Form: This specification covers a polyester resin in the form of film clad on one or both sides with copper foil. Application: Primarily as a base material for fabrication of flexible printed wiring for electronic circuit applications to be operated between -65 and +105 C (-85 and 221 F). Classification: This specification covers two types of copper clad polyester film@ as follows; the type supplied shall be as specified on the drawing or purchase order: Type I- Copper clad on one face Type II- Copper clad on both faces