Process Optimization of Electroless Copper Plating for Printed Circuit Boards

Abstract

Due to the non-uniform copper deposition, through-hole metallization failure, high product defect rate, and insufficient high-frequency and high-speed signal transmission performance, this paper optimized the electroless copper plating process, including: swelling, desmearing, pre-neutralization, neutralization, hole-conditioning and degreasing, micro-etching, pre-dipping, activation, acceleration. The results showed that PCBs achieved 100% continuous coverage of electroless and electrolytic copper layers on via walls, with backlight ratings reaching Grade 10. Interfaces were well-defined, copper cross-sections dense and uniform, and via-wall coatings smooth and continuous with excellent corner coverage. Copper thickness was stable with CV ≤ 26.1% and TP up to 96.00%.