Here is further information on Pb-Free Soldering and Tin Whiskers, at the bottom of this Advanet Japan web page. Of course, the main reason for this company and so many others to move to Pb-free is "global regulation of Pb," as opposed to Pb-free solder being "the best engineering materials choice for electronics use." So if you decide to go with Pb-free solder, keep in mind that Whiskers can be a problem depending on the solder point spacing, and extra heat will be required.