Boron nitride particles, resin composition, and uses therefor

Abstract

The purpose of the present disclosure is to provide: novel boron nitride particles that have a low dielectric property and high thermal conductivity; a resin composition containing the boron nitride particles; and uses therefor.　A boron nitride particle according to the present disclosure comprises: a core that contains boron nitride oriented in a direction intersecting the outer periphery of the particle; and a shell that covers at least a portion of the core part and contains boron nitride oriented along the outer periphery of the particle.

Description

Boron nitride particles, resin compositions and their applications

[0001] The present disclosure relates to boron nitride particles, a resin composition, and applications thereof.

[0002] The amount of transmission loss that occurs when radio waves transmitted for communication are converted into heat in a dielectric is expressed as the product of frequency, the square root of the relative dielectric constant, and the dielectric loss tangent. In other words, since the transmission signal is more likely to be converted into heat in proportion to the frequency, the higher the frequency band, the lower the dielectric properties required for communication component materials in order to suppress transmission loss.

[0003] In the field of information and communications, radio waves are becoming increasingly higher in frequency as the number of channels and the amount of information transmitted increase. Currently, studies on fifth-generation mobile communication systems are underway worldwide, and several frequency bands in the range of approximately 30 GHz to 70 GHz have been identified as candidates for use. Furthermore, in sixth-generation mobile communication systems and beyond, frequencies will continue to increase, requiring materials with low dielectric properties to suppress transmission loss.

[0004] Furthermore, high thermal conductivity is required for sealing materials for semiconductor devices, interlayer insulating materials, copper-clad laminates, heat dissipation sheets, and the like.

[0005] Boron nitride is known as an inorganic filler having a low dielectric constant and high thermal conductivity. For example, a granulated powder is known that includes spherical secondary particles formed by agglomerating primary particles, the primary particles being scaly boron nitride, the secondary particles having a core portion including the center of the secondary particle and a shell portion covering the core portion, and the density of the primary particles in the core portion is lower than the density of the primary particles in the shell portion (see, for example, Patent Document 1).

[0006] Patent No. 6413478

[0007] As described above, in the field of semiconductor devices and the like, low dielectric properties and high thermal conductivity are required, and there is a demand for novel boron nitride having low dielectric properties and high thermal conductivity other than the boron nitride-containing granulated powder disclosed in Patent Document 1.

[0008] An object of the present disclosure is to provide novel boron nitride particles having low dielectric properties and high thermal conductivity, as well as resin compositions containing the same and applications thereof.

[0009] Specific means for achieving the above object are as follows. <1> Boron nitride particles comprising: a core portion containing boron nitride arranged in a direction intersecting the periphery of the particle; and a shell portion covering at least a portion of the core portion and containing boron nitride arranged along the periphery of the particle. <2> Boron nitride particles according to <1>, wherein the average particle diameter of the boron nitride particles is 50 nm to 10 μm. <3> Boron nitride particles according to <1> or <2>, wherein the thickness of the shell portion is 1 nm to 50 nm. <4> Boron nitride particles according to any one of <1> to <3>, wherein the ratio of the length of the core portion to the thickness of the shell portion, i.e., core length / shell thickness, is 1 to 10,000. <5> Boron nitride particles according to any one of <1> to <4>, wherein the aspect ratio of the boron nitride particles is 1 to 5. <6> Boron nitride particles according to any one of <1> to <4>, wherein the specific surface area of ​​the boron nitride particles is 0.3 m ２ / g to 100m ２ / g. <7> A resin composition comprising the boron nitride particles according to any one of <1> to <6> and a curable resin. <8> The resin composition according to <7>, further comprising an inorganic filler other than boron nitride particles. <9> The resin composition according to <8>, wherein the content of the boron nitride particles is 30% by mass to 70% by mass relative to the total of the boron nitride particles and the other inorganic fillers. <10> An encapsulating material comprising the resin composition according to any one of <7> to <9>. <11> An interlayer insulating material comprising the resin composition according to any one of <7> to <9>. <12> A copper-clad laminate comprising a prepreg sheet formed by impregnating a substrate with the resin composition according to any one of <7> to <9>, and copper foil arranged on at least one surface of the prepreg. <13> A heat-dissipating sheet having a resin composition layer comprising the resin composition according to any one of <7> to <9>. <14> A semiconductor device comprising a support member, an element placed on the support member, and a cured product of the resin composition according to any one of <7> to <9> encapsulating the element. <15> A heat dissipation device comprising a heat generating element, a heat dissipation element, and a resin composition layer containing the resin composition according to any one of <7> to <9> placed between the heat generating element and the heat dissipation element. <16> A method for producing boron nitride particles according to any one of <1> to <6>, comprising a step of nitriding boron-containing particles containing boron atoms in a nitrogen gas atmosphere.

[0010] According to the present disclosure, it is possible to provide novel boron nitride particles having low dielectric properties and high thermal conductivity, as well as resin compositions containing the same and applications thereof.

[0011] 1A and 1B are transmission electron microscope images of boron nitride particles of Example 1 and Example 2, respectively.

[0012] The present disclosure will be described in detail below. However, the present disclosure is not limited to the following embodiments. In the following embodiments, the components (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values ​​and their ranges, and do not limit the present disclosure.

[0013] In the present disclosure, the term "process" includes not only processes that are independent of other processes, but also processes that cannot be clearly distinguished from other processes as long as the purpose of the process is achieved. In the present disclosure, numerical ranges indicated using "to" include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in the present disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in numerical ranges described in the present disclosure, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples. In the present disclosure, each component may contain multiple corresponding substances. When multiple substances corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple substances present in the composition, unless otherwise specified. In the present disclosure, particles corresponding to each component may contain multiple types of particles. When multiple types of particles corresponding to each component are present in a composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified.

[0014] <Boron nitride particles> The boron nitride particles of the present disclosure comprise a core portion containing boron nitride arranged along a direction intersecting the periphery of the particle, and a shell portion containing boron nitride that covers at least a portion of the core portion and is arranged along the periphery of the particle.

[0015] The boron nitride particles of the present disclosure have low dielectric properties and high thermal conductivity. Furthermore, since boron nitride is arranged in the core along a direction intersecting the periphery of the particle, they tend to have high isotropic thermal conductivity. Furthermore, since boron nitride is arranged in the shell along the periphery of the particle, the particles can have a low specific surface area, which tends to result in excellent fluidity of the composition when mixed with a resin component such as a curable resin. The boron nitride particles of the present disclosure are not secondary particles formed by agglomerating scaly boron nitride particles, and therefore are applicable to miniaturizing semiconductor devices and narrowing their gaps. The boron nitride particles of the present disclosure are preferably primary particles comprising at least a core and a shell, rather than secondary particles formed by agglomerating boron nitride particles.

[0016] The boron nitride particles of the present disclosure are applicable to fields requiring low dielectric properties and high thermal conductivity, and are also applicable to applications such as sealing materials that require flowability, miniaturization, narrow gaps, etc. The boron nitride particles of the present disclosure can be applied to sealing materials, interlayer insulating materials, copper-clad laminates, heat dissipation sheets, molded products, etc.

[0017] The shape of the boron nitride particles of the present disclosure is preferably spherical or polyhedral from the viewpoint of flowability, filling properties, etc. when used in a resin composition.

[0018] The shape of the boron nitride particles of the present disclosure is preferably spherical. The spherical boron nitride particles may be, for example, particles having an aspect ratio of 1 to 5, as described below.

[0019] The core portion contains boron nitride arranged in a direction intersecting the periphery of the boron nitride particle. The core portion may have layered boron nitride arranged radially or randomly. The boron nitride in the core portion may be continuous layered boron nitride in the radial direction (diagonal direction in the case of a polyhedron shape), or multiple layered boron nitride may be discontinuously arranged.

[0020] The shell portion covers at least a portion of the core portion and contains boron nitride arranged along the periphery of the particle. The shell portion may be a layer in which multiple layers of boron nitride are arranged along the periphery of the particle. Multiple layers of boron nitride may be discontinuously arranged along the periphery of the particle.

[0021] The average particle size of the boron nitride particles may be 50 nm to 10 μm, 100 nm to 8 μm, 1 μm to 6 μm, or 2 μm to 6 μm. The average particle size of the boron nitride particles may be a volume average particle size, and can be measured as a volume average particle size (D50) using, for example, a laser diffraction scattering particle size distribution analyzer.

[0022] The aspect ratio of the boron nitride particles may be 1 to 5, or may be 1 to 3. The aspect ratio of the boron nitride particles can be determined, for example, using a scanning electron microscope, by measuring A / B, where A is the length in the major axis direction and B is the length in the minor axis direction, and then averaging the measured A / B values.

[0023] The specific surface area of ​​the boron nitride particles is 0.3 m ２ / g to 100m ２ / g, and 0.6m ２ / g to 50m ２ / g, and 2m ２ / g to 50m ２ / g, and 12m ２ / g to 30m ２ The specific surface area of ​​the boron nitride particles can be measured by the BET method (nitrogen gas adsorption method).

[0024] The thickness of the shell portion may be 1 nm to 50 nm, 3 nm to 40 nm, or 5 nm to 30 nm. The thickness of the shell portion can be adjusted, for example, by changing the pressure conditions when nitriding the boron-containing particles described below. From the viewpoint of the strength of the boron nitride particles, the thickness of the shell portion is preferably 1 nm or more. From the viewpoint of increasing the thermal conductivity of the boron nitride particles, the thickness of the shell portion is preferably 50 nm or less. The thickness of the shell portion can be determined, for example, using a transmission electron microscope, and is the arithmetic average of measurements obtained at five arbitrarily selected locations.

[0025] The ratio of the length of the core portion to the thickness of the shell portion, i.e., core length / shell thickness, may be 1 to 10,000, 10 to 1,000, or 50 to 1,000. The core length / shell thickness of the boron nitride particles can be determined, for example, using a transmission electron microscope. The core length refers to the length of the major axis of the core portion.

[0026] The method for producing the boron nitride particles of the present disclosure is not particularly limited, and they may be produced by a gas phase method, a liquid phase method, a solid phase method, or the like. For example, boron nitride particles may be produced by nitriding boron-containing particles containing boron atoms in a nitrogen gas atmosphere. When producing the boron nitride particles, the boron-containing particles may be heated, pressurized, or the like in a nitrogen gas atmosphere, as necessary. The heating conditions may be, for example, 1500°C to 2200°C, and the pressurization conditions may be 1 atm to 20 atm. The nitrogen gas atmosphere is preferably an inert gas containing nitrogen gas as the main component. The inert gas may contain components other than nitrogen gas (e.g., oxygen gas) as long as the effects of the invention are achieved.

[0027] The boron-containing particles are not particularly limited as long as they are particles containing boron atoms, and examples thereof include boron particles and boron carbide.

[0028] <Resin Composition> The resin composition of the present disclosure contains the boron nitride particles of the present disclosure and a curable resin. The resin composition may be used to produce an encapsulating material, an interlayer insulating material, a copper-clad laminate, a heat dissipation sheet, a molded article containing boron nitride particles, or the like. In particular, the resin composition is suitable for use in applications requiring high thermal conductivity, low dielectric properties, and the like.

[0029] The curable resin is not particularly limited as long as it is a resin that is cured by heat, active energy rays such as ultraviolet rays, or the like, and examples thereof include epoxy resins, phenolic resins, melamine resins, urea resins, unsaturated polyester resins, alkyd resins, urethane resins, vinyl resins, polyimide resins such as maleimide resins, polyamide resins, polyamideimide resins, silicone resins, (meth)acrylic resins, etc. The resin composition may contain only one type of curable resin, or may contain two or more types.

[0030] The resin composition of the present disclosure may contain components other than the boron nitride particles and curable resin of the present disclosure (also referred to as other components), such as inorganic fillers other than the boron nitride particles, thermoplastic resins, initiators, coupling agents, ion exchangers, mold release agents, flame retardants, colorants, stress relaxation agents, curing accelerators, curing agents, polymerization inhibitors, and solvents.

[0031] The resin composition of the present disclosure may further contain an inorganic filler other than boron nitride particles (also referred to as "other inorganic fillers"). Examples of other inorganic fillers include silica, alumina, magnesium oxide, calcium carbonate, zirconium silicate, calcium silicate, silicon nitride, aluminum nitride, beryllia, zirconia, zircon, fosterite, steatite, spinel, mullite, titania, talc, clay, mica, aluminum hydroxide, magnesium hydroxide, composite metal hydroxides such as magnesium-zinc composite hydroxide, and zinc borate. The resin composition may contain only one type of other inorganic filler, or two or more types.

[0032] The resin composition of the present disclosure may or may not contain boron nitride particles other than the boron nitride particles of the present disclosure (also referred to as "other boron nitride particles"). The other boron nitride particles are not particularly limited as long as they are boron nitride particles that do not have at least one of the core portion and the shell portion of the present disclosure. The aspect ratio of the other boron nitride particles may be greater than 5.

[0033] The content of the boron nitride particles of the present disclosure may be 50% by mass or more, 70% by mass or more, or 90% by mass or more, based on the total mass of the boron nitride particles. The upper limit of the content of the boron nitride particles of the present disclosure may be 100% by mass or less, or may be 95% by mass or less, based on the total mass of the boron nitride particles.

[0034] When the resin composition of the present disclosure contains other inorganic fillers, the mixing ratio of the boron nitride particles of the present disclosure to the other inorganic fillers is not particularly limited and may be adjusted appropriately depending on the application, required physical properties, etc. For example, the content of the boron nitride particles of the present disclosure may be 10% by mass to 90% by mass, 20% by mass to 80% by mass, or 30% by mass to 70% by mass relative to the total of the boron nitride particles of the present disclosure and the other inorganic fillers.

[0035] The content of the boron nitride particles in the resin composition of the present disclosure may be 5% by volume to 95% by volume, 10% by volume to 90% by volume, 10% by volume to 50% by volume, or 50% by volume to 90% by volume.

[0036] (Semiconductor Device) The resin composition of the present disclosure may be used for manufacturing a semiconductor device. For example, the semiconductor device may include a support member, an element disposed on the support member, and a cured product of the resin composition of the present disclosure encapsulating the element.

[0037] (Copper-clad laminate) A laminate may be produced by laminating a prepreg, which is a sheet obtained by impregnating a substrate such as paper or glass with the resin composition of the present disclosure, or a copper-clad laminate may be produced by providing copper foil on both sides of the laminate. For example, the copper-clad laminate may include a prepreg, which is a sheet obtained by impregnating a substrate with the resin composition of the present disclosure, and copper foil arranged on at least one side of the prepreg, preferably on both sides of the prepreg.

[0038] (Heat Dissipation Sheet) A heat dissipation sheet may be produced using the resin composition of the present disclosure. The heat dissipation sheet has a resin composition layer containing the resin composition of the present disclosure. The heat dissipation sheet may be a laminate in which a resin composition layer is disposed on a support. Alternatively, the heat dissipation sheet may be a heat dissipation device in which a heat generating element, a heat dissipation element, and a resin composition layer containing the resin composition of the present disclosure are disposed between the heat generating element and the heat dissipation element.

[0039] [Example 1] Boron particles (average particle diameter 1.4 μm, BET specific surface area 13.4 m) were used as a raw material for boron nitride particles. ２ The boron nitride particles were reacted for 4 hours under conditions of 1 atmosphere and 1750°C in a nitrogen gas atmosphere. This resulted in boron nitride particles having a core portion containing boron nitride arranged along a direction intersecting the periphery of the particle, and a shell portion covering at least a portion of the core portion and also containing boron nitride arranged along the periphery of the particle.

[0040] Example 2 Boron nitride particles were produced in the same manner as in Example 1, except that the pressure when reacting the boron particles was changed to 10 atmospheres.

[0041] [Comparative Example 1] (Scaly boron nitride particles) 40 g of boric acid, 20 g of melamine, and 10 g of water were mixed and stirred, and the mixture was placed in a mold and pressurized to a density of 0.7 g / cm ３ A molded body of the formula (1) was obtained. This molded body was dried in a dryer at 300°C for 8 hours, and then calcined at 1100°C under an ammonia gas atmosphere at 1 atmosphere pressure for 4 hours. The calcined product was then pulverized to obtain crude boron nitride powder. The crude boron nitride powder was then calcined at 1750°C under a nitrogen gas atmosphere at 1 atmosphere pressure for a total of 4 hours, and the calcined product was then washed with warm water at 60°C to obtain scaly boron nitride particles.

[0042] The boron nitride particles obtained in Examples 1 and 2 are shown in Figures 1 and 2 and Table 1. The aspect ratios in the tables represent the range from the minimum to the maximum value when the aspect ratios of multiple boron-containing particles were measured using a scanning electron microscope. The average particle size in the tables is the volume average particle size (D50) measured using a laser diffraction scattering particle size distribution analyzer. The particle size ranges in the tables represent the minimum and maximum particle sizes observed using a transmission electron microscope. As shown in Figures 1 and 2, the obtained boron nitride particles had a core portion containing boron nitride arranged in a direction intersecting the periphery of the particle and a shell portion containing boron nitride arranged along the periphery of the particle. The thickness of the shell portion could be adjusted by changing the pressure during nitriding of the boron particles.

[0043]

[0044] The disclosure of Japanese Patent Application No. 2023-213369, filed on December 18, 2023, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A boron nitride particle comprising: a core portion containing boron nitride arranged along a direction intersecting the periphery of the particle; and a shell portion containing boron nitride covering at least a portion of the core portion and arranged along the periphery of the particle.

2. Boron nitride particles according to claim 1, wherein the average particle size of the boron nitride particles is 50 nm to 10 μm.

3. The boron nitride particles according to claim 1, wherein the shell portion has a thickness of 1 nm to 50 nm.

4. Boron nitride particles according to claim 1, wherein the ratio of the length of the core portion to the thickness of the shell portion, i.e., core portion length / shell portion thickness, is 1 to 10,000.

5. Boron nitride particles according to claim 1, wherein the aspect ratio of the boron nitride particles is 1 to 5.

6. The specific surface area of ​​a boron nitride particle is 0.3 m ２ / g to 100m ２ 2. The boron nitride particles according to claim 1, wherein the molecular weight of the boron nitride particles is 1 / g.

7. A resin composition comprising the boron nitride particles according to any one of claims 1 to 6 and a curable resin.

8. The resin composition according to claim 7, further comprising an inorganic filler other than boron nitride particles.

9. The resin composition according to claim 8, wherein the content of the boron nitride particles is 30% by mass to 70% by mass based on the total content of the boron nitride particles and the other inorganic fillers.

10. An encapsulating material comprising the resin composition according to claim 7.

11. An interlayer insulating material comprising the resin composition according to claim 7.

12. A copper-clad laminate comprising a prepreg, which is a sheet in which a substrate is impregnated with the resin composition according to claim 7, and copper foil arranged on at least one surface of the prepreg.

13. A heat dissipation sheet having a resin composition layer containing the resin composition according to claim 7.

14. A semiconductor device comprising a support member, an element disposed on said support member, and a cured product of the resin composition according to claim 7 encapsulating said element.

15. A heat dissipation device comprising a heat generating element, a heat dissipating element, and a resin composition layer containing the resin composition according to claim 7, disposed between the heat generating element and the heat dissipating element.

16. A method for producing boron nitride particles, comprising a step of nitriding boron-containing particles containing boron atoms in a nitrogen gas atmosphere to produce the boron nitride particles according to any one of claims 1 to 6.

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