| 摘要 |
PROBLEM TO BE SOLVED: To provide a foam and a foam substrate, which are made of a thermoplastic resin, are excellent in solder heat resistance, have small foam diameters, and have a low dielectric constant and a method for producing them. SOLUTION: The foam is obtained by foaming a thermoplastic resin molded product, which has a glass transition temperature of 240°C or higher and an average foam diameter between 0.01 and 10μm. The method for producing foam with a glass transition temperature of 240°C or higher comprises causing a thermoplastic resin molded product to come into contact with a non-reactive gas for permeation under pressure, reducing the pressure, and then foaming the product via heating and softening thereof to obtain the foam. COPYRIGHT: (C)2007,JPO&INPIT |
