Improved adhesion property and electromagnetic interference shielding effectiveness of electroless Cu-plated layer on poly(ethylene terephthalate) by plasma treatment

To develop high-quality electromagnetic interference (EMI) shielding materials, the effect of plasma pretreatment with various gases prior to Cu plating was investigated. Plasma treatment increased the surface roughness in the decreasing order of Ar > O-2 > NH3, but adhesion of the Cu layer on poly(ethylene terephthalate) (PET) film increased in the following order of O-2 < Ar < NH3, indicating that the appropriate surface roughness and introduction of an affinitive functional group to Pd on the surface of the PET film were key factors for improving adhesion of the Cu layer. As investigated by XPS analysis, plasma treatment with NH3 produced N atoms on the PET film, which enhances the chemisorption of Pd2+ on PET film, resulting in improved adhesion and shielding effectiveness of the Cu layer deposited on the Pd-catalyzed surface, because of the high affinity of Pd2+ for nitrogen. Comparatively, 0, plasma treatment allowed the chemisorption of more Sn2+ than of Pd2+ due to a lack in the affinity of Pd2+ for oxygen, resulting in the lowest Pd-3d/Sn-3d ratio; thereby, the lowest EMI-shielding effectiveness (SE) value was obtained. In addition, fairly low adhesion was obtained with Ar plasma-treated PET, even though the PET surface was significantly etched with Ar plasma, due to introduced oxygen groups on the PET surface. (C) 2002 Wiley Periodicals, Inc.