Journal of the Microelectronics and Packaging Society

As the demand for high-performance electronic packaging continues to grow, glass interposers have emerged as a promising solution due to their excellent electrical insulation properties, low dielectric constant, and compatibility with high-density interconnections. However, the realization of a reliable seed layer on glass substrates remains a critical challenge, particularly in TGV (through-glass via) structures where conventional physical vapor deposition (PVD) techniques suffer from poor adhesion and high process costs. To overcome these limitations, electroless plating technology has been introduced as an alternative method that enables uniform metal deposition without requiring an external power source. This study systematically analyzes the feasibility and technical advantages of electroless plating for seed layer formation in glass interposers. Specifically, we compare Cu, Ni, and Ag electroless plating processes and evaluate various activation and surface modification techniques, including Pd-free catalytic layers, nano-silver activation, and silane-based adhesion promoters. Experimental results indicate that Pd-free Cu electroless plating provides high electrical conductivity while reducing material costs, Ni electroless plating offers superior corrosion resistance with improved adhesion through nano-silver catalysis, and Ag electroless plating achieves excellent conductivity while mitigating oxidation issues via silane functionalization. This study identifies electroless plating as a cost-effective alternative to PVD, enhancing adhesion and uniformity in TGV metallization.

Keywords Electroless plating, Glass interposer, Surface modification, Seed layer formation