High-lead content solders are primarily being employed for high-temperature soldering. Public awareness of environmental issues including the use and disposal of potentially toxic materials has never been greater, with lead being the subject of particular scrutiny. This work outlines the criteria for the evaluation of a new high-temperature lead-free solder material with the focus on solidification, surface tension, natural radius of curvature, oxidation and corrosion resistances and environmental oriented issues. This work also reviews the alternative technologies for replacing the high-temperature soldering, since it was determined that even the expensive candidate alloys involving gold too could not cover the spectrum of required properties, for being accepted as a standard soft solder for high-temperature applications. It is hoped that this book can serve as a valuable source of information to those interested in environmentally conscious electronic packagings.