ABSTRACT
This chapter provides a brief overview of semiconductor packages used in surface-mount technology of printed circuit boards. Ball grid array packages, and area array packages in general, have several advantages over surface-mount packages with peripheral leads, beyond that of inputs and outputs density. The development of new and innovative package form factors is often accompanied by changes and difficulties beyond that of package development. The longer a semiconductor and its package will be required to be in service or how critical the application is, the more conservative the technology. Acceptable solder alloys not containing lead typically require peak reflow temperatures in the range of 30°C to 40°C higher than was needed with eutectic lead-tin solder. This elevated temperature exposure often means the old bill of materials, which worked well with eutectic tin-lead solder, will wither under thermal stresses and will be unable perform reliably, either resulting in infant or field failures.
