Double-surface-silvered polyimide films prepared via a direct ion-exchange self-metallization process

Silver metallized polyimide films have been fabricated with excellent reflectivity and conductivity on both sides via a direct ion-exchange self-metallization technique utilizing 3,3', 4,4'-benzophenonetetra-carboxylic acid dianhydride/4,4'-oxidianiline (BTDA/4,4'-ODA)-based poly(amic acid) (PAA) films as the polyimide precursor and aqueous silver nitrate (AgNO3) solution as the silver origin. Silver polyamate was formed during the ion-exchange process. Heat treatment of the silver(I)-containing precursor films effects the cyclization of PAA and the simultaneous reduction of silver(I), giving silvered polyimide films. Surface reflectivity and conductivity were developed as a function of cure time and temperature and they were greatly associated with the variation of surface morphology. Property differences were exhibited on the upside and underside of the composite films. The final metallized BTDA/4,4'-ODA polyimide films maintained the essential mechanical and thermal stability of the pristine polyimide films. Films were characterized by FTIR-ATR, ICP, DSC, CA, XPS, XRD, and SEM, as well as reflectivity and conductivity measurements.