Q14: Re-plating lead-free components for tin/lead assembly We work with an aerospace manufacturer on a PCB assembly that includes Pb-free components (no BGAs). The device is processed using SnPb (60-40) solder, but this does not solve the issue of Sn plating on the leads and the risk of tin whiskers. According to information on this website http://nepp.nasa.gov/whisker/ tin whisker formation is an issue on the exposed component leads outside of the solder region. Is there a process that can be used to re-plate component leads to add Pb?

As you are an aerospace manufacturer you may be conformally coating the boards.

If so, you may be interested to know that HumiSeal has just completed a study with the NPL (National Physical Laboratory) into the interaction between tin whiskers and conformal coating.

Results show that conformal coatings will abate tin whisker growth and although various conformal coating chemistry types perform in different ways with tin whiskers, they all abate growth.

Please contact us if you would like full information on this project.

Wednesday, 10th March 2010