Abstract: Provided are a vapor chamber that makes it possible to inhibit a temperature rise of a semiconductor element by efficiently transport heat generated from the semiconductor element, and a semiconductor package including the vapor chamber. By using a vapor chamber including a thermal diffusion member (2) that has thermal conductivity of not less than 500 W/mK in a planar direction perpendicular to a first outer surface and/or a second outer surface of a chamber body (1) that contains a liquid material in a hermetic space therein, it is possible to inhibit a temperature rise of a semiconductor element provided on the thermal diffusion member.

Abstract: An object is to provide a graphite sheet having excellent peelability from a slightly adhesive film. The object is attained by a method for producing a graphite sheet having a thermal diffusivity of not less than 8.0 cm2/s and an interlaminar strength of not less than 100 gf/inch, the method including the step of heat-treating a polyimide film to a temperature of not lower than 2,400° C., the polyimide film containing: not less than 0.05% by weight and not more than 0.30% by weight of inorganic particles; and a non-metal additive containing not less than 0.055% by weight and not more than 0.097% by weight of phosphorus.

Abstract: An object is to provide, with high productivity, a graphite sheet having good thermal diffusivity and interlaminar strength. The object is attained by a method for producing a graphite sheet having a thermal diffusivity of not less than 10.0 cm2/s, the method including the step of heat-treating a polyimide film to a temperature of not lower than 2,800° C., the polyimide film containing: not less than 0.01% by weight and not more than 0.08% by weight of inorganic particles; and a non-metal additive containing not less than 0.018% by weight and not more than 0.032% by weight of phosphorus.

Abstract: A graphite sheet can be combined with a base even without the need for use of an adhesive. A surface layer porous graphite sheet includes: a graphite layer and a porous layer arranged on one or both surfaces of the graphite layer. The porous layer has pores having a pore diameter X that is measured on a surface of the porous layer and pores having a pore diameter Y that is measured inside the porous layer and that is larger than the pore diameter X. A porosity in a cross section of the surface layer porous graphite sheet satisfies a predetermined condition.

Abstract: In the present invention, (i) a polyamic acid solution for forming a thermoplastic polyimide layer to be in no contact with a support contains no chemical dehydrating agent or imidization catalyst, (ii) a polyamic acid solution for forming a thermoplastic polyimide layer to be in contact with the support contains an imidization catalyst, and (iii) a polyamic acid solution for forming a non-thermoplastic polyimide layer contains a chemical dehydrating agent and an imidization catalyst. This arrangement eliminates a property difference between the thermoplastic polyimide layers.

Abstract: In the present invention, (i) a polyamic acid solution for forming a thermoplastic polyimide layer to be in no contact with a support contains no chemical dehydrating agent or imidization catalyst, (ii) a polyamic acid solution for forming a thermoplastic polyimide layer to be in contact with the support contains an imidization catalyst, and (iii) a polyamic acid solution for forming a non-thermoplastic polyimide layer contains a chemical dehydrating agent and an imidization catalyst. This arrangement eliminates a property difference between the thermoplastic polyimide layers.

Abstract: Provided are a multilayer polyimide film that hardly suffers from the peeling of the layers from each other or the clouding of a space between the layers (turning white in color) during heating at a high temperature and a flexible metal-clad laminate using such a multilayer polyimide film. This object can be attained by a multilayer polyimide film having a thermoplastic polyimide layer on at least one side of a nonthermoplastic polyimide layer, wherein at least 60% of the total number of moles of an acid dianhydride monomer and a diamine monomer that constitute the thermoplastic polyimide is the same type of monomer as at least one type of acid dianhydride monomer and at least one type of diamine monomer that constitute the nonthermoplastic polyimide.

Abstract: The present invention provides a method and an apparatus for producing a polyimide molding which have superior productivity and accuracy of dimension. The invention particularly relates to a tubular polyimide applicable to an electrophotographic device, such as a laser-beam printer and a copying machine, or a precision driving belt required for high strength and high dimensional stability.