(METH)acrylic group-containing polycarboxylic acid compound, thermally conductive composition, and thermally conductive sheet

Abstract

To provide a novel (meth)acrylic group-containing polycarboxylic acid compound that can demonstrate high adhesive strength and effective flux properties, and provide a thermally conductive composition and a thermally conductive sheet that contain the (meth)acrylic group-containing polycarboxylic acid compound and can achieve superior thermal conductivity and reduced thermal resistance.SOLUTION: The present invention provides a (meth)acrylic group-containing polycarboxylic acid compound represented by, for example, formula (1). (R1, R3, and R4 each represent an alkyl group; R2 represents a single bond or an alkyl group; A represents an acrylic group or methacrylic group).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a (meth)acrylic group-containing polycarboxylic acid compound, a thermally conductive composition, and a thermally conductive sheet. [Background technology]

[0002] In LSIs (Large Scale Integration) in various electronic devices, if the LSI itself is exposed to high temperatures for a long period of time due to heat generation from the elements used, this may lead to malfunction or failure. For this reason, thermally conductive materials are widely used to prevent the temperature of LSIs, etc. The thermally conductive materials can prevent the temperature of the equipment from rising by diffusing the heat generated by the elements or by transmitting it to a heat dissipation member for dissipating the heat outside the system, such as the atmosphere.

[0003] When metals or ceramics are used as such thermally conductive materials, there are problems such as difficulty in reducing the weight, poor processability, and low flexibility. Therefore, various thermally conductive materials using polymeric materials such as resins or rubbers as a base material have been proposed. For example, a resin composition has been proposed which contains (A) a polymer compound having one or more structures selected from a polybutadiene structure, a polysiloxane structure, a poly(meth)acrylate structure, a polyalkylene structure, a polyalkyleneoxy structure, a polyisoprene structure, a polyisobutylene structure, and a polycarbonate structure in the molecule, (B) an epoxy resin, (C) a thermally conductive filler, and (D) an active ester curing agent, in which the component (A) is one or more selected from a resin having a number average molecular weight (Mn) of 1,000 to 1,000,000 or a glass transition temperature (Tg) of 25°C or less and a resin which is liquid at 25°C, the content of the component (A) being 10% by mass or more and 65% by mass or less when the resin component is taken as 100% by mass, and the content of the component (C) being 85% by mass or more when the non-volatile components of the resin composition are taken as 100% by mass (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6787210 Summary of the Invention [Problem to be solved by the invention]

[0005] The technology described in Patent Document 1 uses a thermoplastic resin as the base polymer, and therefore there is a problem that the adhesive strength is significantly reduced when the heating temperature exceeds the melting point of the thermoplastic resin. In addition, the curing reaction between the oxetane compound as the curing component and the polycarboxylic acid is restricted by the molecular structure of the oxetane compound, and therefore there is a risk of the adhesive strength being reduced.

[0006] The present invention aims to solve the above-mentioned problems in the prior art and to achieve the following objects: That is, the present invention aims to provide a novel (meth)acrylic group-containing polycarboxylic acid compound capable of exhibiting high adhesive strength and good fluxing effect, a thermally conductive composition containing the (meth)acrylic group-containing polycarboxylic acid compound and capable of realizing high thermal conductivity and low thermal resistance, and a thermally conductive sheet. [Means for solving the problem]

[0007] The means for solving the above problems are as follows. <1> The (meth)acrylic group-containing polycarboxylic acid compound is characterized by being represented by at least one of the following general formula (1) and the following general formula (2). [ka] In the general formula (1), R1 and R3 each represent an alkyl group, R2 represents a single bond or an alkyl group, R4 represents an alkyl group, and A represents an acryl group or a methacryl group. [ka] In the general formula (2), R1 and R2 each represent an alkyl group, R4 represents an alkyl group, R5 represents a hydrogen atom or an alkyl group, and A represents an acryl group or a methacryl group. <2> In the general formula (1), R2 is a single bond, and R1 and R3 are -CH2-. <1> The (meth)acrylic group-containing polycarboxylic acid compound is as described above. <3> The R4 is an ethyl group. <1> from <2> The (meth)acrylic group-containing polycarboxylic acid compound according to any one of the above items. <4> The above-mentioned has flux activity. <1> from <2> The (meth)acrylic group-containing polycarboxylic acid compound according to any one of the above items. <5> The above <1> from <2> a curing component, a radical polymerization initiator, thermally conductive particles, and low-melting point metal particles. <6> The content of the (meth)acrylic group-containing polycarboxylic acid compound is 1% by volume or more and 10% by volume or less. <5> 2 is a thermal conductive composition according to claim 1. <7> The curing component is at least one of an oxirane ring compound and an oxetane compound. <5> 2 is a thermal conductive composition according to claim 1. <8> The thermally conductive particles are at least one of copper particles, silver-coated particles, and silver particles. <5> 2 is a thermal conductive composition according to claim 1. <9> The low melting point metal particles contain Sn and at least one selected from Bi, Ag, Cu, and In. <5> 2 is a thermal conductive composition according to claim 1. <10> The above <5> 2. A thermally conductive sheet comprising a cured product of the thermally conductive composition according to claim 1. Effect of the Invention

[0008] According to the present invention, it is possible to solve the above-mentioned conventional problems and achieve the above-mentioned object, and to provide a novel (meth)acrylic group-containing polycarboxylic acid compound that can exhibit high adhesive strength and a good flux effect, a thermally conductive composition that contains the (meth)acrylic group-containing polycarboxylic acid compound and can achieve high thermal conductivity and low thermal resistance, and a thermally conductive sheet. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of a heat dissipation structure used in the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] ((Meth)acrylic group-containing polycarboxylic acid compound) The (meth)acrylic group-containing polycarboxylic acid compound of the present invention is represented by at least one of the following general formula (1) and general formula (2).

[0011] [ka] In the general formula (1), R1 and R3 each represent an alkyl group, R2 represents a single bond or an alkyl group, R4 represents an alkyl group, and A represents an acrylic group or a methacrylic group.

[0012] [ka] In the general formula (2), R1 and R2 each represent an alkyl group, R4 represents an alkyl group, R5 represents a hydrogen atom or an alkyl group, and A represents an acryl group or a methacryl group.

[0013] In the general formula (1), the alkyl group of R1, R2, and R3 is preferably an alkyl group having 1 to 10 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a hexyl group, a heptyl group, an octyl group, a 2-ethylhexyl group, a tert-octyl group, and a cyclohexyl group.

[0014] In the general formula (2), the alkyl group of R1, R2, and R5 is preferably an alkyl group having 1 to 10 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a hexyl group, a heptyl group, an octyl group, a 2-ethylhexyl group, a tert-octyl group, and a cyclohexyl group.

[0015] In the general formula (1) and the general formula (2), the alkyl group of R4 is preferably an alkyl group having 1 to 5 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group.

[0016] In the general formula (1), it is preferable that R2 is a single bond, and R1 and R3 are -CH2-. In this case, the synthesis is performed using citric acid as the hydroxytricarboxylic acid. In the general formulas (1) and (2), R4 is preferably an ethyl group. In this case, the synthesis is performed using 2-acryloyloxyethyl isocyanate as the (meth)acrylic modified isocyanate.

[0017] The (meth)acrylic group-containing polycarboxylic acid compound represented by at least one of the above general formula (1) and general formula (2) can be synthesized by reacting a polycarboxylic acid having a hydroxyl group with a (meth)acrylic-modified isocyanate, as described below.

[0018] <Method of producing (meth)acrylic group-containing polycarboxylic acid compound> The method for producing the (meth)acrylic group-containing polycarboxylic acid compound used in the present invention includes a step of subjecting a hydroxyl group-containing polycarboxylic acid and a (meth)acrylic-modified isocyanate to a urethane reaction, and further includes other steps as necessary.

[0019] Examples of the polycarboxylic acid having a hydroxyl group include hydroxydicarboxylic acid and hydroxytricarboxylic acid. Examples of the hydroxydicarboxylic acid include tartaric acid, malic acid, and tartronic acid. Examples of the hydroxytricarboxylic acid include citric acid and 1-hydroxy-1,2,3-propanetricarboxylic acid.

[0020] Examples of the (meth)acrylic modified isocyanate include 2-acryloyloxyethyl isocyanate and 2-methacryloyloxyethyl isocyanate. As the (meth)acrylic-modified isocyanate, commercially available products can be used. Examples of the commercially available products include 2-acryloyloxyethyl isocyanate (manufactured by Showa Denko K.K., Karenz AOI) and 2-methacryloyloxyethyl isocyanate (manufactured by Showa Denko K.K., Karenz MOI).

[0021] An example of the urethane reaction between a polycarboxylic acid having a hydroxyl group and a (meth)acrylic-modified isocyanate is shown below.

[0022] [ka] In the above reaction formula, R1 and R3 represent an alkyl group, R2 represents a single bond or an alkyl group, R4 represents an alkyl group, and A represents an acryl group or a methacryl group.

[0023] The conditions for the urethane reaction of the polycarboxylic acid having a hydroxyl group and the (meth)acrylic-modified isocyanate are not particularly limited and can be appropriately selected depending on the purpose. For example, a method in which the mixture is stirred uniformly in an atmosphere maintained at a constant temperature can be mentioned.

[0024] <Other processes> The other steps are not particularly limited and can be appropriately selected depending on the purpose. For example, a concentration step, a separation and purification step, etc. can be mentioned.

[0025] The (meth)acrylic group-containing polycarboxylic acid compound represented by at least one of the general formulas (1) and (2) can achieve both a good flux effect and an adhesive function as a (meth)acrylic resin. During film formation, no reaction occurs, improving the wettability of the coating liquid, and when used as a product, it is heated in stages, with the first stage heating exerting the flux effect, and then the second stage heating starts hardening of the (meth)acrylic group-containing polycarboxylic acid compound by the polymerization initiator blended together, thereby exerting the adhesive function and film function as a (meth)acrylic resin. Furthermore, by using a curing component and a curing agent in combination, hybrid curing can be achieved. The heating temperature in the first stage is preferably 120°C to 150°C, for example. The second stage heating is preferably carried out at a temperature of, for example, 150°C to 190°C.

[0026] (Thermal Conductive Composition) The thermally conductive composition of the present invention contains the (meth)acrylic group-containing polycarboxylic acid compound of the present invention, a curing component, a radical polymerization initiator, thermally conductive particles, and low-melting point metal particles, and further contains other components as necessary.

[0027] <(Meth)acrylic group-containing polycarboxylic acid compound> The content of the (meth)acrylic group-containing polycarboxylic acid compound of the present invention represented by at least one of the above general formula (1) and general formula (2) is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1 vol. % or more and 10 vol. % or less, and more preferably 1 vol. % or more and 5 vol. % or less, based on the total volume of the thermal conductive composition. The (meth)acrylic group-containing polycarboxylic acid compound of the present invention represented by at least one of the above general formula (1) and general formula (2) can be analyzed by Fourier transform infrared spectroscopy (FT-IR) or the like as a thermal conductive composition before curing.

[0028] <Curing component> As the curing component, it is preferable to use at least one of an oxirane ring compound and an oxetane compound.

[0029] -Oxirane ring compounds- The oxirane ring compound is a compound having an oxirane ring, and examples thereof include epoxy resins. The epoxy resin is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include glycidyl ether type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, bisphenol A type epoxy resins, trisphenol type epoxy resins, tetraphenol type epoxy resins, phenol-xylylene type epoxy resins, naphthol-xylylene type epoxy resins, phenol-naphthol type epoxy resins, phenol-dicyclopentadiene type epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins, etc. These may be used alone or in combination of two or more.

[0030] -Oxetane compounds- The oxetane compound is a compound having an oxetanyl group, and may be an aliphatic compound, an alicyclic compound, or an aromatic compound. The oxetane compound may be a monofunctional oxetane compound having only one oxetanyl group, or a polyfunctional oxetane compound having two or more oxetanyl groups.

[0031] The oxetane compound is not particularly limited and can be appropriately selected depending on the purpose. Examples of the oxetane compound include 3,7-bis(3-oxetanyl)-5-oxa-nonane, 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene, 1,2-bis[(3-ethyl-3-oxetanylmethoxy)methyl]ethane, 1,3-bis[(3-ethyl-3-oxetanylmethoxy)methyl]propane, ethylene glycol bis(3-ethyl-3-oxetanylmethyl)ether, triethylene glycol bis(3-ethyl-3-oxetanylmethyl)ether, tetraethylene glycol bis(3-ethyl-3-oxetanylmethyl)ether, 1,4-bis(3-ethyl-3-oxetanylmeth- oxy)butane, 1,6-bis(3-ethyl-3-oxetanylmethoxy)hexane, 3-ethyl-3-(phenoxy)methyloxetane, 3-ethyl-3-(cyclohexyloxymethyl)oxetane, 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, 3-ethyl-3-hydroxymethyloxetane, 3-ethyl-3-(chloromethyl)oxetane, 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane, xylylene bisoxetane, 4,4'-bis[(3-ethyl-3-oxetanyl)methoxymethyl]biphenyl (OXBP), isophthalic acid bis[(3-ethyl-3-oxetanyl)methyl]ester (OXIPA), etc. These may be used alone or in combination of two or more.

[0032] As the oxetane compound, commercially available products can be used. Examples of the commercially available products include the "ARON OXETANE (registered trademark)" series sold by Toagosei Co., Ltd. and the "ETERNACOLL (registered trademark)" series sold by Ube Industries, Ltd.

[0033] Among the above-mentioned oxirane ring compounds and oxetane compounds, glycidyl ether type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, phenol-dicyclopentadiene type epoxy resins, bisphenol A type epoxy resins, aliphatic epoxy resins, 4,4'-bis[(3-ethyl-3-oxetanyl)methoxymethyl]biphenyl (OXBP), and isophthalic acid bis[(3-ethyl-3-oxetanyl)methyl]ester (OXIPA) are preferred.

[0034] The content of the curing component is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.5% by mass or more and 60% by mass or less based on the total amount of the thermal conductive composition.

[0035] <Thermal conductive particles> The thermally conductive particles are preferably at least one of copper particles, silver-coated particles, and silver particles. Examples of the silver-coated particles include silver-coated copper particles, silver-coated nickel particles, and silver-coated aluminum particles. The shape of the thermally conductive particles is not particularly limited and may be appropriately selected depending on the purpose. Examples of the shape include spherical, flat, granular, and acicular shapes. The volume average particle diameter of the thermally conductive particles is preferably 10 μm to 300 μm, more preferably 20 μm to 100 μm. When the volume average particle diameter of the thermally conductive particles is 10 μm to 300 μm, the volume ratio of the thermally conductive particles to the low-melting-point metal particles can be increased, and the thermally conductive composition can have high thermal conductivity and low thermal resistance. The volume average particle size can be measured, for example, by a laser diffraction / scattering type particle size distribution measuring device (device name: Microtrac MT3300EXII, manufactured by Microtrac Bell Co., Ltd.).

[0036] <Low melting point metal particles> As the low melting point metal particles, solder particles as specified in JIS Z3282-1999 are preferably used. Examples of the solder particles include Sn-Pb solder particles, Pb-Sn-Sb solder particles, Sn-Sb solder particles, Sn-Pb-Bi solder particles, Sn-Bi solder particles, Sn-Bi-Ag solder particles, Sn-Cu solder particles, Sn-Pb-Cu solder particles, Sn-In solder particles, Sn-Ag solder particles, Sn-Pb-Ag solder particles, Pb-Ag solder particles, Sn-Ag-Cu solder particles, etc. These may be used alone or in combination of two or more. Among these, solder particles containing Sn and at least one selected from Bi, Ag, Cu, and In are preferred, and Sn-Bi based solder particles, Sn-Bi-Ag based solder particles, Sn-Ag-Cu based solder particles, and Sn-In based solder particles are more preferred.

[0037] The shape of the low melting point metal particles is not particularly limited and may be appropriately selected depending on the purpose. Examples of the shape include spherical, flat, granular, and acicular shapes. The melting point of the low-melting-point metal particles is preferably 100°C or higher and 250°C or lower, and more preferably 120°C or higher and 200°C or lower. It is preferable that the melting point of the low-melting point metal particles is lower than the thermal curing temperature of the thermal conductive composition, because the low-melting point metal particles melted in the cured product of the thermal conductive composition can form a network (continuous metal phase) via the thermal conductive particles, thereby achieving high thermal conductivity and low thermal resistance. The low melting point metal particles react with the thermal conductive particles under the conditions of the thermal curing treatment of the thermal conductive composition to form an alloy having a higher melting point than the low melting point metal particles, which prevents melting at high temperatures and improves reliability and heat resistance of the cured product of the thermal conductive composition. The thermal curing treatment of the thermal conductive composition is carried out, for example, at a temperature of 150° C. to 200° C. for 30 minutes to 2 hours.

[0038] The volume average particle diameter of the low-melting-point metal particles is preferably 10 μm or less, more preferably 1 μm or more and 5 μm or less. When the volume average particle diameter of the low-melting-point metal particles is 10 μm or less, the volume ratio of the low-melting-point metal particles to the thermal conductive particles can be reduced, and the thermal conductive composition can achieve high thermal conductivity and low thermal resistance. The volume average particle size of the low-melting point metal particles can be measured in the same manner as the volume average particle size of the thermally conductive particles.

[0039] <Radical polymerization initiator> Examples of the radical polymerization initiator include aromatic ketones, acylphosphine oxide compounds, aromatic onium salt compounds, organic peroxides, thio compounds (thioxanthone compounds, thiophenyl group-containing compounds, etc.), hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, compounds having a carbon-halogen bond, alkylamine compounds, etc. Among these, organic peroxides are preferred. The organic peroxide is not particularly limited and can be appropriately selected depending on the purpose. Examples of the organic peroxide include benzoyl peroxide, lauryl peroxide, t-butyl peroxide, and cumene hydroperoxide. The content of the radical polymerization initiator in the thermal conductive composition is not particularly limited and can be appropriately selected depending on the purpose.

[0040] <Other ingredients> The thermal conductive composition may contain other components as long as the effects of the present invention are not impaired. The other components are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include flux components, non-metallic thermal conductive particles (e.g., aluminum nitride, alumina, carbon fiber, etc.), and additives (e.g., antioxidants, ultraviolet absorbers, curing accelerators, silane coupling agents, leveling agents, flame retardants, etc.).

[0041] -Flux components- As the flux component, it is preferable to use a carboxylic acid such as levulinic acid, maleic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, etc. This allows good solder connection to be obtained and also allows the hardening component to function as a hardening agent. In addition, a blocked carboxylic acid in which the carboxyl group is blocked with an alkyl vinyl ether may be used as the flux component. This allows the temperature at which the flux effect and hardener function are exerted to be controlled. In addition, since the solubility in resin is improved, mixing and coating unevenness during film formation can be improved.

[0042] The thermally conductive composition of the present invention can be prepared by uniformly mixing the (meth)acrylic group-containing polycarboxylic acid compound of the present invention, a curing component, thermally conductive particles, low-melting point metal particles, a radical polymerization initiator, and, if necessary, other components, by a conventional method.

[0043] The thermally conductive composition may be either a thermally conductive sheet in sheet form or a thermally conductive paste in paste form (also called a thermally conductive adhesive or a thermally conductive grease). Among these, a thermally conductive sheet is preferred from the viewpoint of ease of handling, and a thermally conductive paste is preferred from the viewpoint of cost.

[0044] (Thermal Conduction Sheet) The thermally conductive sheet of the present invention contains a cured product of the thermally conductive composition of the present invention and is formed into a sheet from the thermally conductive composition of the present invention. From the viewpoint of thinning, the average thickness of the heat conductive sheet is preferably 500 μm or less, more preferably 200 μm or less, and even more preferably 100 μm or less. The lower limit of the average thickness of the heat conductive sheet is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 50 μm or more.

[0045] The method for producing the thermally conductive sheet is not particularly limited and may be appropriately selected depending on the purpose, and examples thereof include (1) a method in which the thermally conductive composition is molded into a predetermined shape and cured to form a thermally conductive molded body, and the obtained thermally conductive molded body is sliced ​​into sheets to produce a thermally conductive sheet, and (2) a method in which a cured product layer containing a cured product of the thermally conductive composition is formed on a support with a release layer to produce a thermally conductive sheet, etc. In the above (2), the support is peeled off when the thermally conductive sheet is laminated on the heat dissipation substrate.

[0046] The thermally conductive composition and thermally conductive sheet of the present invention can be suitably used, for example, as a thermal interface material (TIM1) that fills the minute gap between a heat source such as an LSI and a heat sink, thereby allowing heat to flow smoothly between the two, and can be suitably used when adhering a heat dissipation substrate on which an LED chip or an IC chip is mounted to a heat sink to form a power LED module or a power IC module. Here, the power LED module is classified into a wire bonding mounting type and a flip chip mounting type, and the power IC module is classified into a wire bonding mounting type.

[0047] <Heat dissipation structure> The heat dissipation structure used in the present invention is composed of a heat generating body, a thermally conductive material, and a heat dissipation member, and has a cured product of the thermally conductive composition of the present invention between the heat generating body and the heat dissipation member as the heat conductive material.

[0048] The heating element is not particularly limited and can be appropriately selected depending on the purpose. Examples of the heating element include electronic components such as a central processing unit (CPU), a micro processing unit (MPU), and a graphics processing unit (GPU).

[0049] The heat dissipation member is not particularly limited as long as it is a structure that dissipates heat generated by an electronic component (heat generating body), and can be appropriately selected depending on the purpose. Examples of the heat dissipation member include a heat spreader, a heat sink, a vapor chamber, and a heat pipe. The heat spreader is a member for efficiently transferring heat from the electronic component to other components. The material of the heat spreader is not particularly limited and can be appropriately selected depending on the purpose, and examples of the material include copper and aluminum. The heat spreader is usually in a flat plate shape. The heat sink is a member for releasing heat from the electronic component into the air. The material of the heat sink is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include copper and aluminum. The heat sink has, for example, a plurality of fins. The heat sink has, for example, a base portion and a plurality of fins provided so as to extend in a non-parallel direction (for example, a direction perpendicular to) one surface of the base portion. The heat spreader and the heat sink are generally solid structures with no internal voids. The vapor chamber is a hollow structure. A volatile liquid is sealed in the internal space of the hollow structure. Examples of the vapor chamber include a hollow structure of the heat spreader, a hollow plate-shaped structure of the heat sink, and the like. The heat pipe is a hollow structure having a cylindrical, approximately cylindrical, or flattened tubular shape, and a volatile liquid is sealed in the internal space of the hollow structure.

[0050] Here, Fig. 1 is a schematic cross-sectional view showing an example of a semiconductor device as a heat dissipation structure. A cured product (thermal conductive sheet) 1 of the thermal conductive composition of the present invention dissipates heat generated by an electronic component 3 such as a semiconductor element, and is fixed to a main surface 2a of a heat spreader 2 facing the electronic component 3, as shown in Fig. 1, and is sandwiched between the electronic component 3 and the heat spreader 2. The thermal conductive sheet 1 is also sandwiched between the heat spreader 2 and a heat sink 5. The thermal conductive sheet 1, together with the heat spreader 2, constitutes a heat dissipation member that dissipates heat from the electronic component 3.

[0051] The heat spreader 2 is formed, for example, in the shape of a rectangular plate, and has a main surface 2a facing the electronic component 3, and a side wall 2b erected along the outer periphery of the main surface 2a. The heat spreader 2 has a thermally conductive sheet 1 provided on the main surface 2a surrounded by the side wall 2b, and a heat sink 5 provided on the other surface 2c opposite the main surface 2a via the thermally conductive sheet 1. The higher the thermal conductivity of the heat spreader 2, the lower the thermal resistance and the more efficiently it absorbs heat from the electronic component 3 such as a semiconductor element, so the heat spreader 2 can be formed, for example, using copper or aluminum, which have good thermal conductivity.

[0052] The electronic component 3 is, for example, a semiconductor element such as a BGA, and is mounted on the wiring board 6. The tip surface of the side wall 2b of the heat spreader 2 is also mounted on the wiring board 6, so that the side wall 2b surrounds the electronic component 3 at a predetermined distance. Then, by bonding the thermally conductive sheet 1 to the main surface 2a of the heat spreader 2, a heat dissipation member that absorbs heat generated by the electronic components 3 and dissipates the heat through the heat sink 5 is formed. EXAMPLES

[0053] Examples of the present invention will be described below, but the present invention is not limited to these examples. In the following synthesis examples, examples, and comparative examples, the volume average particle size of the thermally conductive particles and the low-melting-point metal particles, the FT-IR absorption of the (meth)acrylic group-containing polycarboxylic acid compound, and 13C-NMR spectrum was measured.

[0054] <Volume average particle size of thermally conductive particles and low-melting-point metal particles> The volume average particle size of the thermally conductive particles and the low-melting-point metal particles was measured using a laser diffraction / scattering type particle size distribution measuring device (device name: Microtrac MT3300EXII, manufactured by Microtrac-Bell Corporation).

[0055] <Measurement of FT-IR absorption of (meth)acrylic group-containing polycarboxylic acid compound> The FT-IR absorption of the (meth)acrylic group-containing polycarboxylic acid compound was measured by the ATR method using a Nicolet iS10 manufactured by Thermo Fisher Scientific K.K.

[0056] <(Meth)acrylic group-containing polycarboxylic acid compound 13 C-NMR spectrum measurement (Meth)acrylic group-containing polycarboxylic acid compound 13 C-NMR spectra were measured using a JNM-ECZ400R / S3 nuclear magnetic resonance spectrometer (JEOL RESONANCE).

[0057] (Synthesis Example 1) <Synthesis of acrylic group-containing tricarboxylic acid compound> In a three-necked glass flask equipped with a thermocouple, a stirrer, a cooling tube, and a heating device, 68.0 parts by mass of 2-acryloyloxyethyl isocyanate (manufactured by Showa Denko K.K., Karenz AOI) and 50 parts by mass of 2-butanone (ultra-dehydrated) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and thoroughly stirred to completely dissolve. After complete dissolution, 50 parts by mass of citric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) represented by the following structural formula was weighed and dropped in a solid form into the three-necked flask using a funnel. Since a side reaction occurs when the temperature rises, the above was kept constant at 30°C and stirred for 24 hours until the reaction was completely completed. The obtained synthetic product was cooled to room temperature, transferred to a recovery flask, concentrated with an evaporator, and then dried under reduced pressure (30°C for 48 hours) to synthesize the desired acrylic group-containing tricarboxylic acid compound (yield 93%). The FT-IR absorption of the obtained acrylic group-containing tricarboxylic acid compound of Synthesis Example 1 was measured to confirm the peaks before and after synthesis. -1 ~2240cm -1 ) was confirmed to have disappeared.

[0058] [Citric acid] [ka]

[0059] <Identification data> The FT-IR absorption of the acrylic group-containing tricarboxylic acid compound of Synthesis Example 1 is shown below. 809cm -1 , 982cm -1 , 1064cm -1 , 1181cm -1 , 1268cm -1 , 1408cm -1 , 1557cm -1 , 1713cm -1 and 2700 cm -1 ~3700cm -1 A broad absorption vibration due to carboxylic acid was observed.

[0060] The obtained acrylic group-containing tricarboxylic acid compound of Synthesis Example 113 The C-NMR peaks are shown below. 13 C-NMR(CDCl3,δppm);39.49(15),39.83(15),40.13(3;8),40.46(3,8),40.79(3;8),62.08(16),62.44(16),62.80(1 6),76.75(2),127.82(22)131.10(23),131.51(23),131.92(23),154.27(6),165.71(18),173.05(11),173.34(4;9)

[0061] the above 13 The numbers in parentheses for the C-NMR peaks are as follows: [ka]

[0062] (Synthesis Example 2) <Synthesis of methacrylic group-containing tricarboxylic acid compound> A methacryl group-containing tricarboxylic acid compound was synthesized (yield 93%) in the same manner as in Synthesis Example 1, except that 2-acryloyloxyethyl isocyanate (Showa Denko K.K., Karenz AOI) was replaced with 2-methacryloyloxyethyl isocyanate (Showa Denko K.K., Karenz MOI). The FT-IR absorption of the methacryl group-containing tricarboxylic acid compound obtained in Synthesis Example 2 was measured to confirm the peaks before and after synthesis, and the NCO peak (approximately 2270 cm -1 ~2240cm -1 ) was confirmed to have disappeared.

[0063] <Identification data> The FT-IR absorption of the methacryl group-containing tricarboxylic acid compound of Synthesis Example 2 is shown below. 810cm -1 , 983cm -1 , 1067cm -1 , 1126cm -1 , 1182cm -1 , 1270cm -1, 1336cm -1 , 1408cm -1 , 1566cm -1 , 1634cm -1 , 1703cm -1 and 2700 cm -1 ~3700cm -1 A broad absorption vibration due to carboxylic acid was observed.

[0064] The methacrylic group-containing tricarboxylic acid compound obtained in Synthesis Example 2 13 The C-NMR peaks are shown below. 13 C-NMR(CDCl3,δppm);17.75(23),39.26(15),39.60(15),40.13(3;8),40.46(3;8),40.79(3;8),62.48(16),62.84(1 6),63.20(16),76.75(2),125.52(24),125.92(24),126.32(24),135.76(22),166.52(18),173.05(11),173.34(4;9)

[0065] the above 13 The numbers in parentheses for the C-NMR peaks are as follows: [ka]

[0066] (Synthesis Example 3) <Synthesis of acrylic group-containing dicarboxylic acid compound> An acrylic group-containing dicarboxylic acid compound was synthesized (yield 93%) in the same manner as in Synthesis Example 1, except that 50 parts by mass of citric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was replaced with 26.6 parts by mass of L(+)-tartaric acid (manufactured by Kanto Chemical Co., Ltd.) represented by the following structural formula. The FT-IR absorption of the acrylic group-containing dicarboxylic acid compound of Synthesis Product 3 was measured to confirm the peaks before and after synthesis, and the NCO peak (approximately 2270 cm -1 ~2240cm -1 ) was confirmed to have disappeared.

[0067] [Tartaric acid] [ka]

[0068] <Identification data> The FT-IR absorption of the acrylic group-containing dicarboxylic acid compound of Synthesis Product 3 is shown below. 810cm -1 , 987cm -1 , 1081cm -1 , 1121cm -1 , 1218cm -1 , 1383cm -1 , 1409cm -1 , 1634cm -1 , 1722cm -1 and 2700 cm -1 ~3700cm -1 A broad absorption vibration due to carboxylic acid was observed.

[0069] The obtained synthetic product 3 is an acrylic group-containing dicarboxylic acid compound. 13 The C-NMR peaks are shown below. 13 C-NMR(CDCl3,δppm);40.03(20;40),61.99(21;15),62.35(21;15),62.71(21;15),73.62(2;3),73.99 (2;3),127.82(29;27),131.10(30;28),131.51(30;28),131.92(30;28),154.11(7;5),170.61(9;11)

[0070] the above 13 The numbers in parentheses for the C-NMR peaks are as follows: [ka]

[0071] Example 1 As a base resin, 3.26 volume % of the acrylic group-containing tricarboxylic acid compound of Synthesis Example 1, 2.24 volume % of a low melting point flux (P303K, manufactured by Dexerials Corporation), and 2.24 volume % of an oxetane compound (OXBP, manufactured by UBE Corporation) were added, and further, 56.30 volume % of Ag-coated Cu particles (manufactured by Fukuda Metal Foil & Powder Co., Ltd., volume average particle size Dv: 40 μm) as thermal conductive particles and Sn as low melting point metal particles were added. 58 Bi 42 35.96% by volume of particles (manufactured by Mitsui Mining & Smelting Co., Ltd., volume average particle size Dv: 4 μm) were added and mixed uniformly using a stirring device (Awatori Rentaro Automatic Revolving Mixer, manufactured by Thinky Corporation). Furthermore, 0.025% by volume of a radical polymerization initiator (Perloyl TCP, manufactured by NOF Corporation) was added and stirred well to prepare the thermal conductive composition of Example 1. The obtained thermally conductive composition was applied by bar coating onto a 38 μm-thick release film (38GS, manufactured by Lintec Corporation), heated at 80° C. for 15 minutes, and dried to produce a thermally conductive sheet with an average thickness of 100 μm.

[0072] Example 2 A thermal conductive composition and a thermal conductive sheet of Example 2 were prepared in the same manner as in Example 1, except that the acrylic group-containing tricarboxylic acid compound of Synthesis Example 1 in Example 1 was replaced with the methacrylic group-containing tricarboxylic acid compound of Synthesis Example 2.

[0073] Example 3 A thermal conductive composition and a thermal conductive sheet of Example 3 were prepared in the same manner as in Example 1, except that the acrylic group-containing tricarboxylic acid compound of Synthesis Example 1 in Example 1 was replaced with the acrylic group-containing dicarboxylic acid compound of Synthesis Example 3.

[0074] Example 4 A thermal conductive composition and a thermal conductive sheet of Example 4 were prepared in the same manner as in Example 1, except that the content of the acrylic group-containing tricarboxylic acid compound in Synthesis Example 1 was changed from 3.26 vol.% to 1 vol.%.

[0075] Example 5 The thermal conductive composition and thermal conductive sheet of Example 5 were prepared in the same manner as in Example 1, except that the content of the acrylic group-containing tricarboxylic acid compound in Synthesis Example 1 was changed from 3.26 vol.% to 10 vol.%.

[0076] Comparative Example 1 A thermally conductive composition and a thermally conductive sheet of Comparative Example 1 were prepared in the same manner as in Example 1, except that the 3.26 vol% of the acrylic group-containing tricarboxylic acid compound in Synthesis Example 1 was changed to 3.26 vol% of M-1276 (polyamide resin, manufactured by Arkema K.K.) and no radical polymerization initiator (Perloyl TCP, manufactured by NOF Corporation) was added.

[0077] Comparative Example 2 A thermally conductive composition and a thermally conductive sheet of Comparative Example 2 were prepared in the same manner as in Example 1, except that the 3.26 vol% of the acrylic group-containing tricarboxylic acid compound in Synthesis Example 1 was changed to 3.26 vol% of an acrylic monomer (UA-306H, manufactured by Kyoeisha Chemical Co., Ltd.).

[0078] <Preparation of cured product> Next, a 0.125 mm spacer was placed between two 30 mm x 30 mm x 2 mm aluminum plates (A5052P), and each thermal conductive composition punched out to a diameter of 20 mm was sandwiched between them. The plates were then oven-cured at 150°C for 60 minutes to obtain a cured product (interface Al) of each thermal conductive composition.

[0079] Next, the adhesiveness and thermal conductivity of each of the obtained cured products were evaluated as follows. The results are shown in Tables 1 and 2.

[0080] <Adhesiveness> The cured product of each thermal conductive composition was heated on a hot plate heated to 130° C. for 1 minute, and the state of peeling was checked, and the adhesion was evaluated according to the following criteria. [Evaluation Criteria] A: The two aluminum plates cannot be peeled apart. B: Can be peeled off using pliers etc. C: Two aluminum plates can be easily peeled apart by shifting them apart.

[0081] <Thermal conductivity> A 0.125 mm spacer was placed between two copper plates measuring 30 mm x 30 mm x 2 mm, and each thermal conductive composition punched out to a diameter of 20 mm was sandwiched between them. The plates were then oven-cured at 150°C for 60 minutes, and the thermal resistance (°C cm) of the cured product (interface Cu) of each thermal conductive composition was measured using a method in accordance with ASTM-D5470. 2 The thermal resistance of the cured product was calculated by subtracting the thermal resistance of the copper plate from the results, and the thermal conductivity (W / m K) was calculated from the thermal resistance and the thickness of the cured product, and was evaluated according to the following criteria. [Evaluation Criteria] A: Thermal conductivity is 11.0 W / m K or more B: Thermal conductivity is 8.0 W / m K or more and less than 11.0 W / m K C: Thermal conductivity is less than 8.0 W / m K

[0082] [Table 1]

[0083] [Table 2]

[0084] Details of each component in Tables 1 and 2 are as follows. *Acrylic monomer: UA-306H, manufactured by Kyoeisha Chemical Co., Ltd., pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer *Polyamide resin: M-1276, manufactured by Arkema Co., Ltd. *P303K: Low melting point flux, manufactured by Dexerials Corporation *OXBP: Oxetane compound, manufactured by UBE Corporation, 4,4'-bis[(3-ethyl-3-oxetanyl)methoxymethyl]biphenyl *Heat conductive particles: Ag-coated Cu particles, manufactured by Fukuda Metal Foil and Powder Co., Ltd., volume average particle size Dv: 40 μm *Low melting point metal particles: Sn 58 Bi 42 Particles, Mitsui Mining & Smelting Co., Ltd., Volume average particle size Dv: 4μm *Radical polymerization initiator: Perloyl TCP, manufactured by NOF Corporation [Industrial Applicability]

[0085] The thermally conductive composition and thermally conductive sheet of the present invention using the (meth)acrylic group-containing polycarboxylic acid compound of the present invention can exhibit high adhesive strength and a good flux effect, and can achieve high thermal conductivity, and therefore are suitably used, for example, around various electric devices such as CPUs, MPUs, power transistors, LEDs, laser diodes, various batteries (various secondary batteries such as lithium ion batteries, various fuel cells, capacitors, amorphous silicon, crystalline silicon, compound semiconductors, various solar cells such as wet solar cells, etc.) whose element operation efficiency and lifespan are adversely affected by temperature, around the heat source of heating equipment where effective use of heat is required, around heat exchangers, and around the heat piping of floor heating equipment, etc. [Explanation of symbols]

[0086] 1. Thermally conductive materials (thermally conductive sheets) 2 Heat dissipation material (heat spreader) 2a Main surface 3 Heating elements (electronic components) 3a Top side 5. Heat dissipation components (heat sinks) 6 Wiring board

Claims

1. A (meth)acrylic group-containing polycarboxylic acid compound characterized by being represented by at least one of the following general formula (1) and the following general formula (2). 【Chemical 1】 However, in the general formula (1), R １ and R ３ represent an alkylene group. R ２ represents a single bond or an alkylene group. R ４ represents an alkylene group. -OCO-A represents an acrylic group or a methacrylic group. [Chemical Formula 2] However, in the general formula (2), R １ and R ２ represent an alkylene group. R ４ represents an alkylene group. R ５ represents a hydrogen atom or an alkylene group. -OCO-A represents an acrylic group or a methacrylic group.

2. In the general formula (1), the R ２ is a single bond, and the R １ and the R ３ are -CH ２ -. The (meth)acrylic group-containing polycarboxylic acid compound according to claim 1.

3. Said R ４ is an ethylene group, and the (meth)acrylic group-containing polycarboxylic acid compound according to any one of claims 1 to 2.

4. The (meth)acrylic group-containing polycarboxylic acid compound according to any one of Claims 1 to 2, having flux activity.

5. A thermal conduction composition comprising the (meth)acrylic group-containing polycarboxylic acid compound according to any one of Claims 1 to 2, a curing component, a radical polymerization initiator, thermal conduction particles, and low melting point metal particles.

6. The thermal conduction composition according to Claim 5, wherein the content of the (meth)acrylic group-containing polycarboxylic acid compound is 1% by volume or more and 10% by volume or less.

7. The thermal conduction composition according to Claim 5, wherein the curing component is at least one of an oxirane ring compound and an oxetane compound.

8. The thermal conduction composition according to Claim 5, wherein the thermal conduction particles are at least one of copper particles, silver-coated particles, and silver particles.

9. The thermal conduction composition according to Claim 5, wherein the low melting point metal particles contain Sn and at least one selected from Bi, Ag, Cu, and In.

10. A thermal conduction sheet comprising a cured product of the thermal conduction composition according to Claim 5.

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