Study on the structure and adhesion of copper thin films on chemically modified polyimide surfaces

Upilex-s((R)) [BPDA-PDA, poly(biphenyldianhydride-p-phenylenediamine)] and 6FDA-ODA [4,4'-(hexafluoroisopropylidene)diphthalic anhydride-4.4'-oxydianiline] polyimide sheets were subjected to wet treatment using ethylenediamine (EDA) and hydrazine as the base. The results of wet treatment were evaluated in terms of elemental analysis (N/C atomic ratio) obtained using XPS as well as surface morphologies determined using AFM and SEM. Furthermore, a copper layer was deposited onto the modified surface via electroless plating. The adhesion strength between the copper layer and the modified surfaces was assessed by the tape-peel test. A large adhesion enhancement was achieved when copper was plated onto the modified surfaces of Pl sheets as compared to the untreated samples.