Abstract: A polyimide fiber paper-manufacturing method is provided that includes a short fiber-preparing step in which shaved short fibers of a non-thermoplastic polyimide are prepared, and a provisionally-bonded paper-forming step in which the short fibers are mixed with water-soluble polymers which are a material having a decomposition temperature lower than a glass transition point of polyimide, and subjected to wet-papermaking to form provisionally-bonded paper.

Abstract: A polyimide fiber paper-manufacturing method is provided that includes a short fiber-preparing step in which shaved short fibers of a non-thermoplastic polyimide are prepared, and a provisionally-bonded paper-forming step in which the short fibers are mixed with water-soluble polymers which are a material having a decomposition temperature lower than a glass transition point of polyimide, and subjected to wet-papermaking to form provisionally-bonded paper.

Abstract: To provide a coverlay for a high-frequency circuit substrate, that uses polyimide film and fluororesin, has excellent mechanical properties and heat resistance, and can increase workability during the manufacture of high-frequency circuit substrates. Resolution Means: The coverlay for a high-frequency circuit substrate including a polyimide film and a fluororesin bonded together, and an adhesive strength between the polyimide film layer and the fluororesin layer being greater than 3.0 N/cm.

Abstract: A polyimide film with advantageous handleability, flexibility, dimensional stability and heat resistance is provided. The polyimide film is characterized by block-copolymerizing an aromatic diamine component comprising 10˜25 mol % of paraphenylenediamine (a1) and 75˜90 mol % of 4,4?-diaminodiphenyl ether (a2) with an aromatic tetracarboxylic acid component consisting of 75˜99.9 mol % of pyromellitic acid dianhydride (b1) and 0.1˜25 mol % of 3,3?,4,4?-biphenyl tetracarboxylic acid dianhydride (b2). The Young's modulus, linear expansion coefficient, water absorption rate and glass transition temperature of such polyimide films can be controlled within very useful ranges.

Abstract: The method of manufacturing a heat exchanging fin is able to restrict forming wrinkles and ring marks in the heat exchanging fin. The method comprises the steps of: forming dome sections having diameters greater than the diameters of collared-through-holes and which are projected from one side face of a thin plate, and a plurality of circular recesses having diameters greater than of the dome sections, each of which encloses one of the dome sections, the circular recesses being depressed toward the opposite face of the thin plate; forming the dome sections and the recesses into truncated cone-shaped sections in a plurality of steps; forming a through-hole in each of the truncated cone-shaped sections; forming edges of the through-holes into collars; and forming a flange at a front end of each of the collars.

Abstract: The method of manufacturing a heat exchanging fin is able to restrict forming wrinkles and ring marks in the heat exchanging fin. The method comprises the steps of: forming dome sections, whose diameter is greater than that of collared-through-holes and which are projected from one side face of a thin plate, and a plurality of circular recesses, whose diameter is greater than that of the dome sections and each of which encloses each of the dome sections and are depressed toward the other face of the thin plate; forming the dome sections and the recesses into truncated cone-shaped sections in a plurality of steps; forming a through-hole in each of the truncated cone-shaped sections; forming edges of the through-holes into collars; and forming a flange at a front end of each of the collars.