JP2016127046A - Granulated powder, resin composition for heat dissipation, heat dissipation sheet, semiconductor device, and heat dissipation member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide granulated powder which enables the materialization of a heat dissipation sheet and a heat dissipation member, both superior in humidity resistance.SOLUTION: Granulated powder 10 comprises secondary cohering particles 30. The secondary cohering particles 30 are formed by the cohesion of primary particles 20. The primary particles 20 are ones of scale-like boron nitride. In a log differential pore volume distribution curve measured on granulated powder 10 according to a method of mercury penetration, at least one maximal value is located in a first range of 5.0 to less than 180 μm in pore size; no maximal value is present in a second range of 0.05 to less than 5.0 μm. In the log differential pore volume distribution curve measured on the granulated powder 10 according to the method of mercury penetration, the following condition is satisfied: I/Iis equal to or less than 0.05, where Irepresents the maximum of maximal values located in the first range, and Irepresents the maximum of maximum values located in the second range.SELECTED DRAWING: 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 the withstand voltage performance of the heat radiating member and the heat radiating sheet becomes insufficient under high humidity.

  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 secondary agglomerated particles formed by agglomerating the primary particles;
The primary particles are scaly boron nitride,
There is at least one maximum value in the first range of 5.0 μm or more and less than 180 μm of the pore diameter in the log differential pore volume distribution curve measured by the mercury intrusion method, and the second range of 0.05 μm or more and less than 5.0 μm. Has no local maximum,
Alternatively, when the maximum value of the maximum values in the first range is I ₁ and the maximum value of the maximum values in the second range is I ₂ , the value of I ₂ / I ₁ is 0.05. The following granulated powder is provided.

According to the present invention,
The granulated powder,
A heat-dissipating resin composition containing 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 the figure which showed typically an example of the structure of the granulated powder which concerns on embodiment. It is the figure which showed typically the modification of the structure of the secondary aggregation particle which concerns on embodiment. It is sectional drawing which showed typically an example of the structure of the thermal radiation sheet which concerns on 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.

  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 diagram schematically illustrating an example of the granulated powder 10 according to the present embodiment.
The granulated powder 10 according to the present embodiment includes secondary agglomerated particles 30. The secondary aggregated particles 30 are formed by aggregating the primary particles 20. The primary particles 20 are scaly boron nitride. There is at least one maximum value in the first range of the pore diameter of 5.0 μm or more and less than 180 μm in the log differential pore volume distribution curve of the granulated powder 10 measured by the mercury intrusion method, and 0.05 μm or more and 5.0 μm. There is no local maximum in the second range below. Alternatively, the maximum value among the maximum values in the first range in the log differential pore volume distribution curve of the granulated powder 10 measured by the mercury intrusion method is I ₁ , and the maximum value among the maximum values in the second range is When I ₂ , the value of I ₂ / I ₁ is 0.05 or less. This will be described in detail below.

  By using such granulated powder 10, it is possible to obtain a heat radiating sheet or a heat radiating member that has few voids and is excellent in withstand voltage performance under high humidity. As a result, a highly durable semiconductor device can be obtained.

  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 log differential pore volume distribution curve obtains a value dV / d (logD) obtained by dividing the difference pore volume dV of the pores in the granulated powder by the difference value d (logD) treated logarithmically of the pore diameter. It is plotted against the average pore diameter of each section. Here, V represents the pore volume of the granulated powder, and D represents the pore diameter. The log differential pore volume distribution curve can be measured by mercury porosimetry. Although it does not specifically limit, it can measure, for example using a mercury porosimeter (the Shimadzu Corporation make, auto pore 9520 type). The secondary agglomerated particles 30 have a strength that can withstand the mercury intrusion method.

  In the log differential pore volume distribution curve of the granulated powder 10, there is at least one maximum value in the pore diameter range (hereinafter referred to as the first range) of 5.0 μm or more and less than 180 μm, and 0.05 μm or more and 5 By making the pore diameter range of less than 0.0 μm (hereinafter referred to as the second range) not to have a maximum value, the granulated powder 10 capable of producing a heat radiation sheet having excellent moisture resistance can be obtained. The reason can be estimated as follows. In the log differential pore volume distribution curve, the pore distribution in the first range mainly reflects the voids 40 between the plurality of secondary agglomerated particles 30, while the pore distribution in the second range is It can be understood that the fine voids formed in the secondary agglomerated particles 30 are mainly reflected. Therefore, in the granulated powder 10 having the maximum value in the first range and not having the maximum value in the second range, it can be said that the voids 40 between the aggregated particles are dominant compared to the fine pores of the aggregated particles. Therefore, it is considered that a heat dissipation sheet or the like that is satisfactorily impregnated with resin and has few voids and excellent moisture resistance can be produced.

  The state where there is no maximum value in the second range means, for example, a state where the range is monotonically increasing or a state where there is no local maximum value (peak) exceeding the measurement limit (noise level). For example, when the base of the peak in the first range extends to the second range, the curve increases monotonously.

Further, when the maximum value of the maximum values in the first range is I ₁ and the maximum value of the maximum values in the second range is I ₂ , the value of I ₂ / I ₁ is 0.05 or less. If, that is, when the first range is no peak of intensity exceeding 0.05 times the I ₁ to the second range has a peak, there is substantially peak in the first range, there is no peak in the second range It can be said. Therefore, it is considered that, similarly to the above, it is possible to manufacture a heat dissipation sheet or the like that is satisfactorily impregnated with resin and has few voids and excellent moisture resistance. In view of the fact that the voids 40 between the aggregated particles become more dominant than the fine pores of the aggregated particles, the value of I ₂ / I ₁ is more preferably 0.03 or less, and further preferably 0.01 or less.

  In addition, from the viewpoint of further improving the moisture resistance performance of the heat-dissipating sheet or the like, the porosity of the granulated powder 10 measured within a pore diameter range of 0.05 μm or more and 5.0 μm or less by a mercury intrusion method may be 30% or less. Preferably, it is 20% or less.

The porosity can be determined by the formula of porosity (%) = (V _p × W × 100) / V, where V _p is the cumulative pore / gap volume (mL / g), W in the measurement range Is the sample weight (g) and V is the sample volume (mL). The porosity can be calculated based on a log differential pore volume distribution curve.

  The outer shape of the secondary agglomerated particles 30 is not particularly limited, but may be 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. Further, the surface may be uneven as long as it is rounded as a whole.

The form of the secondary aggregated particles 30 is not particularly limited. As an example, as shown in FIG. 1, each secondary aggregated particle 30 has at least one domain (region) in which a plurality of primary particles 20 are laminated and oriented. By doing this, a granulated powder having a peak in the first range and no peak in the second range, or a granulated powder having a value of I ₂ / I ₁ of 0.05 or less can be obtained. Laminated orientation refers to a situation where the principal surfaces of the scaly primary particles 20 are stacked facing each other. That is, in the domain, the directions perpendicular to the main surface of the primary particles 20 are aligned in the same direction. In addition, when the primary particle 20 is an elliptical scaly shape, the major axis directions of the plurality of primary particles 20 do not need to be aligned.

FIG. 2 is a diagram schematically showing a modification of the structure of the secondary aggregated particle 30 according to the present embodiment.
The secondary agglomerated particles 30 in this figure include a plurality of domains in which the primary particles 20 are stacked and oriented. The direction perpendicular to the main surface of the granulated powder 10 is uniform in each domain, and is different between adjacent domains.

  In the present embodiment, for example, the secondary agglomerated particles 30 may have at least one of the domains as a main region. Further, one secondary aggregated particle 30 may further include a region where the primary particles 20 aggregate in a random direction. That is, the secondary agglomerated particles 30 can be configured such that the main region is occupied by the primary particles 20 that are laminated and oriented.

  The granulated powder 10 preferably includes secondary agglomerated particles 30 composed of one or more domains, and more preferably includes secondary agglomerated particles 30 composed of one domain. By including such secondary agglomerated particles 30 that include only domains and do not include random orientation regions, the withstand voltage performance under high humidity can be further improved. In addition, it is more preferable that more than half of the secondary aggregated particles 30 included in the granulated powder 10 are composed of one or two or more domains.

  The structure of the secondary agglomerated particles 30 as described above and the orientation of the primary particles 20 can be confirmed by observing the outer shape and cross section of the secondary agglomerated particles 30 with an electron microscope.

  The granulated powder 10 may mainly include the secondary aggregated particles 30 and may further include primary particles 20 that are not aggregated, other constituent particles, impurities, and the like.

  An example of a method for producing the granulated powder 10 including the secondary agglomerated particles 30 will be described below.

As the primary particles 20, hexagonal (scale-like) 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 aggregated particles 30 and obtaining good thermal conductivity. Further, from the same viewpoint, the average major axis of the primary particles 20 is preferably 20 μm or less, and more preferably 10 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 agglomerated particles 30 or the heat dissipation sheet including the secondary agglomerated 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 aggregated 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 content of the primary particles 20 contained in the secondary agglomerated particles 30 is not particularly limited, but from the viewpoint of efficiently obtaining the secondary agglomerated particles 30, the content is 70% by mass or more with respect to 100% by mass of the secondary agglomerated particles. Preferably, 80 mass% or more is more preferable. The content is preferably 95% by mass or less.

The secondary agglomerated 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 aggregated particles can be formed efficiently.

  The content of the binder contained in the secondary aggregated particles 30 is not particularly limited, but is preferably 3% by mass or more with respect to 100% by mass of the secondary aggregated particles 30 from the viewpoint of efficiently obtaining the secondary aggregated particles 30. 5 mass% or more is more preferable. Further, the content is preferably 15% by mass or less, and more preferably 13% by mass or less.

  The secondary agglomerated 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 aggregate obtained in this way is heat-treated using a drying oven to obtain secondary aggregated 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 agglomerated particles 30 as described above are formed by applying mechanical action including compressive force, shear force and impact force to the individual particles by rotating the stirring blade and the like at high speed. In order to efficiently obtain the secondary agglomerated particles 30, it is particularly preferable to agglomerate the primary particles 20 by applying a mechanical action including a compressive shear stress, but the present invention is not limited to this.

  Examples of the mechanical particle compounding device include hybridization manufactured by Nara Machinery Co., Ltd., kryptron manufactured by Kawasaki Heavy Industries, Ltd., mechanofusion and nobilta manufactured 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 200 rpm or more, and more preferably 500 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 at least the above lower limit value, the secondary aggregated particles 30 can be obtained efficiently. By being below the above upper limit value, heat generation during the treatment can be suppressed and overpulverization 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. Further, the treatment time by the mechanical particle compounding apparatus is set according to the raw material, but is preferably 30 seconds or more, more preferably 1 minute or more, and further preferably 5 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 aggregated particles 30 can be obtained more efficiently.

The average sphericity of the secondary agglomerated particles 30 is preferably 0.70 or more, and more preferably 0.75 or more. When the average sphericity of the secondary agglomerated particles 30 is equal to or higher than the lower limit, a heat radiating sheet and a heat radiating member having excellent withstand voltage performance under high humidity can be obtained more reliably. 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 is measured about 10,000 pieces and an average value is obtained as average sphericity. The average sphericity of the secondary agglomerated particles 30 can be measured using, for example, a particle image analyzer (Malburn, Morphologi G3).

  From the viewpoint of improving moisture resistance, the oil absorption amount of the granulated powder 10 is preferably 75 mL or less, more preferably 50 mL or less, and even more preferably 35 mL or less per 100 g of the granulated powder. 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 agglomerated particles 30 is preferably 17 μm or more, and more preferably 35 μm or more, from the viewpoint of improving handling properties. Further, from the same viewpoint, the median diameter D ₅₀ (0) is preferably 55 μm or less, and more preferably 45 μm or less. When the median diameter D ₅₀ (0) is not less than the above lower limit and not more than the upper limit, the withstand voltage performance of the heat radiating sheet and the heat radiating member under high humidity can be improved more reliably. The median diameter D ₅₀ (0) of the secondary agglomerated particles 30 is determined using a laser diffraction particle size distribution analyzer (LA-950V2 manufactured by Horiba, Ltd.) utilizing analysis by the Franhofer diffraction theory and Mie's scattering theory, for example. It can be measured by the method. 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.

The median diameter D ₅₀ (1) after compression when the secondary agglomerated particles 30 are compressed is preferably 20 μm or more, and more preferably 30 μm or more. When the median diameter D ₅₀ (1) is equal to or greater than the above lower limit, the withstand voltage performance of the heat radiating sheet and the heat radiating member under high humidity can be improved more reliably. The secondary agglomerated particles 30 can be compressed using a powder layer shear force measuring apparatus (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 agglomerated particles 30 after compression can be measured, for example, using a laser diffraction particle size distribution meter (LA-950V2 manufactured by Horiba, Ltd.).

The ratio of the median diameter before and after compression of the secondary agglomerated particles 30 is preferably 0.4 or more. Specifically, in the case of compressing the secondary aggregated particles 30 in 10 MPa, the median diameter before compression and _D 50 (0), when the median diameter after compression was _{D 50 (1), D 50} (1 ) / D ₅₀ (0) The median diameter ratio before and after compression is preferably 0.4 or more, and more preferably 0.8 or more. When the value of D ₅₀ (1) / D ₅₀ (0) is equal to or greater than the lower limit, the withstand voltage performance of the heat radiating sheet and the heat radiating member under high humidity can be improved more reliably.

  The arithmetic standard deviation of the particle size of the secondary aggregated particles 30 is preferably 5 μm or more, and more preferably 10 μm or more. If the arithmetic standard deviation is equal to or greater than the above lower limit, the withstand voltage performance of the heat radiating sheet and the heat radiating member under high humidity can be improved more reliably. On the other hand, the arithmetic standard deviation of the particle size of the secondary aggregated particles 30 is preferably 70 μm or less, and more preferably 30 μm or less, from the viewpoint of performance stability. The arithmetic standard deviation of the particle size of the secondary agglomerated particles 30 can be measured using, for example, a laser diffraction type particle size distribution meter (LA-950V2 manufactured by Horiba, Ltd.). Moreover, if it is more than the said minimum and below an upper limit, the withstand voltage performance under the high humidity of a thermal radiation sheet or a thermal radiation member can be improved more reliably.

The specific surface area of the granulated powder 10 is preferably 10.0 m ² / g or less, and more preferably 8.0 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 3.0 m ² / g or more. If a specific surface area is more than the said minimum, the withstand voltage performance under the high humidity of a thermal radiation sheet or a thermal radiation member can be improved 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 20 ° or less and more preferably 15 ° or less from the viewpoint of moldability.
When a part of the object moves inside the object with respect to the other part of the object across the sliding surface, friction occurs between the part of the object and the other part on the sliding surface. When the frictional resistance at this time is expressed by the relationship between the vertical resistance (horizontal axis) and the shearing resistance (vertical axis), the angle between the drawn straight line and the horizontal axis is called the friction angle. In other words, the friction angle is an index indicating the magnitude of the friction force between one substance (the above-mentioned “part of the object”) and another substance (the above-mentioned “other part of the object”). It is. Here, when the friction angle is large, the frictional force between the substances is large, and therefore when the granulated powder is added in a large amount to the resin composition, the viscosity of the resin composition increases and the moldability is impaired. The friction angle of the secondary agglomerated particles 30 can be measured using, for example, a powder layer shear force measuring device (manufactured by Nano Seeds Co., Ltd., NS-S500).

Bulk density a of the granulated powder 10 is preferably 1.50 g / cm ³ or less, more preferably 0.75 g / cm ³ or less. On the other hand, the bulk specific gravity a is preferably 0.40 g / cm ³ or more, and more preferably 0.62 g / cm ³ or more. When the bulk specific gravity a is not more than the above upper limit and not less than the lower limit, a heat radiating sheet or a heat radiating member having excellent thermal conductivity can be obtained. Further, the moisture resistance performance of the heat radiating sheet and the heat radiating member can be improved more reliably. The bulk specific gravity a of the granulated powder 10 can be measured as a hard bulk specific gravity using, for example, a powder tester (manufactured by Hosokawa Micron Corporation, PT-X).

True specific gravity b of the granulated powder 10 is preferably 3.5 g / cm ³ or less, more preferably 3.0 g / cm ³ or less, further preferably 2.40 g / cm ³ or less . On the other hand, the true specific gravity b is preferably 1.0 g / cm ³ or more, and more preferably 2.0 g / cm ³ or more. When the true specific gravity b is not more than the above upper limit and not less than the lower limit, a heat radiating sheet and a heat radiating member excellent in performance balance between thermal conductivity and moldability can be obtained. The true specific gravity b of the granulated powder 10 can be measured by the liquid phase substitution method using, for example, an automatic wet true density measuring device (manufactured by Seishin Enterprise Co., Ltd., MAT-7000).

  Regarding the bulk specific gravity a and the true specific gravity b of the granulated powder 10, the value represented by a / b is preferably 0.1 or more, and more preferably 0.25 or more. If it is more than the said minimum, the heat-radiation sheet and heat-radiation member which are excellent in the withstand voltage performance in quality improvement can be obtained more reliably. Moreover, the value represented by a / b can be 1.0 or less.

  The secondary agglomerated particles 30 and the granulated powder 10 as described above can be obtained by adjusting the composition of the secondary agglomerated particles 30, the driving conditions of the powder processing apparatus, the heat treatment conditions, 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. 3 is a cross-sectional view schematically showing an example of the structure 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, primary particles 20 and a 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). 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.

(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 aggregated particles 30.

  The secondary aggregated particles 30 are preferably contained in an amount of 50% by mass or more, more preferably 60% by mass or more, with respect to 100% by mass of the filler (B) contained in the heat radiation resin composition. Further, the content of the secondary aggregated 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. preferable. On the other hand, the content is preferably 95% by mass or less, and more preferably 80% by mass or less. By setting the content of the secondary agglomerated particles 30 to the above lower limit value or more, the moisture resistance performance of the heat radiation sheet 140 and the heat radiation member can be improved more reliably. On the other hand, by making the content of the secondary agglomerated particles 30 equal to or less than the above upper limit value, the workability in the molding of the heat radiation resin composition is improved, and the film thickness of the heat radiation sheet 140 and the heat radiation member is further improved. It can be good.

  From the viewpoint of further improving the thermal conductivity of the heat-dissipating resin composition, the heat-dissipating sheet 140, and the heat-dissipating member, the filler (B) according to this embodiment includes secondary-aggregated particles 30 It is preferable that particles of flaky (hexagonal) boron nitride not constituting 30 are further included. 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 agglomerated particles 30 included in the heat dissipation resin composition may be appropriately adjusted according to the purpose, and is not particularly limited. As 100 mass%, 10 mass% or more is preferable and 20 mass% or more is more preferable. On the other hand, the content is preferably 40% by mass or less, and more preferably 30% by mass or less. Thereby, the heat-radiation sheet 140 and the heat-radiation member which were much more excellent about the balance of heat conductivity and electrical insulation are realizable.

  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), it is preferable that a hardening | curing agent (C) is further included.
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, more preferably 15% by mass or less, and even more preferably 8.5% by mass or less.

(Coupling agent (D))
Furthermore, the resin composition for heat dissipation may 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.

Furthermore, the resin composition for heat dissipation may 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.

  For example, the content of the phenoxy resin (E) is preferably 3% by mass or more and 10% by mass or less with respect to 100% by mass of the resin composition for heat dissipation.

(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 conductive 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. First, the resin film with a base material is laminated on the metal member so that the exposed surface of the heat radiation 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 a cured body 144 of the heat dissipation resin composition. FIG. 4 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. This will be described in detail 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. In this way, the semiconductor device 100 having a structure as shown in FIG. 4 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. A hardened body 144 of an insulating heat radiation sheet attached to the surface 132 and a sealing resin 180 that seals the semiconductor chip 110 and the heat sink 130 are provided.

  In the heat radiating sheet 140 and the heat radiating member according to the present embodiment, the secondary aggregated particles 30 may be included while being aggregated while maintaining the shape, or the shape of the secondary aggregated particles 30 is not maintained and is primary. It may be included as particles 20. For example, the secondary aggregated particles 30 contained in the heat-dissipating resin composition may lose a spherical shape due to compression when the heat-dissipating sheet 140 or the heat-dissipating member is molded. Even in such a case, it is considered that the primary particles 20 are densely packed and the heat radiation sheet 140 and the heat radiation member with few voids are obtained.

The void occupancy ratio of the heat dissipation resin composition in the heat dissipation sheet 140 and the void occupancy ratio of the cured body of the heat dissipation resin composition in the heat dissipation member can each be, for example, 10% or less, and further 5% or less. be able to. The void occupancy can be measured as follows. First, the heat radiating sheet, the cured body of the heat radiating sheet, or the heat radiating member is cut to expose the cross section. Then, the exposed cross section is observed using a scanning electron microscope to obtain a cross section observation image. Then, the void area seen in the cross-sectional observation image is S _B , and the entire sheet area including the void portion is S _S, and the value of S _B / S _S is obtained. The average value of S _B / S _S × 100 values obtained for the five cross-sectional observation images is defined as a void occupancy (%).

Next, the operation and effect of this embodiment will be described.
According to this embodiment, the heat radiating sheet and heat radiating member which are excellent in moisture resistance can be obtained using the granulated powder 10 containing the secondary agglomerated particles 30. In addition, a semiconductor device having excellent durability can be obtained.

  Further, according to the present embodiment, the secondary aggregated particles 30 are excellent in handling properties. Therefore, in manufacture of a heat radiating sheet and a heat radiating member, manufacturing efficiency is high and it is excellent also in manufacturing stability.

  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 aggregated particles>
A granulated powder containing secondary agglomerated particles was prepared as follows.
First, 90.9% by mass of hexagonal boron nitride 1 (manufactured by Denki Kagaku Kogyo Co., Ltd., SGP) as primary particles, and 9.1% by mass of a resol type phenol resin (manufactured by Sumitomo Bakelite Co., Ltd., PR-940C) as a binder. Was mixed using a mixer for 5 minutes. 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 1000 rpm for 10 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, whereby granulated powder 1 composed of secondary agglomerated particles 1 was obtained.

<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 1 (manufactured by Denki Kagaku Kogyo Co., Ltd., SGP) 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, by using a press machine and pressing for 30 minutes while sandwiching the substrate under the conditions of a tool pressure of 10 MPa and a tool temperature of 180 ° C., a 200 μm thick heat radiation sheet cured body 1 (heat radiation member) is obtained. Obtained.

<Evaluation of secondary agglomerated particles and granulated powder>
The obtained secondary aggregated particles 1 and granulated powder 1 were evaluated as follows.

(Log differential pore volume distribution curve)
A log differential pore volume distribution curve of the granulated powder 1 was obtained using a mercury porosimeter (manufactured by Shimadzu Corporation, Autopore 9520 type). The mercury contact angle was 130 ° and the mercury surface tension was 485 dynes / cm.
As a result, there was a local maximum value of 2.2 in the pore diameter range of 5.0 μm or more and less than 180 μm. On the other hand, in the pore diameter range of 0.05 μm or more and less than 5.0 μm, the strength monotonously increased with the increase of the pore diameter, and there was no maximum value.
In this evaluation of Examples 2 and 3 and Comparative Example 1 described later, when a maximum value was found in the range of pore diameters of 0.05 μm or more and less than 5.0 μm, the strength of the maximum value was measured, The value of I ₂ / I ₁ was determined. Note that I ₁ is the maximum value among the maximum values in the first range (5.0 μm or more and less than 180 μm) in the measured log differential pore volume distribution curve, and I ₂ is the second range (0.05 μm or more 5 The maximum value among the maximum values in less than 0.0 μm).

(Porosity)
Based on the log differential pore volume distribution curve obtained by the above measurement, the porosity of the granulated powder 1 was measured in a pore diameter range of 0.05 μm to 5.0 μm. As a result, the porosity of the granulated powder 1 was 13%.

(Shape observation)
The shape of the secondary aggregated particles 1 was observed using a scanning electron microscope (JSM-7401F, manufactured by JEOL Ltd.). The secondary agglomerated particles 1 were spherical and had domains where the primary particles were laminated and agglomerated. Among them, secondary aggregated particles composed of only one domain and secondary aggregated particles composed of two or more domains were included.

(Sphericity)
The sphericity of the secondary agglomerated particles 1 was measured using a particle image analyzer (Malvern, Morphologi G3). In addition, in the observation by an electron microscope, since the unaggregated primary particle | grains etc. were not seen in the granulated powder 1, it measures without passing through processes, such as isolate | separating the unaggregated primary particle, about the granulated powder 1. The result was defined as the sphericity of the secondary agglomerated 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 average sphericity of the secondary agglomerated particles 1 was 0.79.

(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 agglomerated particles 1 was 6.6 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 30 mL per 100 g.

(Friction angle)
The friction angle of the granulated powder 1 was measured. The measurement was performed using a powder layer shear force measuring device (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 14.5 °.

(Median diameter, arithmetic standard deviation of particle diameter)
The median diameter and the arithmetic standard deviation of the particle diameter of the secondary agglomerated particles 1 were measured. In addition, the result of measuring granulated powder 1 was made into the median diameter and the particle size of secondary agglomerated 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 aggregated particle 1 was 37 μm, and the arithmetic standard deviation of the particle diameter was 12 μm.
Moreover, after compressing about the secondary aggregated 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 agglomerated particles 1 was 36 μm. The ratio of the median diameter before and after compression represented by D ₅₀ (1) / D ₅₀ (0) was calculated to be 0.9.

(Bulk specific gravity)
The bulk specific gravity a of the granulated powder 1 was measured. Specifically, using a powder tester (made by Hosokawa Micron Corporation, PT-X), a bulk specific gravity a (hardening) is performed on granulated powder 1 using a 25 mL sample cell under the conditions of a tapping stroke of 18 mm and a tapping frequency of 180 times. (Bulk specific gravity) was measured. The bulk specific gravity a of the granulated powder 1 was 0.63 g / cm ³ .

(True specific gravity)
The true specific gravity b 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 b of the granulated powder 1 was 2.22 g / cm ³ . And the value of a / b was calculated | required with 0.28.

(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 ◎.

<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. 5 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 radiating sheet cured body 1, it was found that the primary particles were contained in the sheet in a uniformly and densely packed state. Further, the domain in which the primary particles were laminated and oriented was maintained, and there were few voids.

(Void occupation rate)
The void occupancy was measured based on the cross-sectional observation image acquired with the scanning electron microscope as described above. Specifically, the void area seen in the cross-sectional observation image was S _B , and the area of the entire sheet including the void portion was S _S, and the value of S _B / S _S × 100 (%) was obtained. The average value of S _B / S _S × 100 (%) values obtained for the five cross-sectional observation images was defined as the void occupancy rate. In the heat radiating sheet cured body 1, the void occupancy was 3%.

(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 ◎.
Moreover, 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 (circle), 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 more was evaluated as “◯”, and the case where it was less than 1000 V was evaluated as “X”.
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 agglomerated 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 agglomerated particles 2, and heat-dissipating sheet cured body 2 were evaluated in the same manner as in Example 1.
As a result of observing the secondary agglomerated particles 2 with a scanning electron microscope, the secondary agglomerated particles 2 were spherical like the secondary agglomerated particles 1 and had domains in which the primary particles were laminated and aggregated. Among them, secondary aggregated particles composed of only one domain and secondary aggregated particles composed of two or more domains were included.
The other evaluation results are shown in Table 2.

Example 3
Granulated powder 3 comprising secondary agglomerated particles 3 was obtained in the same manner as in Example 1 except that hexagonal boron nitride 2 (manufactured by Denki Kagaku Kogyo Co., Ltd., GP) was used instead of hexagonal boron nitride 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 agglomerated particles 3, and heat-radiating sheet cured body 3 were evaluated in the same manner as in Example 1.
As a result of observing the secondary agglomerated particles 3 with a scanning electron microscope, as with the secondary agglomerated particles 1, the secondary agglomerated particles 3 were spherical and had domains in which the primary particles were laminated and aggregated. Among them, secondary aggregated particles composed of only one domain and secondary aggregated particles composed of two or more domains were included.
The other evaluation results are shown in Table 2.

(Comparative Example 1)
Instead of the granulated powder 1, hexagonal boron nitride agglomerated particles (FP70, manufactured by Denki Kagaku Kogyo) were used as the granulated powder 4, and each component and blending amount were changed as follows, and the same as in Example 1. Thus, a heat radiating sheet cured body 4 was obtained.
The granulated powder 4, the secondary agglomerated particles 4 and the heat radiating sheet cured body 4 were evaluated in the same manner as in Example 1. The aggregated particles contained in the granulated powder 4 were evaluated as secondary aggregated particles 4.

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 4 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

  When the outer shape and cross section of the secondary aggregated particles 4 were observed with a scanning electron microscope, the primary particles were mainly oriented in random directions.

  Moreover, when the cross section of the heat-radiation sheet hardening body 4 was observed with the scanning electron microscope, the dispersion | distribution of the primary particle was uneven and many voids were seen. The other evaluation results are shown in Table 2.

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

The heat dissipation sheets of Examples 1 to 3 had high withstand voltage performance under high humidity in the cured body. On the other hand, the heat dissipation sheet of Comparative Example 1 in which the value of I ₂ / I ₁ was 0.36 was inferior in the withstand voltage performance under high humidity in the cured body. In each comparative example, it was considered that the withstand voltage performance was lowered as a result of the heat dissipation sheet absorbing moisture under high humidity.
Therefore, it was confirmed that a heat radiating sheet and a heat radiating member excellent in moisture resistance can be realized by using granulated powder having a peak in the first range and no peak in the second range.

  Moreover, it was also confirmed that the granulated powder of Examples 1-3 is excellent in handling property.

  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 aggregated particle 40 Void 410 Thermosetting resin

Claims (12)

Including secondary agglomerated particles formed by agglomerating the primary particles;
The primary particles are scaly boron nitride,
There is at least one maximum value in the first range of 5.0 μm or more and less than 180 μm of the pore diameter in the log differential pore volume distribution curve measured by the mercury intrusion method, and the second range of 0.05 μm or more and less than 5.0 μm. Has no local maximum,
Alternatively, when the maximum value of the maximum values in the first range is I ₁ and the maximum value of the maximum values in the second range is I ₂ , the value of I ₂ / I ₁ is 0.05. Granulated powder that is: In the granulated powder according to claim 1,
A granulated powder having a porosity of 30% or less measured by a mercury intrusion method in a pore diameter range of 0.05 μm to 5.0 μm. In the granulated powder according to claim 1 or 2,
When the bulk specific gravity is a and the true specific gravity is b,
Granulated powder whose a / b is 0.1 or more and 1.0 or less. In the granulated powder according to any one of claims 1 to 3,
Granulated powder having a specific surface area of 10.0 m ² / g or less. In the granulated powder according to any one of claims 1 to 4,
Granulated powder having a friction angle of 20 ° or less. In the granulated powder according to any one of claims 1 to 5,
Each of the secondary agglomerated particles has at least one domain in which a plurality of the primary particles are stacked and oriented,
The secondary agglomerated particles are granulated powder having a spherical shape. In the granulated powder according to any one of claims 1 to 6,
The secondary agglomerated particles are granulated powder further comprising one or more binders selected from the group consisting of phenol resins, epoxy resins, melamine resins, and unsaturated polyester resins. The granulated powder according to any one of claims 1 to 7,
A heat-dissipating resin composition comprising a thermosetting resin.   A heat dissipating sheet comprising the heat dissipating resin composition according to claim 8.   The semiconductor device containing the hardening body of the resin composition for heat dissipation of Claim 8.   A heat dissipation member comprising a cured body of the heat dissipation resin composition according to claim 8.   A semiconductor device comprising the heat dissipation member according to claim 11.