Surface modification of polymers and improvement of the adhesion between evaporated copper metal film and a polymer. I. Chemical modification of PET

To improve the interfacial adhesion between evaporated copper film and poly (ethylene terephthalate) (PET), the surface of PET films was modified by tr eating with hydrazine monohydrate. The effect of the treatment time in the range of 5-20 min with 80 wt% hydrazine monohydrate at 60 degrees C on the number of polar groups created on PET was investigated. The surface topogra phy of and water contact angle on the PET film surface, the mechanical prop erties of the PET film, and the adhesion strength of evaporated copper meta l film to the PET film surface were also investigated. The introduction of polar groups on the modified PET film surface was examined by FT-IR and ESC A analyses. The amount of polar groups increased to the maximum value with increasing treatment time to 10 min, and thereafter it decreased markedly. The surface roughness increased with increasing treatment time up to 10 min and cracks occurred after 20 min. The water contact angle and tensile prop erties decreased with increasing treatment time. Using the scratch test, th e adhesion between Cu film and PET was found to increase with increasing tr eatment time up to 10 min and thereafter there was a remarkable decrease in adhesion. From these results, it was concluded that the optimum treatment time with hydrazine monohydrate (80 wt%) at 60 degrees C was about 10 min t o improve copper-PET adhesion.