Desmear and Plating Through Hole Considerations and Experiences for Green PCB Production

摘要

With the latest legislations from RoHS and WEEE dominating the horizon of the PCB landscape there is a need for manufacturers and their suppliers to understand their impacts. The requirement to remove lead from the industry and therefore the need for lead-free soldering operations means a large amount of stress is placed on the PCB substrates. The laminate material suppliers are responding to the new legislation by introducing newer varieties of materials that have better heat stress handling capacities as well as some added benefits like reduced z-expansion. Another concern for the laminate manufacturers is the need to remove halogen based, flame retardants like bromine from their resin systems. This paper will discuss the relevant legislations and the impact of these on the desmear and plating through hole processes. We will introduce and discuss the changes that are taking place in the laminate materials sector needed to meet the newer requirements. We will discuss the most significant advances in the halogen free as well as Pb-free capable materials. The significance of the changes and their influence on the desmear and PTH processes will be highlighted. Test results from investigations and experiences with the newer materials will be presented and compared to results normally found for the more standard materials. We will propose options for handling the various issues arising from these new materials and so help to prepare PCB manufacturers for the coming turbulence in the industry being generated by the new legislative demands.