How does Pb-Free Affect Design/Layout?
The advent of Pb-free manufacturing is having an impact on PCB design layout. In general, design rules for PB-free soldering are similar to tin lead soldering. Bringing up the netlist, making physical aspects of components or footprints, assuring component connections are correct, making board thickness calculations for impedance control or dielectric constant calculations generally do not change. When design layout is performed and Pb-free assembly is involved, the main concern is the physical footprint on the board. If component packaging is manufactured to withstand the higher temperature for Pb-free assembly, then there is no change in the footprint and consequently, no change in the layout. However, there can be exceptions and in these instances, it is prudent for the OEM designer to consult with a knowledgeable EMS provider to minimize issues and concerns regarding the Pb-free impact on design. For example, SMT component selection can be classified as a hardware issue, but it can
