivity, a thermosetting resin composition constituting the resin layer and resin sheet of the heat sink plate, a method for manufacturing a resin sheet, and a method for manufacturing a heat sink plate. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic cross-sectional view of a resin sheet according to an embodiment. [Figure 2] 1 is a schematic cross-sectional view of a heat sink according to an embodiment. [Figure 3] 1 is a schematic cross-sectional view of a substrate on which electronic components are mounted and which includes a heat sink according to an embodiment. [Figure 4] 1 is a schematic cross-sectional view of a substrate on which electronic components are mounted and which includes a heat sink according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, a thermosetting resin composition, a resin sheet, a heat sink, a method for manufacturing a resin sheet, and a method for manufacturing a heat sink, which are modes for carrying out the present invention (hereinafter referred to as embodiments), will be described in detail. The embodiments are examples for explaining the present invention and are not intended to limit the present invention to the following content. The present invention can be practiced by appropriately modifying it within the scope of its gist. Note that in the embodiments, the parts by weight used refer to, for example, the weight of the resin alone excluding volatile components such as organic solvents contained in the resin, or the weight of the non-volatile components. The semi-cured state (B stage) refers to a state in which the curing reaction of the thermosetting resin composition has progressed halfway.

[0023] [Thermosetting resin composition] The thermosetting resin composition of the present embodiment includes an ethylene-acrylic copolymer having a carboxy group in a side chain, at least one of a bifunctional epoxy resin having two epoxy groups in one molecule and a multifunctional epoxy resin having three or more epoxy groups in one molecule, a curing agent, and a spherical filler. The thermosetting resin composition of the present embodiment is suitable for use as a resin composition for forming a resin sheet or a resin composition for forming a resin layer in a heat sink.

[0024] Components contained in the thermosetting resin composition of the embodiment will be described below.

[0025] (ethylene acrylic copolymer with carboxyl groups in the side chains) Examples of ethylene-acrylic copolymers having carboxy groups in their side chains include (meth)acrylic ester copolymers having an ethylene structure in their main chains and carboxy groups in their side chains. The glass transition temperature of ethylene-acrylic copolymers having carboxy groups in their side chains is −20°C or lower, preferably −30°C or lower, more preferably −35°C or lower, and even more preferably −40°C or lower, from the viewpoint of preventing stress caused by heat cycles. Here, the (meth)acrylic ester copolymer refers to an acrylic ester copolymer or a methacrylic ester copolymer. The heat cycle is, for example, a cycle of maintaining a low-temperature environment of −40°C for a certain period of time, followed by a high-temperature environment of 150°C for a certain period of time, and repeating this cycle. The glass transition temperature can be measured by differential scanning calorimetry (DSC).

[0026] A (meth)acrylic acid ester copolymer having a carboxy group in the side chain is composed of, for example, two or more types of monomers. Examples of the monomers constituting this copolymer include a (meth)acrylic acid ester monomer, a carboxy group-containing monomer, and an anhydride of a carboxy group-containing monomer. Here, the (meth)acrylic acid ester monomer means an acrylic acid ester monomer or a methacrylic acid ester monomer.

[0027] An ethylene acrylic copolymer having a carboxy group in its side chain can have an ethylene structure introduced into the main chain of the copolymer by polymerizing the above-mentioned monomers. Examples of the introduction method include Ziegler-Natta catalyst polymerization, metallocene catalyst polymerization, Versipol catalyst polymerization, and free radical polymerization.

[0028] Examples of (meth)acrylic acid ester monomers include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; (meth)acrylic acid hydroxyalkyl esters such as hydroxyethyl (meth)acrylate; N,N-dimethylaminoalkyl (meth)acrylates such as N,N-dimethylaminomethyl (meth)acrylate; and epoxy group-containing (meth)acrylic acid esters such as glycidyl (meth)acrylate. Note that methyl (meth)acrylate refers to methyl acrylate or methyl methacrylate. Furthermore, (meth)acrylic acid refers to acrylic acid or methacrylic acid. The same applies hereinafter in this embodiment.

[0029] Examples of the carboxy group-containing monomer include (meth)acrylic acid, fumaric acid, and maleic acid.

[0030] Examples of the anhydrides of carboxyl group-containing monomers include anhydrides of (meth)acrylic acid, maleic acid, and the like.

[0031] The weight-average molecular weight of the ethylene-acrylic copolymer having a carboxyl group in the side chain is, for example, from 100,000 to 400,000, preferably from 150,000 to 300,000, from the viewpoint of facilitating the processability of the resin sheet and preventing stress from occurring in the resin layer of the heat sink. Here, the weight-average molecular weight can be measured by gel permeation chromatography (GPC) using polystyrene with an average molecular weight of from about 500 to about 1,000,000 as a standard substance. The heat sink comprises a metal plate and a resin layer formed on at least one surface of the metal plate and composed of the thermosetting resin composition of this embodiment.

[0032] The content of the ethylene-acrylic copolymer having a carboxy group in the side chain is from 40 parts by weight to 1,000 parts by weight, preferably from 50 parts by weight to 800 parts by weight, and more preferably from 50 parts by weight to 500 parts by weight, relative to 100 parts by weight of the epoxy resin, from the viewpoint of preventing stress from occurring in the resin layer of the heat sink and from the viewpoint of thermal conductivity.

[0033] From the viewpoint of preventing stress from being generated in the resin layer of the heat sink, the carboxyl group content is, for example, preferably from 3 mgKOH / g to 30 mgKOH / g, more preferably from 10 mgKOH / g to 30 mgKOH / g, and even more preferably from 10 mgKOH / g to 20 mgKOH / g. The carboxyl group content can be measured by titration using a 0.1 N potassium hydroxide aqueous solution.

[0034] Examples of commercially available ethylene acrylic copolymers having carboxy groups in the side chains include Baymac (registered trademark) VMX4017 and Baymac (registered trademark) GLS manufactured by DuPont.

[0035] (epoxy resin) The epoxy resin contains at least one of a bifunctional epoxy resin having two epoxy groups in one molecule and a multifunctional epoxy resin having three or more epoxy groups in one molecule, from the viewpoints of improving compatibility with other components and preventing stress caused by heat cycles.

[0036] Examples of difunctional epoxy resins include bisphenol A epoxy resins, bisphenol F epoxy resins, and bisphenol S epoxy resins. Examples of multifunctional epoxy resins include novolac epoxy resins, amine epoxy resins, biphenyl epoxy resins, alicyclic epoxy resins, phenol novolac epoxy resins, cresol novolac epoxy resins, naphthalene ring-containing epoxy resins, dicyclopentadiene epoxy resins, and trisphenolmethane epoxy resins. Among the above epoxy resins, novolac epoxy resins, phenol novolac epoxy resins, cresol novolac epoxy resins, trisphenolmethane epoxy resins, and bisphenol A epoxy resins are preferred from the viewpoints of improving compatibility with other components and preventing stress caused by heat cycles.

[0037] The epoxy equivalent of the epoxy resin is 100 g / eq or more and 600 g / eq or less, and from the viewpoint of improving compatibility with other components, it is preferably 100 g / eq or more and 400 g / eq or less.

[0038] Two or more types of epoxy resins may be used in combination. The epoxy resin may be dissolved in an organic solvent in advance to facilitate mixing with other materials contained in the thermosetting resin composition.

[0039] (hardening agent) The curing agent may be any agent capable of curing the epoxy resin, and examples thereof include diaminodiphenylmethane, 3,3'-diaminodiphenylsulfone (3,3'-DAS), diaminodiphenyl ether, hexamethylenediamine, dicyandiamide (DICY), phenol novolac phenolic resin, and phenol novolac cyanate ester resin. From the viewpoint of ease of control of the curing reaction, dicyandiamide and 3,3'-diaminodiphenylsulfone are preferred curing agents. Two or more curing agents may also be used in combination.

[0040] The content of the curing agent may be any content sufficient to cure the thermosetting resin composition, and is, for example, preferably 1 to 20 parts by weight, more preferably 5 to 20 parts by weight, and even more preferably 5 to 15 parts by weight, per 100 parts by weight of the epoxy resin. This allows the thermosetting resin composition to exhibit high tensile shear adhesive strength after curing, improving heat resistance. It also prevents stress caused by heat cycles.

[0041] The equivalent weight of the curing agent is sufficient to cure the thermosetting resin composition, and is preferably 0.1 to 1.0 equivalent weight, more preferably 0.3 to 1.0 equivalent weight, and even more preferably 0.3 to 0.9 equivalent weight, relative to 1 equivalent weight of the epoxy group contained in the epoxy resin. This allows the thermosetting resin composition to exhibit high tensile shear adhesive strength after curing and improve heat resistance. It also prevents stress caused by heat cycles.

[0042] (spherical filler) The spherical filler has an average particle diameter (D50) of 5 μm or more and 35 μm or less. By having an average particle diameter (D50) of 5 μm or more and 35 μm or less, the spherical filler is less likely to protrude from the surface of the resin layer of the heat sink. This improves the smoothness of the surface of the resin layer. In addition, spherical fillers having the above particle diameter easily flow in the thermosetting resin composition when heated and molded, and easily form a network between the spherical fillers. This improves the thermal conductivity of the resin layer.

[0043] From the viewpoint of improving the thermal conductivity of the resin layer of the heat sink, the thermal conductivity of the spherical filler is 200 W / (m·K) or more, preferably 230 W / (m·K) or more, and more preferably 250 W / (m·K) or more. The spherical filler may be any filler with excellent thermal conductivity, and is composed of at least one type selected from the group consisting of aluminum, silver, and copper, with aluminum being more preferred. Here, the average particle size (D50) refers to the particle size when the smallest particles are counted in a volume-based particle size distribution and their cumulative size reaches 50% of the total volume. Particle size can be measured by dynamic light scattering.

[0044] From the viewpoints of improving thermal conductivity and processability, the weight proportion of the spherical filler is 75% by weight to 90% by weight, preferably 80% by weight to 90% by weight, and more preferably 80% by weight to 85% by weight, relative to 100% by weight of the total solid content contained in the thermosetting resin composition. Note that the total solid content contained in the thermosetting resin composition refers to the solid content of the thermosetting resin composition after removing the organic solvent.

[0045] A thermosetting resin composition containing an ethylene-acrylic copolymer having a glass transition temperature of −20° C. or lower and the spherical filler described above can prevent stress caused by heat cycles. That is, a heat sink having a resin layer made of this thermosetting resin composition can reduce stress generation in the resin layer even when temperature changes occur, and has excellent heat cycle properties.

[0046] The spherical filler does not need to be a perfect sphere, but only needs to have a shape with minimal surface irregularities to the extent that stress generated inside the resin layer can be released. The spherical filler also includes, for example, fillers formed of polyhedrons with 12 or more sides.

[0047] (Other ingredients) The thermosetting resin composition of the embodiment may contain other additives, such as imidazole-based curing accelerators such as 2-methylimidazole, 2-undecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, and N-benzyl-2-methylimidazole; Lewis acid complex-based curing accelerators such as boron trifluoride monoethylamine and boron trifluoride diethylamine; and curing accelerators for polyamines and melamine resins.

[0048] The content of the curing accelerator in the thermosetting resin composition is 0.1 parts by weight or more and 2 parts by weight or less per 100 parts by weight of the epoxy resin in order to promote the reaction between the epoxy resin and the curing agent contained in the thermosetting resin composition.

[0049] As described above, the thermosetting resin composition of the embodiment can be obtained by mixing the above-mentioned materials.

[0050] This thermosetting resin composition has excellent thermal conductivity, with a thermal conductivity of 10 W / (m·K) or more after curing. This thermosetting resin composition also has a tensile shear bond strength of 2.5 MPa or more after curing. Furthermore, a heat sink comprising a metal plate and a resin layer made of this thermosetting resin composition formed on at least one surface of the metal plate has excellent tensile shear bond strength even after being alternately and repeatedly exposed to two temperature atmospheres: a low-temperature atmosphere of -20°C to -40°C and a high-temperature atmosphere of 100°C to 175°C.

[0051] The conditions for curing the thermosetting resin composition include, for example, heating at 160° C. to 200° C. for 1 hour or longer. The thermal conductivity of the cured thermosetting resin composition can be measured by a laser flash method using an LFA (Laser Flash Analyzer) device.

[0052] [Resin sheet] Next, a resin sheet according to an embodiment will be described. The resin sheet 10 of the embodiment is made of the thermosetting resin composition of the embodiment and has a sheet-like shape, as shown in Fig. 1. The resin sheet 10 is in a semi-cured state. Both sides of the resin sheet 10 are covered with separate films 12 and 14. The resin sheet 10 is used after the separate films 12 and 14 are peeled off.

[0053] The thickness of the resin sheet 10 is, for example, 20 μm or more and 500 μm or less, and preferably 20 μm or more and 300 μm or less, from the viewpoint of interposing the resin sheet 10 between the metal plate and the substrate to bond the metal plate and the substrate, and from the viewpoint of absorbing stress caused by the difference between the thermal expansion of the metal plate and the thermal expansion of the substrate due to a temperature rise.

[0054] The resin sheet 10 is produced, for example, by the following procedure. A predetermined amount of ethylene-acrylic copolymer, epoxy resin, curing agent, and spherical filler is mixed in a container to prepare a thermosetting resin composition. Next, the thermosetting resin composition is applied to a separate film 14 using an applicator and heated. The mixture is then cooled to obtain a resin sheet 10 composed of the thermosetting resin composition. The resulting resin sheet 10 is used by peeling off the separate film 14. The cured state of the resin sheet 10 is semi-cured. The curing conditions are, for example, 100°C to 180°C and 5 seconds to 30 minutes, and can be adjusted depending on the thickness of the resin sheet 10. Before use, the resin sheet 10 may be covered with another separate film 12 to protect the exposed resin surface. Alternatively, the thermosetting resin composition may be applied to the separate film 14 using an applicator, and then the exposed resin surface may be covered with another separate film 12, followed by heating and pressure. This makes the surface of the resin layer smooth and makes it easy to adjust the thickness. The conditions for heating and pressing are, for example, 0.3 MPa to 10 MPa, 100°C to 180°C, and 5 seconds to 30 minutes, and can be adjusted depending on the thickness of the resin sheet 10.

[0055] The thickness of the separate films 12, 14 is selected according to the thickness of the resin sheet 10, and is, for example, 25 μm or more and 100 μm or less. Examples of materials for the separate films 12, 14 include polyethylene, polypropylene, polyimide, polyamide, polyethylene naphthalate, and polyethylene terephthalate. To facilitate peeling of the separate films from the resin sheet 10, the surfaces of the separate films 12, 14 may be subjected to a release treatment. Examples of treatment agents for the release treatment include silicone-based treatment agents and fluorine-based treatment agents.

[0056] The resin sheet of the embodiment may have a configuration in which resin sheets 10 are bonded to both sides of a sheet-like core material. A resin sheet having a core material has high rigidity. Examples of the sheet-like core material include film and nonwoven fabric. Examples of the material of the core material include polyimide, polyamide, polyethylene naphthalate, and polyethylene terephthalate. Furthermore, when the core material is a nonwoven fabric, examples of the material of the fibers constituting the nonwoven fabric include glass, carbon, and the like in addition to the above-mentioned resins. The resin sheet according to the embodiment has been described above.

[0057] [Heat sink] Next, the heat sink of the embodiment will be described. As shown in FIG. 2, the heat sink 20 of the embodiment includes a metal plate 21 and a resin layer 23 made of the thermosetting resin composition of the embodiment. The resin layer 23 is formed on at least one surface of the metal plate 21. The resin layer 23 is in a semi-cured state. As shown in FIG. 3, the heat sink 20 dissipates heat generated by an electronic component 40. Specifically, a substrate 30 is disposed on the surface of the resin layer 23 opposite to the surface on which the metal plate 21 is disposed. The electronic component 40 is mounted on the substrate 30 via a circuit 31 formed on the substrate 30. The metal plate 21 is also referred to as a heat sink.

[0058] The thickness of the resin layer 23 is, for example, 20 μm or more and 500 μm or less, preferably 30 μm or more and 500 μm or less, and more preferably 40 μm or more and 400 μm or less, from the viewpoints of adhesion between the substrate 30 and the metal plate 21 and absorbing stress caused by the difference between the thermal expansion of the metal plate and the substrate due to a rise in temperature.

[0059] The metal plate 21 is preferably made of a metal having high thermal conductivity as long as it can efficiently dissipate heat generated from the electronic components 40 mounted on the substrate 30. Examples of metals having high thermal conductivity include copper, aluminum, and stainless steel. Among these, copper and aluminum are preferred because they are easy to process and have high thermal conductivity.

[0060] The thickness of the metal plate 21 may be any thickness that is easy to process, and is, for example, 9 μm to 10 mm, more preferably 35 μm to 5 mm, and even more preferably 500 μm to 2 mm. The metal plate 21 also includes metal foil.

[0061] 4, in order to further improve the heat dissipation properties of the heat sink 20, a plurality of fins 22 may be provided on the surface of the metal plate 21 opposite to the surface on which the resin layer 23 is formed. The metal plate 21 provided with a plurality of fins 22 is also called a heat sink.

[0062] The thickness of the metal plate 21 on which the multiple fins 22 are provided is, for example, 0.3 mm or more and 50 mm or less. The fins 22 are formed, for example, from plates or rods. The height of the fins 22 is, for example, 1 mm or more and 100 mm or less. The thickness of the plate-like fins is, for example, 0.2 mm or more and 9 mm or less, and is preferably thinner than the thickness of the metal plate 21. Furthermore, the plate-like fins are preferably smaller than the metal plate 21. The rod-like fins have a cross-sectional shape in a direction perpendicular to the longitudinal direction of the fins, for example, a square or circle.

[0063] The heat sink 20 is fabricated, for example, by the following procedure. First, a metal plate 21 and a resin sheet 10 covered on both sides with separate films are prepared. Next, one separate film is peeled off from the resin sheet 10, and the resin sheet 10 is placed on the metal plate 21 so that the exposed resin surface is in contact with the metal plate 21. Thereafter, the metal plate 21 with the resin sheet 10 placed thereon is heated and pressurized under conditions of, for example, 0.3 MPa to 20 MPa, 100°C to 250°C, and 5 seconds to 90 minutes. After cooling, the heat sink 20 is obtained, with a resin layer 23 formed on one side of the metal plate 21. The remaining separate film is peeled off before use. The heating and pressurizing conditions can be adjusted depending on the thickness of the resin layer 23.

[0064] Another method for producing the heat sink 20 is, for example, the following method. A thermosetting resin composition is prepared by adding predetermined amounts of an ethylene-acrylic copolymer, an epoxy resin, a curing agent, and spherical fillers to a container and mixing them. A metal plate 21 is prepared. Next, the prepared thermosetting resin composition is applied to the metal plate 21 using an application device and heated. After cooling, the metal plate 21 with the resin layer 23 formed thereon, i.e., the heat sink 20, is obtained. The heating conditions are, for example, 100°C or higher and 250°C or lower, and 5 seconds or higher and 90 minutes or lower. The heating conditions can be adjusted depending on the thickness of the resin layer 23. The heat sink of the embodiment has been described above.

[0065] An organic solvent may be used when preparing the thermosetting resin composition of the embodiment. Examples of the organic solvent include alcohols such as methanol and ethanol; glycols such as ethylene glycol and propylene glycol; glycol monoalkyl ethers such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether; glycol dialkyl ethers such as ethylene glycol dimethyl ether and ethylene glycol diethyl ether; alkyl esters such as methyl acetate, ethyl acetate, propyl acetate, and methyl acetoacetate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; aliphatic hydrocarbons such as hexane, cyclohexane, and octane; amides such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone; and cyclic ethers such as tetrahydrofuran and dioxane.

[0066] Furthermore, examples of the coating device used when forming the resin sheet 10 and the resin layer 23 of the heat sink 20 of the embodiment include known coaters, such as a die coater and a comma coater. [Example]

[0067] The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples in any way.

[0068] The following components were used as the components contained in the thermosetting resin compositions in the examples and comparative examples. (ethylene acrylic copolymer) (1) Baymac (registered trademark) VMX4017: an ethylene acrylic copolymer having a carboxyl group in the side chain, glass transition temperature -41°C, manufactured by DuPont (2) Baymac (registered trademark) GLS: an ethylene acrylic copolymer having a carboxyl group in the side chain, with a glass transition temperature of -24°C, manufactured by DuPont.

[0069] (epoxy resin) (1) Bifunctional epoxy resin Epiclon (registered trademark) YL980: bisphenol A type epoxy resin, epoxy equivalent 190 g / eq, manufactured by Mitsubishi Chemical Corporation; (2) Multifunctional epoxy resin jER (registered trademark) 1032: trisphenolmethane type epoxy resin, epoxy equivalent 190 g / eq, manufactured by Mitsubishi Chemical Corporation.

[0070] (hardening agent) (1) 3,3'-DAS (diaminodiphenylsulfone), amine value 62 g / eq, manufactured by Wakayama Seika Kogyo Co., Ltd. (2) DICY (dicyandiamide), amine value 21 g / eq, manufactured by Mitsubishi Chemical Corporation.

[0071] (spherical filler) (1) TFH-A30P: Aluminum spherical filler, average particle size (D50) 30 μm, thermal conductivity 236 W / (m·K), manufactured by Toyo Aluminum Co., Ltd. (2) TFH-A20P: Aluminum spherical filler, average particle size (D50) 20 μm, thermal conductivity 236 W / (m·K), manufactured by Toyo Aluminum Co., Ltd. (3) TFH-A10P: Aluminum spherical filler, average particle size (D50) 10 μm, thermal conductivity 236 W / (m·K), manufactured by Toyo Aluminum Co., Ltd. (4) TFH-A02P: Aluminum spherical filler, average particle size (D50) 2 μm, thermal conductivity 236 W / (m·K), manufactured by Toyo Aluminum Co., Ltd.

[0072] (curing accelerator) BF3-MEA: boron trifluoride monoethylamine, manufactured by Tokyo Chemical Industry Co., Ltd.

[0073] Example 1 First, a thermosetting resin composition was prepared. Next, a resin sheet 10 composed of the thermosetting resin composition was produced. Then, the thermal conductivity of the resin sheet 10 was measured. Furthermore, the tensile shear adhesive strength of the resin sheet 10 and the tensile shear adhesive strength of the resin sheet 10 after heat cycling were measured.

[0074] (Preparation of Thermosetting Resin Composition) A container was charged with 0.5 parts by weight of BF3-MEA, 10.6 parts by weight (0.9 equivalents) of DICY, and 170 parts by weight of dimethylacetamide, 170 parts by weight of toluene, and 120 parts by weight of cyclohexanone as organic solvents. The mixture was stirred at room temperature until the BF3-MEA and DICY were dissolved. Next, 50 parts by weight of YL980 and 50 parts by weight of jER® 1032 were added and stirred at room temperature until uniform. Next, 1250 parts by weight of TFH-A20P was added and stirred at room temperature until uniform. Then, 200 parts by weight of toluene was added and stirred. Finally, 100 parts by weight of Baymac® VMX4017 was added and stirred at room temperature until uniform, yielding a thermosetting resin composition. The weight percentage of the spherical filler (TFH-A20P) in the total solids content of the thermosetting resin composition was 85.6% by weight.

[0075] (Production of resin sheet 10) A thermosetting resin composition was applied to the release-treated surface of a 50 μm-thick separate film 14 (PET5011 manufactured by Lintec Corporation) using an application device, and then heated at 130°C for 5 minutes. After cooling, a resin sheet 10 was obtained with a separate film 14 attached to one side. The thickness of the obtained resin sheet 10 was 50 μm. The following evaluations were carried out using this resin sheet 10. The cured state of the resin sheet 10 was a semi-cured state (B stage).

[0076] <Thermal conductivity> The thermal diffusion coefficient (α), specific heat (Cp) and density (ρ) of the sample for measuring thermal conductivity were measured, and the thermal conductivity was calculated using the following formula. Thermal conductivity [W / (m·K)]=α[mm 2 / s]×Cp[J / g·K]×ρ[g / cm 3 ] α [mm 2 / s]: thermal diffusion coefficient, Cp [J / g K]: specific heat, ρ [g / cm 3 ]:density. The evaluation criteria were as follows: Excellent: 10W / (m·K) or more, Good: 5W / (m·K) or more, less than 10W / (m·K), Poor: Less than 5W / (m·K). The higher the thermal conductivity of the sample, the better the thermal conductivity.

[0077] (Preparation of samples for thermal conductivity measurement) Sixteen resin sheets 10 were prepared, and after peeling off the release PET films, the sixteen resin sheets 10 were stacked to obtain a laminate. This laminate was heated and pressed at 180°C, 15 MPa, and for 60 minutes. After cooling, a sample for measuring thermal conductivity was obtained.

[0078] (Measurement of thermal diffusion coefficient (α)) The laser flash method was used to measure the temperature change on one side of a sample when pulsed light was irradiated on the other side. The obtained measurement data was analyzed using the half-time method to determine the thermal diffusivity (α). The measurement was performed using a NETZSCH LFA447 instrument at 25°C.

[0079] (Measurement of specific heat (Cp)) The specific heat capacity Cp (J / g K) of the sample for measuring thermal conductivity was determined by differential scanning calorimetry (DSC) in accordance with JIS K 7123. The measurement was performed using a TA Instruments Q200 at a heating rate of 10°C / min over a temperature range of -30°C to 50°C.

[0080] (Measurement of density (ρ)) The density (ρ) was measured by the immersion method using Shimadzu AUX220 and SMK-401 measuring instruments. The thermal conductivity was calculated by substituting the thermal diffusion coefficient (α), specific heat (Cp), and density (ρ) values ​​obtained above into the thermal conductivity equation. The thermal conductivity of the resin sheet 10 of Example 1 was 15.0 W / (m·K), and was evaluated as Excellent. It was found that the resin sheet 10 of Example 1 had excellent thermal conductivity.

[0081] <Tensile shear adhesive strength> Next, the tensile shear adhesive strength of the resin sheet 10 of Example 1 was measured. For the measurement, a measurement sample was prepared as follows.

[0082] (Preparation of measurement samples) A copper plate and an aluminum plate (manufactured by Chiba Metal Co., Ltd.) having a thickness of 2 mm, a width of 25 mm, and a length of 100 mm, and a resin sheet 10 cut into a rectangle having a width of 25 mm and a length of 13 mm were prepared. The measurement sample was produced in accordance with JIS K 6850 (ISO4587:1995). The bonding conditions were as follows: First, the resin sheet 10 was placed on the edge of the copper plate, and the two plates were bonded together by heating and pressing at 175°C, 3 MPa, and 5 minutes. Next, the release PET film was peeled off from the resin sheet 10 bonded to the copper plate, and the aluminum plate was placed in contact with the exposed resin surface, and the two plates were bonded together by heating and pressing at 180°C, 15 MPa, and 60 minutes.

[0083] (Measurement and evaluation of tensile shear bond strength) Measurement was performed in accordance with JIS K 6850 (ISO4587:1995). The measurement device used was an autograph AGS-5KNX manufactured by Shimadzu Corporation. The measurement conditions were tensile mode and a test speed of 50 mm / min. The value when the resin sheet 10 bonding the copper plate and the aluminum plate broke was measured. The evaluation criteria were as follows: Excellent: 4MPa or more, Good: 2MPa or more and less than 4MPa, Poor: Less than 2MPa. The tensile shear adhesive strength of Example 1 was 4 MPa, and the evaluation was Excellent.

[0084] <Lapsing shear adhesive strength after heat cycle> Next, the tensile shear bond strength of the resin sheet 10 of Example 1 after the heat cycle was measured.

[0085] (Preparation of measurement samples after heat cycle) The measurement sample prepared for the above-mentioned tensile shear adhesive strength measurement was placed in a thermal shock tester (TSA-72EL-A manufactured by Espec Corporation) previously set to 150°C and held there for 30 minutes. The temperature inside the tester was then lowered to -40°C at a rate of 19°C / min and held at that temperature for 30 minutes. This constituted one cycle, and 500 cycles were performed. The sample was removed from the tester and stored at room temperature for 24 hours, after which it was used as the measurement sample after the heat cycle. The temperature inside the tester was also raised to 150°C at a rate of 19°C / min.

[0086] The tensile shear bond strength after the heat cycle was measured using the same measuring equipment and under the same conditions as those used in the measurement of the tensile shear bond strength described above, and was evaluated according to the same evaluation criteria. The tensile shear bond strength after the heat cycle of Example 1 was 3.6 MPa, and the evaluation was Good.

[0087] As described above, it was found that the resin sheet 10 of Example 1 had excellent thermal conductivity and high tensile shear adhesive strength. Furthermore, the resin sheet 10 of Example 1 was evaluated as Good in tensile shear adhesive strength after heat cycling. This shows that the resin sheet 10 of Example 1 has excellent tensile shear adhesive strength even after heat cycling.

[0088] (Example 2) to (Example 8) and (Comparative Example 1) to (Comparative Example 3) As shown in Table 1, thermosetting resin compositions were prepared in the same manner as in Example 1, except that the type and content of each component contained in the thermosetting resin composition was changed, and resin sheets 10 were produced. The thermal conductivity and tensile shear adhesive strength of the resin sheets produced in each Example and Comparative Example were measured using the same test methods as in Example 1. The unit of content in the table is "parts by weight" unless otherwise specified.

[0089] [Table 1]

[0090] As shown in Table 1, the resin sheets 10 of Examples 2 to 8 were found to have excellent thermal conductivity and high tensile shear bond strength. Furthermore, the resin sheet 10 of Example 2 was evaluated as Excellent in tensile shear bond strength after heat cycling. This demonstrates that the resin sheet 10 of Example 2 has excellent tensile shear bond strength even after heat cycling. As described above, the resin sheet of this embodiment reliably bonds a substrate and a metal plate and can efficiently dissipate heat generated from electronic components mounted on the substrate. Furthermore, because the resin sheet of this embodiment has excellent tensile shear bond strength even after heat cycling, it can efficiently dissipate heat generated from electronic components mounted on the substrate even when the ambient temperature environment changes.

[0091] The present invention allows various embodiments and modifications without departing from the broad spirit and scope of the present invention. Furthermore, the above-described embodiments are intended to illustrate the present invention and do not limit the scope of the present invention. That is, the scope of the present invention is defined by the claims, not the embodiments. Various modifications made within the scope of the claims and within the scope of the meaning of the invention equivalent thereto are considered to be within the scope of the present invention.

[0092] (Addendum) (Appendix 1) an ethylene acrylic copolymer having a glass transition temperature of −20° C. or lower and having a carboxy group in a side chain; at least one epoxy resin selected from the group consisting of a bifunctional epoxy resin having two epoxy groups in one molecule and a multifunctional epoxy resin having three or more epoxy groups in one molecule; a curing agent for curing the epoxy resin; A spherical filler having a thermal conductivity of 200 W / (m·K) or more and an average particle diameter (D50) of 5 μm or more and 35 μm or less, the content of the ethylene acrylic copolymer is 40 parts by weight or more and 1000 parts by weight or less relative to 100 parts by weight of the epoxy resin, The weight ratio of the spherical filler is 75% by weight or more and 90% by weight or less with respect to 100% by weight of the total solid content of the thermosetting resin composition.

[0093] (Appendix 2) 2. The thermosetting resin composition according to claim 1, wherein the content of the curing agent is 1 part by weight or more and 20 parts by weight or less relative to 100 parts by weight of the epoxy resin.

[0094] (Appendix 3) 3. The thermosetting resin composition according to claim 1, further comprising a curing accelerator that accelerates the curing of the epoxy resin and the curing agent.

[0095] (Appendix 4) 4. The thermosetting resin composition according to claim 3, wherein the content of the curing accelerator is 0.1 parts by weight or more and 2 parts by weight or less relative to 100 parts by weight of the epoxy resin.

[0096] (Appendix 5) 5. The thermosetting resin composition according to claim 1, wherein the material of the spherical filler is at least one selected from the group consisting of aluminum, silver, and copper.

[0097] (Appendix 6) A resin sheet comprising the thermosetting resin composition according to any one of claims 1 to 5.

[0098] (Appendix 7) 7. The resin sheet according to claim 6, having a thickness of 30 μm or more and 100 μm or less.

[0099] (Appendix 8) 8. The resin sheet according to claim 6 or 7, wherein the cured state is a semi-cured state.

[0100] (Appendix 9) A heat sink comprising a metal plate and a resin layer made of the thermosetting resin composition according to any one of Supplementary Note 1 to Supplementary Note 5, wherein the resin layer is formed on at least one surface of the metal plate.

[0101] (Appendix 10) 10. The heat sink according to claim 9, wherein the resin layer is in a semi-cured state.

[0102] (Appendix 11) a sheet forming step of forming a sheet composed of the thermosetting resin composition according to any one of Supplementary Note 1 to Supplementary Note 5; a heating step of heating the sheet.

[0103] (Appendix 12) An arrangement step of arranging the resin sheet according to any one of Supplementary Note 6 to Supplementary Note 8 on a metal plate; a heating and pressing step of heating and pressing the metal plate on which the resin sheet is arranged.

[0104] (Appendix 13) A preparation step of preparing a thermosetting resin composition according to any one of Supplementary Notes 1 to 5; a forming step of forming a resin layer composed of the thermosetting resin composition on at least one surface of a metal plate; a heating step of heating the metal plate on which the resin layer is formed. [Explanation of symbols]

[0105] 10 resin sheet, 12, 14 separate film, 20 heat sink, 21 metal plate, 22 fin, 23 resin layer, 30 substrate, 31 circuit, 40 electronic component.

Claims

1. an ethylene acrylic copolymer having a glass transition temperature of −20° C. or lower and having a carboxy group in a side chain; at least one epoxy resin selected from the group consisting of a bifunctional epoxy resin having two epoxy groups in one molecule and a multifunctional epoxy resin having three or more epoxy groups in one molecule; a curing agent for curing the epoxy resin; A spherical filler having a thermal conductivity of 200 W / (m·K) or more and an average particle diameter (D50) of 5 μm or more and 35 μm or less, the content of the ethylene acrylic copolymer is 40 parts by weight or more and 1,000 parts by weight or less relative to 100 parts by weight of the epoxy resin, The weight ratio of the spherical filler is 75% by weight or more and 90% by weight or less relative to 100% by weight of the total solid content of the thermosetting resin composition.

2. 2. The thermosetting resin composition according to claim 1, wherein the content of the curing agent is 1 part by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the epoxy resin.

3. The thermosetting resin composition according to claim 1 or 2, further comprising a curing accelerator that accelerates the curing of the epoxy resin and the curing agent.

4. 4. The thermosetting resin composition according to claim 3, wherein the content of the curing accelerator is 0.1 parts by weight or more and 2 parts by weight or less relative to 100 parts by weight of the epoxy resin.

5. The thermosetting resin composition according to claim 1 , wherein the material of the spherical filler is at least one selected from the group consisting of aluminum, silver, and copper.

6. A resin sheet comprising the thermosetting resin composition according to any one of claims 1 to 5.

7. The resin sheet according to claim 6, having a thickness of 30 μm or more and 100 μm or less.

8. The resin sheet according to claim 6 or 7, which is in a semi-cured state.

9. A heat sink comprising: a metal plate; and a resin layer formed from the thermosetting resin composition according to claim 1, wherein the resin layer is formed on at least one surface of the metal plate.

10. The heat sink according to claim 9 , wherein the resin layer is in a semi-cured state.

11. a sheet forming step of forming a sheet composed of the thermosetting resin composition according to any one of claims 1 to 5; a heating step of heating the sheet.

12. an arrangement step of arranging the resin sheet according to any one of claims 6 to 8 on a metal plate; a heating and pressing step of heating and pressing the metal plate on which the resin sheet is arranged.

13. A preparation step of preparing the thermosetting resin composition according to any one of claims 1 to 5; a forming step of forming a resin layer composed of the thermosetting resin composition on at least one surface of a metal plate; a heating step of heating the metal plate on which the resin layer is formed.

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