Aging effect on adhesion strength between electroless copper and polyimide films

Abstract

The effect of atmospheric aging on the adhesion strength between electroless copper and polyimide films was investigated. 100nm thick electroless copper was plated on polyimide film and 10μm of copper electroplating was performed successively. Aging was allowed to occur at room temperature in atmosphere for designated times: either between electroless deposition and electroplating or between electroplating and the peel test. The adhesion strength between copper and polyimide film increased and then saturated as aging progressed for about 1 d, with rapid increase from 0.2 to 0.5 d. Among the samples with equivalent total aging time, samples that were electroplated later showed higher adhesion strength. Inter-diffusion and chemical bonding between copper and polyimide were observed after aging and additionally applied electrical current increased the adhesion strength. It could be suggested that the atmospheric aging and additionally applied current enhance the interdiffusion and the chemical bonding between electroless copper and polyimide film. © 2013 The Japan Institute of Metals and Materials.