Lead-free critical issues such as the RoSH (restriction of hazardous substances) directive, potential solder candidates, and patent issues will be discussed. Emphasis is placed on: (1) lead-free transitions such as forward in-compatibility and backward in-compatibility; (2) component surface finishes; (3) component reliability; (4) printed circuit board (PCB) surface finishes; (5) PCB reliability; and (6) lead-free solder joint reliability.