An insulating filler composed of a mixed powder in which a hydrophobic fumed oxide powder having an average primary particle size D.sub.1, which is smaller than an average primary particle size D.sub.2, is adhered to the surface of a magnesium oxide powder and/or a nitride-based inorganic powder having the average primary particle size D.sub.2, wherein: the ratio D.sub.1/D.sub.2 of the average primary particle size D.sub.1 to the average primary particle size D.sub.2 is 6×10.sup.−5 to 3×10.sup.−3; the volume resistivity of the mixed powder is 1×10.sup.11 Ω.Math.m or more; and the content ratio of the hydrophobic fumed oxide powder in the mixed powder is 5-30 mass %. Also provided is an insulating material in which the above-mentioned insulating filler is contained in a resin molded body.

A composite material according to the present invention includes a solid portion including inorganic particles and a resin. The composite material has a porous structure including a plurality of voids facing a wall surface of the solid portion. At least a portion of the inorganic particles is present on a wall surface. The plurality of voids are in contact with each other directly or via the inorganic particle. A heat transmission path stretching through the plurality of voids is formed of the inorganic particles in contact with each other.

A liquid crystal polyester resin comprising 42 to 80 mol % of structural unit (I) relative to 100 mol % of the total structural unit of the liquid crystal polyester resin, and ΔS (entropy of melting) defined by equation [1] is 0.01×10.sup.−3 to 2.7×10.sup.−3 J/g.Math.K:

ΔS(J/g.Math.K)=ΔHm(J/g)/Tm(K)  [1]

wherein Tm is an endothermic peak temperature determined by: after observation of an endothermic peak temperature (Tm.sub.1) observed when heating a liquid crystal polyester under temperature rising conditions of 20° C./minute from room temperature in differential scanning calorimetry, the liquid crystal polyester was maintained at a temperature of Tm.sub.1+20° C. for 5 minutes, followed by observation of the endothermic peak temperature observed when the temperature has fallen to room temperature under temperature falling conditions of 20° C./minute and then raised under temperature rising conditions of 20° C./minute, and ΔHm is an endothermic peak area of Tm:

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A resin sheet is made using a resin composition containing a thermosetting component (A). The thermosetting component (A) contains a maleimide resin. A thermal diffusion rate of the thermally cured resin sheet is 1.0 × 10.sup.-6 m.sup.2/s or more. The resin sheet has a thickness in a range from 5 .Math.m to 120 .Math.m .

A composite article can comprise a composite body including an organic polymer and ceramic particles comprising hexagonal boron nitride (hBN) particles distributed throughout the organic polymer, wherein an amount of the hBN particles ranges from 40 vol % to 90 vol % based on a total volume of the body; and the body comprises an in plane thermal conductivity of at least 15 W/mK. The hBN particles within the composite body can have a March-Dollase Orientation parameter η of at least 50%.

Thermally conductive electrically insulating compositions and structures and devices comprising such materials. In various embodiments, such materials comprise liquid crystal polymer and fillers, wherein the fillers comprise boron nitride and glass fiber. In various embodiments, the liquid crystal polymer is selected from the group consisting of semi-aromatic copolyesters, copolyamides, polyester-co-amides, and mixtures thereof.

An object of the present invention is to provide a composition capable of forming a thermally conductive sheet having excellent peel strength. In addition, another object of the present invention is to provide a thermally conductive sheet formed of the composition and a device with a thermally conductive sheet.

The composition of the present invention contains a disk-like compound, a high-molecular-weight compound which is at least one selected from the group consisting of a thermoplastic resin and rubber, and inorganic particles.

Provided is a boron nitride agglomerate. The boron nitride agglomerate is of a multi-stage structure formed by arranging flaky hexagonal boron nitride primary particles in three-dimensional directions through adhesion of an inorganic binder. Further provided is a method for preparing the boron nitride agglomerate. The method comprises: mixing flaky hexagonal boron nitride primary particles with an inorganic binder, and controlling the mass of the inorganic binder to account for 0.02-20% of the mass of the flaky hexagonal boron nitride primary particles, so as to obtain the boron nitride agglomerate. The boron nitride agglomerate provided can be added to thermosetting resin compositions, and resin sheets, resin composite metal foil, prepregs, laminates, metal foil-covered laminates, and printed wiring boards prepared using the same have higher boron nitride addition, high thermal conductivity, and high peel strength.

A composite material according to the present invention includes a solid portion including inorganic particles and a resin. The composite material has a porous structure including a plurality of voids surrounded by the solid portion. The composite material compressed by 10% has a reaction force of 0.1 kPa to 1000 kPa, and the composite material has a heat conductivity of 0.5 W/(m.Math.K) or more. The heat conductivity is a value measured for one test specimen in a symmetric configuration according to an American Society for Testing and Materials (ASTM) standard (ASTM) D5470-01.

The present invention is directed towards a powder coating composition comprising a binder; a thermally conductive, electrically insulative filler material; and, optionally, a thermoplastic material and/or a core-shell polymer. The present invention is also directed to a substrate comprising a coating layer deposited from the powder coating composition of the present invention, as well as methods of coating a substrate.