Hexagonal boron nitride particle-dispersed resin composite and method for producing hexagonal boron nitride particle-dispersed resin composite

Abstract

The present invention has developed a technique for easily obtaining a BN particulate resin composite that can be cut to produce a plurality of thin-plate-shaped heat transfer sheets having excellent performance of high thermal conductivity and high insulating properties, can significantly improve the productivity of the thin-plate-shaped heat transfer sheets, has a large and thick large block shape, and has excellent heat transfer properties. And exhibits high thermal conductivity in which the resin is sufficiently impregnated into the interior. A hexagonal boron nitride particle-dispersed resin composite, which is a block-shaped hexagonal boron nitride particle-dispersed resin composite for directly obtaining a plurality of thin-plate-shaped heat transfer sheets by cutting into a plate shape, and which is obtained by curing in a state in which pores of a porous BN molded body are impregnated with a resin, and a method for producing the composite, the porous BN molded body is formed by containing at least hexagonal boron nitride particles, the continuous pores from which traces of a pore-forming agent are removed, and a cured body containing at least one of an inorganic binder and an organic binder, and the cured body containing the binder is interposed between the particles.

Description

Technical Field

[0001] This invention relates to hexagonal boron nitride particle dispersion resin composites and methods for manufacturing such composites. More specifically, it relates to a technique for easily providing a stable resin composite exhibiting high thermal conductivity and high insulation properties, formed by well dispersing hexagonal boron nitride (h-BN) particles (hereinafter referred to as BN particles) in a resin. Particularly relevant is a useful technique that enables the provision of large, block-shaped BN particle dispersion resin composites exhibiting stable high thermal conductivity and high insulation properties. By directly cutting thin, plate-shaped heat transfer sheets with high thermal conductivity and high insulation properties from this block, the productivity of producing these plate-shaped heat transfer sheets can be significantly improved, enabling the direct acquisition of multiple plate-shaped heat transfer sheets from the large, block-shaped BN particle dispersion resin composite. Background Technology

[0002] Conventionally, in electronic control units, ceramics are preferred as high thermal conductivity plates used to diffuse heat generated by semiconductors (ICs) to heat sinks for heat dissipation, considering both electrical insulation and thermal conductivity. However, ceramics are rigid and have hard surfaces, resulting in poor adhesion to contact surfaces. Therefore, there is a need to improve the overall thermal conductivity of the heat dissipation structure, and the following solutions have been proposed. For example, Patent Document 1 proposes a ceramic-resin composite material in which a resin composition is impregnated within a ceramic sintered body with a specific particle size and aspect ratio in the form of a three-dimensional integral ceramic primary particle, and discloses a heat dissipation structure for a circuit device using this ceramic-resin composite material. Other ceramics used include boron nitride, aluminum nitride, and silicon nitride. The heat transfer member provided in Patent Document 1 is designed as a thin plate with a thickness of 0.05 mm or more and 1.0 mm or less, and particularly as a sheet with a thickness of 0.1 to 0.35 mm when it is desirable to reduce thermal resistance.

[0003] Furthermore, hexagonal boron nitride (BN), which exhibits excellent properties as an electrical insulating material, such as high thermal conductivity and high insulation, has attracted attention in Patent Document 2 due to its large anisotropy in thermal conductivity resulting from its crystal structure and flake shape. It also discloses a method for manufacturing heat dissipation components by impregnating resin into the voids inside a boron nitride sintered body and cutting it into a plate shape, thereby enabling arbitrary orientation control and facilitating the fabrication of heat dissipation components of arbitrary thickness with excellent thermal conductivity. Additionally, a resin-impregnated boron nitride sintered body is proposed, consisting of a boron nitride sintered body with a porosity of 10-70% formed by three-dimensional bonding of boron nitride particles and resin, having through-holes filled with adhesive resin. In cited document 2, a cubic resin-impregnated boron nitride sintered body with a side length of approximately 50 mm is obtained, and the thickness of the plate-shaped resin-impregnated boron nitride sintered body is preferably 0.15-1.50 mm.

[0004] In Patent Document 3, as one embodiment of the composite, a thin and lightweight composite is proposed, comprising a boron nitride sintered body formed by sintering a mesh of boron nitride sheets with a mesh size of about 200 to 1000 μm, and a resin filling the pores of the boron nitride sintered body.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent No. 7282950

[0008] Patent Document 2: Japanese Patent No. 6262522

[0009] Patent Document 3: Japanese Patent No. 7322323 Summary of the Invention

[0010] The problem the invention aims to solve

[0011] However, in the aforementioned prior art, resin is impregnated into the voids formed by the unique structure of the material within the ceramic, such as boron nitride sintered body, to form a ceramic-resin composite. That is, as described below, any prior art impregnates resin into the fine voids of a thin-plate or small-shaped (thin) BN or other ceramic sintered body to form a thin-plate or small ceramic-resin composite. According to the present inventors' research, this presents the following problems.

[0012] Specifically, the aforementioned existing technologies all involve impregnating a ceramic resin composite with a resin composition into a ceramic sintered body sintered at temperatures above 1500°C. These technologies suffer from the following technical problems. First, Patent Document 1 relates to a "resin composite of a boron nitride sintered body formed by impregnating a thermosetting resin composition into a boron nitride sintered body formed by three-dimensional sintering of boron nitride powder." The boron nitride sintered body used for resin impregnation is prepared using complex steps at high temperatures and / or high pressures, which is hardly a simple method and results in poor productivity. Specifically, a mixed powder containing boron nitride is filled into a mold, and the pressed body is further pressurized at 75 MPa using a CIP (cold isostatic pressing) device, followed by sintering in an intermittent high-frequency furnace at 2000°C for 10 hours with a nitrogen flow rate of 10 L / min.

[0013] Furthermore, in the technology of Patent Document 1, as in its embodiment, a sheet with a thickness of 0.32 mm is cut from the boron nitride sintered body obtained as described above. The thin sintered body sheet is then impregnated with a thermosetting resin composition such as epoxy resin as described below, and the resin is thermocured after impregnation to form a composite. Specifically, a vacuum heating impregnation apparatus is used. After degassing for 10 minutes in a vacuum at a temperature of 145°C and a pressure of 15 Pa, the impregnation process with the thermosetting resin composition is continued in the apparatus under the heating vacuum. Next, the thin boron nitride sintered body impregnated with the thermosetting resin composition is further placed in a pressurized heating impregnation apparatus and held under pressure at a temperature of 145°C and a pressure of 3.5 MPa for 120 minutes. Then, it is heated at atmospheric pressure, 160°C, for 120 minutes to obtain a sheet-like ceramic resin composite in which the thermosetting resin composition is semi-cured. As described in Patent Document 1 above, thin sheets made of boron nitride sintered bodies are obtained by impregnating the sintered bodies with resin one by one. This process is very time-consuming and complicated, and has a significant practical problem of poor productivity.

[0014] Furthermore, as described in Patent Document 2, if a block-shaped ceramic resin composite is manufactured and then thin sheet-shaped heat transfer plates are cut out, the productivity can be expected to be improved compared to manufacturing them one by one by impregnating the thin sheets cut from the boron nitride sintered body with resin, as described in Patent Document 1. However, in the technology described in Patent Document 2, the boron nitride sintered body before resin impregnation is "preferably manufactured by sintering at 1600°C or above for more than 1 hour. If sintering is not performed, the pore size is small, and resin impregnation becomes difficult." The upper limit of the sintering temperature is actually around 2200°C, and the boron nitride sintered body is obtained by sintering the pressed block-shaped body in an intermittent high-frequency furnace with a nitrogen flow rate of 10 L / min. Thus, the technology described in Patent Document 2, like the case in Patent Document 1, uses high temperature and / or high pressure in a complicated process, which results in poor productivity.

[0015] Furthermore, the technology described in Patent Document 3, which involves sintering a mesh-like coating at temperatures above 1600°C or 1700°C, and below 2200°C or 2100°C to obtain a boron nitride sintered body, suffers from the same technical problems as those in Patent Documents 1 and 2. In the technology of Patent Document 3, since the composite material filling the pores of the boron nitride sintered body is thin, the resin can be sufficiently filled into the pores. Patent Document 3 also involves manufacturing each sintered body individually by impregnating it with resin. Therefore, like Patent Document 1, Patent Document 3 suffers from significant practical problems, including extremely high labor costs, complexity, and significantly low productivity.

[0016] Furthermore, according to the research of the present inventors, the following problem arises when the structure described in Patent Document 2, which involves cutting thin plate-shaped heat transfer sheets from a block-shaped ceramic resin composite formed by impregnating a sintered body with resin, is used. Specifically, when the ceramic resin composite used for cutting the sheets is made large in order to improve the productivity of the thin plate-shaped heat transfer sheets, in the prior art where resin is impregnated into the voids (pores) caused by the structure of the boron nitride sintered body, even when sintering is performed at high temperatures, it is difficult to ensure that the resin sufficiently impregnates the interior of the block-shaped boron nitride sintered body, resulting in a technical problem that the size cannot be increased. This tendency is particularly strong when the thickness of the block-shaped boron nitride sintered body increases.

[0017] According to the inventors' research, if the voids (pores) of the boron nitride sintered body are not impregnated with the matrix resin and remain in a void state, the thermal conductivity of the resulting resin composite is significantly reduced. This is believed to be because the air or vacuum state within the voids acts as a high insulating layer, and the thermal conductivity of the resin composite varies greatly depending on whether the resin impregnates into the voids (pores) of the boron nitride sintered body. Here, the hexagonal boron nitride particles (BN particles) used in this invention are flake-shaped. Therefore, when pressing and / or settling them to obtain a block-shaped molded body, the short sides (thickness) of the flake-shaped particles are stacked in the pressing direction and / or settling direction, and the long sides of the flake-shaped particles are oriented in a direction perpendicular to the pressing direction and / or settling direction. Therefore, for example, if the pressing direction of the pressing process when producing the block-shaped molded body is set to the thickness direction of the resin composite from which thin sheet-like plates are cut, the thermal conductivity of the long side of the cut thin sheet becomes very high. However, as mentioned above, in the prior art, if the thickness of the blocky boron nitride sintered body is increased, there is a major problem that the resin is difficult to fully penetrate into the interior of the sintered body.

[0018] The reasons cited above are the cause of the problem. However, in the existing technology, thin sheet-like heat transfer plates are cut from a blocky boron nitride sintered body and then impregnated with resin. Even when cutting sheets from a composite of boron nitride sintered body and resin, the thin sheet-like heat transfer plates are cut from small blocky composites. When cutting thin sheet-like heat transfer plates from small ceramic-resin composites, the number of heat transfer plates that can be cut from a single ceramic-resin composite is small. Therefore, as a method to improve the productivity of thin sheet-like heat transfer plates, it can hardly be considered an effective method, and there are practical problems.

[0019] Therefore, the object of this invention is to develop a new technology that can cut out sheet-like shapes to produce a larger quantity of thin sheet-like pieces, and the cut thin sheet-like pieces all become heat transfer sheets with excellent performance of high thermal conductivity and high insulation, which can significantly improve the productivity of thin sheet-like heat transfer sheets, and can easily obtain large and thick block shapes with resin fully impregnated inside, resulting in BN particle resin composites exhibiting high thermal conductivity. In this specification, the term "thickness" refers to the length of the shortest side in the large block-shaped molded body or composite; the longest side is referred to as the "maximum length".

[0020] Solution for solving the problem

[0021] The above objective is achieved by the present invention described below. That is, the present invention provides the following hexagonal boron nitride (BN) particle dispersion resin composite.

[0022] [1] A hexagonal boron nitride particle dispersion resin composite, characterized in that it is a block-shaped hexagonal boron nitride particle dispersion resin composite used to cut out plate-shaped heat transfer plates to directly obtain multiple thin plate-shaped heat transfer plates.

[0023] It is formed by curing a porous BN molded body in which resin is impregnated in the pores. The porous BN molded body is formed by at least hexagonal boron nitride (h-BN) particles, continuous pores as traces of pore-forming agent removed, and a cured body containing at least one of inorganic or organic binders, wherein the cured body containing the binder is located between the particles.

[0024] Preferred embodiments of the BN particle dispersion resin composite of the present invention are listed below.

[0025] [2] The BN particle dispersion resin composite described in [1] above is a large composite with a thick shape: the volume is 200 cm³. 3 In addition, when the longest side is set as the maximum length and the shortest side is set as the thickness, the ratio of maximum length to thickness m is 1 ≤ m ≤ 3.

[0026] [3] According to the BN particle dispersion resin composite described in [1] or [2] above, wherein the porosity of the porous BN molded body is more than 20% and less than 50%.

[0027] [4] The BN particle dispersion resin composite according to any one of [1] to [3] above, wherein the composite formed by curing in the state of resin impregnation in the pores of the porous BN molded body has a thermal conductivity of 20 W / m·K or more due to the orientation direction of the hexagonal boron nitride (h-BN) particles.

[0028] As another embodiment, the present invention provides a method for manufacturing the following BN particle dispersion resin composite.

[0029] [5] A method for manufacturing a hexagonal boron nitride particle dispersion resin composite, characterized in that it is a method for manufacturing a block-shaped hexagonal boron nitride particle dispersion resin composite that is directly obtained by cutting out plate-shaped heat transfer plates, the manufacturing method comprising the following steps:

[0030] The molding process is used to mold a one-time BN molded body from a mixture containing at least hexagonal boron nitride (h-BN) particles, a pore-forming agent, and at least one of an inorganic binder or an organic binder.

[0031] The curing process of the adhesive is used to cure the adhesive in the primary BN molded body and make the cured body containing the adhesive serve as an adhesive layer between the particles, thereby forming a secondary BN molded body with improved strength.

[0032] A porousing process is used to remove the porosity-forming agent contained in the molding process for molding the primary BN molded body, thereby forming a porous BN molded body with continuous pores; and

[0033] The composite process is used to impregnate the resin into the porous BN molded body obtained by the curing and porousification to achieve composite formation.

[0034] Preferred methods for manufacturing the BN particle dispersion resin composite of the present invention can be listed below.

[0035] [6] According to the manufacturing method of the BN particle dispersion resin composite described above [5], in the molding process, the mixture is molded into a BN molded body in one step by compression molding or sedimentation method.

[0036] [7] The method for manufacturing BN particle dispersion resin composite according to [5] or [6] above, wherein a porous BN molded body with a porosity of 20% or more and 50% or less is formed by performing the curing and the porousification.

[0037] [8] The method for manufacturing BN particle dispersion resin composite according to any one of [5] to [7] above, wherein the pore-forming agent is composed of a solid with a particle size of 5 to 200 μm, and the curing step of the binder for forming the secondary BN molded body and the porosification step for removing the pore-forming agent are carried out simultaneously by heating.

[0038] [9] The method for manufacturing BN particle dispersion resin composite according to any one of [5] to [8] above, wherein, in the composite process, when impregnating the porous BN molded body with resin, any one of the following methods is used to impregnate the resin: vacuum impregnation method or pressure impregnation method, or a combination of vacuum impregnation method and pressure impregnation method.

[0039] The effects of the invention

[0040] According to the present invention, a BN particle-dispersed resin composite can be easily provided, which is a large, thick block shape with high uniformity, high thermal conductivity, and high insulation, free from defects such as resin impregnation or heterogeneous impregnation, and with resin fully impregnated into its interior. Furthermore, a large number of thin plate-shaped heat transfer sheets can be cut from this large, block-shaped BN particle-dispersed resin composite, and each cut heat transfer sheet is a uniform and stable heat transfer sheet with high thermal conductivity and high insulation. According to the present invention, the production rate of such thin plate-shaped heat transfer sheets with excellent properties can be significantly improved. Furthermore, according to the present invention, by machining the large, thick, block-shaped BN particle-dispersed resin composite exhibiting high thermal conductivity and high insulation, large heat dissipation components, such as heat sinks integrated with heat dissipation plates, can be manufactured, thus possessing extremely high practical value. According to the present invention, a large-block-shaped BN particle dispersion resin composite with high thermal conductivity, exhibiting a thermal conductivity of 20 W / m·K or higher due to the orientation direction of the hexagonal boron nitride (h-BN) particles constituting the composite, and with small deviations in thermal conductivity even among large-scale composites, can be obtained. As a result, according to the present invention, by cutting this large-block-shaped BN particle dispersion resin composite into thin plates, it is possible to stably obtain multiple thin-plate-shaped heat transfer sheets with small deviations and exhibiting approximately the same high thermal conductivity. In the present invention, the thermal conductivity of the composite is determined using a xenon flash analyzer via the xenon flash method based on JIS R1611. Detailed Implementation

[0041] Next, preferred embodiments will be listed to describe the present invention in detail. The hexagonal boron nitride (BN) particle dispersion resin composite of the present invention is characterized in that it is cured and composited in a state in which resin is impregnated in the continuous pores of a porous BN molded body. The porous BN molded body is formed by at least comprising BN particles, the continuous pores having traces of a pore-forming agent removed, and a cured body containing either an inorganic binder or an organic binder, wherein the cured body containing the binder is interposed between the particles. The BN particle dispersion resin composite of the present invention described above can be easily manufactured by the following method for manufacturing the BN particle dispersion resin composite of the present invention. The method for manufacturing the BN particle dispersion resin composite of the present invention is characterized in that it is a method for manufacturing a block-shaped hexagonal boron nitride particle dispersion resin composite for cutting out plate-shaped sheets to directly obtain multiple thin plate-shaped heat transfer sheets. The manufacturing method includes the following steps: a molding step for molding a primary BN molded body from a mixture comprising at least hexagonal boron nitride (BN) particles, a pore-forming agent, and any one of an inorganic binder or an organic binder; a binder curing step for curing the binder in the primary BN molded body and placing the cured body containing the binder as an adhesive layer between the particles, thereby forming a secondary BN molded body with improved strength; a porosification step for removing the pore-forming agent contained in the molding step for molding the primary BN molded body to form a porous BN molded body with continuous pores; and a composite step for impregnating the resin into the porous BN molded body obtained by the curing and porosification to perform composite formation.

[0042] According to the manufacturing method of the present invention described above, it is possible to easily manufacture BN particle dispersion resin composites with large and thick block shapes that stably exhibit high thermal conductivity / high insulation properties, for example, in a volume of 200 cm³. 3 Assuming the longest side is set as the maximum length and the shortest side is set as the thickness, the ratio m of the maximum length / thickness is within the range of 1 ≤ m ≤ 3. According to the research of the inventors, a BN particle resin composite exhibiting high thermal conductivity, which is formed by cutting out a plate shape to produce a larger number of thin plate-shaped heat transfer sheets, and is in a large block shape with resin fully impregnated inside, can be produced with a volume of 800 cm³. 3 The above, and more preferably 1000cm 3 The above-described manner is used. Specifically, for example, it is preferable to manufacture a large composite with a thick shape and the following dimensions.

[0043] For example, as a composite of cubes with a maximum length / thickness ratio m of 1, examples include cubes with side lengths ranging from 93mm to 150mm (with a volume of 804cm³). 3 ~3375cm 3 BN particle dispersion resin composites in the shape of a cuboid. In addition, composites of various shapes can be considered as cuboid blocks. As an example, a BN particle dispersion resin composite satisfying the previously listed requirements can be configured as follows: For example, if the thickness is 50 mm and the maximum length / thickness ratio m is 3, then the maximum length is 150 mm, and the volume of the composite is approximately 800 cm³. 3 This can be represented as 15cm × 10.7cm × 5cm = 802.5cm. 3 The rectangle is rectangular. Furthermore, if the ratio of maximum length to thickness, m, is set to 2.5, and the thickness is set to 7cm, then it becomes 17.5cm × 8.2cm × 7cm = 1004.5cm. 3 A rectangular prism-shaped composite, if the ratio m is set to 3 and the thickness to 8cm, becomes 24cm × 8.3cm × 8cm = 1594cm. 3 The volume is approximately 1600 cm³ 3 The rectangular parallelepiped. According to the research of the inventors, by using a blocky BN particle dispersion resin composite with the thickness described above, it is possible to cut it into plates to produce a greater number of thin plate-shaped sheets. According to the present invention, not limited to the cubes and / or cuboids listed above, it is possible to obtain composites with good properties in blocky shapes of other shapes depending on the intended use. Moreover, by cutting from the large blocky BN particle dispersion resin composite described above, it is possible to stably and efficiently produce a very large number of thin plate-shaped heat transfer sheets, which are the ultimate goal of the present invention, as products exhibiting excellent functionality with high thermal conductivity and high insulation.

[0044] In this invention, the above-described structure of the invention is adopted to solve the problems in the prior art. Specifically, the inventors discovered that, according to the prior art of using boron nitride sintered bodies to increase resin impregnation by sintering at high temperatures of 1600°C to 2000°C or higher to increase small pore sizes, it is difficult to ensure sufficient resin impregnation into the internal voids (pores) even when the blocky sintered body is large. In order to improve this, in-depth research was conducted. To obtain the aforementioned boron nitride sintered body with increased pore size, complex and stringent processing conditions are required, and it was recognized that improvements in this area are also needed.

[0045] The inventors first discovered that, in order to obtain large, thick, blocky BN particle dispersion resin composites, it is necessary to mold large, porous BN molded bodies that allow the resin to stably and effectively impregnate the interior. In contrast, according to the inventors' research, if the porous BN molded body becomes larger and thicker, its weight also increases. Therefore, during handling and / or during setting in the mold for resin impregnation, the porous BN molded body may break due to its own weight or deform / break due to the impregnation pressure during resin impregnation. As a means to solve the above problems, one feature of the manufacturing method of the present invention is that, in the molding process for molding a primary BN molded body, at least one inorganic or organic binder is used in the molding material; furthermore, a curing process is provided for the binder added to the primary BN molded body to cure and form a secondary BN molded body with improved strength. According to the method for manufacturing the BN particle dispersion resin composite of the present invention having the above-described structure, a secondary BN molded body with improved strength can be easily obtained by curing the binder used in the raw material of the primary BN molded body. This secondary BN molded body is useful as an intermediate before resin impregnation, and its state is such that a cured body containing the binder serves as an adhesive layer between the particles.

[0046] Here, when impregnating resin, when using a BN sintered body prepared by the aforementioned prior art and sintered at a high temperature of 1600°C to 2000°C or higher to increase the small pore size, it is difficult to ensure that the resin is sufficiently and stably impregnated into the center of the BN sintered body, resulting in defects such as incomplete impregnation and / or heterogeneous impregnation. The manufacturing method of the present invention is characterized in that, in addition to the previously listed components for improving the strength of the BN sintered body, to solve this problem, as a completely different means from the prior art, a porous BN sintered body is formed as an intermediate that can effectively utilize a pore-forming agent to stably impregnate the resin in a good state. Specifically, the manufacturing method of the present invention is characterized by a porousing step in which a pore-forming agent, capable of being evaporated / vaporized by heating or dissolved in a solvent, is pre-added to the mixture used in the molding step of forming a primary BN molded body. After the primary BN molded body is formed, the pore-forming agent is removed by heating to evaporate / vaporize, or by dissolving / leaching it in a solvent, thereby forming a porous BN molded body. As a means of removing the pore-forming agent, when using a method of evaporation / vaporization by heating, it is sometimes possible to simultaneously perform a curing step of curing the binder of the raw material for the primary BN molded body described above to form a secondary BN molded body with improved strength. With this configuration, the manufacturing process can be further shortened.

[0047] In the porousification process for forming a porous BN molded body with the characteristics of the manufacturing method of the present invention, heat is used to evaporate / vaporize the pore-forming agent in the BN molded body, or to dissolve it in a solvent for removal. Furthermore, pores are formed as traces of the removed pore-forming agent, and these pores become continuous pores. Therefore, if the porous BN molded body obtained by the manufacturing method of the present invention is used when impregnating resin, these continuous pores become a good impregnation path for the resin up to the center of the interior of the large, blocky porous BN molded body. As a result, the technical problem of unimpregnated and / or heterogeneous impregnation of resin occurring inside the composite body in the prior art is solved in the BN particle dispersion resin composite obtained by the manufacturing method of the present invention. That is, according to the present invention, the problem of a significant decrease in the thermal conductivity of the obtained resin composite caused by the presence of portions of the matrix resin remaining in a void state in the voids (pores) of the boron nitride sintered body due to insufficient impregnation of the matrix resin can be solved.

[0048] Furthermore, through the continuous pores formed in the porousification process of the manufacturing method of the present invention, which are traces of the removal of the pore-forming agent, the resin easily permeates into the porous BN molded body, thereby reducing the resin permeation pressure (resistance) and decreasing the stress causing deformation / breakage of the porous BN molded body. Therefore, the problems of deformation and / or breakage occurring in the BN particle-dispersed resin composite after resin permeation into the porous BN molded body can be solved. In addition, in the manufacturing method of the BN particle-dispersed resin composite of the present invention, each step can be performed as described below, thus enabling more efficient manufacturing of superior BN particle-dispersed resin composites. Specifically, the order of the curing process and the pore-forming process of the adhesive can be changed, or both processes can be performed simultaneously. The curing process of the adhesive is used to cure the inorganic or organic adhesive in the primary BN molded body formed by the molding process to form a secondary BN molded body with high strength. The molding process is used to mold the primary BN molded body. The pore-forming process is used to obtain a porous BN molded body. The porous BN molded body has continuous pores with traces of the pore-forming agent in the primary BN molded body being removed from the BN molded body.

[0049] In the previously cited prior art patent document 2, a process for forming through holes in a boron nitride sintered body or a resin-impregnated boron nitride sintered body is described. However, the process for forming these through holes is described as "setting through holes and filling them with an adhesive resin, thereby ensuring adhesion and enabling efficient heat dissipation from the heater to the radiator, etc." Furthermore, it is described as "using an integral drill bit (manufactured by Mitsubishi Precision Machinery Co., Ltd.)" and "the diameter of the through hole is 0.03 mm to 2.0 mm." Therefore, it is clear that this process is not intended to improve the impregnation properties of the resin. Furthermore, according to the present inventors' research, the hole formed by drilling is linear in shape and has a larger diameter. Therefore, when a thin plate is cut to form a thin-walled heat transfer sheet, the VF% (volume fraction) of the high thermal conductivity BN particles differs from that of the low thermal conductivity resin in the area near and away from the through hole. This results in significant differences in thermal conductivity and non-uniformity, leading to very low performance as a heat transfer sheet. In contrast, in the manufacturing method of the present invention, for example, when using a solid pore-forming agent with a particle size of 5 to 200 μm, which can be either an inorganic or organic pore-forming agent, the pores formed in the porous BN molded body have a smaller diameter than the 2 mm or less through-holes disclosed in Patent Document 2, and form continuous pores with a non-linear shape. According to the research of the present inventors, based on the above-mentioned pore characteristics, the BN particle dispersion resin composite of the present invention, when cut into small thin plates to become heat transfer sheets, also exhibits very high uniformity of thermal conductivity and can stably perform its characteristics as a heat transfer sheet.

[0050] Furthermore, Patent Document 3, as a prior art example, describes "a boron nitride sintered body and a resin filling the pores of the boron nitride sintered body." However, these are fine pores (with an average pore size of less than 4.0 μm) naturally formed in the interlayer gaps between boron nitride particles during the molding of the boron nitride molded body by powder pressing and / or scraping, which are very small compared to the pores formed by the removal of the pore-forming agent that gives the characteristics of the present invention. Therefore, in the technology described in Patent Document 3, even when producing large, thick, blocky, porous BN molded bodies, it is impossible for the resin to fully and defect-free penetrate into the center of the molded body in the fine pores naturally formed in the interlayer gaps between the boron nitride particles.

[0051] In any case, the prior art shown in the previously listed patent documents 1-3 does not disclose any technical concept of continuous pores formed by the removal of traces of the pore-forming agent that gives the characteristics of the present invention. Due to the difference in the above-mentioned basic structure, the hexagonal boron nitride particle dispersion resin composite of the present invention and the composite formed by the prior art have the following major differences when observed under a microscope. As explained before, in the prior art, the material used as the impregnation resin is a ceramic sintered body such as BN. When this material is sintered, the raw material particles are set at a high temperature below the melting point (at least 1500°C or higher), so the raw material particles react directly with each other and become bonded (fused). On the other hand, the hexagonal boron nitride particle dispersion resin composite of the present invention is formed by curing at least one of the inorganic or organic binders at a low temperature to bond the raw material particles together. Therefore, it is a state in which a cured body containing the binder is interspersed between the particles, and the cured body exists as an adhesive layer (binder layer) between the raw material particles. Thus, the hexagonal boron nitride particle dispersion resin composite of the present invention is completely different from the composites in the prior art in terms of the presence of the bonding layer (adhesive layer) between the raw material particles, in addition to the completely different morphology of the resin impregnation pores mentioned above. The morphological characteristics of the resin impregnation composites in the two are different from each other.

[0052] In the BN particle-dispersed resin composite of the present invention, the porous BN molded body impregnated with the resin is characterized by having, in addition to the voids caused by the three-dimensional structure of boron nitride used for resin impregnation in the prior art, and / or the fine pores naturally formed in the interlayer gaps between boron nitride particles formed during the molding of the boron nitride molded body, continuous pores intentionally (forcedly) formed by a pore-forming agent used in the molding of the BN molded body in one step. By using the porous BN molded body with the above-described configuration, the BN particle-dispersed resin composite of the present invention achieves significantly improved filling properties in the resin impregnation compounding process, even when forming large, thick, blocky composites, resulting in a composite in which the resin is well impregnated to the interior. As a result, the problems of unimpregnated and / or heterogeneous impregnation of resin in prior art BN particle-dispersed resin composites are solved. Therefore, by cutting the large, thick, blocky BN particle dispersion resin composite of the present invention into sheet-like heat transfer sheets, it is possible to mass-produce sheet-like heat transfer sheets of excellent quality exhibiting uniform and stable high thermal conductivity / high insulation. Specifically, for example, by cutting from the large, blocky BN particle dispersion resin composite of the present invention, thousands of sheet-like heat transfer sheets with uniform and stable high thermal conductivity / high insulation can be provided.

[0053] The hexagonal boron nitride (h-BN) particles constituting the BN particle dispersion resin composite of the present invention can be boron nitride particles used in the prior art as previously listed. Hexagonal boron nitride is a compound composed of boron (B) and nitrogen (N), and has a scaly crystal structure similar to graphite, also known as "white graphite". Due to its characteristics such as being difficult to wet with metals, high thermal conductivity, low thermal expansion coefficient, and electrical insulation, it is mainly used in probe cards for semiconductor / electronic components. BN particles of appropriate particle size can be readily obtained from the market. The BN particles constituting the present invention also depend on their application; for example, high-purity boron nitride powder with an average particle size of about 5 μm to 30 μm is preferably used. The above-mentioned average particle size is the particle size that accounts for 50% of the cumulative value of the cumulative particle size distribution in particle size distribution determination based on laser diffraction light scattering method.

[0054] In the molding process for molding a primary BN molded body in the method for manufacturing the BN particle dispersion resin composite of the present invention, at least one inorganic or organic binder is contained in and used in the mixture of raw materials. The binders listed below can be used. Examples of inorganic binders include colloidal silica, tetraethyl orthosilicate, and sodium silicate (water glass). Examples of organic binders include thermosetting resins such as phenolic resin, epoxy resin, urea-formaldehyde resin, silicone resin, and polyimide resin. These inorganic or organic binders are used for the purpose of forming a secondary BN molded body with increased strength by curing the inorganic or organic binder in the primary BN molded body into a cured body during the binder curing process. As described above, the cured body becomes an adhesive layer (binder layer) between the BN particles.

[0055] The pore-forming agent used in the method for manufacturing the BN particulate dispersion resin composite of the present invention is contained and used in the mixture of raw materials during the molding process for molding a primary BN molded body, and is used to form a porous BN molded body during the porousening process. This porous BN molded body has continuous pores by removing the pore-forming agent from the primary BN molded body through various methods, enabling good resin impregnation. The following substances can be used as pore-forming agents. For example, compounds that can be evaporated / vaporized and removed from BN molded bodies, such as granular melamine cyanurate and granular camphor; organic compounds that can be dissolved in solvents and removed from BN molded bodies, such as polyvinyl alcohol, polyethylene oxide, and water; water-soluble inorganic compounds, such as table salt (NaCl), potassium chloride (KCl), potassium nitrate (KNO3), and sodium nitrate (NaNO3); and compounds that can become water and / or CO2 gas at room temperature and be removed from BN molded bodies, such as ice and dry ice.

[0056] In the molding step for molding a one-time BN molded body in the method for manufacturing the BN particle dispersion resin composite of the present invention, in addition to at least one of the BN particles, pore-forming agent, and inorganic or organic binder as described above, additives listed below may also be used as needed in the mixture used as raw materials. For example, surfactants that improve wettability, defoamers, viscosity modifiers, and solvents may also be added appropriately.

[0057] As a method used in the molding process for molding a one-time BN molded body in the manufacturing method of the BN particle dispersion resin composite of the present invention, methods such as compression molding, sedimentation molding, extrusion molding, cryogenic molding, and pressure molding can be used. As described below, when molding a one-time BN molded body using compression molding, a large, blocky BN particle dispersion resin composite with a defined orientation of the BN particles can be obtained. Therefore, by selecting the cutting direction as described below, a thin plate-shaped heat transfer sheet with an adjusted heat transfer direction can be produced. As mentioned above, since the BN particles are flake-shaped, during compression molding, the short side (thickness) face of the flake-shaped particles is stacked in the compression direction, and the long side face of the flake-shaped particles is oriented in a direction perpendicular to the compression direction. Therefore, for example, if the direction perpendicular to the compression direction is set as the thickness (short side) direction of the BN particle dispersion resin composite, which is the cutting material for the thin plate, the thermal conductivity in the long side direction of the cut thin plate becomes very high. On the other hand, if the pressing direction is the thickness direction of the BN particle dispersion resin composite, which is the cutting material for the thin sheet, the thermal conductivity in the thickness (short side) direction of the cut sheet becomes very high. By selecting the cutting direction as described above, the direction of thermal conductivity of the cut sheet can be adjusted and changed. Not limited to the above, by utilizing the technology of the present invention, if a large block-shaped BN particle dispersion resin composite material can be formed, it is also possible to manufacture a large heat dissipation component whose heat dissipation (thermal movement) direction can be arbitrarily changed by altering the cutting direction.

[0058] The method for impregnating resin into a porous BN molded body with continuous pores formed by removing the pore-forming agent in the curing step of the binder in the manufacturing method of the BN particle dispersion resin composite of the present invention is not particularly limited. For example, methods such as vacuum suction impregnation, pressure impregnation, and vacuum suction pressure impregnation followed by pressure impregnation can be used.

[0059] Example

[0060] The present invention will be described in more detail below with examples and comparative examples, but the present invention is not limited to these examples. It should be noted that, unless otherwise stated, "parts" in the examples and comparative examples refer to mass.

[0061] [Example 1]

[0062] (Preparation of porous BN molded articles)

[0063] A mixed powder was prepared by adding 10 parts of ethyl silicate (as an inorganic binder) and 10 parts of melamine cyanurate particles (as a pore-forming agent) with an average particle size of 100 μm to 90 parts of BN particles with an average particle size of 30 μm and 10 parts of BN particles with an average particle size of 5 μm. The mixed powder was then filled into a mold for preparing a primary BN molded body and pressed at a pressure of 10 MPa to form a cubical shape with a side length of 100 mm. The primary BN molded body was heated to 500 °C to cure the ethyl silicate binder, forming a secondary BN molded body with higher strength than the primary BN molded body. Simultaneously, the melamine cyanurate particles, the pore-forming agent contained in the primary BN molded body, evaporated / vaporized outside the secondary BN molded body, forming continuous pores with traces of the pore-forming agent removed. Finally, a porous BN molded body with a porosity of 30% was produced.

[0064] (Preparation of BN particle dispersion resin composite)

[0065] The porous BN molded body obtained above was placed in a vacuum impregnation apparatus, and epoxy resin (two-component curing type) was impregnated into the porous BN molded body under a reduced pressure of -90 kPa. After 48 hours at room temperature, a large BN particle dispersion resin composite with a side length of 100 mm was produced. The thermal conductivity of the composite obtained in this embodiment was measured using a xenon flash analyzer (trade name: LFA467, manufactured by NETZSCH). First, it was possible to confirm the orientation of the long side face of the BN particles in the direction perpendicular to the pressing direction. Therefore, a test piece (φ10 mm, thickness 2 mm) for measuring thermal conductivity was cut out with the orientation direction of the long side face of the BN particles as the thickness. In addition, regarding the cut-out points of the test pieces, five test pieces were measured at five points along the pressing direction: the top, the center, the bottom, and the middle of each of the five points from the center of the pressing surface of the large BN particle dispersion resin composite with a side length of 100 mm. As a result, the thermal conductivity is as high as 25 W / m·K to 30 W / m·K, with small deviation, and an average value of 27.4 W / m·K ± 9.5%. It can be seen that the large BN particle dispersion resin composite obtained in this embodiment stably exhibits high thermal conductivity.

[0066] (Fabrication of thin plate-shaped heat transfer fins)

[0067] From the large BN particle dispersion resin composite with a cube shape of 100 mm square obtained above, a 1 mm thick sheet is cut into 5 mm square plates in a direction perpendicular to the compression molding direction, enabling the preparation of more than 6000 thin plate-shaped heat transfer sheets. Furthermore, it was confirmed that none of the obtained thin plate-shaped heat transfer sheets exhibited defects such as resin infiltration failure and / or heterogeneous impregnation, demonstrating excellent heat transfer sheet quality with uniform and stable high thermal conductivity and high insulation.

[0068] [Example 2]

[0069] (Preparation of porous BN molded articles)

[0070] A mixed powder was prepared by adding 5 parts of liquid methyl phenolic resin (as an organic binder) and 20 parts of granular camphor (a crystalline terpene compound) with an average particle size of 50 μm to 100 parts of BN particles with an average particle size of 30 μm. The mixed powder was then filled into a mold for preparing a primary BN molded body and pressed under a pressure of 7 MPa to form a cubic shape with a side length of 100 mm. The primary BN molded body was heated to 180 °C to cure the phenolic resin, forming a secondary BN molded body with higher strength than the primary BN molded body. Subsequently, the secondary BN molded body was heated to 250 °C under reduced pressure of -70 kPa, causing the granular camphor (a crystalline terpene compound) in the primary BN molded body to evaporate / vaporize outside the primary BN molded body, forming pores and producing a porous BN molded body with a porosity of 20%.

[0071] (Preparation of BN particle dispersion resin composite)

[0072] The porous BN molded body obtained above was placed in a vacuum impregnation apparatus. Silicone resin was vacuum-impregnated into the porous BN molded body under a reduced pressure of -90 kPa. After continuous impregnation at 5 MPa, the mixture was left at room temperature for 72 hours to produce a large cubic BN particle dispersion resin composite with a side length of 100 mm. The thermal conductivity of the composite obtained in this embodiment was measured using a xenon flash analyzer (trade name: LFA467) in the same manner as in Example 1. The results confirmed the orientation of the long sides of the BN particles in the direction perpendicular to the pressing direction. Then, in the same manner as in Example 1, five test pieces (φ10 mm, thickness 2 mm) for thermal conductivity measurement were cut from five points on the large cubic BN particle dispersion resin composite with a side length of 100 mm, with the orientation direction of the long sides of the BN particles as the thickness. The obtained test pieces exhibited thermal conductivity as high as 30 W / m·K to 35 W / m·K with small deviations, averaging 33.0 W / m·K ± 9.1%. This confirms that the large BN particle dispersion resin composite obtained in this embodiment stably exhibits high thermal conductivity.

[0073] (Fabrication of thin plate-shaped heat transfer fins)

[0074] The large BN particle dispersion resin composite with a cube shape of 100 mm square obtained above can be cut into 10 mm square plates with a thickness of 2 mm in the compression molding direction, which can produce more than 2000 thin plate-shaped heat transfer sheets. No defects such as resin infiltration failure and / or heterogeneous impregnation were found in any of the obtained thin plate-shaped heat transfer sheets, exhibiting excellent quality with uniform and stable high thermal conductivity and high insulation.

[0075] [Example 3]

[0076] (Preparation of porous BN molded articles)

[0077] A mixed powder was prepared by adding 5 parts of powdered phenolic resin and 5 parts of liquid methyl phenolic resin as organic binders, and 25 parts of coarse salt with an average particle size of 100 μm as a pore-forming agent to 100 parts of BN particles with an average particle size of 30 μm. The mixed powder was then filled into a mold for preparing a primary BN molded body and pressed at 30 MPa to form a cubic BN molded body with a side length of 150 mm. The molded primary BN molded body was heated to 180 °C to cure the phenolic resin, forming a secondary BN molded body with higher strength than the primary BN molded body. This high-strength secondary BN molded body was then immersed in running water at room temperature for 24 hours to dissolve / leach the coarse salt used as a pore-forming agent out of the secondary BN molded body and remove it to form pores. Finally, a porous BN molded body with a porosity of 40% was produced.

[0078] (Preparation of BN particle dispersion resin composite)

[0079] After drying the porous BN molded body obtained above, it was placed in a vacuum impregnation apparatus and silicone resin was impregnated into the porous BN molded body under a reduced pressure of -90 kPa. After 72 hours at room temperature, a large BN particle dispersion resin composite with a side length of 150 mm was produced. For the composite obtained in this embodiment, the thermal conductivity was measured using a xenon flash analyzer (trade name: LFA467) in the same manner as in Example 1. As a result, it was confirmed that the orientation of the long side face of the BN particles in the direction perpendicular to the pressing direction could be confirmed. Therefore, a test piece (φ10 mm, thickness 2 mm) for measuring thermal conductivity was cut out with the thickness in the orientation direction of the long side face of the BN particles. In addition, the cut-out points of the test piece were set at five points along the pressing direction from the center of the pressing surface of the large BN particle dispersion resin composite with a side length of 150 mm: the uppermost surface, the middle surface, the lowermost surface, and each of the middle parts. Then, the thermal conductivity of the five cut test pieces was measured. The results showed that the thermal conductivity was as high as 20 W / m·K to 25 W / m·K, with small deviation and an average value of 22.8 W / m·K ± 12.3%. It can be seen that the large BN particle dispersion resin composite obtained in this embodiment stably exhibits high thermal conductivity.

[0080] (Fabrication of thin plate-shaped heat transfer fins)

[0081] The large BN particle dispersion resin composite with a cube shape of 150 mm square obtained above is cut into 10 mm square plates with a thickness of 10 mm in a direction perpendicular to the compression molding direction. This process can produce more than 8,000 thin plate-shaped heat transfer sheets. No defects such as resin infiltration failure and / or heterogeneous impregnation were found in any of the obtained thin plate-shaped heat transfer sheets, exhibiting excellent quality with uniform and stable high thermal conductivity and high insulation.

[0082] [Example 4]

[0083] (Preparation of porous BN molded articles)

[0084] A mixed powder was prepared by adding 5 parts of powdered phenolic resin and 5 parts of liquid methyl phenolic resin as organic binders, and 20 parts of potassium nitrate with an average particle size of 50 μm as a pore-forming agent to 80 parts of BN particles with an average particle size of 30 μm and 20 parts of BN particles with an average particle size of 5 μm. The mixed powder was filled into a primary BN molding mold and pressed at 30 MPa to form a cubic BN molded body with a side length of 150 mm. The molded primary BN molded body was heated to 180 °C to cure the phenolic resin, forming a secondary BN molded body with higher strength than the primary BN molded body. This high-strength secondary BN molded body was immersed in a water bath at 60 °C for 12 hours to dissolve / leach the potassium nitrate pore-forming agent out of the secondary BN molded body and remove it to form pores, thus producing a porous BN molded body with a porosity of 35%.

[0085] (Preparation of BN particle dispersion resin composite)

[0086] The porous BN molded body obtained above was placed in a vacuum impregnation apparatus, and epoxy resin (single-component curing type) was impregnated into the porous BN molded body under a reduced pressure of -85 kPa. After 24 hours at 50°C, a large cubic BN particle dispersion resin composite with a side length of 150 mm was produced. For the composite obtained in this embodiment, the thermal conductivity was measured using a xenon flash analyzer (trade name: LFA467) in the same manner as in Example 1. As a result, it was confirmed that the orientation of the long side face of the BN particles in the direction perpendicular to the pressing direction could be confirmed. Therefore, a test piece (φ10 mm, thickness 2 mm) for measuring thermal conductivity was cut out with the thickness in the orientation direction of the long side face of the BN particles. In addition, the cut-out points of each test piece were set at the same five points as in Example 3, from the center of the pressing surface of the cubic BN particle dispersion resin composite with a side length of 150 mm, resulting in five test pieces. Then, the thermal conductivity of the five cut test pieces was measured. The results showed that the thermal conductivity was as high as 23 W / m·K to 26 W / m·K, with small deviation and an average value of 24.4 W / m·K ± 6.6%. It can be seen that the large BN particle dispersion resin composite obtained in this embodiment stably exhibits high thermal conductivity.

[0087] (Fabrication of thin plate-shaped heat transfer fins)

[0088] The large BN particle dispersion resin composite with a cube shape of 150 mm square obtained above can be cut into 70 mm square plates with a thickness of 2 mm in the compression molding direction, which can produce more than 200 thin plate-shaped heat transfer sheets. No defects such as resin infiltration failure and / or heterogeneous impregnation were found in any of the obtained thin plate-shaped heat transfer sheets, exhibiting excellent quality with uniform and stable high thermal conductivity and high insulation.

[0089] [Example 5]

[0090] (Preparation of porous BN molded articles)

[0091] A slurry was prepared by adding 5 parts of tetraethyl orthosilicate (ethyl silicate) as an inorganic binder and 200 parts of water as a pore-forming agent and solvent to 80 parts of BN particles 1 with an average particle size of 30 μm and 20 parts of BN particles 2 with an average particle size of 5 μm. The prepared slurry was filled into a mold for preparing a primary BN molded body and allowed to stand for 24 hours to allow the BN particles to settle. Then, after removing the supernatant, the molded body was placed in a freezer at -20°C for 24 hours to freeze / solidify, shaping a cubic primary BN molded body with a side length of 100 mm. The shaped primary BN molded body was then placed in a drying oven at 500°C for heating to solidify the tetraethyl orthosilicate and simultaneously evaporate the frozen water to produce a porous BN molded body with a porosity of 40%.

[0092] (Preparation of BN particle dispersion resin composite)

[0093] The porous BN molded body obtained above was placed in a vacuum impregnation apparatus, and epoxy resin (two-component curing type) was impregnated into the porous BN molded body under a reduced pressure of -85 kPa. After 24 hours at room temperature, a large BN particle dispersion resin composite with a side length of 100 mm was produced. For the composite obtained in this embodiment, the thermal conductivity was measured using a xenon flash analyzer (trade name: LFA467) in the same manner as in Example 1. As a result, it was confirmed that the orientation of the long side face of the BN particles was perpendicular to the sedimentation direction. Then, in the same manner as in Example 1, five test pieces (φ10 mm, thickness 2 mm) for thermal conductivity measurement were cut from five points on the large BN particle dispersion resin composite with a side length of 100 mm, with the orientation direction of the long side face of the BN particles as the thickness. The thermal conductivity of the obtained test pieces was as high as 22 W / m·K~25 W / m·K, with small deviation, and an average value of 23.6 W / m·K ± 6.8%. This confirms that the large BN particle dispersion resin composite obtained in this embodiment consistently exhibits high thermal conductivity.

[0094] (Fabrication of thin plate-shaped heat transfer fins)

[0095] From the large BN particle dispersion resin composite with a cube shape of 100 mm square obtained above, a 2 mm thick sheet is cut into 10 mm square plates in a direction perpendicular to the sedimentation direction, which can prepare more than 2000 thin plate-shaped heat transfer sheets. No defects such as resin infiltration failure and / or heterogeneous impregnation were found in any of the obtained thin plate-shaped heat transfer sheets, exhibiting excellent quality with uniform and stable high thermal conductivity and high insulation.

[0096] [Example 6]

[0097] (Preparation of porous BN molded articles)

[0098] 100 parts of BN particles with an average particle size of 30 μm, 5 parts of powdered phenolic resin as an organic binder, 5 parts of liquid methyl phenolic resin, and 15 parts of ice with an average particle size of 100 μm as a pore-forming agent were mixed to obtain the preparation raw material. The obtained preparation raw material was filled into a mold for preparing a one-time BN molded body cooled to -20°C, and pressed under a pressure of 3 MPa to form a cubic one-time BN molded body with a side length of 100 mm. Immediately after molding, the one-time BN molded body was placed in a drying oven at 200°C for heating to solidify the liquid methyl phenolic resin and simultaneously evaporate the ice to produce a porous BN molded body with a porosity of 30%.

[0099] (Preparation of BN particle dispersion resin composite)

[0100] The porous BN molded body obtained above was placed in a vacuum impregnation apparatus, and epoxy resin (single-component curing type) was impregnated into the porous BN molded body under a reduced pressure of -85 kPa. After 24 hours at 50°C, a large BN particle dispersion resin composite with a side length of 100 mm was produced. For the composite obtained in this embodiment, the thermal conductivity was measured using a xenon flash analyzer (trade name: LFA467) in the same manner as in Example 1. As a result, it was possible to confirm the orientation of the long side face of the BN particles in the direction perpendicular to the pressing direction. Then, in the same manner as in Example 1, five test pieces (φ10 mm, thickness 2 mm) for thermal conductivity measurement were cut from five points on the large BN particle dispersion resin composite with a side length of 100 mm, with the orientation direction of the long side face of the BN particles as the thickness. The obtained test pieces exhibited thermal conductivity as high as 25 W / m·K to 30 W / m·K with small deviation, averaging 27.6 W / m·K ± 9.4%. This demonstrates that the large BN particle dispersion resin composite obtained in this embodiment stably exhibits high thermal conductivity.

[0101] (Fabrication of thin plate-shaped heat transfer fins)

[0102] The large BN particle dispersion resin composite with a cube shape of 100 mm square obtained above can be cut into 5 mm square plates with a thickness of 1 mm in the compression molding direction, which can produce more than 6000 thin plate-shaped heat transfer sheets. In addition, no defects such as resin infiltration failure and / or heterogeneous impregnation were found in any of the obtained thin plate-shaped heat transfer sheets, which are of excellent quality with uniform and stable high thermal conductivity and high insulation.

[0103] [Comparative Example 1]

[0104] Except for the absence of a pore-forming agent, the mixed powder prepared in the same manner as in Example 1 was heated to 500°C to cure the ethyl silicate of the inorganic binder to produce the BN molded body of Comparative Example 1. Using the obtained BN molded body, epoxy resin (two-component curing type) was impregnated in the same manner as in Example 1. The resin impregnation into the BN molded body was poor, with a large amount of unimpregnated resin occurring in the central interior, and cracking was observed in the BN molded body. The thermal conductivity of the obtained composite of this Comparative Example was measured using a xenon flash analyzer (trade name: LFA467) in the same manner as in Example 1. Then, in the same manner as in Example 1, five test pieces (φ10 mm, thickness 2 mm) for thermal conductivity measurement were cut from five points on a large cubic BN particle-dispersed resin composite with a side length of 100 mm, with the thickness corresponding to the orientation direction of the long side face of the BN particles. The obtained test pieces were measured, and the results differed from those of the composite in the examples. The thermal conductivity ranged from 1 W / m·K to 30 W / m·K, a very large deviation, making it impossible to obtain a large BN particle dispersion resin composite that stably exhibits high thermal conductivity. Therefore, the fabrication of thin-plate heat transfer sheets was not carried out.

[0105] [Comparative Example 2]

[0106] Except for the absence of an organic binder, the mixed powder prepared in the same manner as in Example 2 was heated to 180°C to cure the phenolic resin and produce the BN molded body of Comparative Example 2. Using the obtained BN molded body, silicone resin was impregnated in the same manner as in Example 2. However, the BN molded body broke during resin impregnation, and the BN particle dispersion resin composite itself could not be obtained.

[0107]

[0108]

Claims

1. A hexagonal boron nitride particle dispersion resin composite, characterized in that, It is a block-shaped hexagonal boron nitride particle dispersion resin composite used to cut out plate-shaped heat transfer plates to directly obtain multiple thin plate-shaped heat transfer plates. It is formed by curing a porous BN molded body in which resin is impregnated in the pores. The porous BN molded body is formed by at least hexagonal boron nitride (h-BN) particles, continuous pores as traces of pore-forming agent removed, and a cured body containing at least one of inorganic or organic binders, wherein the cured body containing the binder is located between the particles.

2. The hexagonal boron nitride particle dispersion resin composite according to claim 1 is a large composite with a thick shape: a volume of 200 cm³. 3 In addition, when the longest side is set as the maximum length and the shortest side is set as the thickness, the ratio of maximum length to thickness m is 1 ≤ m ≤ 3.

3. The hexagonal boron nitride particle dispersion resin composite according to claim 1 or 2, wherein, The porosity of the porous BN molded body is above 20% and below 50%.

4. The hexagonal boron nitride particle dispersion resin composite according to any one of claims 1 to 3, wherein, The composite formed by curing in a state where resin is impregnated in the pores of the porous BN molded body has a thermal conductivity of 20 W / m·K or higher due to the orientation of the hexagonal boron nitride (h-BN) particles.

5. A method for manufacturing a hexagonal boron nitride particle dispersion resin composite, characterized in that, This is a method for manufacturing a block-shaped hexagonal boron nitride particle dispersion resin composite for cutting into plate-shaped sheets to directly obtain multiple thin plate-shaped heat transfer sheets. The manufacturing method includes the following steps: The molding process is used to mold a one-time BN molded body from a mixture containing at least hexagonal boron nitride (h-BN) particles, a pore-forming agent, and at least one of an inorganic binder or an organic binder. The curing process of the adhesive is used to cure the adhesive in the primary BN molded body and make the cured body containing the adhesive serve as an adhesive layer between the particles, thereby forming a secondary BN molded body with improved strength. The pore-forming process is performed before or after the curing process of the adhesive, or simultaneously with the curing process of the adhesive, and is carried out as two separate processes. It is used to remove the pore-forming agent contained in the molding process for molding the one-time BN molded body to form a porous BN molded body with continuous pores. as well as The composite process is used to impregnate the resin into the porous BN molded body obtained by the curing and porousification to achieve composite formation.

6. The method for manufacturing the hexagonal boron nitride particle dispersion resin composite according to claim 5, wherein, In the molding process, the mixture is molded into a BN molded body in one step using pressing or settling methods.

7. The method for manufacturing the hexagonal boron nitride particle dispersion resin composite according to claim 5 or 6, wherein, By performing the curing and porousification processes, a porous BN molded body with a porosity of 20% or more and 50% or less is formed.

8. The method for manufacturing the hexagonal boron nitride particle dispersion resin composite according to any one of claims 5 to 7, wherein, The pore-forming agent is composed of a solid with a particle size of 5~200μm, and is used to perform both the curing process of the binder used to form the secondary BN molded body and the porosification process used to remove the pore-forming agent by heating.

9. The method for manufacturing the hexagonal boron nitride particle dispersion resin composite according to any one of claims 5 to 8, wherein, In the composite process, when impregnating the porous BN molded body with resin, any one of the following methods is used to impregnate the resin: vacuum impregnation, pressure impregnation, or a combination of vacuum impregnation and pressure impregnation.

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