Fabrication of selective electroless copper plating on PET sheet: Effect of PET surface structure on resolution and adhesion of copper coating

A easy method to prepare selective copper coating on polyethylene terephthalate (PET) surface via writing activated solution on primer-modified PET sheet combined with electroless plating is demonstrated, the effects of PET surface structure on resolution and adhesion of copper coating were investigated. Results showed that the PET sheet modified with different primer (SiO2 particles-emulsion mixed liquors) could adsorb the stannum(II) and silver ions, which used as catalyst for selective electroless copper plating. When the SiO2 content increased from 0% to 10%, average surface roughness value, Ag-adsorption capability, plated coating thickness and adhesive force of thick plated coating were enhanced, surface resistivity was decreased, but resolution of activated coating was firstly enhanced and then reduce. The average roughness value was measured to be 12 μm for PET sheet modified with 6% SiO2-primer, resulting in good wettability and high resolution simultaneously. The region-selective copper coating could plate on PET surface and through hole, leading to a high conductivity of both sides. The plated coating was a composite of continuous layer of copper and randomly scattered SiO2 particles, resulting in a better adhesion of the copper coating. The minimum width of copper line was about 250 μm and the thickness of copper coating was 2.4 μm, surface resistivity was 8.6 × 10−6 Ω cm. No matter how the region-selective plated PET sheet was compressed or stretched, even for folded sheet, conductivity and mechanical properties were not affected.