Comparative study on physical and electrochemical characteristics of thin films deposited from electroless platinum plating baths

Physical and electrochemical properties of deposits obtained from two types of electroless platinum plating bath were investigated. One bath contained hydrazine as the reducer and lead monoxide as the stabilizer (HYD bath), and the other contained sodium borohydride (SBH) as the reducer and sodium thiosulfate as the stabilizer (SBH bath). The deposit obtained from the SBH bath had a high electric resistivity (6.0 × 10− 5 Ω cm), large tensile stress (421 MPa at 0.3 μm thickness) and rough surface (Ra = 19.2 nm) compared to HYD bath. Approximately 5 times more gas emission from the SBH bath was confirmed during electroless plating than HYD bath. The hydrogen emission during plating affected the physical properties of the resulting deposit and explained the rougher surface of platinum films from the SBH bath. The CV measurement using the deposits as the working electrode also correlated with surface area. Less than 0.5 wt% of sulfur inclusion deriving from the stabilizer into the SBH bath deposit did not affect the surface roughness or electrochemical properties.