JP2018080326A - Curable material, and laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a curable material capable of effectively increasing heat conductivity.SOLUTION: The curable material of the present invention includes: a first inorganic particle; a second inorganic particle; and a curable compound, where, when measuring respective compression strengths of the first inorganic particle and the second inorganic particle at compression in a range of not less than 10% and not greater than 30% to found a compression strength ratio of the compression strength of the first inorganic particle to the compression strength of the second inorganic particle at the same compression in a range of not less than 10% and not greater than 30%, the minimum value of the compression strength ratio is not less than 2, the maximum value of the compression strength ratio is not greater than 100, the content of the first inorganic particle in a total 100 vol.% of the first inorganic particle and the second inorganic particle is not less than 20 vol.% and less than 50 vol.%, and the content of the second inorganic particle in a total 100 vol.% of the first inorganic particle and the second inorganic particle is greater than 50 vol.% and not greater than 80 vol.%.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a curable material containing inorganic particles and a curable compound. Moreover, this invention relates to the laminated body provided with the hardened | cured material of the curable material containing an inorganic particle and a curable compound as an insulating layer.

  In recent years, downsizing and higher performance of electronic and electrical devices have progressed, and the mounting density of electronic components has increased. For this reason, it is a problem how to dissipate the heat generated from the electronic components in a narrow space. Since heat generated from electronic components is directly linked to the reliability of electronic and electrical equipment, efficient dissipation of the generated heat is an urgent issue.

  As one means for solving the above-mentioned problem, there is a means that uses a ceramic substrate having high thermal conductivity as a heat dissipation substrate for mounting a power semiconductor device or the like. Examples of such a ceramic substrate include an alumina substrate and an aluminum nitride substrate.

  However, the means using the ceramic substrate has a problem that it is difficult to make a multilayer, workability is poor, and cost is very high. Furthermore, since the difference in coefficient of linear expansion between the ceramic substrate and the copper circuit is large, there is also a problem that the copper circuit is easily peeled off during the cooling and heating cycle.

  Therefore, a resin composition using boron nitride having a low linear expansion coefficient, particularly hexagonal boron nitride, has attracted attention as a heat dissipation material. The crystal structure of hexagonal boron nitride is a layered structure of hexagonal network similar to graphite, and the particle shape of hexagonal boron nitride is scaly. For this reason, it is known that hexagonal boron nitride has a property in which the thermal conductivity in the plane direction is higher than the thermal conductivity in the thickness direction and the thermal conductivity is anisotropic.

  Secondary agglomerated particles (boron nitride agglomerated particles) in which the primary particles of hexagonal boron nitride are agglomerated as a method of reducing the thermal conductivity anisotropy of hexagonal boron nitride and improving the thermal conductivity in the thickness direction. It has been proposed to use The following Patent Documents 1 to 3 disclose resin compositions using boron nitride aggregated particles.

  Patent Document 1 below discloses a thermosetting resin composition containing an inorganic filler in a thermosetting resin. The inorganic filler includes a secondary aggregate (A) composed of primary particles of boron nitride having an average major axis of 8 μm or less, and a secondary aggregate composed of primary particles of boron nitride having an average major axis of more than 8 μm and 20 μm or less. The next aggregate (B) is contained in a volume ratio of 40:60 to 98: 2. Content of the said inorganic filler is 40 volume% or more and 80 volume% or less.

  The following Patent Document 2 discloses a curable heat radiation composition comprising two types of fillers having different compressive fracture strengths (except that the above two types of fillers are the same substance) and a curable resin (C). Things are disclosed. The compression fracture strength ratio (compression fracture strength of filler (A) having a high compression fracture strength / compression fracture strength of filler (B) having a small compression fracture strength) of the two kinds of fillers is 5 or more and 1500 or less. The filler (B) is hexagonal boron nitride aggregate particles.

  Patent Document 3 below discloses a thermosetting resin composition containing a thermosetting resin and an inorganic filler. The inorganic filler is formed of secondary particles (A) formed from primary particles of boron nitride having an aspect ratio of 10 or more and 20 or less, and primary particles of boron nitride having an aspect ratio of 2 or more and 9 or less. Secondary particles (B).

JP2011-6586A WO2013 / 1455961A1 WO2014 / 199650A1

  In the curable composition using the conventional boron nitride aggregated particles as described in Patent Documents 1 to 3, the deformation behavior of the boron nitride aggregated particles at the time of pressing such as sheet molding is not sufficiently controlled, and as a result The thermal conductivity in the pressing direction (thickness direction) may decrease. Therefore, the conventional boron nitride aggregate particle design has a limit in increasing the thermal conductivity.

  An object of the present invention is to provide a curable material and a laminate that can effectively increase thermal conductivity.

  In a wide aspect of the present invention, the first inorganic particles, the second inorganic particles, and the curable compound are included, and 10% or more of each of the first inorganic particles and the second inorganic particles, 30 Compressive strength at the time of compression in the range of not more than%, and compressive strength of the compressive strength of the first inorganic particles at the same compression in the range of not less than 10% and not more than 30% relative to the compressive strength of the second inorganic particles. When the ratio is determined, the minimum value of the compressive strength ratio is 2 or more and the maximum value of the compressive strength ratio is 100 or less, and the total volume of the first inorganic particles and the second inorganic particles is 100 volumes. %, The content of the first inorganic particles is 20% by volume or more and less than 50% by volume, and the second inorganic particle in the total of 100% by volume of the first inorganic particles and the second inorganic particles. The content of inorganic particles exceeds 50% by volume and is 80% by volume. Or less, the curable material is provided.

In a specific aspect of the curable material according to the present invention, the compressive strength at 10% compression of the first inorganic particles is ² N / mm ² or more, and the compressive strength of the first inorganic particles is 20%. compressive strength at the time is, and the 4.2 N / mm ² or more, the compressive strength at 30 percent compression of the first inorganic particles, and a 4.4 N / mm ² or more, of the second inorganic particles The compression strength at 10% compression is 1.8 N / mm ² or less, the compression strength at 20% compression of the second inorganic particles is 2.8 N / mm ² or less, and the second The compressive strength at the time of 30% compression of the inorganic particles is 3.5 N / mm ² or less.

In a specific aspect of the curable material according to the present invention, the compression strength at 30% compression of the first inorganic particles is 4.4 N / mm ² or more, and 30% of the second inorganic particles. compressive strength at the time of compression, 2N / mm ² or more and 3.5 N / mm ² or less.

  On the specific situation with the curable material which concerns on this invention, the dielectric constant of the material of a said 1st inorganic particle and the dielectric constant of the material of a said 2nd inorganic particle are respectively 7.5 or less.

  In a specific aspect of the curable material according to the present invention, the first inorganic particles and the second inorganic particles are each boron nitride aggregated particles.

  In a specific aspect of the curable material according to the present invention, the total content of the first inorganic particles and the second inorganic particles in 20% by volume of the curable material is 20% by volume or more and 80% by volume. % Or less.

  In a specific aspect of the curable material according to the present invention, the curable material is a curable sheet.

  In a wide aspect of the present invention, a thermal conductor, an insulating layer laminated on one surface of the thermal conductor, and a conductive layer laminated on the surface of the insulating layer opposite to the thermal conductor. And the insulating layer is a cured product of a curable material including first inorganic particles, second inorganic particles, and a curable compound, and the first inorganic particles and the second inorganic particles Compressive strength at the time of compression in the range of 10% or more and 30% or less of each of the above, the second of the compressive strength of the first inorganic particles at the same compression in the range of 10% or more and 30% or less When the compressive strength ratio with respect to the compressive strength of the inorganic particles is determined, the minimum value of the compressive strength ratio is 2 or more and the maximum value of the compressive strength ratio is 100 or less. In the insulating layer, the first inorganic In a total of 100% by volume of the particles and the second inorganic particles, The content of the first inorganic particles is 20% by volume or more and less than 50% by volume, and the total amount of the first inorganic particles and the second inorganic particles is 100% by volume. A laminate having a content of more than 50% by volume and 80% by volume or less is provided.

  The curable material according to the present invention includes first inorganic particles, second inorganic particles, and a curable compound. The compression strength at the time of compression in the range of 10% or more and 30% or less of each of the first inorganic particles and the second inorganic particles is measured, and at the same compression in the range of 10% or more and 30% or less. A compressive strength ratio of the compressive strength of the first inorganic particles to the compressive strength of the second inorganic particles is obtained. In the curable material according to the present invention, the minimum value of the compression strength ratio is 2 or more, and the maximum value of the compression strength ratio is 100 or less. In the curable material which concerns on this invention, content of the said 1st inorganic particle is 20 volume% or more and less than 50 volume% in the total 100 volume% of the said 1st inorganic particle and the said 2nd inorganic particle. In a total of 100% by volume of the first inorganic particles and the second inorganic particles, the content of the second inorganic particles is more than 50% by volume and 80% by volume or less. In the curable material which concerns on this invention, since said structure is provided, thermal conductivity can be improved effectively.

  The laminate according to the present invention includes a thermal conductor, an insulating layer laminated on one surface of the thermal conductor, and a conductive layer laminated on the surface of the insulating layer opposite to the thermal conductor. Is provided. In the laminated body according to the present invention, the insulating layer is a cured product of a curable material containing first inorganic particles, second inorganic particles, and a curable compound. The compression strength at the time of compression in the range of 10% or more and 30% or less of each of the first inorganic particles and the second inorganic particles is measured, and at the same compression in the range of 10% or more and 30% or less. A compressive strength ratio of the compressive strength of the first inorganic particles to the compressive strength of the second inorganic particles is obtained. In the laminate according to the present invention, the minimum value of the compression strength ratio is 2 or more and the maximum value of the compression strength ratio is 100 or less. In the laminate according to the present invention, in the insulating layer, the total content of the first inorganic particles and the second inorganic particles is 100% by volume, and the content of the first inorganic particles is 20% by volume or more. The content of the second inorganic particles is more than 50% by volume and less than 80% by volume in a total of 100% by volume of the first inorganic particles and the second inorganic particles. is there. In the laminated body which concerns on this invention, since said structure is provided, thermal conductivity can be improved effectively.

FIG. 1 is a cross-sectional view schematically showing a cured product of a curable material according to an embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing a laminate including the cured product of the curable material shown in FIG. 1 as an insulating layer.

  Hereinafter, the present invention will be described in detail.

(Curable material and laminate)
The curable material according to the present invention includes first inorganic particles, second inorganic particles, and a curable compound.

  The laminate according to the present invention includes a thermal conductor, an insulating layer laminated on one surface of the thermal conductor, and a conductive layer laminated on the surface of the insulating layer opposite to the thermal conductor. Is provided. In the laminated body according to the present invention, the insulating layer is a cured product of a curable material containing first inorganic particles, second inorganic particles, and a curable compound.

  In the curable material and laminate according to the present invention, the compression strength at the time of compression in the range of 10% or more and 30% or less of each of the first inorganic particles and the second inorganic particles is measured, and 10% The compression strength ratio of the compression strength of the first inorganic particles to the compression strength of the second inorganic particles during the same compression in the range of 30% or less is obtained. In the curable material and laminate according to the present invention, the minimum value of the compression strength ratio is 2 or more and the maximum value of the compression strength ratio is 100 or less.

  In the curable material which concerns on this invention, content of the said 1st inorganic particle is 20 volume% or more and less than 50 volume% in the total 100 volume% of the said 1st inorganic particle and the said 2nd inorganic particle. In a total of 100% by volume of the first inorganic particles and the second inorganic particles, the content of the second inorganic particles is more than 50% by volume and 80% by volume or less. In the laminate according to the present invention, in the insulating layer, the total content of the first inorganic particles and the second inorganic particles is 100% by volume, and the content of the first inorganic particles is 20% by volume or more. The content of the second inorganic particles is more than 50% by volume and less than 80% by volume in a total of 100% by volume of the first inorganic particles and the second inorganic particles. is there.

  In the curable material and laminated body which concern on this invention, since said structure is provided, thermal conductivity can be improved effectively. When a compressive force is applied to the curable material according to the present invention by a press or the like, for example, the first inorganic particles are not excessively deformed or disintegrated, and the second inorganic particles are appropriately deformed. Some of the second inorganic particles collapse. In the laminate according to the present invention, when a compressive force is applied by a press or the like during the production of the laminate, for example, the first inorganic particles are not excessively deformed or collapsed, and the second inorganic particles are It deforms moderately and some of the second inorganic particles collapse. For this reason, the orientation of the second inorganic particles after compression can be highly controlled by the first inorganic particles, and the thermal conductivity can be further enhanced.

  The compressive strength (hardness) of the first inorganic particles is relatively higher than the compressive strength (hardness) of the second inorganic particles. The compressive strength (hardness) of the second inorganic particles is relatively lower than the compressive strength (hardness) of the first inorganic particles. For this reason, when a compression force is applied by a press or the like, for example, the first inorganic particles do not excessively deform or collapse, and the second inorganic particles deform appropriately or partially collapse. For example, the press pressure at which deformation or collapse of the second inorganic particles occurs is lower than the press pressure at which deformation or collapse of the first inorganic particles occurs.

  For example, boron nitride particles and the like are known as inorganic particles having high thermal conductivity. When pressing is performed by sheet molding or the like using a curable material containing fragile inorganic particles, the inorganic particles are deformed or collapsed by the press, and the inorganic particles are oriented in the plane direction. When the inorganic particles are oriented in the plane direction, the thermal conductivity in the plane direction can be increased, but the thermal conductivity in the thickness direction (press direction) cannot be increased. When a curable material containing hard inorganic particles is used and pressed by sheet molding or the like, the inorganic particles are hardly deformed or collapsed by the press, and the thermal conductivity in the plane direction and the thickness direction can be increased. Voids remain between the particles and the insulating properties deteriorate.

  In the curable material and the laminate according to the present invention, two types of inorganic particles having different compressive strengths are used, and the second inorganic particles that are brittle inorganic particles are more than the first inorganic particles that are hard inorganic particles. Since many are included, when a compression force is applied by a press or the like, the orientation of the second inorganic particles is controlled by the first inorganic particles when the second inorganic particles are deformed or collapsed. Further, the compressed second inorganic particles are not only oriented in the plane direction but also oriented in the thickness direction by the first inorganic particles. As a result, thermal conductivity can be enhanced not only in the surface direction but also in the thickness direction. Further, the second inorganic particles are arranged between the first inorganic particles, so that the gaps between the inorganic particles can be filled, and the insulation can be improved. In order to obtain such an effect, the use of the first inorganic particles and the second inorganic particles satisfying a specific compressive strength relationship greatly contributes. In particular, the second inorganic particles do not collapse, but the compressive strength of the first inorganic particles and the second inorganic particles when the compressive force is applied to such an extent that the second inorganic particles are deformed. It is considered that the difference from the compressive strength contributes to the determination of the orientation of the second inorganic particles.

(First inorganic particles and second inorganic particles)
The minimum value of the compression strength ratio is 2 or more. From the viewpoint of further increasing the thermal conductivity and controlling the orientation of the inorganic particles after compression to a higher degree, the minimum value of the compression strength ratio is preferably 2.2 or more, more preferably 2.5 or more. is there.

  The maximum value of the compression strength ratio is 100 or less. From the viewpoint of further increasing the thermal conductivity and controlling the orientation of the inorganic particles after compression to a higher degree, the maximum value of the compression strength ratio is preferably 80 or less, more preferably 50 or less.

From the viewpoint of further increasing the thermal conductivity and further controlling the orientation of the inorganic particles after compression, the compressive strength at the time of 10% compression of the first inorganic particles is preferably 2 N / mm ² or more. More preferably, it is ^2.5 N / mm ² or more. The upper limit of the compressive strength at the time of 10% compression of the first inorganic particles is not particularly limited. The compressive strength at the time of 10% compression of the first inorganic particles may be 10 N / mm ² or less.

From the viewpoint of further increasing the thermal conductivity and further controlling the orientation of the inorganic particles after compression, the compressive strength at 20% compression of the first inorganic particles is preferably 4.2 N / mm. ² or more, more preferably 5 N / mm ² or more. The upper limit of the compressive strength at the time of 20% compression of the first inorganic particles is not particularly limited. The compressive strength at the time of 20% compression of the first inorganic particles may be 18 N / mm ² or less.

From the viewpoint of further increasing the thermal conductivity and further controlling the orientation of the inorganic particles after compression, the compressive strength at 30% compression of the first inorganic particles is preferably 4.4 N / mm. ² or more, more preferably 6 N / mm ² or more. The upper limit of the compression strength at the time of 30% compression of the first inorganic particles is not particularly limited. The compressive strength at the time of 30% compression of the first inorganic particles may be 20 N / mm ² or less.

From the viewpoint of further increasing the thermal conductivity and controlling the orientation of the inorganic particles after compression to a higher degree, the compressive strength at 10% compression of the second inorganic particles is preferably 1.8 N / mm. ² or less, more preferably 1 N / mm ² or less. The lower limit of the compressive strength at the time of 10% compression of the second inorganic particles is not particularly limited. The compressive strength at the time of 10% compression of the second inorganic particles may be 0.01 N / mm ² or more.

From the viewpoint of further increasing the thermal conductivity and further controlling the orientation of the inorganic particles after compression, the compressive strength at 20% compression of the second inorganic particles is preferably 2.8 N / mm. ² or less, more preferably 2.2 N / mm ² or less. The lower limit of the compression strength at the time of 20% compression of the second inorganic particles is not particularly limited. The compressive strength at the time of 20% compression of the second inorganic particles may be 0.1 N / mm ² or more.

From the viewpoint of further increasing the thermal conductivity and controlling the orientation of the inorganic particles after compression to a higher degree, the compressive strength at 30% compression of the second inorganic particles is preferably 3.5 N / mm. ² or less, more preferably 3 N / mm ² or less. The lower limit of the compression strength at the time of 30% compression of the second inorganic particles is not particularly limited. The compressive strength at the time of 30% compression of the second inorganic particles may be 0.1 N / mm ² or more.

From the viewpoint of further increasing the thermal conductivity and further controlling the orientation of the inorganic particles after compression, the compressive strength at 30% compression of the first inorganic particles is preferably 4.4 N / mm. ² or more, the compressive strength at 30% compression of the second inorganic particles is preferably 2N / mm ² or more, preferably 3.5 N / mm ² or less.

  The compressive strength at the time of compression in the range of 10% or more and 30% or less of each of the first inorganic particles and the second inorganic particles can be measured in accordance with the description of Examples described later.

  The compressive strength may be measured using inorganic particles before blending with the curable material, or may be measured using inorganic particles recovered by removing the curable compound from the curable material.

  From the viewpoint of improving the insulating properties, the dielectric constant of the material constituting the first inorganic particles is preferably 7.5 or less. From the viewpoint of improving the insulation, the dielectric constant of the material constituting the second inorganic particles is preferably 7.5 or less. From the viewpoint of improving the insulation, it is preferable that the difference between the dielectric constant of the material constituting the first inorganic particle and the material constituting the second inorganic particle and the dielectric constant of the curable compound is small. The material constituting the first inorganic particles and the material constituting the second inorganic particles are preferably the same compound. Examples of the material having a dielectric constant of 7.5 or less include hexagonal boron nitride (h-BN), cubic boron nitride (c-BN), diamond, and the like. Each of the first inorganic particles and the second inorganic particles may be hexagonal boron nitride (h-BN), cubic boron nitride (c-BN), and diamond. Aggregates may also be used. From the viewpoint of further improving the insulating properties of the cured product of the curable material, it is preferable that the first inorganic particles and the second inorganic particles each have insulating properties.

  From the viewpoint of further increasing the thermal conductivity and controlling the orientation of the inorganic particles after compression to a higher degree, the first inorganic particles are preferably boron nitride aggregated particles, and the second inorganic particles Is preferably a boron nitride aggregated particle. The boron nitride aggregated particles are preferably secondary particles obtained by aggregating primary particles of boron nitride. The primary particles of the first inorganic particles are preferably boron nitride, and the primary particles of the second inorganic particles are preferably boron nitride.

  It does not specifically limit as a manufacturing method of the said boron nitride aggregate particle, A spray-drying method, a fluidized-bed granulation method, etc. are mentioned. The method for producing the boron nitride aggregated particles is preferably a spray drying (also called spray drying) method. The spray drying method can be classified into a two-fluid nozzle method, a disk method (also called a rotary method), an ultrasonic nozzle method, and the like depending on the spray method, and any of these methods can be applied. From the viewpoint of more easily controlling the total pore volume, the ultrasonic nozzle method is preferable.

  The boron nitride agglomerated particles are preferably manufactured using primary particles of boron nitride as a material. The boron nitride used as the material for the boron nitride aggregated particles is not particularly limited. Examples of the boron nitride include hexagonal boron nitride, cubic boron nitride, boron nitride produced by a reduction nitriding method of a boron compound and ammonia, boron nitride produced from a boron compound and a nitrogen-containing compound such as melamine, and the like. And boron nitride prepared from sodium borohydride and ammonium chloride. From the viewpoint of further improving the thermal conductivity of the boron nitride aggregated particles, the boron nitride used as the material for the boron nitride aggregated particles is preferably hexagonal boron nitride.

  Moreover, as a manufacturing method of boron nitride aggregated particles, a granulation step is not necessarily required. It may be boron nitride aggregated particles formed by spontaneously concentrating boron nitride primary particles as the boron nitride crystal grows. Moreover, in order to make the particle diameter of boron nitride aggregated particles uniform, pulverized boron nitride aggregated particles may be used.

Primary particles of the first inorganic particles and the second inorganic particles:
From the viewpoint of further increasing the thermal conductivity and further controlling the orientation of the inorganic particles after compression, the average major axis of the primary particles of the first inorganic particles is preferably 0.1 μm or more, more preferably It is 1.2 μm or more, preferably 6 μm or less, more preferably 5 μm or less.

  From the viewpoint of further increasing the thermal conductivity and controlling the orientation of the inorganic particles after compression to a higher degree, the average major axis of the primary particles of the second inorganic particles is preferably 2 μm or more, more preferably 3 μm or more. It is preferably 10 μm or less, more preferably 9 μm or less.

  The average major axis of the primary particles of the first inorganic particles and the second inorganic particles is obtained as follows. A sheet prepared by mixing primary particles of the first inorganic particles and the second inorganic particles with a thermosetting resin or the like is prepared. From the electron microscope image of the cross section of this sheet or a laminate using the sheet, the major diameters of primary particles of 50 arbitrarily selected first inorganic particles and second inorganic particles are measured, and the average value is calculated. The average major axis is determined by calculation.

  From the viewpoint of further increasing the thermal conductivity of the first inorganic particles and the second inorganic particles, the aspect ratio of the primary particles of the first inorganic particles and the second inorganic particles is preferably 7 or more, more preferably It is 10 or more, preferably 30 or less, more preferably 20 or less.

  The aspect ratio indicates a major axis / minor axis. The aspect ratio is obtained as follows. A sheet prepared by mixing the first inorganic particles, the second inorganic particles, and the curable resin is prepared. The cross section of this sheet or a laminate using the sheet is observed with an electron microscope or an optical microscope, and the aspect ratio is determined by measuring the major axis / minor axis of the inorganic particles. Further, the aspect ratio can be obtained by averaging the aspect ratios of arbitrary 50 second inorganic particles.

  From the viewpoint of further increasing the thermal conductivity and further controlling the orientation of the inorganic particles after compression, the average particle size of the first inorganic particles is preferably 25 μm or more, more preferably 40 μm or more. , Preferably 150 μm or less, more preferably 100 μm or less.

  From the viewpoint of further increasing the thermal conductivity and further controlling the orientation of the inorganic particles after compression, the average particle size of the second inorganic particles is preferably 20 μm or more, more preferably 40 μm or more. The thickness is preferably 200 μm or less, more preferably 150 μm or less, and particularly preferably 50 μm or less. When the average particle diameter of the second inorganic particles is 50 μm or less, the second inorganic particles can be arranged more densely, and the insulation can be further improved.

  The average particle diameter of the first inorganic particles and the second inorganic particles means the average of the particle diameter on a volume basis. The particle diameters of the first inorganic particles and the second inorganic particles can be measured using a “laser diffraction particle size distribution measuring apparatus” manufactured by Horiba, Ltd. The average particle size of the first inorganic particles and the second inorganic particles is determined by observing 50 arbitrarily selected inorganic particles with an electron microscope or an optical microscope, measuring the particle size, and calculating an average value. You can also

  From the viewpoint of further increasing the thermal conductivity and controlling the orientation of the inorganic particles after compression to a higher degree, the aspect ratio of the first inorganic particles is preferably 3 or less, more preferably 2 or less. The lower limit of the aspect ratio of the first inorganic particles is not particularly limited. The aspect ratio of the first inorganic particles may be 1 or more.

  From the viewpoint of further increasing the thermal conductivity and controlling the orientation of the inorganic particles after compression to a higher degree, the aspect ratio of the second inorganic particles is preferably 3 or less, more preferably 2 or less. The lower limit of the aspect ratio of the second inorganic particles is not particularly limited. The aspect ratio of the second inorganic particles may be 1 or more.

  The aspect ratio of the first inorganic particles and the second inorganic particles indicates a major axis / minor axis. The aspect ratio of the first inorganic particles and the second inorganic particles is preferably an average aspect ratio obtained by averaging the aspect ratios of the plurality of first inorganic particles and the second inorganic particles. The average aspect ratio of the first inorganic particles and the second inorganic particles was determined by observing 50 arbitrarily selected inorganic particles with an electron microscope or an optical microscope, and the average value of the major axis / minor axis of each inorganic particle. It is calculated | required by calculating.

  From the viewpoint of further increasing the thermal conductivity, the thermal conductivity of the first inorganic particles is preferably 5 W / m · K or more, more preferably 10 W / m · K or more. The upper limit of the thermal conductivity of the first inorganic particles is not particularly limited. The thermal conductivity of the first inorganic particles may be 1000 W / m · K or less.

  From the viewpoint of further increasing the thermal conductivity, the thermal conductivity of the second inorganic particles is preferably 5 W / m · K or more, more preferably 10 W / m · K or more. The upper limit of the thermal conductivity of the second inorganic particles is not particularly limited. The second inorganic particles may have a thermal conductivity of 1000 W / m · K or less.

  From the viewpoint of further increasing the thermal conductivity, the total content of the first inorganic particles and the second inorganic particles in 100% by volume of the curable material and 100% by volume of the insulating layer is preferably 20%. Volume% or more, More preferably, it is 45 volume% or more, Preferably it is 80 volume% or less, More preferably, it is 65 volume% or less.

  In the curable material and the insulating layer, the total content of the first inorganic particles and the second inorganic particles is preferably 100% by volume, and the content of the first inorganic particles is preferably 5% by volume or more. Preferably it is 10 volume% or more, More preferably, it is 15 volume% or more, Most preferably, it is 20 volume% or more, Preferably it is 45 volume% or less, More preferably, it is 40 volume% or less. When the content of the first inorganic particles is not less than the above lower limit and not more than the above upper limit, the insulation and thermal conductivity are further enhanced.

  In the curable material and the insulating layer, the content of the second inorganic particles is preferably 50% by volume or more in a total of 100% by volume of the first inorganic particles and the second inorganic particles. Preferably it is 55 volume% or more, Preferably it is 90 volume% or less, More preferably, it is 85 volume% or less, More preferably, it is 80 volume% or less. When the content of the second inorganic particles is not less than the above lower limit and not more than the above upper limit, the insulation and thermal conductivity are further enhanced.

  From the viewpoint of further increasing the thermal conductivity, the first inorganic particles may be composed of two or more types of inorganic particles having a compressive strength in the above-described range and different particle diameters. From the viewpoint of further increasing the thermal conductivity, the second inorganic particles may be composed of two or more kinds of inorganic particles having a compressive strength in the above-described range and different particle diameters.

  From the viewpoint of further increasing the thermal conductivity and insulation, the curable material contains the first inorganic particles and the second inorganic particles in addition to the first inorganic particles and the second inorganic particles. 3rd inorganic particle which is not may be included. From the viewpoint of further improving thermal conductivity and insulation, the curable material preferably contains the third inorganic particles.

  The third inorganic particles are preferably aggregated particles. The third inorganic particles are preferably secondary particles obtained by agglomerating primary particles of boron nitride. The average particle diameter of the third inorganic particles is preferably 10 μm or more, and preferably 50 μm or less. The porosity of the third inorganic particles is preferably 40% or more. The average major axis of the primary particles of the third inorganic particles is preferably 10 μm or less. The aspect ratio of the third inorganic particle is preferably 7 or less. The aspect ratio of the third inorganic particle is the aspect ratio of the primary particle of the third inorganic particle.

(Curable compound)
The curable material according to the present invention includes a curable compound. The insulating layer in the laminate according to the present invention includes a cured product of a curable compound. The curable compound is not particularly limited. The curable compound preferably includes a thermosetting component or a photocurable component, and more preferably includes a thermosetting component. The thermosetting component preferably contains a thermosetting compound and a thermosetting agent. It is preferable that the said photocurable component contains a photocurable compound and a photoinitiator.

  “(Meth) acryloyl group” refers to an acryloyl group and a methacryloyl group. “(Meth) acryl” refers to acrylic and methacrylic. “(Meth) acrylate” refers to acrylate and methacrylate.

(Thermosetting component: thermosetting compound)
Examples of the thermosetting compounds include styrene compounds, phenoxy compounds, oxetane compounds, epoxy compounds, episulfide compounds, (meth) acrylic compounds, phenolic compounds, amino compounds, unsaturated polyester compounds, polyurethane compounds, silicone compounds, and polyimide compounds. Can be mentioned. As for the said thermosetting compound, only 1 type may be used and 2 or more types may be used together.

  As the thermosetting compound, (A1) a thermosetting compound having a molecular weight of less than 10,000 (sometimes simply referred to as (A1) thermosetting compound) may be used, and (A2) a molecular weight of 10,000 or more is used. You may use the thermosetting compound which it has (it may only be described as (A2) thermosetting compound). As the thermosetting compound, both (A1) thermosetting compound and (A2) thermosetting compound may be used.

  In 100% by volume of the curable material, the content of the thermosetting compound is preferably 10% by volume or more, more preferably 20% by volume or more, preferably 90% by volume or less, more preferably 80% by volume or less. is there. When the content of the thermosetting compound is not less than the above lower limit, the adhesiveness and heat resistance of the cured product are further enhanced. When the content of the thermosetting compound is not more than the above upper limit, the coating property of the curable material is further enhanced.

(A1) Thermosetting compound having a molecular weight of less than 10,000:
(A1) As a thermosetting compound, the thermosetting compound which has a cyclic ether group is mentioned. Examples of the cyclic ether group include an epoxy group and an oxetanyl group. The thermosetting compound having a cyclic ether group is preferably a thermosetting compound having an epoxy group or an oxetanyl group. (A1) As for a thermosetting compound, only 1 type may be used and 2 or more types may be used together.

  The (A1) thermosetting compound may contain (A1a) a thermosetting compound having an epoxy group (sometimes simply referred to as (A1a) a thermosetting compound), and (A1b) an oxetanyl group. A thermosetting compound (which may be simply referred to as (A1b) thermosetting compound).

  From the viewpoint of further increasing the heat resistance and moisture resistance of the cured product, the (A1) thermosetting compound preferably has an aromatic skeleton.

  The aromatic skeleton is not particularly limited, and examples thereof include naphthalene skeleton, fluorene skeleton, biphenyl skeleton, anthracene skeleton, pyrene skeleton, xanthene skeleton, adamantane skeleton, and bisphenol A skeleton. From the viewpoint of further improving the cold heat cycle characteristics and heat resistance of the cured product, the aromatic skeleton is preferably a biphenyl skeleton or a fluorene skeleton.

  (A1a) The thermosetting compound includes an epoxy monomer having a bisphenol skeleton, an epoxy monomer having a dicyclopentadiene skeleton, an epoxy monomer having a naphthalene skeleton, an epoxy monomer having an adamantane skeleton, an epoxy monomer having a fluorene skeleton, and a biphenyl skeleton. Epoxy monomers having a bi (glycidyloxyphenyl) methane skeleton, epoxy monomers having a xanthene skeleton, epoxy monomers having an anthracene skeleton, and epoxy monomers having a pyrene skeleton. These hydrogenated products or modified products may be used. (A1a) As for a thermosetting compound, only 1 type may be used and 2 or more types may be used together.

  Examples of the epoxy monomer having a bisphenol skeleton include an epoxy monomer having a bisphenol A type, bisphenol F type, or bisphenol S type bisphenol skeleton.

  Examples of the epoxy monomer having a dicyclopentadiene skeleton include dicyclopentadiene dioxide and a phenol novolac epoxy monomer having a dicyclopentadiene skeleton.

  Examples of the epoxy monomer having a naphthalene skeleton include 1-glycidylnaphthalene, 2-glycidylnaphthalene, 1,2-diglycidylnaphthalene, 1,5-diglycidylnaphthalene, 1,6-diglycidylnaphthalene, 1,7-diglycidyl. Naphthalene, 2,7-diglycidylnaphthalene, triglycidylnaphthalene, 1,2,5,6-tetraglycidylnaphthalene and the like can be mentioned.

  Examples of the epoxy monomer having an adamantane skeleton include 1,3-bis (4-glycidyloxyphenyl) adamantane and 2,2-bis (4-glycidyloxyphenyl) adamantane.

  Examples of the epoxy monomer having a fluorene skeleton include 9,9-bis (4-glycidyloxyphenyl) fluorene, 9,9-bis (4-glycidyloxy-3-methylphenyl) fluorene, and 9,9-bis (4- Glycidyloxy-3-chlorophenyl) fluorene, 9,9-bis (4-glycidyloxy-3-bromophenyl) fluorene, 9,9-bis (4-glycidyloxy-3-fluorophenyl) fluorene, 9,9-bis (4-Glycidyloxy-3-methoxyphenyl) fluorene, 9,9-bis (4-glycidyloxy-3,5-dimethylphenyl) fluorene, 9,9-bis (4-glycidyloxy-3,5-dichlorophenyl) Fluorene and 9,9-bis (4-glycidyloxy-3,5-dibromophenyl) Fluorene, and the like.

  Examples of the epoxy monomer having a biphenyl skeleton include 4,4'-diglycidylbiphenyl and 4,4'-diglycidyl-3,3 ', 5,5'-tetramethylbiphenyl.

  Examples of the epoxy monomer having a bi (glycidyloxyphenyl) methane skeleton include 1,1′-bi (2,7-glycidyloxynaphthyl) methane, 1,8′-bi (2,7-glycidyloxynaphthyl) methane, 1,1′-bi (3,7-glycidyloxynaphthyl) methane, 1,8′-bi (3,7-glycidyloxynaphthyl) methane, 1,1′-bi (3,5-glycidyloxynaphthyl) methane 1,8'-bi (3,5-glycidyloxynaphthyl) methane, 1,2'-bi (2,7-glycidyloxynaphthyl) methane, 1,2'-bi (3,7-glycidyloxynaphthyl) Examples include methane and 1,2′-bi (3,5-glycidyloxynaphthyl) methane.

  Examples of the epoxy monomer having a xanthene skeleton include 1,3,4,5,6,8-hexamethyl-2,7-bis-oxiranylmethoxy-9-phenyl-9H-xanthene.

  Specific examples of the (A1b) thermosetting compound include, for example, 4,4′-bis [(3-ethyl-3-oxetanyl) methoxymethyl] biphenyl, 1,4-benzenedicarboxylic acid bis [(3-ethyl- 3-oxetanyl) methyl] ester, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene, oxetane-modified phenol novolak, and the like. (A1b) Only 1 type may be used for a thermosetting compound and 2 or more types may be used together.

  From the viewpoint of further improving the heat resistance of the cured product, the (A1) thermosetting compound preferably includes a thermosetting compound having two or more cyclic ether groups.

  From the viewpoint of further improving the heat resistance of the cured product, the content of the thermosetting compound having two or more cyclic ether groups is preferably 70% by weight or more in 100% by weight of the (A1) thermosetting compound. More preferably, it is 80% by weight or more, and preferably 100% by weight or less. (A1) The content of the thermosetting compound having two or more cyclic ether groups in 100% by weight of the thermosetting compound may be 10% by weight or more and 100% by weight or less. Further, the whole (A1) thermosetting compound may be a thermosetting compound having two or more cyclic ether groups.

  (A1) The molecular weight of the thermosetting compound is less than 10,000. (A1) The molecular weight of the thermosetting compound is preferably 200 or more, preferably 1200 or less, more preferably 600 or less, and even more preferably 550 or less. (A1) When the molecular weight of the thermosetting compound is not less than the above lower limit, the adhesiveness of the surface of the cured product is lowered, and the handling property of the curable material is further enhanced. (A1) When the molecular weight of the thermosetting compound is not more than the above upper limit, the adhesiveness of the cured product is further enhanced. Furthermore, the cured product is hard and hard to be brittle, and the adhesiveness of the cured product is further enhanced.

  In this specification, (A1) the molecular weight of the thermosetting compound is (A1) when the thermosetting compound is not a polymer, and (A1) when the structural formula of the thermosetting compound can be specified. It means the molecular weight that can be calculated from the structural formula. When the thermosetting compound (A1) is a polymer, it means the weight average molecular weight. The weight average molecular weight is a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

  In 100% by volume of the curable material, the content of the (A1) thermosetting compound is preferably 10% by volume or more, more preferably 20% by volume or more, preferably 90% by volume or less, more preferably 80% by volume. It is as follows. (A1) When the content of the thermosetting compound is not less than the above lower limit, the adhesiveness and heat resistance of the cured product are further enhanced. (A1) When content of a thermosetting compound is below the said upper limit, the applicability | paintability of a curable material becomes still higher.

(A2) Thermosetting compound having a molecular weight of 10,000 or more:
(A2) The thermosetting compound is a thermosetting compound having a molecular weight of 10,000 or more. Since the molecular weight of the (A2) thermosetting compound is 10,000 or more, the (A2) thermosetting compound is generally a polymer, and the above molecular weight generally means a weight average molecular weight.

  From the viewpoint of further improving the heat resistance and moisture resistance of the cured product, the (A2) thermosetting compound preferably has an aromatic skeleton. (A2) When the thermosetting compound is a polymer and (A2) the thermosetting compound has an aromatic skeleton, (A2) the thermosetting compound has an aromatic skeleton in any part of the whole polymer. What is necessary is just to have, it may have in the main chain frame | skeleton, and you may have in a side chain. From the viewpoint of further increasing the heat resistance of the cured product and further increasing the moisture resistance of the cured product, the (A2) thermosetting compound preferably has an aromatic skeleton in the main chain skeleton. (A2) As for a thermosetting compound, only 1 type may be used and 2 or more types may be used together.

  The aromatic skeleton is not particularly limited, and examples thereof include naphthalene skeleton, fluorene skeleton, biphenyl skeleton, anthracene skeleton, pyrene skeleton, xanthene skeleton, adamantane skeleton, and bisphenol A skeleton. From the viewpoint of further improving the cold heat cycle characteristics and heat resistance of the cured product, the aromatic skeleton is preferably a biphenyl skeleton or a fluorene skeleton.

  (A2) The thermosetting compound is not particularly limited. Styrene resin, phenoxy resin, oxetane resin, epoxy resin, episulfide compound, (meth) acrylic resin, phenol resin, amino resin, unsaturated polyester resin, polyurethane resin, silicone Examples thereof include resins and polyimide resins.

  From the viewpoint of suppressing the oxidative deterioration of the cured product, further improving the heat cycle resistance and heat resistance of the cured product, and further reducing the water absorption of the cured product, (A2) the thermosetting compound is a styrene resin, It is preferably a phenoxy resin or an epoxy resin, more preferably a phenoxy resin or an epoxy resin, and further preferably a phenoxy resin. In particular, use of a phenoxy resin or an epoxy resin further increases the heat resistance of the cured product. Moreover, use of a phenoxy resin further lowers the elastic modulus of the cured product and further improves the cold-heat cycle characteristics of the cured product. In addition, the (A2) thermosetting compound does not need to have cyclic ether groups, such as an epoxy group.

  As the styrene resin, specifically, a homopolymer of a styrene monomer, a copolymer of a styrene monomer and an acrylic monomer, or the like can be used. Styrene polymers having a styrene-glycidyl methacrylate structure are preferred.

  Examples of the styrene monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, p-ethylstyrene, and pn-. Butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, 2,4-dimethyl Examples include styrene and 3,4-dichlorostyrene.

  Specifically, the phenoxy resin is, for example, a resin obtained by reacting an epihalohydrin with a divalent phenol compound, or a resin obtained by reacting a divalent epoxy compound with a divalent phenol compound.

  The phenoxy resin has a bisphenol A skeleton, bisphenol F skeleton, bisphenol A / F mixed skeleton, naphthalene skeleton, fluorene skeleton, biphenyl skeleton, anthracene skeleton, pyrene skeleton, xanthene skeleton, adamantane skeleton or dicyclopentadiene skeleton. It is preferable. More preferably, the phenoxy resin has a bisphenol A skeleton, a bisphenol F skeleton, a bisphenol A / F mixed skeleton, a naphthalene skeleton, a fluorene skeleton, or a biphenyl skeleton, and at least one of the fluorene skeleton and the biphenyl skeleton. More preferably, it has a skeleton. Use of the phenoxy resin having these preferable skeletons further increases the heat resistance of the cured product.

  The epoxy resin is an epoxy resin other than the phenoxy resin. Examples of the epoxy resins include styrene skeleton-containing epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, phenol novolac type epoxy resins, biphenol type epoxy resins, naphthalene type epoxy resins, and fluorene type epoxy resins. , Phenol aralkyl type epoxy resin, naphthol aralkyl type epoxy resin, dicyclopentadiene type epoxy resin, anthracene type epoxy resin, epoxy resin having adamantane skeleton, epoxy resin having tricyclodecane skeleton, and epoxy resin having triazine nucleus in skeleton Etc.

  (A2) The molecular weight of the thermosetting compound is 10,000 or more. (A2) The molecular weight of the thermosetting compound is preferably 30000 or more, more preferably 40000 or more, preferably 1000000 or less, more preferably 250,000 or less. (A2) When the molecular weight of the thermosetting compound is not less than the above lower limit, the cured product is hardly thermally deteriorated. When the molecular weight of the (A2) thermosetting compound is not more than the above upper limit, the compatibility between the (A2) thermosetting compound and other components is increased. As a result, the heat resistance of the cured product is further increased.

  In 100% by volume of the curable material, the content of the (A2) thermosetting compound is preferably 20% by volume or more, more preferably 30% by volume or more, preferably 60% by volume or less, more preferably 50% by volume. It is as follows. (A2) When the content of the thermosetting compound is not less than the above lower limit, the handleability of the curable material is further improved. (A2) When content of a thermosetting compound is below the said upper limit, the applicability | paintability of a curable material becomes still higher.

(Thermosetting component: thermosetting agent)
The thermosetting agent is not particularly limited. As the thermosetting agent, a thermosetting agent capable of curing the thermosetting compound can be appropriately used. In the present specification, the thermosetting agent includes a curing catalyst. As for a thermosetting agent, only 1 type may be used and 2 or more types may be used together.

  From the viewpoint of further improving the heat resistance of the cured product, the thermosetting agent preferably has an aromatic skeleton or an alicyclic skeleton. The thermosetting agent preferably includes an amine curing agent (amine compound), an imidazole curing agent, a phenol curing agent (phenol compound), or an acid anhydride curing agent (acid anhydride), and more preferably includes an amine curing agent. preferable. The acid anhydride curing agent includes an acid anhydride having an aromatic skeleton, a water additive of the acid anhydride or a modified product of the acid anhydride, or an acid anhydride having an alicyclic skeleton, It is preferable to include a water additive of an acid anhydride or a modified product of the acid anhydride.

  Examples of the amine curing agent include dicyandiamide, imidazole compounds, diaminodiphenylmethane, and diaminodiphenylsulfone. From the viewpoint of further improving the adhesiveness of the cured product, the amine curing agent is more preferably a dicyandiamide or an imidazole compound. From the viewpoint of further improving the storage stability of the curable material, the thermosetting agent preferably includes a curing agent having a melting point of 180 ° C. or higher, and more preferably includes an amine curing agent having a melting point of 180 ° C. or higher. preferable.

  Examples of the imidazole curing agent include 2-undecylimidazole, 2-heptadecylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, and 1-benzyl. 2-methylimidazole, 1-benzyl-2-phenylimidazole, 1,2-dimethylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2- Undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6- [2 '-Methyl Midazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino-6- [2′-undecylimidazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino-6 [2′-Ethyl-4′-methylimidazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino-6- [2′-methylimidazolyl- (1 ′)]-ethyl-s-triazine Isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-methylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole and 2-phenyl-4-methyl-5-dihydroxymethylimidazole Can be mentioned.

  Examples of the phenol curing agent include phenol novolak, o-cresol novolak, p-cresol novolak, t-butylphenol novolak, dicyclopentadiene cresol, polyparavinylphenol, bisphenol A type novolak, xylylene modified novolak, decalin modified novolak, poly ( And di-o-hydroxyphenyl) methane, poly (di-m-hydroxyphenyl) methane, and poly (di-p-hydroxyphenyl) methane. From the viewpoint of further enhancing the flexibility of the cured product and the flame retardancy of the cured product, the phenol curing agent is a phenol resin having a melamine skeleton, a phenol resin having a triazine skeleton, or a phenol resin having an allyl group. Is preferred.

  Commercially available products of the phenol curing agent include MEH-8005, MEH-8010, and MEH-8015 (all of which are manufactured by Meiwa Kasei Co., Ltd.), YLH903 (manufactured by Mitsubishi Chemical Corporation), LA-7052, LA-7054, and LA-7751. LA-1356 and LA-3018-50P (all of which are manufactured by DIC Corporation), PS6313 and PS6492 (all of which are manufactured by Gunei Chemical Co., Ltd.), and the like.

  Examples of the acid anhydride having an aromatic skeleton, a water additive of the acid anhydride, or a modified product of the acid anhydride include, for example, a styrene / maleic anhydride copolymer, a benzophenone tetracarboxylic acid anhydride, and a pyromellitic acid anhydride. , Trimellitic anhydride, 4,4'-oxydiphthalic anhydride, phenylethynyl phthalic anhydride, glycerol bis (anhydrotrimellitate) monoacetate, ethylene glycol bis (anhydrotrimellitate), methyltetrahydroanhydride Examples include phthalic acid, methylhexahydrophthalic anhydride, and trialkyltetrahydrophthalic anhydride.

  Examples of commercially available acid anhydrides having an aromatic skeleton, water additives of the acid anhydrides, or modified products of the acid anhydrides include SMA Resin EF30, SMA Resin EF40, SMA Resin EF60, and SMA Resin EF80 (any of the above Also manufactured by Sartomer Japan), ODPA-M and PEPA (all manufactured by Manac), Ricacid MTA-10, Ricacid MTA-15, Ricacid TMTA, Ricacid TMEG-100, Ricacid TMEG-200, Ricacid TMEG-300, Ricacid TMEG-500, Ricacid TMEG-S, Ricacid TH, Ricacid HT-1A, Ricacid HH, Ricacid MH-700, Ricacid MT-500, Ricacid DSDA and Ricacid TDA-100 (all of which are manufactured by Shin Nippon Rika Co., Ltd.) PICLON B4400, EPICLON B650, and EPICLON B570 (all manufactured by both DIC Corporation).

  The acid anhydride having an alicyclic skeleton, a water additive of the acid anhydride, or a modified product of the acid anhydride is an acid anhydride having a polyalicyclic skeleton, a water additive of the acid anhydride, or the A modified product of an acid anhydride, or an acid anhydride having an alicyclic skeleton obtained by addition reaction of a terpene compound and maleic anhydride, a water additive of the acid anhydride, or a modified product of the acid anhydride It is preferable. By using these curing agents, the flexibility of the cured product and the moisture resistance and adhesion of the cured product are further increased.

  Examples of the acid anhydride having an alicyclic skeleton, a water addition of the acid anhydride, or a modified product of the acid anhydride include methyl nadic acid anhydride, acid anhydride having a dicyclopentadiene skeleton, and the acid anhydride And the like.

  Examples of commercially available acid anhydrides having the alicyclic skeleton, water additions of the acid anhydrides, or modified products of the acid anhydrides include Ricacid HNA and Ricacid HNA-100 (all of which are manufactured by Shin Nippon Rika Co., Ltd.) , And EpiCure YH306, EpiCure YH307, EpiCure YH308H, EpiCure YH309 (all of which are manufactured by Mitsubishi Chemical Corporation) and the like.

  It is also preferable that the thermosetting agent is methyl nadic anhydride or trialkyltetrahydrophthalic anhydride. Use of methyl nadic anhydride or trialkyltetrahydrophthalic anhydride increases the water resistance of the cured product.

  In 100% by volume of the curable material, the content of the thermosetting agent is preferably 0.1% by volume or more, more preferably 1% by volume or more, preferably 40% by volume or less, more preferably 25% by volume or less. It is. When the content of the thermosetting agent is equal to or higher than the lower limit, it becomes much easier to sufficiently cure the thermosetting compound. When the content of the thermosetting agent is not more than the above upper limit, it is difficult to generate an excessive thermosetting agent that does not participate in curing. For this reason, the heat resistance and adhesiveness of hardened | cured material become still higher.

(Photocurable component: Photocurable compound)
The said photocurable compound will not be specifically limited if it has photocurability. As for the said photocurable compound, only 1 type may be used and 2 or more types may be used together.

  The photocurable compound preferably has two or more ethylenically unsaturated bonds.

  Examples of the group containing an ethylenically unsaturated bond include a vinyl group, an allyl group, and a (meth) acryloyl group. A (meth) acryloyl group is preferred from the viewpoint of effectively advancing the reaction and further suppressing foaming, peeling and discoloration of the cured product. The photocurable compound preferably has a (meth) acryloyl group.

  From the viewpoint of further improving the adhesion of the cured product, the photocurable compound preferably contains an epoxy (meth) acrylate. From the viewpoint of further increasing the heat resistance of the cured product, the epoxy (meth) acrylate preferably contains a bifunctional epoxy (meth) acrylate and a trifunctional or higher functional epoxy (meth) acrylate. The bifunctional epoxy (meth) acrylate preferably has two (meth) acryloyl groups. The tri- or higher functional epoxy (meth) acrylate preferably has three or more (meth) acryloyl groups.

  Epoxy (meth) acrylate is obtained by reacting (meth) acrylic acid with an epoxy compound. Epoxy (meth) acrylate can be obtained by converting an epoxy group into a (meth) acryloyl group. Since the photocurable material is cured by light irradiation, the epoxy (meth) acrylate preferably has no epoxy group.

  As the epoxy (meth) acrylate, bisphenol type epoxy (meth) acrylate (for example, bisphenol A type epoxy (meth) acrylate, bisphenol F type epoxy (meth) acrylate, bisphenol S type epoxy (meth) acrylate), cresol novolac type Examples include epoxy (meth) acrylate, amine-modified bisphenol-type epoxy (meth) acrylate, caprolactone-modified bisphenol-type epoxy (meth) acrylate, carboxylic acid anhydride-modified epoxy (meth) acrylate, and phenol novolac-type epoxy (meth) acrylate. .

  In 100% by volume of the curable material, the content of the photocurable compound is preferably 5% by volume or more, more preferably 10% by volume or more, preferably 40% by volume or less, more preferably 30% by volume or less. is there. When the content of the photocurable compound is not less than the above lower limit and not more than the above upper limit, the adhesion of the cured product is further enhanced.

(Photocurable component: Photopolymerization initiator)
The photopolymerization initiator is not particularly limited. As said photoinitiator, the photoinitiator which can harden the said photocurable compound by irradiation of light can be used suitably. As for the said photoinitiator, only 1 type may be used and 2 or more types may be used together.

  Examples of the photopolymerization initiator include acylphosphine oxide, halomethylated triazine, halomethylated oxadiazole, imidazole, benzoin, benzoin alkyl ether, anthraquinone, benzanthrone, benzophenone, acetophenone, thioxanthone, benzoate, acridine, phenazine, Examples include titanocene, α-aminoalkylphenone, oxime, and derivatives thereof.

  Examples of the benzophenone photopolymerization initiator include methyl o-benzoylbenzoate and Michler's ketone. EAB (made by Hodogaya Chemical Co., Ltd.) etc. are mentioned as a commercial item of a benzophenone series photoinitiator.

  Examples of commercially available acetophenone photopolymerization initiators include Darocur 1173, Darocur 2959, Irgacure 184, Irgacure 907, and Irgacure 369 (all of which are manufactured by BASF).

  Examples of commercially available benzoin photopolymerization initiators include Irgacure 651 (manufactured by BASF).

  Examples of commercially available acylphosphine oxide photopolymerization initiators include Lucirin TPO (BASF) and Irgacure 819 (BASF).

  Examples of commercially available thioxanthone photopolymerization initiators include isopropyl thioxanthone and diethyl thioxanthone.

  Examples of commercially available oxime photopolymerization initiators include Irgacure OXE-01 and Irgacure OXE-02 (all of which are manufactured by BASF).

  The content of the photopolymerization initiator with respect to 100 parts by weight of the photocurable compound is preferably 1 part by weight or more, more preferably 3 parts by weight or more, preferably 20 parts by weight or less, more preferably 15 parts by weight. Less than parts by weight. When the content of the photopolymerization initiator is not less than the above lower limit and not more than the above upper limit, the photocurable compound can be favorably photocured.

(Insulating filler)
The curable material according to the present invention may contain an insulating filler. The insulating layer in the laminate according to the present invention may contain an insulating filler. The insulating filler is not the first inorganic particle but not the second inorganic particle. The insulating filler has an insulating property. The insulating filler may be an organic filler or an inorganic filler. The insulating filler is preferably not an aggregate of particles. As for the said insulating filler, only 1 type may be used and 2 or more types may be used together.

  From the viewpoint of further increasing the thermal conductivity, the insulating filler is preferably an inorganic filler. From the viewpoint of further increasing the thermal conductivity, the insulating filler preferably has a thermal conductivity of 10 W / m · K or more.

  From the viewpoint of further increasing the thermal conductivity of the cured product, the thermal conductivity of the insulating filler is preferably 10 W / m · K or more, more preferably 20 W / m · K or more. The upper limit of the thermal conductivity of the insulating filler is not particularly limited. Inorganic fillers having a thermal conductivity of about 300 W / m · K are widely known, and inorganic fillers having a thermal conductivity of about 200 W / m · K are easily available.

  The material of the insulating filler is not particularly limited. Insulating filler materials are nitrogen compounds (boron nitride, aluminum nitride, silicon nitride, carbon nitride, titanium nitride, etc.), carbon compounds (silicon carbide, fluorine carbide, boron carbide, titanium carbide, tungsten carbide, diamond, etc.) And metal oxides (silica, alumina, zinc oxide, magnesium oxide, beryllium oxide, etc.) are preferable. The material of the insulating filler is more preferably alumina, boron nitride, aluminum nitride, silicon nitride, silicon carbide, zinc oxide or magnesium oxide. Use of these preferable insulating fillers further increases the thermal conductivity of the cured product.

  The insulating filler is preferably spherical particles, non-aggregated particles having an aspect ratio of more than 2, or aggregate particles having an aspect ratio of more than 2, and preferably spherical particles and non-aggregated particles having an aspect ratio of more than 2. . Use of these insulating fillers further increases the thermal conductivity of the cured product. The aspect ratio of the spherical particles is 2 or less.

  The new Mohs hardness of the insulating filler material is preferably 12 or less, more preferably 9 or less. When the new Mohs hardness of the insulating filler material is 9 or less, the workability of the cured product is further enhanced.

  From the viewpoint of further improving the workability of the cured product, the material of the insulating filler is preferably boron nitride, synthetic magnesite, crystalline silica, zinc oxide, or magnesium oxide. The new Mohs hardness of these inorganic filler materials is 9 or less.

  From the viewpoint of further increasing the thermal conductivity, the average particle size of the insulating filler is preferably 0.1 μm or more, and preferably 20 μm or less. When the average particle diameter is not less than the above lower limit, the insulating filler can be easily filled at a high density. When the average particle size is not more than the above upper limit, the thermal conductivity of the cured product is further increased.

  The “average particle diameter” is an average particle diameter obtained from a volume average particle size distribution measurement result measured by a laser diffraction particle size distribution measuring apparatus.

  From the viewpoint of further increasing the thermal conductivity, the content of the insulating filler is preferably 1% by volume or more, more preferably 3% by volume or more in 100% by volume of the curable material and 100% by volume of the insulating layer. Preferably, it is 20 volume% or less, More preferably, it is 10 volume% or less.

(Other ingredients)
The curable material and the insulating layer may contain, in addition to the components described above, curable materials such as a dispersant, a chelating agent, and an antioxidant, and other components generally used for curable sheets and insulating layers. Good.

(Other details of curable materials and cured products)
The curable material may be a curable paste or a curable sheet. A cured product can be obtained by curing the curable material. This cured product is a cured product of a curable material, and is formed of a curable material.

  FIG. 1 is a cross-sectional view schematically showing a cured product of a curable material according to an embodiment of the present invention. In FIG. 1, the actual size and thickness are different for convenience of illustration.

  A cured product 1 shown in FIG. 1 includes a cured product portion 11, first inorganic particles 12, and second inorganic particles 13. The 1st inorganic particle 12 and the 2nd inorganic particle 13 are the 1st inorganic particle and the 2nd inorganic particle which were mentioned above, respectively, and the 1st inorganic particle 12 and the 2nd inorganic particle 13 are boron nitride aggregation, respectively. Particles are preferred. The first inorganic particles 12 and the second inorganic particles 13 have different compressive strengths.

  The first inorganic particles 12 are preferably not deformed or collapsed by a compression force such as a press. The first inorganic particles 12 are preferably aggregated particles (secondary particles). The first inorganic particles 12 are preferably present in the form of aggregated particles (secondary particles) in the cured product.

  The second inorganic particles 13 may be deformed or partially collapsed by a compression force such as a press. The second inorganic particles 13 may be deformed aggregated particles (secondary particles), or may be primary particles by the collapse of the aggregated particles (secondary particles). The second inorganic particles 13 may exist in the form of deformed aggregated particles (secondary particles) in the cured product, and exist in the form of primary particles by the collapse of the aggregated particles (secondary particles). You may do it.

  In the cured product portion 11, the second inorganic particles 13 are not only oriented in the plane direction but also oriented in the thickness direction by the first inorganic particles 12. The orientation of the second inorganic particles 13 is controlled by the first inorganic particles 12. The cured product 1 can improve thermal conductivity not only in the plane direction but also in the thickness direction (press direction).

  The cured product portion 11 is a portion where the curable compound is cured. The cured product portion 11 may be a portion where a thermosetting component including a thermosetting compound and a thermosetting agent is cured, or a portion where a photocurable component including a photocurable compound and a photopolymerization initiator is cured. There may be. The hardened | cured material part 11 is obtained by hardening a thermosetting component or a photocurable component.

  The said curable material, the said insulating layer, and the said hardened | cured material can be used for various uses as which heat conductivity, mechanical strength, etc. are calculated | required. For example, in the electronic device, the cured product portion is disposed between a heat generating component and a heat radiating component.

(Other details of laminate)
The laminate according to the present invention includes a heat conductor, an insulating layer, and a conductive layer. The insulating layer is laminated on one surface of the heat conductor. The conductive layer is laminated on the surface of the insulating layer opposite to the thermal conductor. The insulating layer may be laminated on the other surface of the heat conductor. In the laminate according to the present invention, the material of the insulating layer is the curable material described above. The insulating layer is a cured product of the curable material. The cured product may be obtained by heating and pressurizing the curable material using a press or the like.

  FIG. 2 is a cross-sectional view schematically showing a laminate including the cured product of the curable material shown in FIG. 1 as an insulating layer.

  The laminated body 21 shown in FIG. 2 includes a heat conductor 31, a cured product 1, and a conductive layer 32. The cured product 1 is laminated on one surface of the heat conductor 31. The conductive layer 32 is laminated on the surface of the cured product 1 opposite to the heat conductor 31. The cured product 1 is an insulating layer.

Thermal conductor:
The thermal conductivity of the thermal conductor is preferably 10 W / m · K or more. An appropriate heat conductor can be used as the heat conductor. The heat conductor is preferably a metal material. Examples of the metal material include a metal foil and a metal plate. The heat conductor is preferably the metal foil or the metal plate, and more preferably the metal plate.

  Examples of the metal material include aluminum, copper, gold, silver, and a graphite sheet. From the viewpoint of more effectively increasing the thermal conductivity, the metal material is preferably aluminum, copper, or gold, and more preferably aluminum or copper.

Conductive layer:
The metal for forming the conductive layer is not particularly limited. Examples of the metal include gold, silver, palladium, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, thallium, germanium, cadmium, silicon, and tungsten. , Molybdenum, and alloys thereof. Examples of the metal include tin-doped indium oxide (ITO) and solder. From the viewpoint of more effectively increasing the thermal conductivity, aluminum, copper or gold is preferable, and aluminum or copper is more preferable.

  The method for forming the conductive layer is not particularly limited. Examples of the method for forming the conductive layer include a method by electroless plating, a method by electroplating, and a method in which the insulating layer and the metal foil are thermocompression bonded. Since the formation of the conductive layer is simple, a method of thermocompression bonding the insulating layer and the metal foil is preferable.

  Hereinafter, the present invention will be clarified by giving specific examples and comparative examples of the present invention. The present invention is not limited to the following examples.

Thermosetting compound:
(1) “Epicoat 828US” manufactured by Mitsubishi Chemical Corporation, epoxy compound

Thermosetting agent:
(1) “Dicyandiamide” manufactured by Tokyo Chemical Industry Co., Ltd.
(2) “2MZA-PW” manufactured by Shikoku Kasei Kogyo Co., Ltd., isocyanuric modified solid dispersion type imidazole

First inorganic particles or alternatives thereof:
(1) “PCTH7MHF” manufactured by Saint-Gobain (dielectric constant: 4)
(2) “Inorganic particles 1” (dielectric constant: 4)
(3) “PTX25S” manufactured by Momentive (dielectric constant: 4)
(4) “PCTL7MHF” manufactured by Saint-Gobain (dielectric constant: 4)
(5) “CB-A30S” manufactured by Showa Denko KK (dielectric constant: 9)

Method for producing “inorganic particles 1”:
Inorganic particles 1 were produced by agglomerating primary particles of boron nitride having an average major axis of 3.3 μm and an aspect ratio of 12.7 by a spray drying method so that the porosity is 41%.

Second inorganic particles or alternatives thereof:
(1) “PTX25S” manufactured by Momentive (dielectric constant: 4)
(2) “PTX60S” manufactured by Momentive (dielectric constant: 4)
(3) "PT350" manufactured by Momentive (dielectric constant: 4)
(4) “Aggregate 100” manufactured by 3M (dielectric constant: 4)
(5) “PCTL7MHF” manufactured by Saint-Gobain (dielectric constant: 4)

(Compressive strength of first inorganic particles and second inorganic particles)
The compression strength at the time of compression in the range of 10% or more and 30% or less of each of the first inorganic particles and the second inorganic particles was measured as follows.

Method for measuring compressive strength of first inorganic particles and second inorganic particles:
Using a micro compression tester, a rectangular prism made of diamond was used as a compression member under the condition of a compression speed of 0.67 mN / second, and the smooth end surface of the compression member was lowered toward the inorganic particles to compress the inorganic particles. The first inorganic particles had a maximum test load of 100 mN, and the second inorganic particles had a maximum test load of 40 mN. As a measurement result, the relationship between the compression load value and the compression displacement is obtained, and the compression load value per unit area is calculated using the average cross-sectional area obtained by calculating the compression load value using the average particle diameter of the inorganic particles. Compressive strength. Further, the compression rate (compression rate = compression displacement / average particle size × 100) was calculated from the compression displacement and the average particle size of the inorganic particles, and the relationship between the compression strength and the compression rate was obtained. The inorganic particles to be measured were measured by observing the particles using a microscope, and selecting particles with an error of less than 10% from the average particle diameter. Moreover, the compressive strength in each compression rate was computed as average compressive strength which averaged the measurement result of 20 times. As the micro compression tester, for example, “Micro compression tester HM2000” manufactured by Fischer Instruments is used.

(Average particle diameter of the first inorganic particles and the second inorganic particles)
The particle diameters of the first inorganic particles and the second inorganic particles were measured using a “laser diffraction particle size distribution measuring apparatus” manufactured by Horiba, Ltd. In the first inorganic particles and the second inorganic particles, the value of the particle diameter (d50) of the inorganic particles when the cumulative volume is 50% was calculated.

(Examples 1 to 10)
(1) Preparation of curable material The components shown in Tables 1 and 2 below were blended in the blending amounts shown in Tables 1 and 2 below, followed by stirring for 25 minutes at 500 rpm using a planetary stirrer. Got.

(2) Production of thermal conductive sheet (curable sheet) The obtained curable material was applied on a release PET sheet (thickness 50 μm) so as to have a thickness of 350 μm, and then in an oven at 90 ° C. for 10 minutes. A curable sheet was formed by drying to obtain a laminated sheet. Thereafter, the release PET sheet was peeled off, and both sides of the curable sheet were sandwiched between a copper foil and an aluminum plate, and vacuum-pressed under conditions of a temperature of 150 ° C. and a pressure of 10 MPa to prepare a heat conductive sheet.

(Comparative Example 1)
Alternative to the first inorganic particles:
(3) “PTX25S” manufactured by Momentive (dielectric constant: 4)
A curable material and a thermally conductive sheet (curable sheet) were prepared in the same manner as in Example 2 except that “PTX25S” manufactured by Momentive Co. was used instead of the first inorganic particles.

(Comparative Example 2)
Alternative to the first inorganic particles:
(3) “PTX25S” manufactured by Momentive (dielectric constant: 4)
A curable material and a thermally conductive sheet (curable sheet) were prepared in the same manner as in Example 5 except that “PTX25S” manufactured by Momentive Co. was used instead of the first inorganic particles.

(Comparative Example 3)
Alternative to the first inorganic particles:
(1) “PCTH7MHF” manufactured by Saint-Gobain (dielectric constant: 4)
Alternative to second inorganic particles:
(4) “Aggregate 100” manufactured by 3M (dielectric constant: 4)

  A curable material and a thermally conductive sheet (curable sheet) were produced in the same manner as in Example 1 except that the following changes were made.

Using “PCTH7MHF” manufactured by Saint-Gobain instead of the first inorganic particles, the blending amount of “PCTH7MHF” manufactured by Saint-Gobain was changed to 35% by weight. “Aggregate100” manufactured by 3M was used instead of the second inorganic particles. The amount of 3M “Aggregate 100” was changed to 35% by weight.

(Comparative Example 4)
Alternative to the first inorganic particles:
(5) “CB-A30S” manufactured by Showa Denko KK (dielectric constant: 9)
Alternative to second inorganic particles:
(2) “PTX60S” manufactured by Momentive (dielectric constant: 4)

  A curable material and a thermally conductive sheet (curable sheet) were produced in the same manner as in Example 1 except that the following changes were made.

Change the blending amount of the thermosetting compound and the thermosetting agent In place of the first inorganic particles, “CB-A30S” manufactured by Showa Denko KK is used, and the blending amount of “CB-A30S” manufactured by Showa Denko KK is 30% by weight. In place of the second inorganic particles, “PTX60S” manufactured by Momentive was used, and the blending amount of “PTX60S” manufactured by Momentive was changed to 49% by weight.

(Evaluation)
(1) Thermal conductivity After the obtained thermal conductive sheet was cut into 1 cm square, a measurement sample was prepared by spraying carbon black on both sides. Using the obtained measurement sample, thermal conductivity was calculated by a laser flash method. The thermal conductivities in Tables 1 to 3 are relative values with the value of Comparative Example 1 being 1.00.

(2) Dielectric breakdown strength Copper was patterned into a circle having a diameter of 2 cm on the obtained thermal conductive sheet to obtain a test sample. An AC voltage was applied at 25 ° C. using a withstand voltage tester (“MODEL7473” manufactured by ETECH Electronics) so that the voltage increased at a rate of 0.33 kV / sec between test samples. The voltage at which a current of 10 mA flowed through the test sample was taken as the breakdown voltage. The dielectric breakdown voltage was normalized by dividing by the sample thickness, and the dielectric breakdown strength was calculated. The dielectric breakdown strength was determined according to the following criteria.

[Criteria for dielectric breakdown strength]
○: 90 kV / mm or more ○: 60 kV / mm or more, less than 90 kV / mm Δ: 30 kV / mm or more, less than 60 kV / mm ×: less than 30 kV / mm

  The results are shown in Tables 1 to 3 below.

DESCRIPTION OF SYMBOLS 1 ... Hardened | cured material 11 ... Hardened | cured material part (cured part of the curable compound)
DESCRIPTION OF SYMBOLS 12 ... 1st inorganic particle 13 ... 2nd inorganic particle 21 ... Laminated body 31 ... Thermal conductor 32 ... Conductive layer

Claims (8)

Including first inorganic particles, second inorganic particles, and a curable compound;
The compression strength at the time of compression in the range of 10% or more and 30% or less of each of the first inorganic particles and the second inorganic particles is measured, and at the same compression in the range of 10% or more and 30% or less When the compressive strength ratio of the compressive strength of the first inorganic particles to the compressive strength of the second inorganic particles is determined, the minimum value of the compressive strength ratio is 2 or more and the maximum value of the compressive strength ratio is 100. And
The content of the first inorganic particles is 20% by volume or more and less than 50% by volume in a total of 100% by volume of the first inorganic particles and the second inorganic particles, and the first inorganic particles The curable material in which the content of the second inorganic particles exceeds 50% by volume and is 80% by volume or less in a total of 100% by volume of the second inorganic particles. The compressive strength at the time of 10% compression of the first inorganic particles is 2 N / mm ² or more,
The compressive strength at the time of 20% compression of the first inorganic particles is 4.2 N / mm ² or more,
The compressive strength at the time of 30% compression of the first inorganic particles is 4.4 N / mm ² or more,
The compressive strength at the time of 10% compression of the second inorganic particles is 1.8 N / mm ² or less,
The compressive strength at the time of 20% compression of the second inorganic particles is 2.8 N / mm ² or less,
The curable material according to claim 1, wherein the second inorganic particles have a compressive strength of 3.5 N / mm ² or less when compressed by 30%. The compressive strength at the time of 30% compression of the first inorganic particles is 4.4 N / mm ² or more,
The compressive strength at 30% compression of the second inorganic particles, 2N / mm ² or more and 3.5 N / mm ² or less, the curable material according to claim 1 or 2.   The curable material according to any one of claims 1 to 3, wherein a dielectric constant of the material of the first inorganic particles and a dielectric constant of the material of the second inorganic particles are each 7.5 or less. .   The curable material according to any one of claims 1 to 4, wherein each of the first inorganic particles and the second inorganic particles is boron nitride aggregated particles.   The total content of the first inorganic particles and the second inorganic particles in 100% by volume of the curable material is 20% by volume or more and 80% by volume or less. The curable material according to Item.   The curable material according to any one of claims 1 to 6, which is a curable sheet. A heat conductor, an insulating layer laminated on one surface of the heat conductor, and a conductive layer laminated on the surface of the insulating layer opposite to the heat conductor,
The insulating layer is a cured product of a curable material containing first inorganic particles, second inorganic particles, and a curable compound;
The compression strength at the time of compression in the range of 10% or more and 30% or less of each of the first inorganic particles and the second inorganic particles is measured, and at the same compression in the range of 10% or more and 30% or less When the compressive strength ratio of the compressive strength of the first inorganic particles to the compressive strength of the second inorganic particles is determined, the minimum value of the compressive strength ratio is 2 or more and the maximum value of the compressive strength ratio is 100. And
In the insulating layer, the content of the first inorganic particles is 20% by volume or more and less than 50% by volume in a total of 100% by volume of the first inorganic particles and the second inorganic particles, The laminated body whose content of a said 2nd inorganic particle exceeds 50 volume% and is 80 volume% or less in the total 100 volume% of a 1st inorganic particle and a said 2nd inorganic particle.

Images