JP7150598B2 - Resin material and laminate - Google Patents

Description

The present invention relates to a resin material containing aggregated boron nitride particles and a binder resin. The present invention also relates to a laminate using the above resin material.

2. Description of the Related Art In recent years, the miniaturization and performance enhancement of electronic and electrical equipment have progressed, and the mounting density of electronic components has increased. Therefore, how to dissipate the heat generated from electronic components in a narrow space has become a problem. Since the heat generated from electronic components directly affects the reliability of electronic and electrical equipment, efficient dissipation of the generated heat is an urgent issue.

One means of solving the above problems is to use a ceramic substrate having high thermal conductivity as a heat dissipation substrate on which power semiconductor devices and the like are mounted. Examples of such ceramic substrates include alumina substrates and aluminum nitride substrates.

However, the method using the ceramic substrate has the problems that it is difficult to form multiple layers, the workability is poor, and the cost is very high. Furthermore, since there is a large difference in coefficient of linear expansion between the ceramic substrate and the copper circuit, there is also the problem that the copper circuit tends to peel off during thermal cycles.

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

As a method of reducing the anisotropy of the thermal conductivity of hexagonal boron nitride and improving the thermal conductivity in the thickness direction, secondary aggregated particles (boron nitride aggregated particles) obtained by aggregating primary particles of hexagonal boron nitride It is proposed to use Patent Documents 1 to 3 below disclose resin compositions using aggregated particles of boron nitride.

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

Patent Document 2 below discloses a curable heat-dissipating composition containing two types of fillers having different compression breaking strengths (except when the two types of fillers are the same substance) and a curable resin (C). things are disclosed. The compression breaking strength ratio of the two fillers (compressive breaking strength of filler (A) having high compressive breaking strength/compressive breaking strength of filler (B) having low compressive breaking strength) is 5 or more and 1500 or less. The filler (B) is hexagonal boron nitride agglomerates.

Patent Document 3 below discloses a thermosetting resin composition containing a thermosetting resin and an inorganic filler. The inorganic filler includes 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. and secondary particles (B) to be formed.

JP 2011-6586 A WO2013/145961A1 WO2014/199650A1

In the curable composition using conventional boron nitride aggregated particles as described in Patent Documents 1 to 3, in order to maintain the isotropy of the thermal conductivity of the boron nitride aggregated particles, during pressing such as sheet molding, It is necessary not to collapse the aggregated boron nitride particles by pressing. For this reason, voids may remain between the aggregated boron nitride particles. As a result, the thermal conductivity in the thickness direction can be improved, but the insulation may be degraded. Conventional boron nitride agglomerated particles have limitations in improving insulation.

In addition, in a conventional curable composition using aggregated boron nitride particles, it is difficult to completely eliminate voids between the aggregated boron nitride particles, and variations in dielectric breakdown strength may occur.

In addition, in a curable composition using conventional boron nitride aggregated particles, the area of the end surface where relatively many functional groups of boron nitride constituting the boron nitride aggregated particles are present may be small. As a result, the adhesiveness between the aggregated boron nitride particles and the curable compound may be lowered, or the adhesiveness between the curable composition and the adherend may be lowered.

An object of the present invention is to provide a resin material capable of effectively enhancing insulation, effectively suppressing variations in dielectric breakdown strength, and effectively enhancing adhesiveness, and the resin material. It is to provide a laminate using

According to a broad aspect of the present invention, the first aggregated boron nitride particles, the second aggregated boron nitride particles, and a binder resin are included, and the first aggregated boron nitride particles have a pore size exceeding 0 μm, In the volume-based pore size distribution of the pore volume of pores that are 5 μm or less, the cumulative 50% pore size is less than 2 μm, and the second boron nitride aggregated particles have a pore size of more than 0 μm and 5 μm. In the volume-based pore size distribution of the pore volume of the pores, the cumulative 50% pore size is 2 μm or more, and the aspect ratio of the primary particles constituting the second boron nitride aggregated particles is 7. A resin material is provided which is:

In a specific aspect of the resin material according to the present invention, the primary particles forming the first aggregated boron nitride particles have an aspect ratio of 3 or more and 17 or less.

In a specific aspect of the resin material according to the present invention, the particle diameter of the first aggregated boron nitride particles exceeds 40 μm, and the average length of the primary particles constituting the first aggregated boron nitride particles is 2 μm or more. , and less than 20 μm, and the average length of the primary particles constituting the second aggregated boron nitride particles is 8 μm or less.

In a specific aspect of the resin material according to the present invention, the total content of the first aggregated boron nitride particles and the second aggregated boron nitride particles in 100% by volume of the resin material is 20% by volume or more, 80% by volume or less.

On the specific situation with the resin material which concerns on this invention, the said resin material is a resin sheet.

According to a broad 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 wherein the material of the insulating layer is the resin material described above.

The resin material according to the present invention includes first aggregated boron nitride particles, second aggregated boron nitride particles, and a binder resin. In the resin material according to the present invention, in the first boron nitride aggregated particles, the pore size distribution of the pores having a pore size of more than 0 μm and 5 μm or less is based on the volume of the pore volume. Cumulative 50% pore diameter is less than 2 μm. In the resin material according to the present invention, in the second boron nitride aggregated particles, the pore size distribution of the pores having a pore size of more than 0 μm and 5 μm or less is based on the volume of the pore volume. Cumulative 50% pore diameter is 2 μm or more. In the resin material according to the present invention, the aspect ratio of the primary particles constituting the second aggregated boron nitride particles is 7 or less. Since the resin material according to the present invention has the above configuration, it is possible to effectively improve the insulation, effectively suppress variations in dielectric breakdown strength, and further improve the adhesiveness. can be significantly increased.

FIG. 1 is a cross-sectional view schematically showing a resin sheet according to one embodiment of the invention. FIG. 2 is a cross-sectional view schematically showing a laminate obtained using a resin material according to one embodiment of the present invention. FIG. 3 is a diagram showing an example of the relationship between pore volume difference and pore diameter in the present invention. FIGS. 4(a) and 4(b) are diagrams showing an example of the difference between the first aggregated boron nitride particles and the second aggregated boron nitride particles in the present invention.

The present invention will be described in detail below.

(resin material)
The resin material according to the present invention includes first aggregated boron nitride particles, second aggregated boron nitride particles, and a binder resin.

In the resin material according to the present invention, in the first boron nitride aggregated particles, the pore size distribution of the pores having a pore size of more than 0 μm and 5 μm or less is based on the volume of the pore volume. Cumulative 50% pore diameter is less than 2 μm.

In the resin material according to the present invention, in the second boron nitride aggregated particles, the pore size distribution of the pores having a pore size of more than 0 μm and 5 μm or less is based on the volume of the pore volume. Cumulative 50% pore diameter is greater than or equal to 2 μm.

In the resin material according to the present invention, the aspect ratio of the primary particles constituting the second aggregated boron nitride particles is 7 or less.

Since the resin material according to the present invention has the above configuration, it is possible to effectively improve the insulation, effectively suppress variations in dielectric breakdown strength, and further improve the adhesiveness. can be significantly increased.

In the resin material according to the present invention, since the pore size of the first boron nitride aggregated particles is relatively small compared to the pore size of the second boron nitride aggregated particles, the first boron nitride aggregated particles are Easy to fill with binder resin. Even when a compressive force such as a press is applied, the first aggregated boron nitride particles can retain their shape. Further, in the resin material according to the present invention, since the pore diameter of the second boron nitride aggregated particles is relatively large, the second boron nitride aggregated particles are difficult to fill with the binder resin, and the second boron nitride aggregated particles Even if the binder resin adheres to the surfaces of the primary particles that make up the aggregated particles, voids tend to remain inside the pores. When a compressive force such as a press is applied to the second boron nitride aggregated particles, the second boron nitride aggregated particles do not retain their shape and are appropriately deformed or collapsed. . Therefore, the moderately deformed or collapsed second boron nitride aggregated particles can fill the gaps existing between the first boron nitride aggregated particles whose shape is maintained, and the second boron nitride aggregated particles can be filled. Since the voids in the aggregated boron nitride particles can be filled by the deformation of the second aggregated boron nitride particles, the insulation can be effectively improved. Further, since the binder resin is attached to the surface of the primary particles of the second boron nitride aggregated particles, the binder resin can fill the spaces between the primary particles of the second boron nitride aggregated particles after deformation, Insulation can be effectively improved.

Further, the reason why the first aggregated boron nitride particles can be filled with the binder resin is that the resin material according to the present invention uses at least two types of aggregated boron nitride particles, and the actual concentration of the first aggregated boron nitride particles is lower than the total concentration of the first aggregated boron nitride particles and the second aggregated boron nitride particles.

For example, if a resin material containing only the first boron nitride aggregated particles is pressed by sheet molding or the like, the first boron nitride aggregated particles cannot be pressed to eliminate the voids between the aggregated particles, Insulation deteriorates. On the other hand, when the pressing is carried out enough to eliminate the voids, even the first aggregated boron nitride particles cannot maintain their shape, and the thermal conductivity in the thickness direction is lowered. In addition, when a resin material containing only the second boron nitride aggregated particles is pressed by sheet molding or the like, the second boron nitride aggregated particles are easily deformed or collapsed by pressing. It may be oriented in the plane direction, and the thermal conductivity in the thickness direction may decrease.

The resin material according to the present invention uses two types of aggregated boron nitride particles having different pore sizes, and the first aggregated boron nitride particles having a relatively small pore size have primary particles that are close to each other and are entangled. Sometimes there are. Therefore, even if a compressive force such as a press is applied, it is necessary to move a large number of primary particles, so deformation or collapse of the first aggregated boron nitride particles is unlikely to occur. As a result, it is easy to maintain the shape after pressing. Furthermore, since the first aggregated boron nitride particles are easily filled with the binder resin, they are even easier to maintain their shape (see FIG. 4(a)). The second boron nitride agglomerated particles having relatively large pore diameters have few contacts of primary particles within the agglomerated particles. Therefore, the primary particles are difficult to interact with each other, and the pore size is large, so that they are easily deformed or collapsed (see FIG. 4(b)). When a compressive force is applied by pressing or the like, the second boron nitride aggregated particles are moderately deformed or collapsed around the first boron nitride aggregated particles. In addition, the second aggregated boron nitride particles after compression can fill the gaps between the first aggregated boron nitride particles, thereby effectively enhancing the insulation.

Moreover, in the resin material according to the present invention, the aspect ratio of the primary particles constituting the second aggregated boron nitride particles is relatively small, so the second aggregated boron nitride particles are easily deformed or collapsed. Therefore, the second aggregated boron nitride particles after compression and the primary particles constituting the second aggregated boron nitride particles can completely fill the gaps existing between the first aggregated boron nitride particles. Due to the formation of voids, partial discharge (internal discharge) may occur and the dielectric breakdown strength may decrease. Since the resin material according to the present invention has the above configuration, it is possible to suppress the occurrence of partial discharge (internal discharge) and effectively suppress variations in dielectric breakdown strength. In addition, since the resin material according to the present invention can fill the voids existing between the first aggregated boron nitride particles without gaps, the long-term insulation reliability can be effectively improved.

In addition, in the resin material according to the present invention, since the aspect ratio of the primary particles constituting the second aggregated boron nitride particles is relatively small, the primary particles constituting the second aggregated boron nitride particles have a large end surface area. Functional groups such as hydroxyl groups and amino groups are present on the end face, and the amount of functional groups such as hydroxyl groups and amino groups can be increased in the second aggregated boron nitride particles. Further, the second aggregated boron nitride particles and the primary particles constituting the second aggregated boron nitride particles can be bonded to the binder resin, the adherend, etc. via the functional groups. As a result, the adhesiveness between the aggregated boron nitride particles and the binder resin and the adhesiveness between the aggregated boron nitride particles and the adherend can be effectively enhanced.

In order to obtain such an effect, the use of the first aggregated boron nitride particles and the second aggregated boron nitride particles that satisfy the specific pore diameter and the specific aspect ratio relationship greatly contributes.

In the resin material according to the present invention, the hardness of the first aggregated boron nitride particles is preferably relatively higher than the hardness of the second aggregated boron nitride particles. Preferably, the hardness of the second aggregated boron nitride particles is relatively lower than the hardness of the first aggregated boron nitride particles. Therefore, the compressive strength of the first boron nitride aggregated particles when compressed by 20% is preferably greater than the compressive strength of the second boron nitride aggregated particles when compressed by 20%. It is easy to satisfy the relationship of compressive strength during compression. Therefore, when a compressive force is applied by pressing or the like, it is preferable that the first boron nitride aggregated particles do not deform or collapse excessively in the initial stage of compression, and the second boron nitride aggregated particles are moderately Deformation or collapse is preferred.

(First boron nitride aggregated particles and second boron nitride aggregated particles)
The cumulative 50% pore size of the first aggregated boron nitride particles is less than 2 μm. From the viewpoint of more effectively increasing the insulating properties, the cumulative 50% pore size of the first aggregated boron nitride particles is preferably 1.5 μm or less, more preferably 1 μm or less. The lower limit of the cumulative 50% pore size of the first aggregated boron nitride particles is not particularly limited. The cumulative 50% pore size of the first aggregated boron nitride particles may be 0.1 μm or more.

The cumulative 50% pore size of the second aggregated boron nitride particles is 2 μm or more. From the viewpoint of more effectively increasing the insulating properties, the cumulative 50% pore size of the second aggregated boron nitride particles is preferably 2.5 μm or more, more preferably 3 μm or more. The upper limit of the cumulative 50% pore size of the second aggregated boron nitride particles is not particularly limited. The cumulative 50% pore size of the second aggregated boron nitride particles may be 4.5 μm or less.

The volume-based pore size distributions of the first aggregated boron nitride particles and the second aggregated boron nitride particles can be measured as follows.

Using a mercury porosimeter "Poremaster 60" manufactured by QUANTACHROME, the integrated penetration amount of mercury is measured with respect to the pressure applied by the mercury porosimetry. From the data obtained, a distribution curve showing the pore volume per unit interval of pore diameter is obtained.

From the measurement result of the pore size distribution, the cumulative 50% pore size of the first aggregated boron nitride particles and the second aggregated boron nitride particles can be calculated. Specifically, in the aggregated boron nitride particles, the pore size distribution of the pore volume of pores having a pore size of more than 0 μm and 5 μm or less is integrated in order from the pore volume of the smallest pore size. The pore diameter when the cumulative value of the pore volume is 50% of the total pore volume of pores with pore diameters exceeding 0 μm and 5 μm or less is defined as the cumulative 50% pore diameter. In addition, in the relationship between the pore volume difference and the pore diameter (see FIG. 3), in the boron nitride aggregated particles used in the present invention, the pore volume once approaches 0 at around 5 μm, so the pore diameter of 5 μm or less aggregates. It is believed that this indicates pores inside the particles. Therefore, the total pore volume of pores having a pore diameter of more than 0 μm and 5 μm or less is used as the basis for calculating the cumulative 50% pore diameter. In addition, in the range of 4 μm to 5 μm, some pores between aggregated particles can be included, but the pore volume is within the range of error, and it is said that the pores in the aggregated particles are uniquely defined. Therefore, the total pore volume of pores having a pore diameter of more than 0 μm and 5 μm or less is defined as the pore volume (void volume) of the aggregated particles. On the other hand, pore sizes greater than 5 μm are believed to indicate pores between agglomerated particles. This is also consistent with the cross-sectional data of aggregated particles. FIG. 3 is a schematic diagram showing an example. Although it is thought that there are also closed pores into which mercury does not enter, the amount is small, and the effects of the present invention can be sufficiently exhibited even with a definition that does not consider closed pores.

The cumulative 50% pore diameters of the first boron nitride aggregated particles and the second boron nitride aggregated particles are the cumulative 50% pore diameters obtained in the measurement results of the pore size distribution, and the results of five or more measurements. It is preferable to calculate on average.

From the viewpoint of more effectively improving the insulation and the more effectively improving the thermal conductivity, the particle size of the first aggregated boron nitride particles is preferably more than 40 μm, more preferably 50 μm. more than 120 μm, preferably 100 μm or less.

From the viewpoint of more effectively improving the insulation and the more effectively improving the thermal conductivity, the particle diameter of the second boron nitride aggregated particles is preferably 10 μm or more, more preferably 20 μm or more. Yes, preferably 70 μm or less, more preferably 50 μm or less.

The particle diameters of the first aggregated boron nitride particles and the second aggregated boron nitride particles are preferably average particle diameters obtained by averaging particle diameters on a volume basis. The particle diameters of the first aggregated boron nitride particles and the second aggregated boron nitride particles can be measured using a "laser diffraction particle size distribution analyzer" manufactured by Horiba, Ltd. The particle diameters of the first boron nitride aggregated particles and the second boron nitride aggregated particles are obtained by sampling 3 g of each boron nitride aggregated particle and averaging the particle diameters of the boron nitride aggregated particles contained therein. , is preferably calculated. Regarding the method of calculating the average particle size, in each of the first boron nitride aggregated particles and the second boron nitride aggregated particles, the particle size (d50) of the boron nitride aggregated particles when the cumulative volume is 50% is the average particle size It is preferable to adopt it as the diameter.

From the viewpoint of further effectively improving the insulation and the viewpoint of further effectively improving the thermal conductivity, the aspect ratio of the first aggregated boron nitride particles is preferably 3 or less, more preferably 2 or less. be. The lower limit of the aspect ratio of the first aggregated boron nitride particles is not particularly limited. The first aggregated boron nitride particles may have an aspect ratio of 1 or more.

From the viewpoint of further effectively improving the insulating properties and the viewpoint of further effectively improving the thermal conductivity, the aspect ratio of the second aggregated boron nitride particles is preferably 3 or less, more preferably 2 or less. be. The lower limit of the aspect ratio of the second aggregated boron nitride particles is not particularly limited. The second aggregated boron nitride particles may have an aspect ratio of 1 or more.

The aspect ratios of the first aggregated boron nitride particles and the second aggregated boron nitride particles indicate major axis/shorter axis. The aspect ratios of the first aggregated boron nitride particles and the second aggregated boron nitride particles are preferably an average aspect ratio obtained by averaging the aspect ratios of the plurality of aggregated boron nitride particles. The average aspect ratio of the first boron nitride aggregated particles and the second boron nitride aggregated particles is obtained by observing 50 arbitrarily selected boron nitride aggregated particles with an electron microscope or an optical microscope, and observing each boron nitride aggregated particle. It is obtained by calculating the average value of the major axis/minor axis of

From the viewpoint of more effectively increasing thermal conductivity, the thermal conductivity of the first aggregated boron nitride 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 aggregated boron nitride particles is not particularly limited. The first aggregated boron nitride particles may have a thermal conductivity of 1000 W/m·K or less.

From the viewpoint of more effectively increasing the thermal conductivity, the thermal conductivity of the second aggregated boron nitride 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 aggregated boron nitride particles is not particularly limited. The second aggregated boron nitride particles may have a thermal conductivity of 1000 W/m·K or less.

From the viewpoint of more effectively improving the insulation property and the viewpoint of more effectively improving the thermal conductivity, the first boron nitride aggregated particles and the second boron nitride aggregated particles in 100% by volume of the resin material is preferably 20% by volume or more, more preferably 45% by volume or more, and preferably 80% by volume or less, more preferably 70% by volume or less.

The method for producing the first aggregated boron nitride particles and the second aggregated boron nitride particles is not particularly limited, and examples thereof include a spray drying method and a fluidized bed granulation method. The method for producing the first aggregated boron nitride particles and the second aggregated boron nitride 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, and any of these methods can be applied. An ultrasonic nozzle system is preferable from the viewpoint of being able to control the total pore volume more easily.

The first aggregated boron nitride particles and the second aggregated boron nitride particles are preferably manufactured using primary particles of boron nitride as materials. Boron nitride as a material for the first aggregated boron nitride particles and the second aggregated boron nitride particles is not particularly limited. Examples of boron nitride used as the material include hexagonal boron nitride, cubic boron nitride, boron nitride produced by a reduction nitriding method using a boron compound and ammonia, and nitride produced from a boron compound and a nitrogen-containing compound such as melamine. Examples include boron and boron nitride made from sodium borohydride and ammonium chloride. From the viewpoint of more effectively increasing the thermal conductivity of the first boron nitride aggregated particles and the second boron nitride aggregated particles, the boron nitride as a material of the boron nitride aggregated particles is hexagonal boron nitride. is preferred.

From the viewpoint of further effectively improving the insulation and the viewpoint of further effectively improving the thermal conductivity, the first aggregated boron nitride particles are aggregates of the first boron nitride, which are primary particles. Preferably, the second aggregated boron nitride particles are aggregates of the second boron nitride particles, which are primary particles. The first boron nitride aggregated particles are preferably secondary particles obtained by aggregating the first boron nitride which is the primary particles, and the second boron nitride aggregated particles are the primary particles, the second are preferably secondary particles obtained by agglomeration of boron nitride.

Moreover, the granulation step is not necessarily required as a method for producing aggregated boron nitride particles. Boron nitride agglomerated particles may be formed by naturally aggregating primary particles of boron nitride as boron nitride crystals grow. Moreover, in order to make the particle size of the aggregated boron nitride particles uniform, pulverized aggregated boron nitride particles may be used.

From the viewpoint of more effectively improving the insulating properties, the first aggregated boron nitride particles have the cumulative 50% pore diameter within the above range, and are composed of two or more types of aggregated particles having different particle diameters. may have been From the viewpoint of more effectively improving the insulating properties, the second boron nitride aggregated particles have the cumulative 50% pore diameter within the above range, and the primary particles constituting the aggregated particles have an aspect ratio within the range described later. and may be composed of two or more types of agglomerated particles having different particle diameters.

From the viewpoint of more effectively improving the insulation property and the viewpoint of more effectively improving the thermal conductivity, the resin material includes the first aggregated boron nitride particles and the second aggregated boron nitride particles. may contain third inorganic particles that are not the first aggregated boron nitride particles and the second aggregated boron nitride particles. The resin material preferably contains the third inorganic particles from the viewpoint of more effectively improving the insulation and the more effectively improving the thermal conductivity.

The third inorganic particles are preferably aggregated particles. The third inorganic particles are preferably secondary particles obtained by aggregating primary particles of boron nitride.

Primary particles (first boron nitride and second boron nitride) constituting the first boron nitride aggregated particles and the second boron nitride aggregated particles:
The average major axis of the primary particles (first boron nitride) constituting the first aggregated boron nitride particles is preferably 2 μm or more, more preferably 3 μm or more, preferably less than 20 μm, more preferably 16 μm or less. . When the average length of the primary particles (first boron nitride) constituting the first aggregated boron nitride particles is equal to or more than the lower limit and equal to or less than the upper limit, the insulating property can be further effectively improved, and the insulation Variation in breaking strength can be suppressed more effectively, and adhesion can be improved more effectively.

The average length of the primary particles (second boron nitride) constituting the second aggregated boron nitride particles is preferably 3 μm or more, more preferably 4 μm or more, and preferably 8 μm or less, more preferably 7.5 μm or less. is. When the average length of the primary particles (second boron nitride) constituting the second aggregated boron nitride particles is equal to or more than the lower limit and equal to or less than the upper limit, the insulation can be further effectively improved, and the insulation Variation in breaking strength can be suppressed more effectively, and adhesion can be improved more effectively.

The average length of the primary particles (first boron nitride and second boron nitride) constituting the first boron nitride aggregated particles and the second boron nitride aggregated particles can be calculated as follows. .

A sheet produced by mixing primary particles (first boron nitride and second boron nitride) constituting the first boron nitride aggregated particles and the second boron nitride aggregated particles and a thermosetting resin or the like, or A cross section of the laminate produced by pressing is observed with an electron microscope. From the obtained electron microscope image, the major diameter of the primary particles (each boron nitride) constituting each of 50 arbitrarily selected boron nitride aggregated particles is measured, and the average value is calculated.

From the viewpoint of more effectively increasing insulation, more effectively suppressing variations in dielectric breakdown strength, and more effectively improving adhesiveness, the first boron nitride aggregated particles constitute The aspect ratio of the primary particles (first boron nitride) is preferably 3 or more, more preferably 5 or more, and preferably 17 or less, more preferably 15 or less.

In the resin material according to the present invention, the aspect ratio of the primary particles (second boron nitride) constituting the second aggregated boron nitride particles is 7 or less. From the viewpoint of more effectively improving insulation, more effectively suppressing variations in dielectric breakdown strength, and more effectively improving adhesiveness, the second boron nitride aggregated particles constitute The aspect ratio of the primary particles (second boron nitride) is preferably 6.5 or less, more preferably 6.1 or less. The lower limit of the aspect ratio of the primary particles constituting the second aggregated boron nitride particles is not particularly limited. The aspect ratio of the primary particles constituting the second aggregated boron nitride particles may be 2 or more.

The aspect ratio of the primary particles (the first boron nitride and the second boron nitride) constituting the first aggregated boron nitride particles and the second aggregated boron nitride particles indicates the major axis/minor axis. The aspect ratio of the primary particles (first boron nitride and second boron nitride) constituting the first boron nitride aggregated particles and the second boron nitride aggregated particles can be calculated as follows. .

A sheet produced by mixing primary particles (first boron nitride and second boron nitride) constituting the first boron nitride aggregated particles and the second boron nitride aggregated particles and a thermosetting resin or the like, or A cross section of the laminate produced by pressing is observed with an electron microscope. From the obtained electron microscope image, the major axis/minor axis of primary particles (each boron nitride) constituting 50 arbitrarily selected boron nitride aggregated particles are measured, and the average value is calculated.

From the viewpoint of more effectively improving insulation and thermal conductivity, in the primary particles constituting the first boron nitride aggregated particles and the second boron nitride aggregated particles, all the primary particles are scaly It does not have to be a shaped particle, and may contain at least one or more curved shaped particles. For curved particles, divide into two particles at the bending site, measure the major diameter / minor diameter of each particle, and measure the major diameter / minor diameter of the particle with the longer major diameter / short diameter. The aspect ratio is calculated from the obtained value of major axis/minor axis.

In the electron microscope image of the cross section of the sheet or laminate, the first boron nitride aggregated particles relatively maintain the form of aggregated particles even after pressing, so it can be confirmed from the electron microscope image of the cross section of the sheet or laminate. can. On the other hand, since the second aggregated boron nitride particles are deformed or collapsed while maintaining isotropy after pressing, their existence is strongly suggested. Temporarily, the phosphate flakes obtained by crushing the second boron nitride aggregated particles in advance (primary particles constituting the second boron nitride aggregated particles: the second boron nitride), and the first When a sheet or a laminate is produced by mixing boron nitride aggregated particles with a thermosetting resin or the like, the above-mentioned scales are relatively easily oriented in the plane direction as compared with the aggregated particles. Therefore, compared to the case of using aggregated particles, it is difficult for the scaly flakes to maintain isotropy even after pressing. As a result, the first boron nitride agglomerated particles having a large specific surface area and relatively easy to maintain the shape, and the second agglomerated boron nitride particles having a large porosity and a small specific surface area that are easily collapsed are used. This can be determined from an electron microscope image of a cross section of the sheet or laminate even after pressing.

(binder resin)
The resin material according to the present invention contains a binder resin. The binder resin is not particularly limited. A known insulating resin is used as the binder resin. The binder resin preferably contains a thermoplastic component (thermoplastic compound) or a curable component, and more preferably contains a curable component. The curable component includes a thermosetting component and a photocurable component. The thermosetting component preferably contains a thermosetting compound and a thermosetting agent. The photocurable component preferably contains a photocurable compound and a photopolymerization initiator. The binder resin preferably contains a thermosetting component. Only one type of the binder resin may be used, or two or more types may be used in combination.

A "(meth)acryloyl group" refers to an acryloyl group and a methacryloyl group. "(Meth)acryl" indicates acryl and methacryl. "(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, phenol compounds, amino compounds, unsaturated polyester compounds, polyurethane compounds, silicone compounds and polyimide compounds. 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) a thermosetting compound) may be used, and (A2) having a molecular weight of 10,000 or more. A thermosetting compound having a molecular weight (sometimes simply referred to as (A2) thermosetting compound) may be used, and both (A1) thermosetting compound and (A2) thermosetting compound may be used.

The content of the thermosetting compound in 100% by volume of the resin material is preferably 10% by volume or more, more preferably 20% by volume or more, and preferably 90% by volume or less, more preferably 80% by volume or less. . When the content of the thermosetting compound is at least the lower limit, the adhesiveness and heat resistance of the cured product are further enhanced. When the content of the thermosetting compound is equal to or less than the above upper limit, the coating property of the resin material is further enhanced.

(A1) A thermosetting compound having a molecular weight of less than 10,000:
(A1) The thermosetting compound includes a thermosetting compound having a cyclic ether group. 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) Thermosetting compounds may be used alone or in combination of two or more.

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

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

The aromatic skeleton is not particularly limited, and includes naphthalene skeleton, fluorene skeleton, biphenyl skeleton, anthracene skeleton, pyrene skeleton, xanthene skeleton, adamantane skeleton, bisphenol A skeleton, and the like. The aromatic skeleton is preferably a biphenyl skeleton or a fluorene skeleton, from the viewpoint of more effectively improving the thermal cycle resistance and heat resistance of the cured product.

(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. Hydrogenated products or modified products thereof may also be used. (A1a) Thermosetting compounds may be used alone or in combination of two or more.

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

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

Examples of epoxy monomers having a fluorene skeleton include 9,9-bis(4-glycidyloxyphenyl)fluorene, 9,9-bis(4-glycidyloxy-3-methylphenyl)fluorene, 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, 9,9-bis(4-glycidyloxy-3,5-dibromophenyl)fluorene, and the like.

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

Examples of epoxy monomers 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)methane methane, 1,2′-bi(3,5-glycidyloxynaphthyl)methane, and the like.

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.

(A1b) Specific examples of the 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, and oxetane-modified phenol novolak. (A1b) Thermosetting compounds may be used alone or in combination of two or more.

From the viewpoint of further improving the heat resistance of the cured product, (A1) the thermosetting compound preferably contains 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 (A1) the thermosetting compound having two or more cyclic ether groups in 100% by weight of the thermosetting compound is preferably 70% by weight or more. , more preferably 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. In addition, the entire thermosetting compound (A1) may be a thermosetting compound having two or more cyclic ether groups.

(A1) The thermosetting compound has a molecular weight of less than 10,000. (A1) The thermosetting compound preferably has a molecular weight of 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 at least the above lower limit, the adhesiveness of the surface of the cured product becomes low, and the handleability of the resin material becomes even higher. (A1) When the molecular weight of the thermosetting compound is equal to or less than the above upper limit, the adhesiveness of the cured product is further enhanced. Furthermore, the cured product is less likely to become hard and brittle, and the adhesiveness of the cured product is further enhanced.

In the present specification, (A1) the molecular weight of the thermosetting compound means, (A1) when the thermosetting compound is not a polymer, and (A1) when the structural formula of the thermosetting compound can be specified, It means a molecular weight that can be calculated from the structural formula, and means a weight average molecular weight when the thermosetting compound (A1) is a polymer. The weight average molecular weight is a polystyrene-equivalent weight average molecular weight measured by gel permeation chromatography (GPC). In gel permeation chromatography (GPC) measurement, it is preferable to use tetrahydrofuran as an eluent.

The content of (A1) the thermosetting compound in 100% by volume of the resin material is preferably 10% by volume or more, more preferably 20% by volume or more, and preferably 90% by volume or less, more preferably 80% by volume or less. is. (A1) When the content of the thermosetting compound is at least the above lower limit, the adhesiveness and heat resistance of the cured product are further enhanced. (A1) When the content of the thermosetting compound is equal to or less than the above upper limit, the coatability of the resin material is further enhanced.

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

From the viewpoint of more effectively increasing the heat resistance and moisture resistance of the cured product, (A2) the 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 entire polymer It is sufficient if it has it, and it may have it in the backbone of the main chain, or it may have it in the 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, (A2) the thermosetting compound preferably has an aromatic skeleton in its main chain skeleton. (A2) Thermosetting compounds may be used alone or in combination of two or more.

The aromatic skeleton is not particularly limited, and includes naphthalene skeleton, fluorene skeleton, biphenyl skeleton, anthracene skeleton, pyrene skeleton, xanthene skeleton, adamantane skeleton, bisphenol A skeleton, and the like. The aromatic skeleton is preferably a biphenyl skeleton or a fluorene skeleton, from the viewpoint of more effectively improving the thermal cycle resistance and heat resistance of the cured product.

(A2) Thermosetting compounds are not particularly limited, and include styrene resins, phenoxy resins, oxetane resins, epoxy resins, episulfide compounds, (meth)acrylic resins, phenolic resins, amino resins, unsaturated polyester resins, polyurethane resins, silicones. Examples include resins and polyimide resins.

From the viewpoint of suppressing oxidative deterioration of the cured product, further improving the cold-heat cycle resistance and heat resistance of the cured product, and further lowering the water absorption rate of the cured product, (A2) the thermosetting compound is a styrene resin, A phenoxy resin or an epoxy resin is preferred, a phenoxy resin or an epoxy resin is more preferred, and a phenoxy resin is even more preferred. In particular, the use of phenoxy resin or epoxy resin further increases the heat resistance of the cured product. In addition, the use of the phenoxy resin further lowers the elastic modulus of the cured product and further enhances the resistance to heat and cold cycles of the cured product. In addition, (A2) the thermosetting compound may not have a cyclic ether group such as an epoxy group.

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

Examples of the styrene monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, p-ethylstyrene, pn- Butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, 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, a bisphenol F skeleton, a bisphenol A/F mixed skeleton, a naphthalene skeleton, a fluorene skeleton, a biphenyl skeleton, anthracene skeleton, a pyrene skeleton, a xanthene skeleton, an adamantane skeleton, or a dicyclopentadiene skeleton. is preferred. The phenoxy resin more preferably 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. It is more preferable to have a skeleton. By using a phenoxy resin having these preferred skeletons, the heat resistance of the cured product is further enhanced.

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 epoxy resins, naphthol aralkyl epoxy resins, dicyclopentadiene epoxy resins, anthracene epoxy resins, epoxy resins having an adamantane skeleton, epoxy resins having a tricyclodecane skeleton, and epoxy resins having a triazine nucleus in their skeleton etc.

(A2) The thermosetting compound has a molecular weight of 10,000 or more. (A2) The thermosetting compound preferably has a molecular weight of 30,000 or more, more preferably 40,000 or more, and preferably 1,000,000 or less, more preferably 250,000 or less. (A2) When the molecular weight of the thermosetting compound is at least the above lower limit, the cured product is less likely to be thermally deteriorated. (A2) When the molecular weight of the thermosetting compound is equal to or less than the above upper limit, the compatibility between the (A2) thermosetting compound and other components is enhanced. As a result, the heat resistance of the cured product is further enhanced.

The content of (A2) the thermosetting compound in 100% by volume of the resin material is preferably 20% by volume or more, more preferably 30% by volume or more, and preferably 60% by volume or less, more preferably 50% by volume or less. is. (A2) When the content of the thermosetting compound is at least the above lower limit, the handleability of the resin material becomes even better. (A2) When the content of the thermosetting compound is equal to or less than the above upper limit, the coatability of the resin material is further enhanced.

(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. Moreover, in this specification, the thermosetting agent includes a curing catalyst. Only one kind of thermosetting agent may be used, or two or more kinds thereof may be used in combination.

From the viewpoint of more effectively increasing the heat resistance of the cured product, the thermosetting agent preferably has an aromatic skeleton or an alicyclic skeleton. The heat curing agent preferably contains 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 contains an amine curing agent. preferable. The acid anhydride curing agent includes an acid anhydride having an aromatic skeleton, a hydrogenated product of the acid anhydride or a modified product of the acid anhydride, or an acid anhydride having an alicyclic skeleton, the It is preferable to contain 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 more effectively increasing the adhesiveness of the cured product, the amine curing agent is more preferably a dicyandiamide or imidazole compound. From the viewpoint of more effectively increasing the storage stability of the resin material, the thermosetting agent preferably contains a curing agent having a melting point of 180°C or higher, and preferably contains an amine curing agent having a melting point of 180°C or higher. is more preferred.

Examples of the imidazole curing agent include 2-undecylimidazole, 2-heptadecylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 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 '-Methylimidazolyl-(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 isocyanurate, 2-phenylimidazole isocyanurate, 2-methylimidazole isocyanurate, 2-phenyl-4,5-dihydroxymethylimidazole and 2-phenyl-4-methyl-5-dihydroxymethyl imidazole and the like.

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( Di-o-hydroxyphenyl)methane, poly(di-m-hydroxyphenyl)methane, poly(di-p-hydroxyphenyl)methane, and the like. From the viewpoint of more effectively increasing the flexibility of the cured product and the flame retardancy of the cured product, the phenolic curing agent may be a phenolic resin having a melamine skeleton, a phenolic resin having a triazine skeleton, or a phenolic resin having an allyl group. is preferably

Commercially available phenolic curing agents 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 (both of which are manufactured by DIC), and PS6313 and PS6492 (both of which are manufactured by Gun Ei Kagaku).

Examples of the acid anhydride having an aromatic skeleton, the hydrogenated product of the acid anhydride, or the modified product of the acid anhydride include styrene/maleic anhydride copolymer, benzophenonetetracarboxylic anhydride, and pyromellitic anhydride. , trimellitic anhydride, 4,4′-oxydiphthalic anhydride, phenylethynyl phthalic anhydride, glycerol bis(anhydrotrimellitate) monoacetate, ethylene glycol bis(anhydrotrimellitate), methyltetrahydroanhydride Phthalic acid, methylhexahydrophthalic anhydride, trialkyltetrahydrophthalic anhydride, and the like.

Commercially available products of the acid anhydride having an aromatic skeleton, the hydrogenated product of the acid anhydride, or the modified product of the acid anhydride 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 (both manufactured by Manac), Rikashid MTA-10, Rikashid MTA-15, Rikashid TMTA, Rikashid TMEG-100, Rikashid TMEG-200, Rikashid TMEG-300, Rikashid TMEG-500, Rikashid TMEG-S, Rikashid TH, Rikashid HT-1A, Rikashid HH, Rikashid MH-700, Rikashid MT-500, Rikashid DSDA and Rikashid TDA-100 (all manufactured by Shin Nippon Rika Co., Ltd.), and EPICLON B4400, EPICLON B650, and EPICLON B570 (all of which are manufactured by DIC Corporation).

The acid anhydride having an alicyclic skeleton, the hydrogenated product of the acid anhydride, or the modified product of the acid anhydride is an acid anhydride having a polyalicyclic skeleton, the hydrogenated product of the acid anhydride, or the modified product of the acid anhydride. A modified acid anhydride, an acid anhydride having an alicyclic skeleton obtained by an addition reaction of a terpene compound and maleic anhydride, a hydrogen additive of the acid anhydride, or a modified acid anhydride. is preferred. The use of these curing agents further enhances the flexibility of the cured product, as well as the moisture resistance and adhesiveness of the cured product.

Examples of the acid anhydride having an alicyclic skeleton, the hydrogenated product of the acid anhydride, or the modified product of the acid anhydride include methyl nadic acid anhydride, the acid anhydride having a dicyclopentadiene skeleton, or the acid anhydride. Modified products of are also included.

Commercially available products of the acid anhydride having an alicyclic skeleton, the hydrogenated product of the acid anhydride, or the modified product of the acid anhydride include Rikacid HNA and Rikacid HNA-100 (both of which are manufactured by Shin Nippon Rika Co., Ltd.). , Epicure YH306, Epicure YH307, Epicure YH308H and Epicure YH309 (all manufactured by Mitsubishi Chemical Corporation).

The thermosetting agent is also preferably methylnadic anhydride or trialkyltetrahydrophthalic anhydride. The use of methylnadic anhydride or trialkyltetrahydrophthalic anhydride increases the water resistance of the cured product.

The content of the thermosetting agent in 100% by volume of the resin material is preferably 0.1% by volume or more, more preferably 1% by volume or more, and preferably 40% by volume or less, more preferably 25% by volume or less. be. When the content of the thermosetting agent is at least the above lower limit, it becomes much easier to sufficiently cure the thermosetting compound. When the content of the thermosetting agent is equal to or less than the above upper limit, excess thermosetting agent that does not participate in curing is less likely to occur. Therefore, the heat resistance and adhesiveness of the cured product are further enhanced.

(Photocurable component: photocurable compound)
The photocurable compound is not particularly limited as long as it has photocurable properties. 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 more effectively enhancing the adhesiveness of the cured product, the photocurable compound preferably contains epoxy (meth)acrylate. From the viewpoint of more effectively increasing the heat resistance of the cured product, the epoxy (meth)acrylate preferably contains a bifunctional epoxy (meth)acrylate and a trifunctional or higher epoxy (meth)acrylate. The bifunctional epoxy (meth)acrylate preferably has two (meth)acryloyl groups. The tri- or more 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 compound is cured by irradiation with light, the epoxy (meth)acrylate preferably does not have an epoxy group.

Examples of the epoxy (meth)acrylate include bisphenol type epoxy (meth)acrylate (e.g., bisphenol A type epoxy (meth)acrylate, bisphenol F type epoxy (meth)acrylate, bisphenol S type epoxy (meth)acrylate), cresol novolak type 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 novolak-type epoxy (meth)acrylate, etc. .

The content of the photocurable compound in 100% by volume of the resin material is preferably 5% by volume or more, more preferably 10% by volume or more, and preferably 40% by volume or less, more preferably 30% by volume or less. . When the content of these photocurable compounds is at least the above lower limit and below the above upper limit, the adhesiveness of the cured product is further enhanced.

(Photocurable component: photopolymerization initiator)
The photopolymerization initiator is not particularly limited. As the photopolymerization initiator, a photopolymerization initiator capable of curing the photocurable compound by irradiation with light can be appropriately used. Only one kind of the photopolymerization initiator may be used, or two or more kinds thereof may be used in combination.

Examples of the photopolymerization initiator include acylphosphine oxide, halomethylated triazine, halomethylated oxadiazole, imidazole, benzoin, benzoin alkyl ether, anthraquinone, benzanthrone, benzophenone, acetophenone, thioxanthone, benzoic acid ester, acridine, phenazine, Titanocene, α-aminoalkylphenones, oximes, and derivatives thereof.

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

Commercially available acetophenone-based photopolymerization initiators include Darocure 1173, Darocure 2959, Irgacure 184, Irgacure 907, and Irgacure 369 (all of which are manufactured by BASF).

Irgacure 651 (manufactured by BASF) and the like are examples of commercially available benzoin-based photopolymerization initiators.

Commercially available acylphosphine oxide photopolymerization initiators include Lucirin TPO and Irgacure 819 (both of which are manufactured by BASF).

Commercially available thioxanthone-based photopolymerization initiators include isopropylthioxanthone and diethylthioxanthone.

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

The content of the photopolymerization initiator 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, relative to 100 parts by weight of the photocurable compound. Part by weight or less. When the content of the photopolymerization initiator is at least the above lower limit and below the above upper limit, the photocurable compound can be favorably photocured.

(insulating filler)
The resin material according to the present invention may contain an insulating filler. The insulating filler is neither the first aggregated boron nitride particles nor the second aggregated boron nitride particles. The insulating filler has insulating properties. The insulating filler may be an organic filler or an inorganic filler. Only one type of the insulating filler may be used, or two or more types may be used in combination.

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

From the viewpoint of more effectively 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 with a thermal conductivity of about 300 W/m·K are widely known, and inorganic fillers with a thermal conductivity of about 200 W/m·K are readily available.

The material of the insulating filler is not particularly limited. Materials for the insulating filler include 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.). The material of the insulating filler is preferably the nitrogen compound, the carbon compound, or the metal oxide, and more preferably alumina, boron nitride, aluminum nitride, silicon nitride, silicon carbide, zinc oxide, or magnesium oxide. preferable. Use of these preferred insulating fillers further increases the thermal conductivity of the cured product.

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

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

From the viewpoint of more effectively 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 more effectively increasing thermal conductivity, the particle size of the insulating filler is preferably 0.1 μm or more and preferably 20 μm or less. When the particle diameter is at least the lower limit, the insulating filler can be easily filled at a high density. When the particle diameter is equal to or less than the upper limit, the thermal conductivity of the cured product is further increased.

The particle size means an average particle size obtained from the volume-average particle size distribution measured by a laser diffraction particle size distribution analyzer. The particle size of the insulating filler is preferably calculated by sampling 3 g of the insulating filler and averaging the particle sizes of the insulating filler contained therein. Regarding the method for calculating the average particle size of the insulating filler, it is preferable to adopt the particle size (d50) of the insulating filler when the cumulative volume is 50% as the average particle size.

From the viewpoint of more effectively increasing thermal conductivity, the content of the insulating filler in 100% by volume of the resin material is preferably 1% by volume or more, more preferably 3% by volume or more, and preferably 20% by volume. % by volume or less, more preferably 10% by volume or less.

(other ingredients)
In addition to the components described above, the resin material may contain other components commonly used in resin materials, resin sheets, and curable sheets, such as dispersants, chelating agents, and antioxidants.

(Other details of resin material and cured product)
The resin material may be a paste or a curable paste. The resin material may be a resin sheet or a curable sheet. When the resin material contains a curable component, a cured product can be obtained by curing the resin material. The cured product is a cured product of the resin material, and is made of the resin material.

From the viewpoint of more effectively enhancing insulation and thermal conductivity, the resin material may be prepared by laminating two or more layers of resin sheets. Moreover, one or more layers of the resin sheet having two or more layers may be the resin sheet according to the present invention.

(Laminate)
A 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 heat conductor side. The insulating layer may also 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 resin material described above.

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. It is preferable to use a metal material for the heat conductor. Examples of the metal material include metal foil and metal plate. The heat conductor is preferably the metal foil or the metal plate, more preferably the metal plate.

Examples of materials for the metal material include aluminum, copper, gold, silver, and graphite sheets. From the viewpoint of more effectively increasing thermal conductivity, the material of 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 above metals 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. Further, examples of the metal include tin-doped indium oxide (ITO) and solder. From the viewpoint of more effectively increasing thermal conductivity, aluminum, copper or gold is preferred, and aluminum or copper is more preferred.

A method for forming the conductive layer is not particularly limited. Examples of the method for forming the conductive layer include a method using electroless plating, a method using electroplating, and a method of thermocompression bonding the insulating layer and the metal foil. Since the formation of the conductive layer is simple, the method of thermocompression bonding the insulating layer and the metal foil is preferable.

FIG. 1 is a cross-sectional view schematically showing a resin sheet according to one embodiment of the invention. In addition, in FIG. 1, for convenience of illustration, the actual size and thickness are different.

A resin sheet 1 (resin material) shown in FIG. 1 includes a binder resin 11 , first aggregated boron nitride particles 12 , and second aggregated boron nitride particles 13 . The first aggregated boron nitride particles 12 and the second aggregated boron nitride particles 13 are preferably the first aggregated boron nitride particles and the second aggregated boron nitride particles described above. The pore size of the first aggregated boron nitride particles 12 and the pore size of the second aggregated boron nitride particles 13 are different. Further, the aspect ratio of the primary particles constituting the second aggregated boron nitride particles 13 is 7 or less.

In the resin sheet 1 according to this embodiment, the binder resin 11 contains a curable component. The binder resin 11 may contain a thermosetting component containing a thermosetting compound and a thermosetting agent, or may contain a photocurable component containing a photocurable compound and a photopolymerization initiator. The binder resin is preferably not completely cured. The binder resin may be B-staged by heating or the like. The binder resin may be a B-staged product that has been B-staged.

The resin sheet may have voids inside the sheet. In the resin sheet, voids may exist between the first aggregated boron nitride particles and the second aggregated boron nitride particles.

FIG. 2 is a cross-sectional view schematically showing a laminate obtained using a resin material according to one embodiment of the present invention. In addition, in FIG. 2, for convenience of illustration, the size and thickness are different from the actual size.

A laminate 21 shown in FIG. 2 includes a thermal conductor 22 , an insulating layer 23 and a conductive layer 24 . The thermal conductor 22, the insulating layer 23, and the conductive layer 24 are the thermal conductor, insulating layer, and conductive layer described above. 2, the resin sheet 1 shown in FIG. 1 is used as the insulating layer 23. As shown in FIG.

The heat conductor 22 has one surface 22a (first surface) and the other surface 22b (second surface). The insulating layer 23 has one surface 23a (first surface) and the other surface 23b (second surface). The conductive layer 24 has one surface 24a (first surface) and the other surface 24b (second surface).

A conductive layer 24 is laminated on one surface 23 a (first surface) of the insulating layer 23 . A thermal conductor 22 is laminated on the other surface 23 b (second surface) of the insulating layer 23 . An insulating layer 23 is laminated on the other surface 24 b (second surface) side of the conductive layer 24 . An insulating layer 23 is laminated on one surface 22 a (first surface) of the heat conductor 22 . An insulating layer 23 is arranged between the thermal conductor 22 and the conductive layer 24 .

The method for manufacturing the laminate is not particularly limited. Examples of the method for producing the laminate include a method of laminating the heat conductor, the insulating layer, and the conductive layer, and bonding them under heat and pressure using a vacuum press or the like.

In the laminate 21 according to the present embodiment, the insulating layer 23 includes the cured material portion 14 , the first aggregated boron nitride particles 12 , and the second aggregated boron nitride particles 13 . The insulating layer 23 is made of the resin sheet 1 shown in FIG. It is preferable that the insulating layer is formed by heat-pressing the resin sheet by a vacuum press or the like.

In the laminate 21 according to the present embodiment, the first aggregated boron nitride particles 12 are preferably not deformed or collapsed by compression force such as pressing, and preferably maintain their shape. The first aggregated boron nitride particles 12 preferably exist in the form of aggregated particles (secondary particles) in the cured product.

In the laminate 21 according to this embodiment, the second aggregated boron nitride particles 13 may be deformed or collapsed by compression force such as pressing. The second boron nitride aggregated particles 13 may be deformed aggregated particles (secondary particles), or may become primary particles by collapsing the aggregated particles (secondary particles). The second boron nitride aggregated particles 13 may exist in the form of deformed aggregated particles (secondary particles) in the cured product, and the aggregated particles (secondary particles) are collapsed to form primary particles. may exist in

In the cured product portion 14 , the second aggregated boron nitride particles 13 are deformed or collapsed around the first aggregated boron nitride particles 12 . The deformed or collapsed second boron nitride aggregated particles 13 exist between the first boron nitride aggregated particles 12 . The deformed or collapsed second boron nitride aggregated particles 13 can fill the gaps existing between the first boron nitride aggregated particles 12, and can effectively improve the insulation. In addition, since the laminate 21 can fill the gaps between the first boron nitride aggregated particles 12 with the second boron nitride aggregated particles 13 without gaps, variations in dielectric breakdown strength can be effectively suppressed. can.

In this embodiment, the cured product portion 14 is a portion where the binder resin 11 is cured. The cured product portion 14 is obtained by curing the binder resin 11 . The cured product portion 14 may be a portion where a thermosetting component containing a thermosetting compound and a thermosetting agent is cured, or a portion where a photocurable component containing a photocurable compound and a photopolymerization initiator is cured. There may be. The cured product portion 14 is obtained by curing a thermosetting component or a photocurable component.

The above resin material and the above cured product can be used in various applications that require high thermal conductivity, mechanical strength, and the like. The laminate is used, for example, in an electronic device by being arranged between a heat-generating component and a heat-radiating component. For example, the laminate is used as a heat radiator installed between a CPU and a fin, or as a heat radiator for a power card used in an inverter of an electric vehicle or the like. Further, by forming a circuit on the conductive layer of the laminate by etching or the like, the laminate can be used as an insulated circuit board.

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

Thermosetting compounds:
(1) "Epikote 828US" manufactured by Mitsubishi Chemical Co., Ltd., an epoxy compound (2) "DL-92" manufactured by Meiwa Kasei Co., Ltd., a phenol novolak compound

Heat curing agent:
(1) “Dicyandiamide” manufactured by Tokyo Chemical Industry Co., Ltd.
(2) "2MZA-PW" manufactured by Shikoku Kasei Co., Ltd., isocyanurate-modified solid-dispersed imidazole

First boron nitride agglomerate particles (including alternatives thereof):
(1) “PTX60S” manufactured by Momentive
(2) “PT350” manufactured by Momentive
(3) “AC6091” manufactured by Momentive
(4) Aggregated boron nitride particles 3
(5) Aggregated boron nitride particles 4

Second Boron Nitride Aggregate Particles (including substitutes thereof):
(1) Aggregated boron nitride particles 1
(2) Aggregated boron nitride particles 2
(3) Aggregated boron nitride particles 5
(4) “AC6091” manufactured by Momentive
(5) Showa Denko "UHP-G1F"

Method for producing “boron nitride aggregated particles 1”:
Primary particles of boron nitride having an average length of 7.2 μm and an aspect ratio of 5.3 were aggregated by a spray drying method so as to have a porosity of 44% and an average particle diameter of 40 μm. The porosity was measured with a mercury porosimeter, and the porosity was calculated when only the intra-particle voids were defined as voids of 5 μm or less.

The porosity was measured as follows.

Porosity measurement method:
Using a mercury porosimeter "Poremaster 60" manufactured by QUANTACHROME, the integrated penetration amount of mercury was measured with respect to the pressure applied by the mercury penetration method. 0.2 to 0.3 g of aggregated boron nitride particles were weighed and measured in low pressure mode and high pressure mode. From the obtained data, a distribution curve showing the pore volume per unit interval of pore diameter was obtained. Based on the distribution curve, a value (V) was calculated by subtracting the inter-particle voids from the total voids. According to the distribution curve, voids with pore diameters of 5 μm or more were defined as interparticle voids. Using the density (ρ=2.34) of the boron nitride particles of the primary particles, the porosity (ε) can be expressed by the following formula.

ε=V(V+(1/ρ))×100

The porosity was calculated by substituting the obtained value of V into the above formula.

Method for producing “boron nitride aggregated particles 2”:
Primary particles of boron nitride having an average length of 6.5 μm and an aspect ratio of 6.1 were agglomerated by a spray drying method so as to have a porosity of 39% and an average particle diameter of 30 μm.

Method for producing “boron nitride aggregated particles 3”:
Primary particles of boron nitride having an average length of 7 μm and an aspect ratio of 18 were aggregated by a spray drying method so as to have a porosity of 68% and an average particle diameter of 50 μm.

Method for producing “boron nitride aggregated particles 4”:
Primary particles of boron nitride having an average length of 7.3 μm and an aspect ratio of 12 were agglomerated by a spray drying method so as to have a porosity of 65% and an average particle diameter of 35 μm.

Method for producing “boron nitride aggregated particles 5”:
Primary particles of boron nitride having an average length of 8.5 μm and an aspect ratio of 6.5 were agglomerated by a spray drying method so as to have a porosity of 25% and an average particle diameter of 80 μm.

(Volume-based pore size distribution of the first aggregated boron nitride particles and the second aggregated boron nitride particles)
The volume-based pore size distributions of the first aggregated boron nitride particles and the second aggregated boron nitride particles were measured as follows.

Method for measuring the volume-based pore size distribution of the first aggregated boron nitride particles and the second aggregated boron nitride particles:
Using a mercury porosimeter "Poremaster 60" manufactured by QUANTACHROME, the integrated penetration amount of mercury was measured with respect to the pressure applied by the mercury penetration method. 0.2 to 0.3 g of aggregated boron nitride particles were weighed and measured in low pressure mode and high pressure mode. From the obtained data, a distribution curve showing the pore volume per unit interval of pore diameter was obtained.

From the measurement results of the pore size distribution, the cumulative 50% pore sizes of the first aggregated boron nitride particles and the second aggregated boron nitride particles were calculated. Specifically, in the aggregated boron nitride particles, the pore size distribution of the pore volume of pores having a pore size of more than 0 μm and 5 μm or less is integrated in order from the pore volume of the smallest pore size. The pore diameter when the cumulative value of the pore volume was 50% of the total pore volume of pores with pore diameters exceeding 0 μm and 5 μm or less was defined as the cumulative 50% pore diameter.

From the measurement results of the pore size distribution, the cumulative 50% pore sizes of the first aggregated boron nitride particles and the second aggregated boron nitride particles were calculated.

(Particle diameters of first aggregated boron nitride particles and second aggregated boron nitride particles)
The particle sizes of the first aggregated boron nitride particles and the second aggregated boron nitride particles were measured using a "laser diffraction particle size distribution analyzer" manufactured by Horiba, Ltd. The particle diameters of the first boron nitride aggregated particles and the second boron nitride aggregated particles are obtained by sampling 3 g of each boron nitride aggregated particle and averaging the particle diameter of each boron nitride aggregated particle contained therein. Calculated. Regarding the method of calculating the average particle size, in each of the first boron nitride aggregated particles and the second boron nitride aggregated particles, the particle size (d50) of the boron nitride aggregated particles when the cumulative volume is 50% is the average particle size diameter.

(Aspect ratio of primary particles (first boron nitride and second boron nitride) constituting first boron nitride aggregated particles and second boron nitride aggregated particles)
Aspect ratios of primary particles (first boron nitride and second boron nitride) constituting the first aggregated boron nitride particles and the second aggregated boron nitride particles were measured as follows.

Method for measuring the aspect ratio of the primary particles (first boron nitride and second boron nitride) constituting the first boron nitride aggregated particles and the second boron nitride aggregated particles:
Cross section of a laminate produced by mixing primary particles (first boron nitride and second boron nitride) constituting the first aggregated boron nitride particles and the second aggregated boron nitride particles with a thermosetting resin or the like From the electron microscope image, the major axis / minor axis of the primary particles (each boron nitride) constituting 50 arbitrarily selected boron nitride aggregate particles are measured, and the average value is calculated.

Method for measuring the average length of the primary particles (first boron nitride and second boron nitride) constituting the first boron nitride aggregated particles and the second boron nitride aggregated particles:

Cross section of a laminate produced by mixing primary particles (first boron nitride and second boron nitride) constituting the first aggregated boron nitride particles and the second aggregated boron nitride particles with a thermosetting resin or the like From the electron microscope image, the major diameter of the primary particles (each boron nitride) constituting 50 arbitrarily selected boron nitride aggregated particles was measured, and the average value was calculated.

(Examples 1 to 9 and Comparative Examples 1 to 5)
(1) Preparation of resin material The components shown in Tables 1 and 2 below were blended in the amounts shown in Tables 1 and 2 below, and the resin material was obtained by stirring at 500 rpm for 25 minutes using a planetary stirrer. rice field.

(2) Production of laminate The obtained resin material was coated on a release PET sheet (thickness 50 µm) so as to have a thickness of 350 µm, dried in an oven at 90 ° C. for 10 minutes, and cured into a curable sheet (insulating film). layer) to obtain a laminated sheet. Thereafter, the release PET sheet was peeled off, and both sides of the curable sheet (insulating layer) were sandwiched between a copper foil and an aluminum plate, and vacuum pressed at a temperature of 200° C. and a pressure of 12 MPa to prepare a laminate.

(evaluation)
(1) Thermal conductivity After cutting the obtained laminate into 1 cm squares, carbon black was sprayed on both sides to prepare measurement samples. Using the obtained measurement sample, the thermal conductivity was calculated by the laser flash method. The thermal conductivity in Tables 1 and 2 is a relative value with the value of Comparative Example 1 set to 1.00. "LFA447" manufactured by NETZSCH was used for the measurement of thermal conductivity.

(2) Dielectric Breakdown Strength By etching the copper foil in the obtained laminate, the copper foil was patterned into a circle with a diameter of 2 cm to obtain a test sample. Using a withstand voltage tester ("MODEL7473" manufactured by ETECH Electronics), an alternating voltage was applied between test samples at 25°C so that the voltage increased at a rate of 0.33 kV/sec. The voltage at which a current of 10 mA was applied to the test sample was taken as the dielectric breakdown voltage. The dielectric breakdown voltage was normalized by dividing it by the thickness of the test sample to calculate the dielectric breakdown strength. Dielectric breakdown strength was determined according to the following criteria.

[Determination Criteria for Dielectric Breakdown Strength]
○: 60 kV/mm or more △: 30 kV/mm or more and less than 60 kV/mm ×: less than 30 kV/mm

(3) Variation in Dielectric Breakdown Strength The obtained laminate was cut into 5 cm squares from different locations to obtain 20 measurement samples. Twenty test samples were produced in the same manner as in (2) above, and the dielectric breakdown strength was calculated for each test sample. Variation in dielectric breakdown strength was determined according to the following criteria.

[Determination Criteria for Variation in Dielectric Breakdown Strength]
○: The difference between the maximum value and the minimum value of the dielectric breakdown strength is less than 20 kV / mm △: The difference between the maximum value and the minimum value of the dielectric breakdown strength is 20 kV / mm or more and less than 40 kV / mm ×: Dielectric breakdown strength The difference between the maximum and minimum values of is 40 kV/mm or more

(4) Adhesion (peel strength)
The resulting curable sheet (insulating layer 350 μm) was pressed between an electrolytic copper foil (thickness 35 μm) and an aluminum plate (thickness 1 mm) with a pressure of 10 MPa, and heated at 200 ° C. for 1 hour to obtain a measurement sample. Obtained. After that, a measurement sample was cut out to a size of 5 cm×12 cm, and the copper foil was peeled off from the remaining part, leaving only the center of 1 cm×12 cm on the short side. The peel strength between the central 1 cm electrodeposited copper foil and the cured insulating layer was measured by a 90° peel test. Adhesiveness (peel strength) was determined according to the following criteria.

[Determination Criteria for Adhesion (Peel Strength)]
○: Peel strength is 5 N / cm or more △: Peel strength is 2 N / cm or more and less than 5 N / cm ×: Peel strength is less than 2 N / cm

The results are shown in Tables 1 and 2 below.

1... Resin sheet (resin material)
DESCRIPTION OF SYMBOLS 11... Binder resin 12... 1st boron nitride aggregated particle 13... 2nd boron nitride aggregated particle 14... Hardened material part (part where binder resin hardened)
21... Laminated body 22... Thermal conductor 22a... One surface (first surface)
22b... The other surface (second surface)
23... Insulating layer 23a... One surface (first surface)
23b... The other surface (second surface)
24... Conductive layer 24a... One surface (first surface)
24b... The other surface (second surface)

Claims (7)

Containing first aggregated boron nitride particles, second aggregated boron nitride particles, and a binder resin,
In the first aggregated boron nitride particles, in the pore size distribution based on the volume of the pore volume of the pores having a pore size of more than 0 μm and 5 μm or less, the cumulative 50% pore size is less than 2 μm,
In the second aggregated boron nitride particles, in the pore size distribution based on the volume of the pore volume of the pores having a pore size of more than 0 μm and 5 μm or less, the cumulative 50% pore size is 2 μm or more,
The first aggregated boron nitride particles have a particle diameter of 120 μm or less,
The second aggregated boron nitride particles have a particle diameter of 10 μm or more and 80 μm or less,
The resin material, wherein the aspect ratio of the primary particles constituting the second aggregated boron nitride particles is 7 or less. 2. The resin material according to claim 1, wherein the primary particles constituting said first aggregated boron nitride particles have an aspect ratio of 3 or more and 17 or less. 3. The resin material according to claim 1, wherein the first aggregated boron nitride particles have a particle diameter of 35 μm or more. The particle diameter of the first boron nitride aggregate particles exceeds 40 μm,
The average length of the primary particles constituting the first aggregated boron nitride particles is 2 μm or more and less than 20 μm,
The resin material according to any one of claims 1 to 3 , wherein the primary particles constituting the second aggregated boron nitride particles have an average length of 8 µm or less. The total content of the first boron nitride aggregated particles and the second boron nitride aggregated particles in 100% by volume of the resin material is 20% by volume or more and 80% by volume or less. The resin material according to any one of items 1 and 2. The resin material according to any one of claims 1 to 5 , which is a resin sheet. 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,
A laminate, wherein the material of the insulating layer is the resin material according to any one of claims 1 to 6 .

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