Effects of Catalyst Deposition on Adhesion Between Electroless Ni-P Films and Polished Sapphire Substrate

Abstract

The effects of the catalyst deposition on the adhesion between electroless Ni-P film and polished sapphire substrate were investigated with AFM, XPS and SEM. The adhesion strength was measured with the direct pull-off test. It was found that the adhesion strength was affected by the dispersed state of catalyst. The higher the dispersed state of the catalyst, the stronger the adhesion achieved. In order to explain the difference in adhesion strength, the fracture surfaces of samples were analyzed with XPS. This analysis showed that Sn was present on both sapphire fracture surface and NiP fracture surface. Therefore, it was considered that fracture took place through the Sn layer. It was concluded that the catalyst deposition condition was one of the most important factors in improving the adhesion strength between electroless Ni-P films and polished sapphire substrates.