Effects of temperature/humidity treatments on the peel strength of CuCr alloy films on polyimide

Abstract

A single layer of CuCr alloy was sputter deposited on polyimide films instead of Cu/Cr double layers. The adhesion strengths of the metal/polyimide thin films were measured by the peel test. In order to study the effects of temperature and humidity on the adhesion strength, 85 degrees C/85% R.H. (T/H) treatments were applied to the specimens. Results showed that the peel strength without T/H treatments increased proportionally with the Cr content in the CuCr alloy layer (x) up to 17 at %, and then saturated. Among the samples studied, the peel strength decreased with hold time under T/H conditions for all the cases, but most drastically for the sample with x = 8.5. The very poor peel strength of that sample (x = 8.5) was attributed to the occurrence of interfacial failures, which were thought to take place along CuCr oxide/polyimide interfaces.