X-RAY PHOTOELECTRON-SPECTROSCOPY INVESTIGATION OF INTERFACIAL INTERACTIONS IN THE CR BPDA-PDA AND TI BPDA-PDA SYSTEMS

Interfacial interactions of evaporated chromium and titanium with BPDA -PDA polyimide surfaces have been studied using x-ray photoelectron sp ectroscopy. The results reveal two stages in the metallization process . At low coverage, the behavior is dominated by the reaction of metal with the C=O function, as in the case of PMDA-ODA polyimide. The nitro gen atoms are slightly perturbed following the C=O attack. At relative ly higher coverage, additional interfacial reactions occur, involving the formation of chromium and titanium carbides and nitrides. The resu lts indicate clearly that the chemical interactions of Cr or Ti at BPD A-PDA and PMDA-ODA surfaces are quite similar. Thus, the diamine porti ons, PDA and ODA, can affect the adhesion strength, probably by modify ing the polyimide chain conformation. In PMDA-ODA, the polyimide chain is flexible and can rotate around the ether oxygen, while in the BPDA -PDA the conjugation effect is more important and makes the macromolec ules more rigid. This is most probably the way by which PDA and ODA se gments can influence the adhesion performance of polyimide.