IPC-2221

7.3.2 Thermal Transfer

Components, which for thermal reasons require extensive surface contact with the board or with a heatsink mounted on the board, shall be compatible with or protected from processing solutions at the conductive interface.

IPC-2221

7.3.3 Thermal Matching

A primary thermal concern with through-hole mounted glass components and with ceramic surface-mounted components is the thermal expansion mismatch between the component and the printed board. This mismatch may result in fractured solder joint interconnections if the assembly is subjected to thermal shock, thermal cycling, power cycling and high operating temperatures.

IPC-2221

7.3.3 Thermal Matching

The number of fatigue cycles before solder joint failure is dependent on, but not limited to, the thermal expansion mismatch between the component and the printed board, the temperature excursion over which the assembly must operate, the solder joint size, the size of the component, and the power cycling that may cause an undesirable thermal expansion mismatch if a significant temperature difference exists between the component and the board.