Surface modification of plasma-pretreated high density polyethylene films by graft copolymerization for adhesion improvement with evaporated copper

Surface modification of Ar plasma-pretreated high density polyethylene (HDP E) film via UV-induced graft copolymerization with glycidyl methacrylate (G MA) and 2-hydroxyethylacrylate (HEA) was carried out to improve the adhesio n with evaporated copper. The surface compositions of the modified HDPE sur faces were characterized by X-ray photoelectron spectroscopy (XPS). The adh esion strengths of evaporated copper with the graft-copolymerized HDPE film s were affected by the Ar plasma pretreatment time, the monomer concentrati on used for graft copolymerization, and the graft concentration. Post-treat ments, such as plasma post-treatments after graft copolymerization and ther mal treatment (curing) after metallization, further enhanced the adhesion s trength of the Cu/HDPE laminates. The T-type peel strengths of the laminate s involving the graft-modified and plasma posttreated HDPE films were great er than 15 N/cm. The enhanced adhesion strength resulted from the strong af finity of the graft chains for Cu and the fact that the graft chains were c ovalently tethered on the HDPE surface. XPS characterization of the delamin ated surfaces of the Cu/HDPE laminates revealed that the failure mode of th e laminates with T-peel adhesion strengths greater than 5 N/cm was cohesive in nature.