EFFECTS OF SURFACE MODIFICATIONS ON THE PEEL STRENGTH OF COPPER-BASEDPOLYMER-METAL INTERFACES WITH CHARACTERISTIC MORPHOLOGIES

This paper summarizes a study on the effect of changes in surface chem istry on the peel strength of copper/polymer interfaces. Two different surface topographies were created and evaluated, one produced by clea ning and etching in sodium persulfate, the other by etching then mecha nically roughening using 180 grit sandpaper. Both surfaces were then o xidized in an alkaline/oxidizing treatment to form cupric oxide. Ion i mplantation and benzotriazole priming modified the surface chemistry o f the cupric oxide samples. After lamination to form an epoxy/copper i nterface, peel strength measurements were taken. The results showed th at ion implantation degraded the peel strength while priming with benz otriazole improved the peel strength compared with the unmodified cupr ic oxide. In a separate comparison study, peel strength measurements w ere taken on interfaces formed from copper oxides with the same oxide structure but with widely different gross morphologies. ''As laminated '' adhesive strength was virtually the same. The bonded interfaces wer e aged at elevated temperature and the peel strength obeyed first orde r degradation kinetics. Two terms can be determined from the degradati on studies, the first is the long term peel strength, A(infinity), and the other is OMEGA, the degradation rate with units of time-1. A valu e of A(infinity) was 3.0 lbs/in for etched copper interfaces while A(i nfinity) was 0.5 lbs/in for the sanded interfaces.