JP2018145090A - Granulated powder, heat radiation resin composition, heat radiation sheet, semiconductor device, and heat radiation member - Google Patents

Abstract

Disclosed is a granulated powder capable of realizing a heat radiating sheet or a heat radiating member having excellent moisture resistance. A granulated powder includes secondary particles. The secondary particles 30 are spherical particles formed by aggregating the primary particles 20. The primary particles 20 are scaly boron nitride. The secondary particle 30 has a core part 310 and a shell part 320. The core part 310 includes the center of the secondary particle 30. The shell part 320 covers the core part 310. The density of the primary particles 20 in the core part 310 is lower than the density of the primary particles 20 in the shell part 320. [Selection] Figure 1

Description

  The present invention relates to granulated powder, a heat radiation resin composition, a heat radiation sheet, a semiconductor device, and a heat radiation member.

High heat conductivity and high heat resistance are required for heat dissipation sheets used in electronic devices and the like.
In order to improve the characteristics of the heat-dissipating sheet, there is a technique using hexagonal boron nitride as in Patent Document 1 and Patent Document 2.

JP 2010-157563 A JP 2013-241321 A

  However, as a result of intensive studies by the present inventors, a problem has been found that sufficient withstand voltage performance cannot be obtained in a high humidity environment.

  The present invention provides a granulated powder capable of realizing a heat radiating sheet and a heat radiating member excellent in moisture resistance.

According to the present invention,
Including spherical secondary particles formed by agglomerating primary particles,
The primary particles are scaly boron nitride,
The secondary particle has a core part including the center of the secondary particle, and a shell part covering the core part,
Granulated powder is provided in which the density of the primary particles in the core part is lower than the density of the primary particles in the shell part.

According to the present invention,
A heat-dissipating resin composition containing the granulated powder and a thermosetting resin is provided.

According to the present invention,
A heat dissipating sheet comprising the above heat dissipating resin composition is provided.

According to the present invention,
Provided is a semiconductor device including a cured body of the heat-dissipating resin composition.

According to the present invention,
There is provided a heat dissipating member including a cured body of the heat dissipating resin composition.

According to the present invention,
A semiconductor device including the heat dissipation member is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the granulated powder which can implement | achieve the heat radiating sheet and heat radiating member which are excellent in moisture resistance can be provided.

It is typical sectional drawing of the secondary particle which concerns on embodiment. It is a typical sectional view of a heat dissipation sheet concerning an embodiment. It is sectional drawing which showed typically an example of the structure of the semiconductor device which concerns on embodiment. It is a figure which shows the result of having observed the cross section of the thermal radiation sheet hardening body which concerns on Example 1 with the scanning electron microscope. (A) is a figure which shows the result of having observed the cross section of the secondary particle which concerns on the comparative example 1 with the scanning electron microscope, (b) is a cross section of the thermal radiation sheet hardening body which concerns on the comparative example 1, and a scanning electron It is a figure which shows the result observed with the microscope.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

FIG. 1 is a schematic cross-sectional view of a secondary particle 30 according to the present embodiment.
The granulated powder 10 according to this embodiment includes secondary particles 30. The secondary particles 30 are spherical particles formed by aggregating the primary particles 20. The primary particles 20 are scaly boron nitride. The secondary particle 30 has a core part 310 and a shell part 320. The core part 310 includes the center of the secondary particle 30. The shell part 320 covers the core part 310. The density of the primary particles 20 in the core part 310 is lower than the density of the primary particles 20 in the shell part 320. This will be described in detail below.

  In the present embodiment, the “heat dissipating sheet” refers to a sheet containing a B-stage resin. Further, the “heat radiating member” refers to a member containing a cured C-stage resin, and may further include a metal member, for example. The shape of the heat radiating member is not particularly limited, and may be an arbitrary shape.

  The granulated powder 10 is difficult to absorb moisture because the secondary particles 30 have shell portions 320 with high density. Therefore, the moisture resistance performance of the resin composition, the heat radiating sheet, and the heat radiating member manufactured using the granulated powder 10 can be improved.

  Moreover, the pressure resistance of the secondary particle 30 becomes high because the secondary particle 30 has the shell part 320 with a high density. Therefore, when manufacturing the resin composition containing the granulated powder 10, the heat radiating sheet, and the heat radiating member, the shape of the secondary particles 30 is maintained even when compressed. By maintaining the shape of the secondary particles 30 without being crushed, the primary particles 20 can be isotropically contained in the heat-dissipating sheet or the heat-dissipating member, and isotropic heat conduction characteristics can be obtained.

  On the other hand, the granulated powder 10 can reduce the quantity of the primary particle 20 because the secondary particle 30 has the core part 310 with low density, and can achieve cost reduction.

  The secondary particles 30 are spherical particles formed by aggregating the primary particles 20. Here, the spherical shape is not limited to a true sphere, but includes an elliptic rotating body and an aggregate of primary particles 20 that are rounded and rounded.

  The granulated powder 10 may mainly include the secondary particles 30, and the primary particles 20 that are not aggregated, the aggregate particles of the primary particles 20 that do not have the core portion 310 and the shell portion 320, other constituent particles, Impurities may be further included.

  Below, the manufacturing method of the granulated powder 10 is demonstrated. The granulated powder 10 includes secondary particles 30 formed by aggregating the primary particles 20.

As the primary particles 20, hexagonal boron nitride particles can be used. The average major axis of the primary particles 20 is not particularly limited, but is preferably 0.01 μm or more and more preferably 0.1 μm or more from the viewpoint of efficiently forming the secondary particles 30 and obtaining good thermal conductivity. Further, from the same viewpoint, the average major axis of the primary particles 20 is preferably 50 μm or less, and more preferably 20 μm or less.
The average major axis can be measured by observation using a scanning electron microscope (SEM). For example, the measurement is performed according to the following procedure. First, the secondary particles 30 or the heat dissipation sheet containing the secondary particles 30 is cut with a microtome or the like to produce a cross section. Next, several cross-sectional images magnified several thousand times are taken with a scanning electron microscope. Next, an arbitrary secondary particle 30 is selected, and the longest cross-sectional length of each primary particle 20 that can be confirmed from the photograph is measured as the major axis. At this time, a major axis is measured about 100 or more primary particles 20, and let those average values be an average major axis.

The secondary particles 30 preferably further contain a binder resin. The binder resin is not particularly limited as long as it can act as a binder. For example, the binder resin may be a thermoplastic resin or a thermosetting resin. Examples of the binder resin include acrylonitrile-styrene copolymer (AS) resin, acrylonitrile-butadiene-styrene copolymer (ABS) resin, polycarbonate, polystyrene, polyvinyl chloride, polyester resin, polyamide, polyphenylene sulfide (PPS). ) One or more selected from the group consisting of resin, acrylic resin, polyethylene, polypropylene, fluororesin, phenol resin, epoxy resin, unsaturated polyester resin, melamine resin, and polyurethane can be used.
Among these, as the binder, it is preferable to use one or more selected from the group consisting of phenol resins, epoxy resins, melamine resins, and unsaturated polyester resins. By including such a binder, secondary particles can be formed efficiently.

  The content of the binder contained in the secondary particles 30 is not particularly limited, but from the viewpoint of efficiently obtaining the secondary particles 30 having the core part 310 and the shell part 320, with respect to 100% by mass of the secondary particles, 5 mass% or more is preferable and 12 mass% or more is more preferable. The content is preferably 30% by mass or less, and more preferably 25% by mass or less.

  The secondary particles 30 may further include inorganic powder, metal powder, resin curing catalyst, curing accelerator, and the like for the purpose of improving characteristics.

  The granulated powder 10 according to the present embodiment can be produced, for example, as follows. First, the primary particles 20 and the binder resin are mixed using a mixer or the like. In addition, a binder resin can be dissolved and added to a solvent as needed. The slurry thus obtained is put into a processing container of a mechanical particle composite device, and the mechanical particle composite device is driven. As a result, the primary particles 20 are aggregated and spheroidized. The agglomerates thus obtained are heat-treated using a drying oven to obtain secondary particles 30. The heat treatment can be performed in the atmosphere. The temperature of the heat treatment can be, for example, 90 ° C. or more and 150 ° C. or less, and the heating time can be, for example, 30 minutes or more and 5 hours or less. Thus, the granulated powder 10 according to the present embodiment can be manufactured without sintering, and the manufacturing cost can be reduced.

  Here, the mechanical particle composite apparatus will be described. The mechanical particle compounding device combines raw materials such as multiple types of powders by applying mechanical action including compressive force, shear force and impact force to multiple types of raw materials such as powders. It is an apparatus that can obtain powder. As a method of applying a mechanical action, a rotating body having one or a plurality of stirring blades and the like and a mixing container having an inner peripheral surface close to a tip portion of the stirring blades and the like are provided, and the stirring blades and the like are rotated. Examples thereof include a method and a method of rotating a mixing container while fixing or rotating a stirring blade or the like. The shape of the stirring blade is not particularly limited as long as a mechanical action can be applied, and examples thereof include an elliptical shape and a plate shape. Further, the stirring blade or the like may have an angle with respect to the rotation direction. Moreover, you may process a groove | channel etc. in the inner surface of a mixing container.

  The secondary particles 30 having the core portion 310 and the shell portion 320 are formed by applying mechanical action including compression force, shearing force and impact force to the individual particles by rotating the stirring blade and the like at high speed. The

  Examples of the mechanical particle compounding apparatus include hybridization by Nara Machinery Co., Ltd., kryptron by Kawasaki Heavy Industries, Ltd., mechanofusion and nobilta by Hosokawa Micron Co., Ltd. Examples include, but are not limited to, mechano mills manufactured by Nippon Coke Industries Co., Ltd., COMPOSI, and CF mills manufactured by Ube Industries, Ltd.

  The rotation speed of the stirring blade is preferably 500 rpm or more, and more preferably 2000 rpm or more. The rotation speed of the stirring blade is preferably 5000 rpm or less, and more preferably 4000 rpm or less. By being more than the said lower limit, the surface of the core part 310 is fully coat | covered with the shell part 320, and when it is below the said upper limit, the heat_generation | fever at the time of a process can be suppressed and an excessive grinding | pulverization can be prevented.

  When the primary particles 20 are agglomerated using the mechanical particle composite device, the temperature in the processing container is set according to the base material and the coated particles, and may be, for example, 5 ° C. or more and 50 ° C. or less. The processing time by the mechanical particle composite device is set according to the raw material, but is preferably 30 seconds or more, more preferably 1 minute or more, and further preferably 10 minutes or more. On the other hand, the treatment time is preferably 120 minutes or less, more preferably 90 minutes or less, and further preferably 60 minutes or less. By setting the above lower limit value to the upper limit value, the secondary particles 30 can be obtained more efficiently.

In the secondary particles 30 according to the present embodiment, it is preferable that the primary particles 20 are aggregated in an irregular direction in the core portion 310.
The primary particles 20 in the shell part 320 are preferably oriented so as to cover the core part 310 along the outer peripheral surface of the secondary particles 30 and to be laminated in the radial direction of the secondary particles 30.
In addition, although it is preferable that the primary particle 20 in the shell part 320 covers the whole outer peripheral surface of the core part 310, a part of the core part 310 may be exposed. Moreover, the secondary particle 30 which has these structures may be mixed.
The plurality of primary particles 20 that form the outermost surface of the shell portion 320, that is, the outermost surface of the secondary particles 30 may be compressed and integrated.
The shape of the secondary particles 30 and the state of the core portion 310 and the shell portion 320 can be confirmed by observing the appearance and cross section using a scanning electron microscope.
In addition, when the primary particles 20 are oriented in the shell part 320, the primary particles 20 are integrated with each other, and the interface may not always be clearly observed. In this case, in the cross-sectional image of the secondary particle 30 obtained by the electron microscope, the vacancies seen in the shell part 320 are observed in a line shape along the outer periphery of the secondary particle 30, and thus the primary particle 20 as described above. Can be understood. Here, the linear shape along the outer periphery means a shape in which the length in the direction along the outer periphery is longer than the length in the direction perpendicular to the direction.

  Although the average thickness of the shell part 320 of the secondary particle 30 can be changed according to the use which uses the granulated powder 10, it is preferable that it is generally 5.0 nm or more, and is 20 nm or more. More preferably, it is more preferably 50 nm or more. On the other hand, the average thickness of the shell part 320 is preferably 50 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less. By making the average thickness of the shell part 320 into the above-mentioned range, the shell part 320 can stably maintain the shape, and the function as the coating layer can be effectively expressed. The shell portion 320 is preferably formed with a constant thickness. However, for example, the thickness may vary depending on the portion, and a part of the core portion 310 is covered with the shell portion 320. It can be used without it.

  The average thickness of the shell part 320 can be calculated by the following method, for example. First, using a cross section polisher (SM-09010, manufactured by JEOL Ltd.), the secondary particles 30 are cut to expose the cross section. And the cross section of the exposed secondary particle 30 is observed using a scanning electron microscope (the JEOL Co., Ltd. make, JSM-7401F). The average distance from the interface between the core part 310 and the shell part 320 of the image obtained by observation to the outermost surface of the secondary particle 30 is obtained by image analysis, and is calculated as the thickness of the shell part 320 of the secondary particle 30. Let the average value of the thickness calculated about 20 or more secondary particles 30 be the average thickness of the shell part 320.

From the viewpoint of further improving the moisture resistance and pressure resistance, the thickness of the shell part 320 preferably occupies 20% or more with respect to the diameter of the secondary particles 30.
From the viewpoint of further improving the moisture resistance and pressure resistance, the thickness of the shell part 320 is preferably 10 times or more the average thickness of the scale of the primary particles 20.
From the viewpoint of further improving the moisture resistance and pressure resistance, the thickness of the shell portion 320 is preferably 10 nm or more from the surface layer on average.
The thickness of the shell part 320 of the secondary particle 30 can be confirmed by observing a cross section using a scanning electron microscope as described above.

The average sphericity of the secondary particles 30 is preferably 0.70 or more, and more preferably 0.75 or more. If the average sphericity of the secondary particles 30 is not less than the above lower limit, it can be added in a large amount to the resin composition. This is because, even when added in a large amount, the viscosity of the resin composition is increased and the production efficiency is unlikely to decrease. Specifically, the average sphericity can be measured as follows. When the perimeter of the projected image of the particle is L and the area of the projected image of the particle is S, a value represented by 4πS / L ² is obtained as the sphericity. And the said sphericity can be measured about 10,000 pieces and an average value can be obtained as average sphericity. The average sphericity of the secondary particles 30 can be measured using, for example, a particle image analyzer (Malvern, Morphologi G3).

  The oil absorption amount of the granulated powder 10 is preferably 70 mL or less per 100 g of the granulated powder, more preferably 50 mL or less, and even more preferably 25 mL or less. If it is below the said upper limit, using the granulated powder 10, the heat-radiation sheet and heat-radiation member which are excellent in heat conductivity can be obtained. Since the secondary particles 30 according to the present embodiment have the shell portion 320 having a high density, the granulated powder 10 having a low oil absorption can be obtained. Therefore, it is difficult to absorb moisture even in a high humidity environment, and the insulation and thermal conductivity are not easily affected. The oil absorption can be measured using, for example, an oil absorption measuring device (A-500, manufactured by Asahi Research Institute).

The median diameter D ₅₀ (0) of the secondary particles 30 is preferably 30 μm or more, more preferably 50 μm or more, and even more preferably 60 μm or more from the viewpoint of improving handling properties. The median diameter D ₅₀ (0) of the secondary particles 30 is determined by a wet method using, for example, a laser diffraction particle size distribution analyzer (LA-950V2 manufactured by Horiba, Ltd.) using analysis based on the Franhofer diffraction theory and Mie's scattering theory. Measurement can be performed with The particle size distribution is analyzed on a volume basis, and when the powder is divided into two from a certain particle diameter, the median diameter is the diameter where the larger side and the smaller side are equivalent. In the measurement by the wet method, a small amount of a measurement sample (for example, about 3 mg. The optimum amount for the measurement is adjusted by the sample) is added to 50 mL of pure water, and then a surfactant is added in an ultrasonic bath. A solution in which the sample is dispersed for 3 minutes is used.

When the secondary particles 30 are compressed, the median diameter D ₅₀ (1) after compression is preferably 30 μm or more, more preferably 50 μm or more, and more preferably 60 μm or more from the viewpoint of improving handling properties. Is more preferable. The compression of the secondary particles 30 can be performed using NS-S500 (manufactured by Nano Seeds Co., Ltd.), and the granulated powder 10 is compressed at 10 MPa for 120 seconds. The median diameter D ₅₀ (1) of the secondary particles 30 after compression can be measured using, for example, a laser diffraction particle size distribution meter (LA-950V2 manufactured by Horiba, Ltd.).

The median diameter ratio before and after compression of the secondary particles 30 is preferably 0.4 or more. Specifically, when the secondary particle 30 is compressed at 10 MPa, the median diameter before compression is D ₅₀ (0), and the median diameter after compression is D ₅₀ (1), D ₅₀ (1) The ratio of the median diameter before and after compression represented by / D ₅₀ (0) is preferably 0.4 or more, and more preferably 0.8 or more. If the value of D ₅₀ (1) / D ₅₀ (0) is equal to or greater than the above lower limit, the shape of the secondary particles 30 is also produced when compressed in the production of a heat radiating sheet or a heat radiating member containing the granulated powder 10. A heat radiating sheet and a heat radiating member which are maintained without being crushed and have excellent moisture resistance can be obtained. Further, by maintaining the shape of the secondary particles 30 without being crushed, the primary particles 20 can be isotropically contained in the heat-dissipating sheet or the heat-dissipating member, and isotropic heat conduction characteristics are obtained. It is done.

  The arithmetic standard deviation of the particle size of the secondary particles 30 is preferably 5 μm or more, more preferably 40 μm or more, and further preferably 60 μm or more from the viewpoint of improving handling properties. On the other hand, the arithmetic standard deviation of the particle size of the secondary particles 30 is preferably 70 μm or less from the viewpoint of performance stability. The arithmetic standard deviation of the particle size of the secondary particles 30 can be measured using, for example, a laser diffraction particle size distribution meter (manufactured by Horiba, Ltd., LA-950V2).

The specific surface area of the granulated powder 10 is preferably 5.0 m ² / g or less, and more preferably 3.0 m ² / g or less. If a specific surface area is below the said upper limit, even if it adds to a resin composition, a viscosity will not rise easily and a moldability will not be impaired. Therefore, the amount of granulated powder 10 added to the resin composition can be increased. On the other hand, the specific surface area of the granulated powder 10 is preferably 2.0 m ² / g or more, and more preferably 2.6 m ² / g or more. If a specific surface area is more than the said minimum, the heat radiating member and heat radiating sheet which are excellent in the voltage resistance under high humidity can be obtained more reliably. The specific surface area of the granulated powder 10 can be measured by, for example, a BET method using nitrogen adsorption with a gas / vapor adsorption amount measuring apparatus (BELSORP-max, manufactured by Nippon Bell Co., Ltd.).

  The friction angle of the granulated powder 10 is preferably 10.0 ° or less, and more preferably 8.0 ° or less, from the viewpoint of ease of handling and formability. By setting the friction angle to be equal to or less than the above upper limit, the fluidity of the powder is increased and the handling property can be improved. The friction angle of the secondary particles 30 can be measured using, for example, a powder layer shear force measurement assumption (NS-S500, manufactured by Nano Seeds Co., Ltd.).

The bulk density of the granulated powder 10 is preferably 1.50 g / cm ³ or less, more preferably 1.20 g / cm ³ or less. On the other hand, the bulk density is preferably 0.50 g / cm ³ or more, and more preferably 0.90 g / cm ³ or more, from the viewpoint of improving handling properties. Moreover, if a bulk density is below the said upper limit and more than the lower limit, the heat-radiation sheet and heat-radiation member which are excellent in the performance balance of thermal conductivity and a moldability can be obtained. The bulk density of the granulated powder 10 can be measured as a hard bulk density using, for example, a powder tester (manufactured by Hosokawa Micron Corporation, PT-X).

The true specific gravity of the granulated powder 10 is preferably 3.5 g / cm ³ or less, and more preferably 3.0 g / cm ³ or less. On the other hand, the true specific gravity is preferably 1.0 g / cm ³ or more, and more preferably 2.0 g / cm ³ or more. When the true specific gravity is not more than the above upper limit and not less than the lower limit, a heat radiating sheet or a heat radiating member excellent in the performance balance between thermal conductivity and moldability can be obtained. The true specific gravity of the granulated powder 10 can be measured by a liquid phase substitution method using, for example, an automatic wet true density measuring device (manufactured by Seishin Enterprise Co., Ltd., MAT-7000).

  The secondary particles 30 and the granulated powder 10 as described above can be obtained by adjusting the composition of the secondary particles 30, the driving conditions of the powder processing apparatus, the conditions of the heat treatment, and the like.

  Below, the resin composition for thermal radiation, the thermal radiation sheet 140, and the thermal radiation member which concern on this embodiment are demonstrated.

FIG. 2 is a schematic cross-sectional view of the heat dissipation sheet 140 according to the present embodiment.
The resin composition for heat dissipation which concerns on this embodiment contains said granulated powder 10 and a thermosetting resin (A). The heat radiating sheet 140 is made of the heat radiating resin composition, and includes, for example, the secondary particles 30 and the thermosetting resin 410 as shown in FIG. The thermosetting resin 410 in the heat radiation sheet 140 is, for example, a B-stage of a thermosetting resin (A). The secondary particle 30 has the core part 310 and the shell part 320 as described above. Moreover, the heat radiating member according to the present embodiment includes a cured body of the heat radiating resin composition. This will be described in detail below.

  Since the secondary particle 30 has the shell part 320 with high density, the secondary particle 30 can maintain the spherical shape in the heat dissipation sheet 140 and the heat dissipation member. Moreover, since the secondary particle 30 has the shell part 320, the hygroscopic sheet 140 and the heat radiating member having low moisture absorption and excellent moisture resistance can be realized.

(Thermosetting resin (A))
Examples of the thermosetting resin (A) include epoxy resins, cyanate resins, polyimide resins, benzoxazine resins, unsaturated polyester resins, phenol resins, melamine resins, silicone resins, bismaleimide resins, acrylic resins, and the like. As the thermosetting resin (A), one of these may be used alone, or two or more may be used in combination.
As the thermosetting resin (A), an epoxy resin (A1) is preferable. By using the epoxy resin (A1), the glass transition temperature can be increased, and the thermal conductivity of the heat radiation resin composition, the heat radiation sheet 140, and the heat radiation member can be improved.

  Examples of the epoxy resin (A1) include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, bisphenol S type epoxy resin, bisphenol M type epoxy resin (4,4 ′-(1,3- Phenylenediisopridiene) bisphenol type epoxy resin), bisphenol P type epoxy resin (4,4 '-(1,4-phenylenediisopridiene) bisphenol type epoxy resin), bisphenol Z type epoxy resin (4,4' -Cyclohexiene bisphenol type epoxy resin), etc .; phenol novolac type epoxy resin, cresol novolac type epoxy resin, trisphenol group methane type novolac type epoxy resin, tetraphenol group ethane type novo Type epoxy resins, novolak type epoxy resins such as novolak type epoxy resins having a condensed ring aromatic hydrocarbon structure; biphenyl type epoxy resins; xylylene type epoxy resins, arylalkylene type epoxy resins such as biphenyl aralkyl type epoxy resins; Naphthalene type epoxy resins such as renether type epoxy resins, naphthol type epoxy resins, naphthalene diol type epoxy resins, bifunctional or tetrafunctional epoxy type naphthalene resins, binaphthyl type epoxy resins, naphthalene aralkyl type epoxy resins, etc .; anthracene type epoxy resins; phenoxy Type epoxy resin; dicyclopentadiene type epoxy resin; norbornene type epoxy resin; adamantane type epoxy resin; fluorene type epoxy resin.

  As the epoxy resin (A1), one of these may be used alone, or two or more may be used in combination.

  Among the epoxy resins (A1), from the viewpoint of further improving the heat resistance and insulation reliability of the obtained heat radiation resin composition, heat radiation sheet 140, and heat radiation member, bisphenol type epoxy resin, novolac type epoxy resin, biphenyl type One or more selected from the group consisting of epoxy resins, arylalkylene type epoxy resins, naphthalene type epoxy resins, anthracene type epoxy resins and dicyclopentadiene type epoxy resins are preferred.

  The content of the thermosetting resin (A) contained in the heat-dissipating resin composition is not particularly limited as long as it is appropriately adjusted according to the purpose, but the heat-dissipating resin composition is 100% by mass, and 1 mass. % Or more is preferable, and 5 mass% or more is more preferable. On the other hand, the content is preferably 30% by mass or less, and more preferably 20% by mass or less. When the content of the thermosetting resin (A) is not less than the above lower limit, the handling property of the heat radiation resin composition is improved, and it becomes easy to form the heat radiation sheet 140 and the heat radiation member, and the heat radiation sheet 140 and The strength of the heat dissipation member is improved. When the content of the thermosetting resin (A) is not more than the above upper limit value, the linear expansion coefficient and the elastic modulus of the heat dissipation sheet 140 and the heat dissipation member are further improved, or the heat conductivity of the heat dissipation sheet 140 and the heat dissipation member. Can be further improved.

(Filler (B))
The resin composition for heat dissipation which concerns on this embodiment contains a filler (B). The filler (B) includes the granulated powder 10 described above, and the granulated powder 10 includes secondary particles 30. The secondary particles 30 are spherical particles formed by aggregating the primary particles 20. The primary particles 20 are scaly boron nitride. The secondary particle 30 has a core part 310 and a shell part 320. The core part 310 includes the center of the secondary particle 30. The shell part 320 covers the core part 310. The density of the primary particles 20 in the core part 310 is lower than the density of the primary particles 20 in the shell part 320.

The secondary particles 30 are preferably contained in an amount of 50% by mass or more, more preferably 60% by mass or more, based on 100% by mass of the filler (B) contained in the heat radiation resin composition. If it is more than the said minimum, there will be few voids and a favorable heat conductive characteristic and insulation will be acquired.
Further, the content of the secondary particles 30 contained in the heat dissipation resin composition is preferably 30% by mass or more, more preferably 40% by mass or more, with the heat dissipation resin composition being 100% by mass. . On the other hand, the content is preferably 95% by mass or less, and more preferably 80% by mass or less. By making content of the secondary particle 30 more than the said lower limit, the thermal conductivity and mechanical strength improvement in the thermal radiation sheet 140 and a thermal radiation member can be aimed at more effectively. On the other hand, by making the content of the secondary particles 30 equal to or less than the above upper limit value, workability in molding the heat radiation resin composition is improved, and the film thickness uniformity of the heat radiation sheet 140 and the heat radiation member is further improved. Can be.

  From the viewpoint of further improving the thermal conductivity of the heat dissipation resin composition, the heat dissipation sheet 140, and the heat dissipation member, the filler (B) according to the present embodiment contains the secondary particles 30 in addition to the secondary particles 30. It is preferable to further include scaly boron nitride particles that are not constituted. The particles may be the same particles as the primary particles 20 or may be different particles. The average major axis of the scaly boron nitride particles is preferably 0.01 μm or more, and more preferably 0.1 μm or more. On the other hand, the average major axis is preferably 70 μm or less, and more preferably 30 μm or less. The content of the scaly boron nitride particles that do not constitute the secondary particles 30 contained in the heat dissipation resin composition is not particularly limited, but is preferably 10% by mass or more, with the heat dissipation resin composition being 100% by mass, 20 The mass% or more is more preferable. On the other hand, the content is preferably 50% by mass or less, and more preferably 40% by mass or less. Thereby, the heat-radiation sheet 140 and the heat-radiation member which were further excellent by the balance of heat conductivity and electrical insulation are realizable. In the case of containing only scaly boron nitride as a filler, when compressed, the main surface of boron nitride is oriented so as to be parallel to the main surface of the heat dissipation sheet, and heat in the thickness direction of the heat dissipation sheet In contrast, the heat dissipation sheet 140 and the heat dissipating member according to the present embodiment include secondary particles 30 so that the particles of flaky boron nitride that do not constitute the secondary particles 30 are secondary particles. Since it is dispersed between 30 and faces in a random direction, the thermal conductivity in the thickness direction is improved.

  The filler (B) may further contain, for example, silica, alumina, boron nitride, aluminum nitride, silicon carbide, etc., as long as the effects of the present invention are not impaired, from the viewpoint of balancing thermal conductivity and electrical insulation. Good. These may be used alone or in combination of two or more.

(Curing agent (C))
When the resin composition for heat dissipation uses an epoxy resin (A1) as a thermosetting resin (A), respectively, it is preferable to contain a hardening | curing agent (C) further.
As a hardening | curing agent (C), 1 or more types selected from a hardening catalyst (C-1) and a phenol type hardening | curing agent (C-2) can be used.
Examples of the curing catalyst (C-1) include organic metal salts such as zinc naphthenate, cobalt naphthenate, tin octylate, cobalt octylate, bisacetylacetonate cobalt (II), trisacetylacetonate cobalt (III); Tertiary amines such as triethylamine, tributylamine, 1,4-diazabicyclo [2.2.2] octane; 2-phenyl-4-methylimidazole, 2-ethyl-4-methylimidazole, 2,4-diethylimidazole, Imidazoles such as 2-phenyl-4-methyl-5-hydroxyimidazole and 2-phenyl-4,5-dihydroxymethylimidazole; triphenylphosphine, tri-p-tolylphosphine, tetraphenylphosphonium tetraphenylborate, triphenyl Phosphine Organic phosphorus compounds such as rephenylborane and 1,2-bis- (diphenylphosphino) ethane; phenolic compounds such as phenol, bisphenol A and nonylphenol; organic acids such as acetic acid, benzoic acid, salicylic acid and p-toluenesulfonic acid; Etc., or mixtures thereof. As the curing catalyst (C-1), one kind including these derivatives can be used alone, or two or more kinds including these derivatives can be used in combination.
Although content of the curing catalyst (C-1) contained in the resin composition for heat dissipation is not specifically limited, 0.001 mass% or more and 1 mass% or less are preferable considering the resin composition for heat dissipation as 100 mass%.

Examples of the phenolic curing agent (C-2) include phenol novolak resins, cresol novolak resins, trisphenol methane type novolak resins, naphthol novolak resins, aminotriazine novolak resins and the like; Modified phenolic resins such as cyclopentadiene modified phenolic resins; Aralkyl type resins such as phenol aralkyl resins having a phenylene skeleton and / or biphenylene skeleton, naphthol aralkyl resins having a phenylene skeleton and / or biphenylene skeleton; Bisphenols such as bisphenol A and bisphenol F Compound; resol type phenol resin and the like may be mentioned, and these may be used alone or in combination of two or more.
Among these, from the viewpoint of improving the glass transition temperature and reducing the linear expansion coefficient, the phenolic curing agent (C-2) is preferably a novolac type phenol resin or a resol type phenol resin.
Although content of a phenol type hardening | curing agent is not specifically limited, 1 mass% or more is preferable and the resin composition for heat dissipation is 100 mass%, and 5 mass% or more is more preferable. On the other hand, the content is preferably 30% by mass or less, and more preferably 15% by mass or less.

(Coupling agent (D))
The resin composition for heat dissipation may further contain a coupling agent. The coupling agent (D) can improve the wettability of the interface between the thermosetting resin (A) and the filler (B).

As the coupling agent (D), any commonly used one can be used. Specifically, an epoxy silane coupling agent, a cationic silane coupling agent, an aminosilane coupling agent, a titanate coupling agent, and a silicone oil type. It is preferable to use one or more coupling agents selected from coupling agents.
The addition amount of the coupling agent (D) is not particularly limited, but is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, based on 100% by mass of the filler (B). On the other hand, the addition amount is preferably 3% by mass or less, and more preferably 2% by mass or less.

The resin composition for heat dissipation may further contain a phenoxy resin (E). By including the phenoxy resin (E), the bending resistance of the heat radiation sheet 140 and the heat radiation member can be improved.
Moreover, by including a phenoxy resin (E), it becomes possible to reduce the elasticity modulus of the thermal radiation sheet 140 and a thermal radiation member, and can improve the stress relaxation force of the thermal radiation sheet 140 and a thermal radiation member.
Moreover, when a phenoxy resin (E) is included, fluidity | liquidity will reduce by viscosity increase and it can suppress that a void etc. generate | occur | produce. In addition, when the heat dissipation sheet 140 is used in close contact with a metal member, or when the heat dissipation member includes a metal member, the adhesion between the metal and the cured body of the heat dissipation resin composition can be improved. These synergistic effects can further increase the insulation reliability of the semiconductor device.

  Examples of the phenoxy resin (E) include a phenoxy resin having a bisphenol skeleton, a phenoxy resin having a naphthalene skeleton, a phenoxy resin having an anthracene skeleton, and a phenoxy resin having a biphenyl skeleton. A phenoxy resin having a structure having a plurality of these skeletons can also be used.

  The content of the phenoxy resin (E) is preferably 3% by mass or more and 10% by mass or less, for example, with the resin composition for heat dissipation, the heat dissipation sheet 140, and the heat dissipation member being 100% by mass, respectively.

(Other ingredients)
The heat-dissipating resin composition can further contain an antioxidant, a leveling agent and the like as long as the effects of the present invention are not impaired.

The heat radiating resin composition, the heat radiating sheet 140, and the heat radiating member according to the present embodiment can be manufactured, for example, as follows.
First, the above-mentioned components are added to a solvent to obtain a varnish-like heat radiation resin composition. In the present embodiment, for example, a thermosetting resin (A) or the like is added to a solvent to prepare a resin varnish, and then the filler (B) is added to the resin varnish and kneaded using a three-roll roll or the like. Thus, a heat radiating resin composition can be obtained. Thereby, a filler (B) can be disperse | distributed more uniformly in a thermosetting resin (A).
Although it does not specifically limit as said solvent, Methyl ethyl ketone, methyl isobutyl ketone, propylene glycol monomethyl ether, cyclohexanone, etc. are mentioned.

  Next, the heat dissipation resin composition is formed into a sheet shape to form the heat dissipation sheet 140. In the present embodiment, for example, the varnish-like resin composition for heat dissipation is applied on a substrate, and then heated and dried. By this drying treatment, the resin film made of the heat radiating resin composition is B-staged, and the heat radiating sheet 140 formed on the substrate can be obtained. The base material and the heat dissipation sheet 140 are collectively referred to as “resin film with base material” hereinafter. Examples of the substrate include a metal foil and a PET (Polyethylene terephthalate) film that constitute a peelable carrier material. Moreover, the drying process of the resin composition for thermal radiation is performed on conditions, for example, 80 degreeC or more and 150 degrees C or less, 5 minutes or more and 1 hour or less. The film thickness of the resin layer is, for example, 50 μm or more and 500 μm or less.

  In addition, it is preferable to remove the bubble in the resin film (heat dissipation sheet 140) by passing the resin film with a base material between two rolls and compressing it after the drying treatment. In this embodiment, the thermal conductivity of the heat radiating sheet 140 and the heat radiating member can be improved by including the step of removing bubbles by applying the compression pressure by the roll as described above. This is presumed due to the fact that the density of the resin component in the heat radiating sheet 140 and the heat radiating member is increased by removing the bubbles. Here, the compression pressure can be, for example, 5 MPa or more and 20 MPa or less. In addition, when compressing, it can also heat and harden | cure at the same time, and can also be C-staged. Here, the heating temperature can be, for example, 150 ° C. or more and 200 ° C. or less.

  The heat conductivity at 25 ° C. of the heat radiation sheet 140 is preferably 6 W / (m · K) or more, and more preferably 7 W / (m · K) or more. Further, the heat conductivity of the heat dissipation sheet 140 at 175 ° C. is preferably 6 W / (m · K) or more. When each thermal conductivity is equal to or higher than the lower limit, a semiconductor device having excellent operation stability can be obtained using the heat dissipation sheet 140.

  Moreover, the heat radiating member containing the hardened | cured body of said heat radiating resin composition can be obtained by hardening, after applying the heat radiating sheet 140 of a B-stage state to a metal member etc. Specifically, first, the resin film with a base material is laminated on the metal member so that the exposed surface of the heat dissipation sheet 140 faces the metal member. The metal member is, for example, a metal heat sink or lead frame. And after peeling a base material, it heats at 150 degreeC or more and 200 degrees C or less, for example, and the thermal radiation sheet 140 is hardened.

  In addition, you may apply | coat a varnish-like heat radiation resin composition directly on a metal member etc., and make it harden | cure, without producing the resin film with a base material, and obtain a heat radiating member. Moreover, the heat radiating member can also be obtained by forming the heat radiating resin composition on the varnish into a desired shape. For molding, for example, methods such as injection molding and compression molding can be used. The heat dissipating member may be composed only of the heat dissipating resin composition, or may further include a metal member as described above.

  As a semiconductor device including the heat radiating member and the heat radiating sheet, it is possible to obtain a semiconductor device that is excellent in heat dissipation and is excellent in operational stability and reliability.

  The heat dissipation sheet 140 can also be used as a heat conductive sheet, for example. Moreover, a heat radiating member can also be used as a heat conductive member, for example.

Hereinafter, the semiconductor device 100 according to this embodiment will be described.
The semiconductor device 100 includes the cured body 144 of the heat dissipation resin composition as a heat dissipation member. FIG. 3 is a cross-sectional view schematically showing an example of the structure of the semiconductor device 100.

  In the following, in order to simplify the description, the positional relationship (vertical relationship and the like) of each component of the semiconductor device 100 may be described as the relationship shown in each drawing. However, the positional relationship in this description is independent of the positional relationship when the semiconductor device 100 is used or manufactured.

The semiconductor device 100 according to the present embodiment is bonded to the heat sink 130, the semiconductor chip 110 provided on the first surface 131 side of the heat sink 130, and the second surface 132 opposite to the first surface 131 of the heat sink 130. The cured body 144 and a sealing resin 180 that seals the semiconductor chip 110 and the heat sink 130 are provided.
Details will be described below.

  The semiconductor device 100 includes, for example, a conductive layer 120, a metal layer 150, a lead 160, and a wire (metal wiring) 170 in addition to the above configuration.

  An electrode pattern (not shown) is formed on the upper surface 111 of the semiconductor chip 110, and a conductive pattern (not shown) is formed on the lower surface 112 of the semiconductor chip 110. The lower surface 112 of the semiconductor chip 110 is fixed to the first surface 131 of the heat sink 130 via a conductive layer 120 such as silver paste. The electrode pattern on the upper surface 111 of the semiconductor chip 110 is electrically connected to the electrode 161 of the lead 160 via the wire 170.

  The heat sink 130 is made of a metal plate.

  In addition to the semiconductor chip 110 and the heat sink 130, the sealing resin 180 seals the wires 170, the conductive layer 120, and part of the leads 160 inside. Another part of each lead 160 protrudes from the side surface of the sealing resin 180 to the outside of the sealing resin 180. In the present embodiment, for example, the lower surface 182 of the sealing resin 180 and the second surface 132 of the heat sink 130 are located on the same plane.

  The upper surface 141 of the cured body 144 is attached to the second surface 132 of the heat sink 130 and the lower surface 182 of the sealing resin 180. That is, the sealing resin 180 is in contact with the surface (upper surface 141) of the cured body 144 on the heat sink 130 side around the heat sink 130.

  The upper surface 151 of the metal layer 150 is fixed to the lower surface 142 of the cured body 144. That is, one surface (upper surface 151) of the metal layer 150 is fixed to a surface (lower surface 142) opposite to the heat sink 130 side in the cured body 144.

  In plan view, it is preferable that the outline of the upper surface 151 of the metal layer 150 and the outline of the surface (lower surface 142) on the opposite side of the heat sink 130 in the cured body 144 overlap.

  Further, the entire surface of the metal layer 150 opposite to the one surface (upper surface 151) (lower surface 152) is exposed from the sealing resin 180. In the case of the present embodiment, as described above, since the upper surface 141 of the cured body 144 is attached to the second surface 132 of the heat sink 130 and the lower surface 182 of the sealing resin 180, the cured body 144 is , Except for the upper surface 141, it is exposed to the outside of the sealing resin 180. The entire metal layer 150 is exposed outside the sealing resin 180.

  In addition, the 2nd surface 132 and the 1st surface 131 of the heat sink 130 are each formed flat, for example.

  Although the mounting floor area of the semiconductor device 100 is not particularly limited, it can be set to 10 × 10 mm or more and 100 × 100 mm or less as an example. Here, the mounting floor area of the semiconductor device 100 is the area of the lower surface 152 of the metal layer 150.

  Further, the number of semiconductor chips 110 mounted on one heat sink 130 is not particularly limited. There may be one or more. For example, it may be 3 or more (6 etc.). That is, as an example, three or more semiconductor chips 110 may be provided on the first surface 131 side of one heat sink 130, and the sealing resin 180 may collectively seal these three or more semiconductor chips 110. .

  The semiconductor device 100 is, for example, a power semiconductor device. The semiconductor device 100 includes, for example, 2 in 1 in which two semiconductor chips 110 are sealed in a sealing resin 180, 6 in 1 in which six semiconductor chips 110 are sealed in a sealing resin 180, or a sealing resin 180. A 7-in-1 configuration in which seven semiconductor chips 110 are sealed can be employed.

  Next, an example of a method for manufacturing the semiconductor device 100 according to the present embodiment will be described.

  First, the heat sink 130 and the semiconductor chip 110 are prepared, and the lower surface 112 of the semiconductor chip 110 is fixed to the first surface 131 of the heat sink 130 via the conductive layer 120 such as silver paste.

  Next, a lead frame (not shown) including the lead 160 is prepared, and the electrode pattern on the upper surface of the semiconductor chip 110 and the electrode 161 of the lead 160 are electrically connected to each other through the wire 170.

  Next, the semiconductor chip 110, the conductive layer 120, the heat sink 130, the wire 170, and a part of the lead 160 are collectively sealed with a sealing resin 180.

Next, the heat dissipation sheet 140 is prepared, and the upper surface 141 of the heat dissipation sheet 140 is attached to the second surface 132 of the heat sink 130 and the lower surface 182 of the sealing resin 180. Furthermore, one surface (upper surface 151) of the metal layer 150 is fixed to a surface (lower surface 142) on the side opposite to the heat sink 130 side of the heat dissipation sheet 140. Next, the heat dissipation sheet 140 is cured by heating to obtain a cured body 144. Note that the metal layer 150 may be fixed to the lower surface 142 of the heat dissipation sheet 140 in advance before the heat dissipation sheet 140 is attached to the heat sink 130 and the sealing resin 180.
Next, each lead 160 is cut from a frame (not shown) of the lead frame. Thus, the semiconductor device 100 having a structure as shown in FIG. 3 is obtained.

  According to the embodiment as described above, the semiconductor device 100 includes the heat sink 130, the semiconductor chip 110 provided on the first surface 131 side of the heat sink 130, and the second side opposite to the first surface 131 of the heat sink 130. An insulating cured body 144 attached to the surface 132 and a sealing resin 180 that seals the semiconductor chip 110 and the heat sink 130 are provided.

Next, the operation and effect of this embodiment will be described.
According to this embodiment, since the secondary particle 30 has the shell part 320 with high density, in the heat dissipation sheet 140 and the heat dissipation member manufactured using the granulated powder 10 including the secondary particle 30, the secondary particle 30 is A spherical shape can be maintained. Furthermore, since the secondary particle 30 has the shell part 320 with high density, the hygroscopicity is low. Therefore, by these combined effects, a heat radiating sheet and a heat radiating member excellent in moisture resistance can be realized. In addition, a semiconductor device having excellent durability can be obtained.

  Moreover, according to this embodiment, since the secondary particle 30 is spherical, it is excellent in handling property and dispersibility. In addition, since it is spherical, the viscosity of the thermosetting resin composition is unlikely to increase even if it is contained in a large amount in the thermosetting resin composition. That is, many secondary particles 30 can be contained in the thermosetting resin composition. Furthermore, since the secondary particle 30 has the shell part 320 with a high density, it can maintain a spherical shape even when compressed. Due to these combined effects, when the granulated powder 10 containing the secondary particles 30 is used, a thermosetting resin composition, a heat radiating sheet, and a heat radiating member excellent in thermal conductivity and insulation are manufactured with high manufacturing stability. can do.

  Moreover, according to this embodiment, the direction of the primary particle 20 is isotropic in the secondary particle 30 as the secondary particle 30 whole. In addition, since the secondary particle 30 has the shell part 320 with a high density, the secondary particle 30 maintains a spherical shape in the heat dissipation sheet 140 and the heat dissipation member manufactured using the granulated powder 10 including the secondary particle 30. be able to. Therefore, due to these combined effects, the heat radiating sheet 140 and the heat radiating member having isotropic thermal conductivity and electrical resistivity can be obtained.

  It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.

  Hereinafter, although an example and a comparative example explain the present invention, the present invention is not limited to these. Moreover, each thickness is represented by the average film thickness.

Example 1
<Formation of secondary particles>
A granulated powder containing secondary particles was produced as follows.
First, 87.8% by mass of hexagonal boron nitride 1 (manufactured by Showa Denko KK, UHP-1K) as primary particles and 12.2% by mass of resol type phenol resin 1 (manufactured by Sumitomo Bakelite Co., Ltd., PR-940C) as binders. % For 5 minutes using a mixer. The mixture A1 thus obtained was set in a casing (processing vessel) of a mechanical particle compounding apparatus (manufactured by Hosokawa Micron Corporation, Nobilta). The mechanical particle compounding device (powder processing device) is rotated relative to the casing that receives the powder to be processed and the casing, and is compressed into the powder to be processed between the outer periphery and the inner surface of the casing. And a rotor blade provided with a blade portion for applying a shearing force. The stirring blade was driven at a rotational speed of 3000 rpm for 40 minutes while maintaining the jacket of the mechanical particle composite device at 15 ° C. with chiller water. Thus, an aggregate of the mixture A1 was obtained in the casing.

  The obtained agglomerate was taken out from the casing and subjected to heat treatment at 120 ° C. for 2 hours in the air using a drying oven to obtain granulated powder 1 composed of secondary particles 1.

<Production of heat dissipation sheet>
A heat radiating sheet was prepared using the obtained granulated powder. First, a filler (B) containing granulated powder 1 is added to a solution prepared by mixing a thermosetting resin (A), a curing catalyst (C-1), a phenolic curing agent (C-2), and a dilution solvent in advance. The mixture was mixed for 10 minutes using a disperser to obtain a mixture B1.

Details of each component and blending amount of the heat dissipation sheet are as follows.
Thermosetting resin (A): Biphenyl type epoxy resin (Mitsubishi Chemical Corporation, YX4000K) 15.2% by mass
Filler (B): granulated powder 1 47.2% by mass, and hexagonal boron nitride 2 (manufactured by Showa Denko KK, UHP-2) 29.6% by mass
Curing catalyst (C-1): 2-phenyl-4,5-dihydroxymethylimidazole (manufactured by Shikoku Chemicals Co., Ltd., 2PHZ-PW) 0.1% by mass
Phenol-based curing agent (C-2): Trisphenol methane type novolak resin (Maywa Kasei Co., Ltd., MEH-7500) 7.9% by mass

  Next, the obtained mixture B1 was applied onto a copper foil using a commar, and was heat-treated at 120 ° C. for 15 minutes in a dryer to form a B stage. Thereafter, using a press machine, pressing is performed for 30 minutes while sandwiching the substrate under the conditions of a tool pressure of 10 MPa and a tool temperature of 180 ° C., whereby a 200 μm thick C-stage heat radiation sheet cured body 1 ( A heat radiating member was obtained.

<Evaluation of secondary particles and granulated powder>
About the obtained secondary particle 1 and granulated powder 1, each following evaluation was performed.

(Cross section observation)
The cross section of the secondary particle 1 was observed. The cross section of the secondary particle 1 was observed as follows. First, a small amount of the obtained secondary particles 1 were adhered onto the substrate, and the secondary particles 1 on the substrate were cut using a cross section polisher (SM-09010, manufactured by JEOL Ltd.) to expose the cross section. And the cross section of the exposed secondary particle was observed using the scanning electron microscope (The JEOL Co., Ltd. make, JSM-7401F).

  As a result of observation, it was found that the secondary particle 1 has a core part and a shell part, and the density of the primary particles in the core part is lower than the density of the primary particles in the shell part. Further, the primary particles in the shell portion are entirely covered so as to be along the outer peripheral surface of the secondary particles, and are oriented so as to be laminated in the radial direction of the secondary particles. The primary particles in the core part were aggregated in an irregular direction and were not oriented.

(Sphericity)
The sphericity of the secondary particles 1 was measured using a particle image analyzer (Malvern, Morphologi G3). In addition, in observation with an electron microscope, unagglomerated primary particles or the like were not seen in the granulated powder 1, and all of the 50 particles whose cross section was confirmed had a core part and a shell part. The powder 1 was measured without undergoing a separation treatment, and the result was defined as the sphericity of the secondary particles 1. In this apparatus, when the perimeter of the projected image of the particle is L and the area of the projected image of the particle is S, the value represented by 4πS / L ² is obtained as the sphericity. Measurement was performed on 10,000 pieces, and the average value was obtained as the average sphericity. The sphericity of the secondary particle 1 was 0.76.

(Specific surface area)
The specific surface area of the granulated powder 1 was measured. The measurement was performed by a BET method by nitrogen adsorption with a gas / vapor adsorption amount measuring apparatus (BELSORP-max, manufactured by Nippon Bell Co., Ltd.).
The specific surface area of the secondary particles 1 was 2.8 m ² / g.

(Oil absorption)
The oil absorption of the granulated powder 1 was measured. The measurement was performed using an oil absorption amount measuring device (Asahi Research Institute, S-500). The oil absorption of the granulated powder 1 was 23 mL per 100 g.

(Median diameter, arithmetic standard deviation of particle diameter)
The median diameter of secondary particles 1 and the arithmetic standard deviation of the particle diameter were measured. In addition, the result of measuring granulated powder 1 was made into the median diameter and particle size of secondary particle 1 like the measurement of the sphericity mentioned above. The median diameter and the arithmetic standard deviation of the particle diameter were measured using a laser diffraction particle size distribution meter (LA-950V2 manufactured by Horiba, Ltd.). The median diameter D ₅₀ (0) of the secondary particles 1 was 60 μm, and the arithmetic standard deviation of the particle diameter was 60 μm.
Moreover, after compressing about the secondary particle 1, the median diameter was measured similarly. The compression treatment was performed using a powder layer shear force measuring apparatus (NS-S500, manufactured by Nano Seeds Co., Ltd.), and a pressure of 10 MPa was applied to 7 g of the granulated powder 1 for 120 seconds. The median diameter D ₅₀ (1) after compression of the secondary particles 1 was 60 μm. The ratio of the median diameter before and after compression represented by D ₅₀ (1) / D ₅₀ (0) was calculated to be 1.0.

(Bulk density)
The bulk density of the granulated powder 1 was measured. Specifically, using a powder tester (manufactured by Hosokawa Micron Corporation, PT-X) and using a 25 mL sample cell, the bulk density (hardness) on the granulated powder 1 under the conditions of a tapping stroke of 18 mm and a tapping frequency of 180 times. Density) was measured. The bulk density of the granulated powder 1 was 1.02 g / cm ³ .

(True specific gravity)
The true specific gravity of the granulated powder 1 was measured. The measurement was performed by a liquid phase substitution method using an automatic wet true density measuring device (MAT-7000, manufactured by Seishin Enterprise Co., Ltd.). N-butanol was used as a liquid medium. The true specific gravity of the granulated powder 1 was 2.17 g / cm ³ .

(Handling properties)
The handling property of the granulated powder 1 was evaluated.
First, 200 g of the granulated powder was put into a 400 L mixer, and the mixer was driven at 1000 rpm for 5 minutes. After stopping the mixer, the adsorbed state of the granulated powder on the inner wall of the mixer was confirmed. The case where granulated powder adheres to the entire inner wall is marked as x, the case where granulated powder adheres to a part of the inner wall is marked as ○, and the case where granulated powder adheres to the inner wall is marked as ◎. evaluated. In the granulated powder 1, no adhesion was observed and it was evaluated as ◎.

(Friction angle)
The friction angle of the granulated powder 1 was measured. The measurement was performed using a powder layer shear force measurement assumption (NS-S500, manufactured by Nano Seeds Co., Ltd.). Specifically, the friction angle was measured as follows. First, the granulated powder 1 was put in the sample cell. This sample cell is vertically divided into two with a gap on the side, and has a cylindrical shape with a diameter of 15 mm. Next, the upper punch was gently put on the sample cell containing the granulated powder 1, and the upper punch was lowered to apply a vertically downward force to the granulated powder 1. At this time, the force applied to the upper eyelid was measured by a load sensor, and when the magnitude of the force reached the target value, the lowering of the upper eyelid was stopped. After the value of the load sensor was monitored and the force was sufficiently relaxed to reduce the fluctuation, the lower cell was moved in the horizontal direction at 10 μm / second to shear the gap between the sample cells. At this time, the force in the shear direction applied to the lower cell and the force in the hydraulic direction applied to the lower cell by the upper arm are monitored by a load sensor, and the force in the shear direction is maximized. The magnitude of the force at that time and the magnitude of the vertical force at that time were recorded. The force applied to the sample from the upper arm was once released, and the lower cell was returned to the position before the start of measurement. The upper iron was lowered again to apply a force having a target value to the coated particles, and the magnitude of each force when the granulated powder 1 was sheared by the same method as described above was recorded. In this operation, the target values were set to 50N, 100N, and 150N in order, and the measurement results were recorded three times in total. The stress was calculated by dividing the magnitude of the recorded force by the cross-sectional area of the sample cell. The vertical stress was plotted on the graph with the horizontal axis and the stress in the shear direction on the vertical axis, and the angle between the approximate line obtained by the least square method and the horizontal axis was determined as the friction angle.
The friction angle of the granulated powder 1 was 7.6 °.

<Evaluation of heat dissipation sheet>
About the obtained thermal radiation sheet hardening body 1, each following evaluation was performed.

(Cross section observation)
The cross section of the heat-radiation sheet hardening body 1 was observed. The cross-sectional observation of the heat radiating sheet cured body 1 was performed as follows.
First, the heat radiating sheet cured body 1 was cut using a cross section polisher (SM-09010, manufactured by JEOL Ltd.) to expose the cross section. And the cross section of the exposed heat-radiation sheet hardening body 1 was observed using the scanning electron microscope (JSM-7401F, JEOL make).
FIG. 4 is a view showing a result of observing a cross section of the heat radiating sheet cured body 1 with a scanning electron microscope. In the heat-radiation sheet hardening body 1, it turned out that it is disperse | distributing in the sheet | seat, with the form of a secondary particle maintained.

(Thermal conductivity)
The density of the heat radiating sheet cured body 1 was measured by an underwater substitution method, the specific heat was measured by differential scanning calorimetry (DSC), and the thermal diffusivity was measured by a laser flash method. And the heat conductivity in the thickness direction was computed from the following formula | equation (1).
λ = ρ × c × α × 1000 (1)
Here, λ is thermal conductivity [W / (m · K)], ρ is density [kg / m ³ ], c is specific heat [kJ / (kg · K)], and α is thermal diffusivity [m ² / s]. In addition, the thermal conductivity in 25 degreeC and 175 degreeC was measured, respectively.

Regarding thermal conductivity at 25 ° C., ◎ when the obtained thermal conductivity is 7 W / (m · K) or more, ○ when 6 W / (m · K) or more and less than 7 W / (m · K), 6 W / The case of less than (m · K) was evaluated as x.
Since the thermal conductivity of the heat radiating sheet cured body 1 was 7 W / (m · K) or more at 25 ° C., it was evaluated as ◎.
About the heat conductivity in 175 degreeC, the case where the calculated | required heat conductivity was 6 W / (m * K) or more was evaluated as x, and the case of less than 6 W / (m * K) was evaluated as x.
Since the thermal conductivity of the heat radiating sheet cured body 1 was 6 W / (m · K) or more at 175 ° C., it was evaluated as “good”.

(Withstand voltage)
The withstand voltage was measured with a withstand voltage tester. The frequency was 60 Hz. The case where the obtained withstand voltage was 1000 V or higher was evaluated as ◯, and the case where it was less than 1000 V was evaluated as ×.
Furthermore, the withstand voltage performance under high humidity was evaluated. The withstand voltage performance under high humidity is ◯ when the dielectric breakdown does not occur during the elapse of 500 hours in the environment of 85 ° C and 85% RH when the voltage of 60Hz and 1000V is continuously applied. Was evaluated as x.
The withstand voltage performance of the heat radiating sheet cured body 1 and the withstand voltage performance under high humidity were both evaluated as ◯.

(Example 2)
Granulated powder 2 composed of secondary particles 2 was obtained in the same manner as in Example 1 except that the drive time of the stirring blade of the powder processing apparatus was 20 minutes. Moreover, the heat-radiation sheet hardening body 2 was obtained like Example 1 except having used the granulated powder 2 instead of the granulated powder 1. FIG. The obtained granulated powder 2, secondary particles 2, and heat-dissipating sheet cured body 2 were evaluated in the same manner as in Example 1.
From the result of observing the secondary particles 2 with a scanning electron microscope, the secondary particles 2 have a core part and a shell part, and the density of the primary particles in the core part is lower than the density of the primary particles in the shell part. I understood. Further, the primary particles in the shell portion are entirely covered so as to be along the outer peripheral surface of the secondary particles, and are oriented so as to be laminated in the radial direction of the secondary particles. The primary particles in the core part were aggregated in an irregular direction and were not oriented. Moreover, it turned out that it was contained in the sheet | seat, with the form of the secondary particle maintained, from the result of having observed the cross section of the thermal radiation sheet hardening body 2 with the scanning electron microscope. The other evaluation results are shown in Table 2.

(Example 3)
Granulated powder 3 comprising secondary particles 3 was obtained in the same manner as in Example 1 except that resol type phenol resin 2 (manufactured by Sumitomo Bakelite Co., Ltd., PR-53074) was used instead of resol type phenol resin 1. . Moreover, the heat-radiation sheet hardening body 3 was obtained like Example 1 except having used the granulated powder 3 instead of the granulated powder 1. FIG. The obtained granulated powder 3, secondary particles 3, and heat-dissipating sheet cured body 3 were evaluated in the same manner as in Example 1.
From the result of observing the secondary particles 3 with a scanning electron microscope, the secondary particles 3 have a core part and a shell part, and the density of the primary particles in the core part is lower than the density of the primary particles in the shell part. I understood. Further, the primary particles in the shell portion are entirely covered so as to be along the outer peripheral surface of the secondary particles, and are oriented so as to be laminated in the radial direction of the secondary particles. The primary particles in the core part were aggregated in an irregular direction and were not oriented. Moreover, it turned out that it was contained in the sheet | seat, with the form of the secondary particle maintained, from the result of having observed the cross section of the thermal radiation sheet hardening body 3 with the scanning electron microscope. The other evaluation results are shown in Table 2.

(Example 4)
Granulated powder 4 comprising secondary particles 4 was obtained in the same manner as in Example 1 except that hexagonal boron nitride 2 (manufactured by Showa Denko KK, UHP-2) was used instead of hexagonal boron nitride 1. . Moreover, the heat-radiation sheet hardening body 4 was obtained like Example 1 except having used the granulated powder 4 instead of the granulated powder 1. FIG. The obtained granulated powder 4, secondary particles 4, and heat radiation sheet cured body 4 were evaluated in the same manner as in Example 1.
As a result of observing the secondary particles 4 with a scanning electron microscope, the secondary particles 4 have a core part and a shell part, and the density of the primary particles in the core part is lower than the density of the primary particles in the shell part. I understood. Further, the primary particles in the shell portion are entirely covered so as to be along the outer peripheral surface of the secondary particles, and are oriented so as to be laminated in the radial direction of the secondary particles. The primary particles in the core part were aggregated in an irregular direction and were not oriented. Moreover, it turned out that it was contained in the sheet | seat, with the form of the secondary particle being maintained from the result of having observed the cross section of the thermal radiation sheet hardening body 4 with the scanning electron microscope. The other evaluation results are shown in Table 2.

(Comparative Example 1)
The same as Example 1 except that hexagonal boron nitride aggregated particles (HP-40, made of Mizushima alloy iron) are used as the granulated powder 5 instead of the granulated powder 1, and the composition and blending amount are changed as follows. Thus, a heat radiating sheet cured body 5 was obtained.
The granulated powder 5, the secondary particles 5, and the heat radiating sheet cured body 5 were evaluated in the same manner as in Example 1. The aggregated particles contained in the granulated powder 5 were evaluated as secondary particles 5.

Details of each component and blending amount of the heat dissipation sheet are as follows.
Thermosetting resin (A): Biphenyl type epoxy resin (Mitsubishi Chemical Corporation, YX4000K) 16.8% by mass
Filler (B): Granulated powder 5 74.4% by mass
Curing catalyst (C-1): 2-phenyl-4,5-dihydroxymethylimidazole (manufactured by Shikoku Chemicals Co., Ltd., 2PHZ-PW) 0.1% by mass
Phenol curing agent (C-2): Trisphenol methane type novolak resin (Maywa Kasei Co., Ltd., MEH-7500) 8.7% by mass

  FIG. 5A is a diagram showing a result of observing a cross section of the secondary particle 3 with a scanning electron microscope. It was found that there was no difference in the density of primary particles between the central part and the outer peripheral part in the secondary particles 5, and the primary particles were aggregated in a random direction. Thus, the secondary particle 5 did not have a core part and a shell part with different primary particle densities.

  Moreover, FIG.5 (b) is a figure which shows the result of having observed the cross section of the thermal radiation sheet hardening body 5 with the scanning electron microscope. It turned out that the form of particle | grains is hardly maintained in the thermal radiation sheet hardening body 5. FIG. The other evaluation results are shown in Table 2.

(Comparative Example 2)
A heat-radiating sheet cured body 6 was obtained in the same manner as in Comparative Example 1 except that hexagonal boron nitride aggregated particles (FP70, manufactured by Denki Kagaku Kogyo) were used as the granulated powder 6 instead of the granulated powder 5.
The granulated powder 6, the secondary particles 6 and the heat radiating sheet cured body 6 were evaluated in the same manner as in Example 1. The aggregated particles contained in the granulated powder 6 were evaluated as secondary particles 6.

  When the cross section of the secondary particle 6 was observed with a scanning electron microscope, the secondary particle 6 did not have a core part and a shell part with different primary particle densities. Moreover, when the cross section of the heat-radiation sheet hardening body 6 was observed with the scanning electron microscope, it turned out that the form of particle | grains is hardly maintained in the heat-radiation sheet hardening body 6. FIG. The other evaluation results are shown in Table 2.

  The above conditions and evaluation results are shown in Tables 1 and 2.

  The heat radiating sheet cured bodies of Examples 1 to 4 had high withstand voltage performance under high humidity. Therefore, it was confirmed that a heat radiating sheet having excellent moisture resistance was obtained. On the other hand, the heat-dissipating sheet cured bodies of Comparative Examples 1 and 2 were inferior in the withstand voltage performance under high humidity. In each comparative example, it is considered that the secondary particles absorbed moisture under high humidity, and the insulation was lowered.

  As mentioned above, although embodiment of this invention was described with reference to drawings, these are the illustrations of this invention, Various structures other than the above are also employable.

10 Granulated powder 100 Semiconductor device 110 Semiconductor chip 111 Upper surface 112 Lower surface 120 Conductive layer 130 Heat sink 131 First surface 132 Second surface 140 Heat radiation sheet 141 Upper surface 142 Lower surface 144 Hardened body 150 Metal layer 151 Upper surface 152 Lower surface 160 Lead 161 Electrode 170 Wire 180 Sealing resin 182 Lower surface 20 Primary particle 30 Secondary particle 310 Core portion 320 Shell portion 410 Thermosetting resin

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
Hereinafter, examples of the reference form will be added.
1. Including spherical secondary particles formed by agglomerating primary particles,
The primary particles are scaly boron nitride,
The secondary particle has a core part including the center of the secondary particle, and a shell part covering the core part,
The granulated powder, wherein the density of the primary particles in the core part is lower than the density of the primary particles in the shell part.
2. 1. In the granulated powder described in
The granulated powder in which the primary particles in the shell part are covered so as to be along the outer peripheral surface of the secondary particles and are oriented so as to be laminated in the radial direction of the secondary particles.
3. 2. In the granulated powder described in
The primary particles are agglomerated powder aggregated in an irregular direction in the core part.
4). 1. To 3. In the granulated powder according to any one of
A granulated powder, wherein the secondary particles have an average sphericity of 0.70 or more.
5). 1. To 4. In the granulated powder according to any one of
Granulated powder whose oil absorption per 100 g is 70 mL or less.
6). 1. To 5. In the granulated powder according to any one of
When the secondary particles are compressed at 10 MPa, the median diameter before compression is D ₅₀ (0), and the median diameter after compression is D ₅₀ (1), D ₅₀ (1) / D ₅₀ ( 0) is 0.4 or more, granulated powder.
7). 1. To 6. In the granulated powder according to any one of
The granulated powder whose arithmetic standard deviation of the particle size of the secondary particles is 5 μm or more and 70 μm or less.
8). 1. To 7. In the granulated powder according to any one of
The secondary particle is a granulated powder further comprising at least one binder selected from the group consisting of a phenol resin, an epoxy resin, a melamine resin, and an unsaturated polyester resin.
9. 1. To 8. Granulated powder according to any one of
A heat-dissipating resin composition comprising a thermosetting resin.
10. 9. A heat-dissipating sheet comprising the heat-dissipating resin composition described in 1.
11. 9. A semiconductor device comprising a cured body of the heat-dissipating resin composition described in 1.
12 9. The heat radiating member containing the hardening body of the resin composition for heat dissipation as described in any one of.
13. 12 A semiconductor device comprising the heat dissipating member described in 1.

Claims (13)

Including spherical secondary particles formed by agglomerating primary particles,
The primary particles are scaly boron nitride,
The secondary particle has a core part including the center of the secondary particle, and a shell part covering the core part,
The granulated powder, wherein the density of the primary particles in the core part is lower than the density of the primary particles in the shell part. In the granulated powder according to claim 1,
The granulated powder in which the primary particles in the shell part are covered so as to be along the outer peripheral surface of the secondary particles and are oriented so as to be laminated in the radial direction of the secondary particles. In the granulated powder according to claim 2,
The primary particles are agglomerated powder aggregated in an irregular direction in the core part. In the granulated powder according to any one of claims 1 to 3,
A granulated powder, wherein the secondary particles have an average sphericity of 0.70 or more. In the granulated powder according to any one of claims 1 to 4,
Granulated powder whose oil absorption per 100 g is 70 mL or less. In the granulated powder according to any one of claims 1 to 5,
When the median diameter before compression is D ₅₀ (0) and the median diameter after compression is D ₅₀ (1) when the secondary particles are compressed at 10 MPa, D ₅₀ (1) / D ₅₀ ( 0) is 0.4 or more, granulated powder. In the granulated powder according to any one of claims 1 to 6,
The granulated powder whose arithmetic standard deviation of the particle size of the secondary particles is 5 μm or more and 70 μm or less. In the granulated powder according to any one of claims 1 to 7,
The secondary particle is a granulated powder further comprising at least one binder selected from the group consisting of a phenol resin, an epoxy resin, a melamine resin, and an unsaturated polyester resin. Granulated powder according to any one of claims 1 to 8,
A heat-dissipating resin composition comprising a thermosetting resin.   A heat dissipating sheet comprising the heat dissipating resin composition according to claim 9.   The semiconductor device containing the hardening body of the resin composition for thermal radiation of Claim 9.   A heat dissipating member comprising a cured body of the heat dissipating resin composition according to claim 9.   A semiconductor device comprising the heat dissipation member according to claim 12.