To provide a polyimide film excellent in laser processability excellent in a through-hole surface state and capable of forming a through-hole reduced in taper and almost vertical to the front and rear surfaces of the film by applying laser processing to the polyimide film of a flexible metal layer laminate, a substrate and a processing method.
A polyimide film excellent in laser processability comprises a highly heat-resistant aromatic polyimide, which contains a biphenyltetracarboxylic acid component as an aromatic tetracarboxylic acid component and has a glass transition temperature of 300°C or higher, as a principal constituent material. A metal layer is laminated on at least the single surface of the polyimide film through a polyimide resin layer having a low glass transition temperature of 200-375°C and having thermal contact bonding properties and/or flexibility to form a laminate and the polyimide film of the laminate is subjected to laser processing to form a through-hole almost vertical to the upper and rear surfaces of the film.
KATO KATSUZO
HOSOMA TOSHINORI
HASHIGUCHI SHUICHI
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