JP2012238819A - Thermally conductive sheet, insulating sheet and heat dissipating member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermally conductive sheet which is obtained by easy operation and has excellent thermal conductivity in both the thickness direction and the surface direction, and to provide an insulating sheet and a heat dissipating member obtained by using the thermally conductive sheet.SOLUTION: A thermally conductive sheet 1 includes a resin 3 and a plate like or scale like filler 2. In the thermally conductive sheet 1, the average orientation angle of the filler 2 with respect to a surface direction SD of the thermally conductive sheet 1 is set to 29 degrees or larger, and the maximum orientation angle is 65 degrees or larger. Further, an insulating sheet and a heat dissipating member are obtained by using the thermally conductive sheet 1.

Description

  The present invention relates to a heat conductive sheet, an insulating sheet, and a heat radiating member, and more particularly to a heat conductive sheet used for power electronics technology and the like, and an insulating sheet and a heat radiating member obtained using the heat conductive sheet.

  In recent years, power electronics technology that converts and controls electric power using a semiconductor element has been adopted in hybrid devices, high-brightness LED devices, electromagnetic induction heating devices, and the like. In power electronics technology, in order to convert a large current into heat or the like, a material disposed in the vicinity of a semiconductor element is required to have high heat dissipation (high thermal conductivity) and insulation.

  For example, a thermally conductive sheet obtained by dispersing an inorganic filler having thermal conductivity and insulating properties, for example, flaky boron nitride, in a resin is known.

  Since the scaly boron nitride has a high thermal conductivity in the longitudinal direction and a low thermal conductivity in the short direction, for example, if the longitudinal direction of boron nitride is along the thickness direction of the thermal conductive sheet, The thermal conductivity in the thickness direction can be improved, and if the longitudinal direction of boron nitride is aligned with the surface direction of the heat conductive sheet, the thermal conductivity in the surface direction can be improved.

  However, when a heat conductive sheet is produced by press molding or roll molding, boron nitride is likely to be along the surface direction of the heat conductive sheet, and thus the obtained heat conductive sheet is excellent in surface direction heat conductivity, There is a problem that the thermal conductivity in the thickness direction is inferior.

  On the other hand, the thermal conductive sheet may be required to have thermal conductivity not only in the surface direction but also in the thickness direction depending on the application.

  Therefore, for example, secondary agglomerated particles obtained by aggregating primary particles of boron nitride and having a porosity of 50% or less and an average pore diameter of 0.05 to 3 μm are obtained by dispersing them in a thermosetting resin. A thermally conductive sheet has been proposed (see, for example, Patent Document 1).

  In this heat conductive sheet, boron nitride is contained as secondary aggregated particles, that is, contained without being oriented in the thickness direction or the surface direction of the heat conductive sheet. Sex can be secured.

JP 2010-157563 A

  However, in order to obtain the heat conductive sheet described in Patent Document 1, it is necessary to produce secondary agglomerated particles of boron nitride. For this reason, for example, boron nitride is calcined and pulverized at a high temperature, and then slurried. Thereafter, there is a problem that a complicated process such as firing is required.

  An object of the present invention is to provide a thermal conductive sheet that can be obtained by a simple operation and has excellent thermal conductivity in the thickness direction and in the plane direction, and an insulating sheet and a heat dissipation member obtained by using such a thermal conductive sheet. There is to do.

  In order to achieve the above object, the thermally conductive sheet of the present invention is a thermally conductive sheet containing a resin and a plate-like or scale-like filler, and is in the plane direction of the thermally conductive sheet. The filler has an average orientation angle of 29 degrees or more and a maximum orientation angle of 65 degrees or more.

  In the thermally conductive sheet of the present invention, the resin contains a first resin and a second resin, and the difference between the softening temperature of the first resin and the softening temperature of the second resin is 20 ° C. It is suitable that it is above.

  In the thermally conductive sheet of the present invention, the difference between the softening temperature of the first resin and the softening temperature of the second resin is 40 ° C. or more, and the second resin has an average particle diameter of 10 to 10 ° C. It is preferably 500 μm, and the shape is retained at a temperature between the softening temperature of the first resin and the softening temperature of the second resin.

  Moreover, in the heat conductive sheet of this invention, it is suitable that content of the said filler is 50-95 mass parts with respect to 100 mass parts of total amounts of the said heat conductive sheet.

  Moreover, the insulating sheet of the present invention is characterized by being obtained using the above-described heat conductive sheet.

  Moreover, the heat radiating member of this invention is obtained using said heat conductive sheet, It is characterized by the above-mentioned.

  In the heat conductive sheet, insulating sheet and heat dissipation member of the present invention, the plate-like or scale-like filler is contained so that the average orientation angle is 29 degrees or more and the maximum orientation angle is 65 degrees or more. Thermal conductivity in the thickness direction and the surface direction of the conductive sheet can be ensured.

  Therefore, it can be used for various uses as a heat conductive sheet, an insulating sheet, and a heat dissipation member that are excellent in heat conductivity in the thickness direction and in the surface direction.

The perspective view of one Embodiment of the heat conductive sheet of this invention is shown. The X-ray CT image of the heat conductive sheet of Example 1 is shown. The frequency distribution map of the orientation angle obtained by analyzing the X-ray CT image of the heat conductive sheet of Example 1 is shown. The X-ray CT image of the heat conductive sheet of Example 2 is shown. The frequency distribution map of the orientation angle obtained by analyzing the X-ray CT image of the heat conductive sheet of Example 2 is shown. The X-ray CT image of the heat conductive sheet of Example 4 is shown. The frequency distribution figure of the orientation angle obtained by analyzing the X-ray CT image of the heat conductive sheet of Example 4 is shown. The X-ray CT image of the heat conductive sheet of the comparative example 1 is shown. The frequency distribution figure of the orientation angle obtained by analyzing the X-ray CT image of the heat conductive sheet of the comparative example 1 is shown.

  The thermally conductive sheet of the present invention contains a resin and a filler.

  The resin can disperse the filler, that is, a dispersion medium (matrix) in which the filler is dispersed, and examples thereof include a thermosetting resin and a thermoplastic resin.

  Examples of the thermosetting resin include epoxy resins, thermosetting polyimides, phenol resins, urea resins, melamine resins, unsaturated polyester resins, diallyl phthalate resins, silicone resins, thermosetting urethane resins, and the like.

  Examples of the thermoplastic resin include polyolefin (for example, polyethylene, polypropylene, ethylene-propylene copolymer), acrylic resin (for example, polymethyl methacrylate), polyvinyl acetate, ethylene-vinyl acetate copolymer, poly Vinyl chloride, polystyrene, polyacrylonitrile, polyamide (nylon (registered trademark)), polycarbonate, polyacetal, polyethylene terephthalate, polyphenylene oxide, polyphenylene sulfide, polysulfone, polyethersulfone, polyetheretherketone, polyallylsulfone, thermoplastic polyimide, heat Plastic urethane resin, polyamino bismaleimide, polyamideimide, polyetherimide, bismaleimide triazine resin, polymethylpentene, fluoride tree , Liquid crystal polymers, olefin - vinyl alcohol copolymer, ionomer, polyarylate, acrylonitrile - ethylene - Styrene copolymer, acrylonitrile - butadiene - styrene copolymer, acrylonitrile - styrene copolymer.

  Of the thermosetting resins, an epoxy resin is preferable.

  The epoxy resin is in a liquid, semi-solid, or solid form at normal temperature.

  Specifically, as the epoxy resin, for example, bisphenol type epoxy resin (for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, water-added bisphenol A type epoxy resin, dimer acid modified bisphenol type) Epoxy resin), novolak epoxy resin (eg, phenol novolac epoxy resin, cresol novolac epoxy resin, biphenyl epoxy resin), naphthalene epoxy resin, fluorene epoxy resin (eg, bisarylfluorene epoxy resin, etc.) ), Aromatic epoxy resins such as triphenylmethane type epoxy resin (for example, trishydroxyphenylmethane type epoxy resin), for example, triepoxypropyl isocyanurate (Triglycidyl isocyanurate), nitrogen-containing ring epoxy resins such as hydantoin epoxy resins, for example, aliphatic type epoxy resins, for example, alicyclic epoxy resins (for example, dicyclocyclic type epoxy resins), for example, glycidyl ether type An epoxy resin, for example, a glycidylamine type epoxy resin can be used.

  These epoxy resins can be used alone or in combination of two or more.

  The epoxy resin has an epoxy equivalent of, for example, 100 to 1000 g / eqiv. , Preferably, 150 to 700 g / eqiv. It is.

  Moreover, the melt viscosity at 80 ° C. of the epoxy resin is, for example, 10 to 20000 mPa · s, and preferably 50 to 10000 mPa · s.

  Moreover, an epoxy resin can be prepared as an epoxy resin composition by containing a hardening | curing agent and a hardening accelerator, for example.

  The curing agent is a latent curing agent (epoxy resin curing agent) that can cure the epoxy resin by heating. For example, an imidazole compound, an amine compound, an acid anhydride compound, an amide compound, a hydrazide compound, an imidazoline compound, and the like. Is mentioned. In addition to the above, phenol compounds, urea compounds, polysulfide compounds and the like can also be mentioned.

  Examples of the imidazole compound include 2-phenylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and the like.

  Examples of the amine compound include aliphatic polyamines such as ethylenediamine, propylenediamine, diethylenetriamine, and triethylenetetramine, and aromatic polyamines such as metaphenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone.

  Examples of the acid anhydride compound include phthalic anhydride, maleic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 4-methyl-hexahydrophthalic anhydride, methyl nadic acid anhydride, and pyromellitic acid. Anhydride, dodecenyl succinic anhydride, dichlorosuccinic anhydride, benzophenone tetracarboxylic acid anhydride, chlorendic acid anhydride and the like can be mentioned.

  Examples of the amide compound include dicyandiamide and polyamide.

  Examples of the hydrazide compound include adipic acid dihydrazide.

  Examples of the imidazoline compound include methyl imidazoline, 2-ethyl-4-methyl imidazoline, ethyl imidazoline, isopropyl imidazoline, 2,4-dimethyl imidazoline, phenyl imidazoline, undecyl imidazoline, heptadecyl imidazoline, 2-phenyl-4-methyl. Examples include imidazoline.

  These curing agents can be used alone or in combination of two or more.

  As the curing agent, an imidazole compound is preferable.

  Examples of the curing accelerator include tertiary amine compounds such as triethylenediamine and tri-2,4,6-dimethylaminomethylphenol, such as triphenylphosphine, tetraphenylphosphonium tetraphenylborate, tetra-n-butylphosphonium- Phosphorus compounds such as o, o-diethyl phosphorodithioate, for example, quaternary ammonium salt compounds, for example, organometallic salt compounds, for example, derivatives thereof and the like can be mentioned. These curing accelerators can be used alone or in combination of two or more.

  The compounding ratio of the curing agent in the epoxy resin composition is, for example, 0.5 to 50 parts by mass, preferably 1 to 10 parts by mass with respect to 100 parts by mass of the epoxy resin. For example, 0.1 to 10 parts by mass, preferably 0.2 to 5 parts by mass.

  The above-mentioned curing agent and / or curing accelerator can be prepared and used as a solvent solution and / or a solvent dispersion dissolved and / or dispersed with a solvent, if necessary.

  Examples of the solvent include organic solvents such as ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate, and amides such as N, N-dimethylformamide (DMF). Examples of the solvent also include aqueous solvents such as water, for example, alcohols such as methanol, ethanol, propanol, and isopropanol. The solvent is preferably an organic solvent, more preferably ketones and amides.

  Of the thermoplastic resins, polyolefin is preferable.

  Preferred examples of the polyolefin include polyethylene and ethylene-propylene copolymer.

  Examples of polyethylene include low density polyethylene and high density polyethylene.

  Examples of the ethylene-propylene copolymer include a random copolymer, a block copolymer, or a graft copolymer of ethylene and propylene.

  These polyolefins can be used alone or in combination of two or more.

  Moreover, the weight average molecular weight and / or number average molecular weight of polyolefin are 1000-10000, for example.

  Polyolefins can be used alone or in combination.

  The resin includes, for example, a polymer precursor (for example, a low molecular weight polymer including an oligomer) and / or a monomer.

  These resins can be used alone or in combination of two or more.

  Preferably, two or more kinds of the above-described resins are used in combination.

  In the case where two or more kinds of resins are used in combination, the resin contains a first resin and a second resin.

  The first resin is selected from the above resins. The first resin is preferably a thermosetting resin, more preferably an epoxy resin.

  These first resins can be used alone or in combination of two or more.

  The softening temperature (ring and ball method) of the first resin is, for example, 40 to 120 ° C, preferably 40 to 110 ° C, and more preferably 40 to 100 ° C.

  The average particle size of the first resin is defined as the average value of the particle size including the primary particle size and the secondary particle size (particle size of the secondary aggregate), and specifically, for example, 10 to 10,000 μm. The thickness is preferably 10 to 8000 μm, more preferably 10 to 6000 μm.

  In addition, the average particle diameter of 1st resin can be calculated | required by the image analysis etc. by a scanning electron microscope (SEM).

  As the second resin, a resin having a softening temperature (ring ball method) higher than the softening temperature (ring ball method) of the first resin is used.

  Such a second resin is selected from the above-described resins. The second resin is preferably a thermosetting resin having a higher softening temperature (ring ball method) than the softening temperature (ring ball method) of the first resin, and more preferably than the softening temperature of the first resin (ring ball method). And an epoxy resin having a high softening temperature (ring and ball method).

  These second resins can be used alone or in combination of two or more.

  The softening temperature of the second resin (ring and ball method (when two or more kinds of second resins are used in combination, the total temperature of the softening temperatures)) is the softening temperature of the first resin (ring and ball method (the first resin is 2 When two or more types are used in combination, for example, 20 ° C., preferably 40 ° C. higher than the total softening temperature)), the softening temperature of the first resin and the softening temperature of the second resin Specifically, the difference is, for example, 40 to 80 ° C, preferably 45 to 80 ° C, and more preferably 50 to 80 ° C.

  If the difference between the softening temperature of the first resin and the softening temperature of the second resin is in the above range, the orientation of the filler can be controlled.

  The softening temperature (ring and ball method) of the second resin is, for example, 100 to 180 ° C, preferably 110 to 170 ° C, and more preferably 110 to 160 ° C.

  The average particle diameter of the second resin is defined as the average value of the particle diameter including the primary particle diameter and the secondary particle diameter (particle diameter of the secondary aggregate), and specifically, for example, 10 to 800 μm. The thickness is preferably 10 to 500 μm, more preferably 10 to 300 μm.

  In addition, the average particle diameter of 2nd resin can be calculated | required by the image analysis etc. by a scanning electron microscope (SEM).

  If the average particle diameter of the second resin is within the above range, the orientation of the filler can be controlled.

Also, kinematic viscosity test (temperature: 25 ° C. ± 0.5 ° C., solvent: butyl carbitol, resin (solid content) concentration: 40% by mass) based on JIS K 7233 (foam viscometer method) (1986) of the resin Is, for example, 0.22 × 10 ^{−4 to} 2.00 × 10 ⁻⁴ m ² / s, preferably 0.3 × 10 ^{−4 to} 1.9 × 10 ⁻⁴ m ^2. / S, more preferably 0.4 × 10 ^{−4 to} 1.8 × 10 ⁻⁴ m ² / s. Further, the kinematic viscosity of the, for ^{example, 0.22 × 10 -4 ~1.00 × 10} -4 m 2 / s, ^{preferably, 0.3 × 10 -4 ~0.9 × 10} -4 m 2 / S, more preferably 0.4 × 10 ^{−4 to} 0.8 × 10 ⁻⁴ m ² / s.

  In addition, in the kinematic viscosity test based on JIS K 7233 (foam viscometer method) (1986), the rising speed of the foam in the resin sample is compared with the rising speed of the foam in the standard sample (kinematic viscosity is known). The dynamic viscosity of the resin is measured by determining that the dynamic viscosity of the standard sample with the matching speed is the dynamic viscosity of the resin.

  Examples of the filler include inorganic particles, and examples of such inorganic particles include carbides, nitrides, oxides, hydroxides, metals, and carbon-based materials.

  Examples of the carbide include silicon carbide, boron carbide, aluminum carbide, titanium carbide, and tungsten carbide.

  Examples of the nitride include silicon nitride, boron nitride, aluminum nitride, gallium nitride, chromium nitride, tungsten nitride, magnesium nitride, molybdenum nitride, and lithium nitride.

  Examples of the oxide include iron oxide, silicon oxide (silica), aluminum oxide (alumina) (including aluminum oxide hydrates (boehmite, etc.)), magnesium oxide, titanium oxide, cerium oxide, and zirconium oxide. Can be mentioned. Examples of the oxide include transition metal oxides such as barium titanate, and further doped with metal ions such as indium tin oxide and antimony tin oxide.

  Examples of the hydroxide include aluminum hydroxide, calcium hydroxide, and magnesium hydroxide.

  Examples of the metal include copper, gold, nickel, tin, iron, and alloys thereof.

  Examples of the carbon-based material include carbon black, graphite, diamond, fullerene, carbon nanotube, carbon nanofiber, nanohorn, carbon microcoil, and nanocoil.

  In addition, the inorganic particles may be surface-treated by a known method with a silane coupling agent, if necessary, from the viewpoint of fluidity.

  The shape of these fillers is plate-like, scale-like, spherical, massive, etc., depending on the production method, crystal structure, etc. In the present invention, the thermally conductive sheet contains at least a plate-like or scale-like filler. doing.

  Specific examples of the plate-like or scale-like filler include boron nitride (plate-like), aluminum oxide monohydrate (boehmite) (plate-like), and the like.

  These fillers can be used alone or in combination of two or more.

  The average particle diameter (length in the longitudinal direction) measured by the light scattering method of the filler is, for example, 10 to 1000 μm, preferably 10 to 500 μm, and more preferably 10 to 300 μm.

  Moreover, the length of the transversal direction of a filler is 0.1-300 micrometers, for example, Preferably, it is 0.1-100 micrometers. Further, the aspect ratio (length in the longitudinal direction / length in the short direction) is, for example, 1/100 to 1/10, and preferably 1/100 to 1/20.

  In addition, the average particle diameter measured by the light scattering method is a volume average particle diameter measured by a dynamic light scattering particle size distribution measuring apparatus.

  Moreover, a commercial item or the processed product which processed it can be used for a filler.

  Examples of commercially available products include commercially available products of boron nitride particles, and specific examples of commercially available products of boron nitride particles include the “PT” series (for example, Momentive Performance Materials Japan) (for example, , “PT-110”, etc.), “Shoby N UHP” series (for example, “Shoby N UHP-1”, etc.) manufactured by Showa Denko KK and the like.

  Moreover, the heat conductive sheet can also contain a spherical or lump filler, specifically, for example, aluminum oxide (spherical), aluminum hydroxide (lump), or the like at an appropriate ratio, if necessary.

  The content ratio (total amount) of the filler is, for example, 10 to 90 parts by mass, preferably 50 to 90 parts by mass, and more preferably 60 to 90 parts by mass with respect to 100 parts by mass of the total amount of the heat conductive sheet. .

  If the content rate of a filler is the said range, the outstanding heat conductivity can be ensured.

  FIG. 1 shows a perspective view of one embodiment of the thermally conductive sheet of the present invention.

  Next, a method for producing an embodiment of the thermally conductive sheet of the present invention will be described with reference to FIG.

  In this method, first, the above-mentioned components (filler 2 and resin 3) are blended at the blending ratio described above, and the mixture is prepared by stirring and mixing.

  In the stirring and mixing, in order to mix each component efficiently, for example, a solvent can be blended with the above-described components, or a resin (preferably a thermoplastic resin) can be melted by heating, for example.

  Examples of the solvent include the same organic solvents as described above. In addition, when the above-described curing agent and / or curing accelerator is prepared as a solvent solution and / or a solvent dispersion, the solvent of the solvent solution and / or the solvent dispersion without adding a solvent in the stirring and mixing. Can be used as a mixed solvent for stirring and mixing as it is. Alternatively, a solvent can be further added as a mixed solvent in the stirring and mixing.

  When stirring and mixing using a solvent, the solvent is removed after stirring and mixing.

  To remove the solvent, for example, it is allowed to stand at room temperature for 1 to 48 hours, for example, heated at 40 to 100 ° C. for 0.5 to 3 hours, or reduced pressure of 0.001 to 50 kPa, for example. Heat at 20-60 ° C. for 0.5-3 hours under atmosphere.

  When the resin (preferably a thermoplastic resin) is melted by heating, the heating temperature is, for example, a temperature near or exceeding the softening temperature of the resin, specifically, 40 to 150 ° C., preferably Is 70-150 degreeC.

  In this method, the resulting mixture is then hot pressed.

  Specifically, the press sheet (thermally conductive sheet 1) is obtained by, for example, heat-pressing the mixture through two release films (not shown) as necessary. The conditions of the hot press are that the temperature is, for example, 50 to 150 ° C., preferably 60 to 150 ° C., the pressure is, for example, 1 to 100 MPa, preferably 5 to 50 MPa, and the time is, for example, 0 .1 to 100 minutes, preferably 1 to 10 minutes.

  More preferably, the mixture is vacuum hot pressed. The degree of vacuum in the vacuum hot press is, for example, 1 to 100 Pa, preferably 5 to 50 Pa, and the temperature, pressure, and time are the same as those in the above-described hot press.

  In such a hot press, although not shown in detail, for example, when the resin 3 includes the first resin and the second resin, first, the temperature of the hot-pressed mixture is raised to the softening temperature of the first resin, The first resin is softened. At this time, since the second resin having a softening temperature higher than the softening temperature of the first resin does not soften, the mixture (heat conductive sheet) is retained in the hot press state. And in this heat press, after that, a mixture (thermally conductive sheet) is heated up to the softening temperature of 2nd resin, and 2nd resin is softened. By such hot pressing, the orientation angle α (described later) of the plate-like or scale-like filler 2 can be adjusted.

  Moreover, when the resin 3 is a thermosetting resin, the heat conductive sheet 1 can be thermoset. In order to harden the heat conductive sheet 1, it heats more than the softening temperature of 2nd resin. For heating, for example, the above-described hot press or dryer is used. The thermosetting conditions are such that the temperature is, for example, 60 to 250 ° C., preferably 80 to 200 ° C., and the pressure is, for example, 100 MPa or less, preferably 50 MPa or less.

  In this method, the temperature can be raised to the softening temperature of the second resin by a single hot press, and further, the thermal conductive sheet 1 can be cured by a single hot press.

  The thickness of the obtained heat conductive sheet 1 is, for example, 1 mm or less, preferably 0.8 mm or less, usually, for example, 0.05 mm or more, preferably 0.1 mm or more.

  And in the heat conductive sheet 1 obtained in this way, as shown in FIG. 1 and its partial enlarged schematic view, the filler 2 (plate-like or flake-like filler 2) has a longitudinal direction LD thereof, It is contained so as to form a predetermined angle (orientation angle α) with respect to the surface direction SD intersecting (orthogonal) with the thickness direction TD of the heat conductive sheet 1.

The orientation angle α formed by the longitudinal direction LD of the filler 2 in the plane direction SD of the heat conductive sheet 1 has an arithmetic average (average orientation angle α ₁ ) of 29 degrees or more, preferably 29.5 degrees or more. Preferably, it is 30 degrees or more, and usually less than 45 degrees.

Further, the maximum value of the orientation angle α (maximum orientation angle α ₂ ) formed by the longitudinal direction LD of the filler 2 in the plane direction SD of the heat conductive sheet 1 is 65 degrees or more, preferably 70 degrees or more, more preferably It is 75 degrees or more and is usually less than 90 degrees.

If the average orientation angle α ₁ of the filler 2 with respect to the surface direction SD of the thermally conductive sheet 1 is in the above range and the maximum orientation angle α ₂ is in the above range, in the thermally conductive sheet, in the thickness direction and the surface direction. Good thermal conductivity in both directions can be ensured.

  Note that the orientation angle α of the filler 2 with respect to the heat conductive sheet 1 is obtained by cutting out the heat conductive sheet 1, taking a continuous transmission image at 0 to 180 degrees by X-ray CT, and reconstructing based on the total transmission image. A tomographic image is created, and the obtained image is analyzed to create a three-dimensional reconstructed image, and measurement is performed based on the obtained image.

  And the heat conductivity of the surface direction SD of the heat conductive sheet 1 obtained by this is 30-60 W / m * K, Preferably, it is 35-60 W / m * K, More preferably, it is 40-60 W / m *. K.

  In addition, the heat conductivity of the surface direction SD of the heat conductive sheet 1 is measured by the pulse heating method. In the pulse heating method, a xenon flash analyzer “LFA-447 type” (manufactured by NETZSCH) is used.

  The thermal conductivity in the thickness direction TD of the thermal conductive sheet 1 is 5 to 15 W / m · K, preferably 6 to 15 W / m · K, more preferably 7 to 15 W / m · K. .

  The thermal conductivity in the thickness direction TD of the thermal conductive sheet 1 is measured by a pulse heating method, a laser flash method, or a TWA method. In the pulse heating method, the same one as described above is used, in the laser flash method, “TC-9000” (manufactured by ULVAC-RIKO) is used, and in the TWA method, “ai-Phase mobile” (manufactured by Eye Phase). Is used.

  In such a heat conductive sheet 1, the plate-like or scale-like filler 2 is contained so that the average orientation angle is 29 degrees or more and the maximum orientation angle is 65 degrees or more. The thermal conductivity in the thickness direction Td and the surface direction SD of the sheet 1 can be ensured.

  Therefore, the heat conductive sheet 1 is excellent in heat conductivity in the thickness direction and in the surface direction. For example, a power electronics technology that converts and controls electric power by a semiconductor element, such as a hybrid device, a high-intensity LED device, and an electromagnetic induction heating device. Can be used as a heat radiating member for converting a large current into heat or an insulating sheet. Specifically, for example, a semiconductor element used in a light-emitting diode device, an imaging element used in an imaging device, and a liquid crystal display It is arranged in the vicinity of various other power modules such as the backlight of the device, and it is arranged between the heat radiating members to dissipate heat from the members and between these members, and each member is electrically insulated. It can use suitably as an insulating sheet for making it do.

  Specifically, the heat conductive sheet 1 is, for example, a heat spreader or a heat sink of a light emitting diode device, for example, a heat dissipation sheet attached to a casing of a liquid crystal display device or an imaging device, for example, an electronic circuit board. It is suitably used as a sealing material for sealing.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the examples.

Example 1
6.71 g of PT-110 (trade name, plate-like boron nitride particles, average particle diameter (light scattering method) of 35 to 60 μm, manufactured by Momentive Performance Materials Japan) was prepared.

  EPPN-501HY (trade name, phenol novolac type epoxy resin, solid, epoxy equivalent of 163 to 175 g / eqiv., Softening temperature (ring and ball method) 61 ° C., manufactured by Nippon Steel Chemical Co., Ltd.) 1.2 g and YSLV-120TE (trade name) , Bisphenol type epoxy resin, solid, average particle size (analysis of SEM image) about 100 μm (after pulverization, classification by sieving), epoxy equivalent 250 g / eqiv., Softening temperature (ring and ball method) 120 ° C., manufactured by Nippon Steel Chemical Co. 0.3 g was dissolved in 2 g of solvent (acetone). Next, after adding 0.05 imidazole-based curing catalyst (2P4MHZ-PW, manufactured by Shikoku Kasei Co., Ltd.), the PT-110 was mixed, and then dried at 60 ° C. for 1 hour to remove the solvent. Next, the obtained powder was held under pressure at 10 MPa for 10 minutes in a press machine at 150 ° C., the resin was cured, and a heat conductive sheet was obtained.

  The SEM image was analyzed under the following conditions (hereinafter the same).

  That is, as the SEM sample, an embedding with an epoxy resin, cross-sectional polishing, and surface milling of the surface by ion milling were used.

  Measure 100 points of the obtained sample arbitrarily, then connect the obtained 100 SEM images with Image Pro software, extract resin particles with WinRoof software, perform image analysis, and measure the particle size distribution The average particle size was determined.

Example 2
Instead of EPPN-501HY, 1.2 g of JER1001 (trade name, bisphenol A type epoxy resin, solid, epoxy equivalent 450 to 500 g / eqiv., Softening temperature (ring and ball method) 64 ° C., manufactured by Mitsubishi Chemical Corporation) was used. Except for the above, a heat conductive sheet was obtained in the same manner as in Example 1.

Example 3
Instead of EPPN-501HY, 1.2 g of JER1002 (trade name, bisphenol A type epoxy resin, solid, epoxy equivalent of 600 to 700 g / eqiv., Softening temperature (ring and ball method) 74 ° C., manufactured by Mitsubishi Chemical Corporation) is used. In place of YSLV-120TE, YSLV-80XY (trade name, bisphenol type epoxy resin, crystalline epoxy resin, solid, average particle size (analysis of SEM image) about 100 μm (after pulverization and classification by sieving), epoxy equivalent 200 g / Eqiv., Softening temperature (ring and ball method) 140 ° C., manufactured by Nippon Steel Chemical Co., Ltd.) was used in the same manner as in Example 1 to obtain a heat conductive sheet, except that 0.5 g was used.

Example 4
Example except that EPPN-501HY (0.5 g) was used instead of EPPN-501HY (1.2 g), and YSLV-80XY (0.3 g) was used instead of YSLV-120TE (0.3 g). In the same manner as in No. 1, a heat conductive sheet was obtained.

Comparative Example 1
A thermally conductive sheet was obtained in the same manner as in Example 1 except that 1.2 g of EPPN-501HY was changed to 1.5 g and YSLV-120TE was not used.

Comparative Example 2
Instead of using 0.3 g of YSLV-120TE, 0.3 g of JER1055 (trade name, bisphenol A type epoxy resin, pellet form, average size of about 1 cm, softening temperature (ring ball method) 145 ° C., manufactured by Mitsubishi Chemical Corporation) was used. In the same manner as in Example 1, a heat conductive sheet was obtained.

Comparative Example 3
In place of 1.2 g of EPPN-501HY, 1.2 g of JER1001 was used, and in place of 0.3 g of YSLV-120TE, JER1003 (trade name, bisphenol A type epoxy resin, solid, average particle diameter (SEM image Analysis) Same as Example 1 except that about 100 μm (classified by sieving after pulverization), epoxy equivalent of 660 to 770 g / eqiv, softening temperature (ring ball method) 80 ° C., manufactured by Nippon Steel Chemical Co., Ltd.) 0.3 g was used. Thus, a heat conductive sheet was obtained.

Evaluation (1) Thermal conductivity The thermal conductivity in the thickness direction TD and the thermal conductivity in the surface direction SD of the thermal conductive sheets obtained in each of the examples and the comparative examples were measured using a xenon flash analyzer “LFA-447. It was measured by a pulse heating method using a “type” (manufactured by NETZSCH). The results are shown in Table 1.
(2) Orientation angle The heat conductive sheet obtained in each Example and each Comparative Example was cut into a width of 2 mm, fixed to a sample stage, and a continuous transmission image was 0.2 to 0 to 180 degrees by X-ray CT. Taken every degree, then reconstructs based on the total transmission image, creates a tomographic image, analyzes the obtained image, creates a three-dimensional reconstructed image, and creates an orientation angle (average orientation angle) , Maximum orientation angle). As analysis software, ImageJ. (Developer: National Institutes of Health (NIH)) was used. The results are shown in Table 1.

  Moreover, the X-ray CT image of the heat conductive sheet of Example 1 is shown in FIG. 2, and the frequency distribution diagram of the orientation angle obtained by analyzing the X-ray CT image is shown in FIG.

  Further, FIG. 4 shows an X-ray CT image of the thermal conductive sheet of Example 2, and FIG. 5 shows a frequency distribution diagram of orientation angles obtained by analyzing the X-ray CT image.

  Further, FIG. 6 shows an X-ray CT image of the thermally conductive sheet of Example 4, and FIG. 7 shows a frequency distribution diagram of orientation angles obtained by analyzing the X-ray CT image.

  Further, FIG. 8 shows an X-ray CT image of the heat conductive sheet of Comparative Example 1, and FIG. 9 shows a frequency distribution diagram of orientation angles obtained by analyzing the X-ray CT image.

Details of the abbreviations shown in Table 1 are shown below.
EPPN-501HY: phenol novolac type epoxy resin, solid, epoxy equivalent of 163 to 175 g / eqiv. , Softening temperature (ring ball method) 61 ° C., Nippon Steel Chemical Co., Ltd. JER1001: bisphenol A type epoxy resin, solid, epoxy equivalent 450-500 g / eqiv. , Softening temperature (ring and ball method) 64 ° C., Mitsubishi Chemical Corporation JER1002: bisphenol A type epoxy resin, solid, epoxy equivalent of 600 to 700 g / eqiv. , Softening temperature (ring and ball method) 74 ° C., YSLV-120TE manufactured by Mitsubishi Chemical Corporation: bisphenol type epoxy resin, solid, average particle diameter (SEM image analysis) 100 μm, epoxy equivalent 250 g / eqiv. , Softening temperature (ring and ball method) 120 ° C., YSLV-80XY manufactured by Nippon Steel Chemical Co., Ltd .: bisphenol type epoxy resin, crystalline epoxy resin, solid average particle diameter (SEM image analysis) about 100 μm, epoxy equivalent 200 g / eqiv. , Softening temperature (ring and ball method) 140 ° C., Nippon Steel Chemical Co., Ltd. JER1055: bisphenol A type epoxy resin, pellets, average size about 1 cm, softening temperature (ring and ball method) 145 ° C., Mitsubishi Chemical Corporation JER1003: bisphenol A type epoxy resin , Solid, average particle size (SEM image analysis) 100 μm, epoxy equivalent 660-770 g / eqiv. Softening temperature (ring and ball method) 80 ° C, manufactured by Nippon Steel Chemical Co., Ltd.

DESCRIPTION OF SYMBOLS 1 Thermal conductive sheet 2 Filler 3 Resin TD Thickness direction SD Plane direction (perpendicular direction)
LD Longitudinal direction

Claims (6)

A thermally conductive sheet containing a resin and a plate-like or scale-like filler,
The heat conductive sheet, wherein the filler has an average orientation angle of 29 degrees or more and a maximum orientation angle of 65 degrees or more with respect to a surface direction of the heat conductive sheet. The resin contains a first resin and a second resin;
The heat conductive sheet according to claim 1, wherein a difference between a softening temperature of the first resin and a softening temperature of the second resin is 20 ° C. or more. The difference between the softening temperature of the first resin and the softening temperature of the second resin is 40 ° C. or more,
The second resin has an average particle size of 10 to 500 μm,
The heat conductive sheet according to claim 1, wherein the heat conductive sheet is held at a temperature between a softening temperature of the first resin and a softening temperature of the second resin.   The thermal conductivity according to any one of claims 1 to 3, wherein the filler content is 50 to 95 parts by mass with respect to 100 parts by mass of the total amount of the thermal conductive sheet. Sheet.   It is obtained using the heat conductive sheet as described in any one of Claims 1-4, The insulating sheet characterized by the above-mentioned. It is obtained using the heat conductive sheet as described in any one of Claims 1-4, The heat radiating member characterized by the above-mentioned.