Method for electroless nickel plating on poly(ethylene terephthalate) substrate modified with primer and self-assembled monolayer

In this work, the electroless nickel plating on poly(ethylene terephthalate) (PET) surface was developed based on printing primer and then immersing in 3-aminopropyltriethoxysilane (KH550) solution. The mechanism of the surface activating and structural properties of nickel plating were investigated using Fourier transform infrared spectroscopy, Hall measurements, optical microscope and T-peel adhesion strength. Results showed the formation of crystalline Ni and Ni–P coatings on the pretreated PET surface. The surface electrical resistivity of nickel coating was reduced from 12.18 to 0.09 ohm cm, and the adhesion strength were 9.74–9.89 N/cm, when the deposited time increased from 1 to 30 min. The average electromagnetic interference-shielding effectiveness of nickel-plated PET sheets maintained a relatively stable value (38.4–37.5 dB) in a frequency range of 0.05–1.5 GHz. The electroless nickel plating was most possibly due to the formation of higher density of carboxyl groups and then graft copolymerization of amine groups onto the pretreated PET surface. Therefore, the pretreated PET surface was more prone to absorb tin sensitizer and palladium catalyst to form an active layer for electroless nickel plating.