This book provides a comprehensive overview of important aspects of solder materials including solderability and soldering reaction, physical metallurgy, mechanical properties, electromigration, and reliability of solder joint. The scope of this book covers mainly, but not limited to, the important research achievements of all the subjects having been disclosed and discussed in the literatures. It is a very informative book for those who are interested in learning the material properties of solders, carrying out fundamental research, and in carrying out practical applications. This book is an important resource for the various important subjects relating to solder materials.