Lead-free PCBs may run into assembly problems

Comments by an engineer from printed-circuit-board (PCB) manufacturer, Exception PCB, suggest that replacing a leaded PCB with a RoHS compliant version is not enough to produce an effective and compliance product. “While a designer may be right to tick the ‘compliance required’ box on his submitted drawings, we are aware of instances where adopting the letter of the law and blindly adopting lead-free solders in isolation would be product suicide,” says Andy Hughes, a technical engineer from Exception PCB in an article on the Website, PCB 007.

Hughes notes that the laminates are the problem with lead-free PCBs. “Laminates – even those that pass the stringent FR4 test for quality – are generally unable to withstand the much higher temperatures required to work with lead-free solders. Hence, designers looking for the best quality boards – the FR4 standard laminates – would find their RoHS compliant PCBs suffering from the effects of Z axis expansion during assembly as well as potential board decomposition.” Hughes goes on to note that “Even if the boards survive the assembly process, the potential for failure in the field is vastly increased.”