Abstract
In this work, we pioneer to develop a process that combines a novel polymer-capped Pd nanoparticle as the catalyst in ELP and a special surface treatment which is able to create micro-craters on surface but without largely increasing surface roughness. Specifically, the catalyst agent was synthesized in the laboratory. We synthesized 2-5 nm Pd nanoparticles using polyvinyl alcohol (PVA) as the protecting agent in water. The PVA-Pd activator then work with a novel amine-based surfactant (polyethylenimine, PEI) via a molecular interaction between Pd core and amino-moieties on PEI. Due to this interaction, the adhesion of resultant ELP Cu on substrate is significantly enhanced. T-Peel adhesion of ELP Cu is further enhanced by applying a special surface roughening. This special surface treatment modifies traditional potassium permanganate desmear process but omitting swelling step in order to maintain the backbone structure of PID while mildly sculptures the surface to form micro-craters. Evaluated by water contact angle (WAC), scanning electron microscope (SEM) and surface profiler (alpha step), average T-peel adhesion of ELP-Cu on PID is enhanced from 185 to 571 gf/cm using this process. We believe this process paves a bright way for next generation SAP in advanced PCB application.