At APEX 2007 Indium Corp's Dr. Ning-Cheng Lee and I were interviewed by PCB007 Re China RoHS. Dr. Lee discussed the "Chinese" lead-free alloys that contain 0.03 to 0.05% Cerium. Chinese researchers claim that this small amount of cerium improves wettability and mechanical properties of lead-free alloys. This is a topic that I admit I knew little about. Click here to see the taped interview.
I was surprised to learn, that although Cerium is classified as a rare earth element it is more common in the earth's crust than lead and not very expensive.