Abstract
Polymer thin films were sputtered with two kinds of polyimide (PI) targets, pyromellitic dianhydride-oxydianiline (PMDA-ODA) and biphenyl dianhydride-p-phenylene diamine (BPDA-PDA), onto a copper substrate by a conventional RF sputtering with argon (Ar) and nitrogen (N2). These polymer thin films were characterized, and their adhesion and tribological properties were evaluated.
Sputtering rate of the polymer thin film with PMDA-ODA target (sputtered PMDA-ODA thin film) with Ar was higher than that with BPDA-PDA target. Although the sputtering rate of the polymer thin film with the BPDA-PDA target (sputtered BPDA-PDA thin film) with Ar showed highest value at a pressure of 5 mTorr, that with N2 showed highest value at a pressure of 60 mTorr. Nitrogen content in the sputtered BPDA-PDA thin film with N2 increased compared to that of the sputtered BPDA-PDA thin film with Ar and target material (pristine).
Although friction coefficients of these sputtered BPDA-PDA thin films with Ar were almost the same as those of the pristine PIs, that of the sputtered BPDA-PDA thin film with N2 was much higher than that of the pristine BPDA-PDA. The wear durability of the sputtered PMDA-ODA thin film with Ar was slightly higher than that of sputtered BPDA-PDA thin film. The wear durability of the sputtered BPDA-PDA thin film with N2 was much higher than that of the polymer thin film sputtered with Ar.
The adhesion strength between the sputtered BPDA-PDA thin film with N2 and copper substrate was higher than that between the thin film sputtered with Ar and copper substrate. In addition, the sputtered BPDA-PDA thin film with N2 was introduced between the copper substrate and the sputtered BPDA-PDA thin film with Ar (Ar/N2 laminate). The adhesion strength of this laminate was higher value than that between the sputtered BPDA-PDA thin film with Ar and copper substrate.
Acknowledgments
The authors would like to thank Mr. Itsuo Nishiyama of DAIPLA WINTES CO. LTD for adhesion strength measurement of sputtered thin films with SAICAS.