Introduction: This document provides PCB designers with a set of guidelines for successful board mounting of Atmel surface mount packages. Package Land Pattern descriptions are depicted by the package family, and although each family is represented by a single body size and lead count, the individual land description apply to all packages within a particular family. Land Pattern descriptions were provided by IPC-7351 Calculator from the Mentor Graphics Corporation. These are only general guidelines that Atmel received from the IPC-7351 Calculator. The solder reflow guidelines are derived from IPC -9502. Atmel does not make direct recommendation for board design, nor does it take legal liability and responsibility for the information in this document. Please refer to the IPC website for more information regarding board design and processing.