INTERFACIAL REACTIONS BETWEEN ALUMINUM AND BPDA-PDA

Interaction of evaporated aluminum with BPDA-PDA polyimide surfaces ha ve been studied using x-ray photoelectron spectroscopy. At low coverag e, aluminum reacts primarily with carbonyl groups as in the PMDA-ODA a nd also diffuses into the polyimide substrate to react with inner carb onyls. No trace of metal clusters are detected in the initial metalliz ation. When the covering rate becomes somewhat higher, additional inte rfacial reactions occur, involving the formation of N-Al and C-Al bond s. In general, the chemical interactions of Al at BPDA-PDA and PMDA-OD A are similar. It is suggested that the observed difference in adhesio n strength between the two polyimides comes from the diamine moiety (P DA and ODA). In the PMDA-ODA the macromolecules can rotate around the ether function which is not the case in the BPDA-PDA where the conjuga tion makes the macromolecule more rigid. Thus the difference in adhesi on may be attributed to the chain conformation of polyimide.