Which Pb-free surface finish does IEC recommend for printed circuit boards?
IEC has done all of its development and qualification work using immersion silver and immersion gold (ENIG). I am converting an existing assembly to RoHS-compliance. Do I need to change my circuit board material? IEC recommends that you first check with your PCB fabricator and determine exactly what material is being used and if it meets the chemical definition of RoHS-compliance. Many fabrication drawings are not very specific, and just specify “FR4 or equivalent”. If your board material meets the RoHS definition (no banned substances above threshold levels) then it may be possible to keep using the same material. In general, if you have a relatively simple board (2-6 layers, 0.062 inch, non-challenging via aspect ratios) you may want to build some prototypes to evaluate the existing material before you change. If you have a moderate to highly complex PCB, or are creating a new design, IEC recommends that you select one of the board materials that were developed specifically for use w
