| 摘要 |
PURPOSE:To improve dimensional stability or the like of a printed wiring material by bonding a metallic conductor foil and at least two polyimide resin layers directly to each other, and incorporating an inorganic insulating powder in at least one of the polyimide resin layers. CONSTITUTION:One solution of a polyamide acid varnish, a polyimide varnish and solutions prepared by dispersely mixing an inorganic insulating powder in these varnishes is applied directly to a metallic conductor foil 1, followed by drying to provide a polyamide acid film or polyimide film 2 as a first layer. A solution other than the above is applied to the film 2, followed by drying to provide a polyamide acid film or polyimide film 3 as a second layer, thereby producing a multilayer flexible printed wiring material. The metallic conductor foil may be, for example, a foil of copper, aluminum or nickel. The inorganic insulating powder may be, for example, a powder of alumina, silicon nitride, silicon dioxide or talc. |
