Optimisation of electroless nickel electroless palladium immersion silver (ENEPImAg) surface finish parameters using the Taguchi method for enhanced solder joint reliability

Purpose Palladium (Pd) is now more commonly used in electronic products because of its numerous benefits, particularly its ability to improve solder joint reliability. Due to its advantages, this study aims to focus on optimising a new surface finish known as electroless nickel electroless palladium immersion silver (ENEPImAg) to reduce surface roughness. Design/methodology/approach The optimisation process used the Taguchi method, using an orthogonal array and analysis of variance (ANOVA) to evaluate the effectiveness of various parameters on the surface finish. The microstructural characteristics were examined by field-emission scanning electron microscopy and X-ray diffraction. Findings The optimal conditions for achieving minimal surface roughness were identified as follows. Electroless nickel : pH = 4.5, temperature = 85 and time = 20 min. Electroless palladium : pH = 8, temperature = 35 and time = 10 min. Immersion silver : pH = 7, temperature = 35 and time = 5 min. ANOVA revealed that temperature (ImAg) and deposition time (EP) significantly affected surface roughness. Additionally, the intermetallic compound (IMC) thickness for NAC305/ENEPImAg was found to be thinner (0.6 µm) than that of SAC305/ENImAg (1.6 µm), which correlates with improved solder joint quality. Originality/value This research presents a novel approach to developing and optimising the ENEPImAg surface finish, which integrates nickel, palladium and silver layers. This combination enhances solder joint reliability and offers a viable alternative to traditional finishes used in electronic manufacturing.