阅读说明：本技术 粒子材料和导热物质 (Particle material and heat conductive substance ) 是由 野口真宜 仓木优 中村展步 于 2019-02-18 设计创作，主要内容包括：本发明提供导热性高的粒子材料和含有该粒子材料的导热物质。通过采用球形度略低的粒子材料作为在导热物质中所采用的由氧化铝构成的粒子材料,能够使构成粒子材料的粒子间的接触点增加而表现出高导热性。进而发现通过将构成粒子材料的氧化铝的α化率控制在一定范围,能够得到兼具导热性和对设备的攻击性降低的粒子材料。本发明的粒子材料以氧化铝为主成分,体积平均粒径为70～200μm,球形度为0.89以上且小于0.99,α化率为40～85％,设备磨损试验的结果为0.017g以下。通过将α化率和球形度控制在上述范围,能够提高导热性的同时还能够降低对设备的攻击性。(The invention provides a particle material with high heat conductivity and a heat conductive substance containing the particle material. By using a particle material having a slightly low sphericity as the particle material made of alumina used in the heat conductive substance, the contact points between particles constituting the particle material can be increased to exhibit high heat conductivity. Further, it has been found that a particulate material having both heat conductivity and reduced offensive power to a device can be obtained by controlling the degree of α formation of alumina constituting the particulate material to a certain range. The particulate material of the present invention comprises alumina as a main component, and has a volume average particle diameter of 70 to 200 μm, a sphericity of 0.89 or more and less than 0.99, an alpha conversion of 40 to 85%, and a result of an equipment wear test of 0.017g or less. By controlling the α formation rate and the sphericity in the above ranges, the thermal conductivity can be improved and the aggressivity to the device can be reduced.)

1. A particulate material comprising alumina as a main component, having a volume average particle diameter of 70 to 200 μm, a sphericity of 0.89 or more and less than 0.99, and an alpha conversion of 40 to 85%,

the result of the machine wear test was 0.017g or less.

2. The particulate material of claim 1, wherein the sphericity is 0.96 or less.

3. A thermally conductive substance having the particle material according to claim 1 or 2 and a resin material in which the particle material is dispersed.

Technical Field

The present invention relates to a particulate material and a thermally conductive substance.

Background

With the progress of miniaturization of semiconductor devices, generation of a large amount of heat has become a problem. The generated heat is required to be rapidly transferred from the semiconductor element to the outside. Therefore, a thermally conductive substance having high thermal conductivity is desired.

A conventional heat conductive substance generally employs a resin composition in which a particulate material made of alumina or the like is dispersed in a resin material such as a silicone resin (see, for example, patent document 1).

Since the higher the degree of α formation of alumina, the more excellent the thermal conductivity, patent document 1 also discloses that the degree of α formation is as high as possible.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object to be solved by the present invention is to provide: provided are a particle material having high thermal conductivity and a thermally conductive substance containing the particle material.

As a result of intensive studies to solve the above problems, the present inventors have found that the use of a particulate material having a slightly low sphericity as a particulate material made of alumina used for a heat conductive substance can increase the contact points between particles constituting the particulate material to exhibit high heat conductivity. However, if the sphericity of the particulate material is slightly reduced, unevenness occurs on the surface of the particulate material, and the particulate material or a processing apparatus containing a heat conductive substance containing the particulate material is highly aggressive, which is problematic.

The present inventors have found that by controlling the degree of α formation of alumina constituting a particulate material within a certain range, a particulate material can be obtained in which both thermal conductivity and reduced equipment aggressivity can be achieved even when the sphericity of the particulate material is in a range of excellent thermal conductivity, and have completed the following invention.

(1) The particulate material of the present invention for solving the above problems comprises alumina as a main component, has a volume average particle diameter of 70 to 200 μm, a sphericity of 0.89 or more and less than 0.99, an alphatization ratio of 40 to 85%, and a result of an equipment wear test of 0.017g or less.

By controlling the α formation rate and the sphericity to the above ranges, the thermal conductivity can be improved, and the aggressivity to the device can be reduced. In particular, when the α -conversion ratio is within the above range, the thermal conductivity can be sufficiently exhibited, and the offensive property can be sufficiently reduced.

(2) The heat conductive substance of the present invention to solve the above problems has the particle material of (1) above and a resin material in which the particle material is dispersed. Since the contained particle material has both high thermal conductivity and low aggressivity to a device, the obtained thermally conductive substance can also have both high thermal conductivity and low aggressivity to a device.

Drawings

FIG. 1 is a graph showing the shear rate dependence of the viscosity of test examples 1 to 4 (volume average particle diameter: 90 μm) measured in examples.

FIG. 2 is a graph showing the shear rate dependence of the viscosity of test examples 5 to 7 (volume average particle diameter: 70 μm) measured in the examples.

Detailed Description

Hereinafter, the particle material and the heat conductive substance of the present invention will be described in detail based on the embodiments. The heat conductive substance according to the present embodiment can be formed by dispersing the particle material according to the present embodiment in a resin material.

Particle materials

The particulate material of the present embodiment contains alumina as a main component. The term "alumina as a main component" means that the alumina is contained in an amount of 50% or more, preferably 60% or more, 80% or more, 90% or more, 95% or more, or 99% or more, based on the entire mass, and more preferably, the alumina is contained entirely except for unavoidable impurities. Examples of the material that may be contained in addition to alumina include inorganic materials other than alumina. Examples of the inorganic material other than alumina include silica, zirconia, titania, boron nitride, and the like. These inorganic materials may be contained in the form of a mixture or may be contained in 1 particle.

The alpha conversion of alumina is 40-85%. In particular, 75%, 77%, and 80% can be used as the upper limit, and 50%, 48%, and 45% can be used as the lower limit. These upper and lower limits may be independently combined. By setting the α -formation ratio to an upper limit or less, the aggressivity to the device can be reduced, and by setting the α -formation ratio to a lower limit or more, the thermal conductivity can be improved. The α conversion ratio is a ratio of an α crystal phase to the mass of alumina calculated based on the mass of all the alumina contained in the particulate material.

The volume average particle diameter of the particulate material of the present embodiment is 70 to 200 μm. The volume average particle diameter may be 170 μm, 180 μm, or 190 μm as the upper limit, or 100 μm, 90 μm, or 80 μm as the lower limit. These upper and lower limits may be independently combined. When the volume average particle diameter is not more than the upper limit, the heat conductive substance produced by dispersing in the resin material is easily filled in the fine gaps, and when the volume average particle diameter is not less than the lower limit, the number of contacts between the particle materials can be reduced, and the heat conductivity can be improved.

The sphericity of the particle material of the present embodiment is 0.89 or more and less than 0.99. The upper limit of the sphericity may be 0.96, 0.97, or 0.98, and the lower limit may be 0.92, 0.91, or 0.90. These upper and lower limits may be independently combined. When the sphericity is not less than the lower limit, the fluidity and thermal conductivity when dispersed in the resin material can be improved, and when the sphericity is not more than the upper limit, the thermal conductivity can be improved.

For sphericity, a photograph was taken by SEM as represented by (sphericity) ═ {4 pi × (area) ÷ (perimeter) based on the area and perimeter of the particles observed therein²Calculated value. The closer to 1, the more nearly a positive sphere. Specifically, an average value obtained by measuring 100 particles using image analysis software (Asahi Kasei Co., Ltd.: image A) was used.

The particulate material of the present embodiment has a result of an equipment wear test of 0.017g or less, preferably 0.015g or less, and more preferably 0.010g or less.

In the "equipment wear test" in this specification, a steel ball made of SUS304 having a diameter of 5mm (model: 1-9762-02, manufactured by MISUMI) of about 10g (9.5g to 10.5g) and the above particulate material having a mass (about 10 g) equivalent to that of the steel ball were put into a 250mL (62 mm in diameter, 132mm in length, manufactured by As-One) cylindrical vessel, the cylindrical vessel was rotated at 60rpm with the cylinder center axis thereof As a rotation axis for 56 hours, the steel ball and the alumina powder were classified with a sieve having 1mm mesh, the steel ball was washed with water and dried, and the amount of mass reduction per 10g of the steel ball before and after the wear test was measured.

The particle material of the present embodiment may be surface-treated. For example, the surface treatment agent capable of introducing a functional group reactive with the resin material may be used to improve the affinity with the resin material contained in the heat conductive material described later, or the surface treatment agent composed of organic silane may be used to suppress the aggregation of the particle material. Examples of the surface treatment agent that can be used for the surface treatment include silane compounds and silazanes.

Method for producing particulate material

The particulate material is produced by a deflagration method (VMC method) in which a metallic aluminum powder is oxidized in an oxidizing atmosphere and burned and then rapidly cooled, a melting method in which a powder made of alumina is heated and melted and then rapidly cooled, a sol-gel method, or the like. Then, the conversion into the α phase is performed to a desired degree to enable the production. The conversion to the alpha phase can be controlled according to the time of exposure to the high temperature at which the alphatization is carried out, the time being controlled so as to achieve an appropriate alphatization rate. A little zinc (1ppm to 5000ppm) may be added to reduce the change in particle shape due to heating. Alternatively, the catalyst may be produced by adjusting the raw material, fuel, oxygen amount, and atmosphere in the furnace supplied by the VMC method or the melting method.

Thermally conductive substance

The heat conductive substance of the present embodiment is composed of the above-described particle material and a resin material in which the particle material is dispersed. As the resin material, any of a thermosetting resin and a thermoplastic resin can be used. The state of use may be solid or liquid. As the resin material, a precursor such as a monomer before curing may be used, and in this case, the precursor may be superposed in a use state. As the resin material, a silicone resin (precursor), an epoxy resin (precursor), and the like are preferable.

Preferably, the resin material and the particle material are in close contact with each other, and the resin material fills the gaps between the particle materials, thereby improving the thermal conductivity.

The mixing ratio of the particulate material and the resin material is not particularly limited, and it is preferable that the particulate material is mixed in an amount of about 40 to 97% by mass based on the total of the particulate material and the resin material. In particular, 95% by mass or 90% by mass may be used as the upper limit, and 45% by mass or 50% by mass may be used as the lower limit. These upper and lower limits may be arbitrarily combined. The thermal conductivity can be improved by setting the mixing amount of the particulate material to be not less than the lower limit, and the fluidity can be improved by setting the mixing amount of the particulate material to be not more than the upper limit.