The use of modified oxide process for lead-free application

The laws legislated recently such as RoHs and WEEE restrain strictly the use of lead and cause the revolution in SMT soldering technology. Compared to the traditional tin-lead soldering, the reflow temperature of lead-free soldering is 30degC higher and the total thermal mass also increases. The tremendous change leads to large amount of panel scrap and compensation between PCB manufacturer and SMT house. Delamination is a common issue for base material manufactures after conducting lead-free soldering. It might be caused by the lamination material itself or the insufficient adhesion between resin and copper foil. In this study, we focus on the oxide pretreatment prior to lamination, and find the proper condition, including the properties of base materials and immersion duration in brown oxide bath, to enhance the adhesion between copper foil and resin to against the higher thermal shock.