Gives requirements for flexible polyimide films coated on one side or both sides with acrylic or epoxide type adhesive for use in the fabrication of flexible printed wiring. Films coated on only one side are used as a coverlay or covercoat in the fabrication of flexible printed wiring. This coverlay or covercoat is also used to provide local support to areas subjected to mechanical or environmental stress. Films coated on both sides are used as bonding films in the fabrication of printed boards.