IPC 4203B establishes the classification system, the qualification and quality conformance requirements for dielectric films coated with an adhesive on one or both sides. These materials are to be used as cover material for flexible printed circuitry as well as supported or unsupported adhesive films to be used in the fabrication of flexible printed circuitry. The standard does not address nonflexible adhesives designed to be used in the rigid board areas of rigid flex constructions which are addressed in IPC-4101. Materials such as liquid-applied covercoat are delineated in IPC-SM-840 and are excluded from this document. The requirements herein meet or exceed the requirements for Class 3 which, in turn, meet or exceed conformance to Classes 1 and 2.