Abstract
Copper sputtered polyimide films with very high heat resistance have been successfully made with a newly developed DC sputtering system with RF substrate bias (Roll to Roll) . The room temperature peeling strength was over 2.0kg/cm and after heating at 260°C for 30 minutes, it remained greater than 1.5kg/cm. The copper was sputtered to various kinds of polyimide materials and the best conditions and atmospheres for continuous production were determined. As many reseachers have pointed out, the existence of chromium at the interface (several hundred angstroms) between the copper and the polyimide layer increases its peeling strength and stability. The copper/polyimide interlayer and the surface of the sputtered films were observed using SEM. Because of the absence of the adhesive layer between the copper and polyimide layer, the clad films had very high heat resistance and very low dielectric constant. Moreover the polyimide layer can be etched with chemical reagents, increasing its versatility to make different printed circuits and electronic components.They were used to make special FPCs and TABs such as double sided TABs with viaholes, photodiode chip carriers, double sided microcoils, COF (chip on flexible printed circuits) and special nets for TV masks.
