Lead-free soldering is demanded after 1-6-2006. Today many companies are in the transition stage going from tin-lead solder to lead-free solder; however, not all components are yet available with a lead-free lead finish.
This raises the question: "What can be used for which process?"
This article gives a brief overview of the arguments as to why some mixes are allowed and others are not recommended.
See attached for complete article.