Board and system level effects on plastic package thermal performance

The objective of this work is to understand the effect of the board/system environment on package thermal performance. It is found that for most plastic packages and in typical application environment, the majority of heat is conducted to the board. The junction to ambient thermal resistance can be obtained by the package thermal resistance and board thermal resistance. For a particular package, as the board and system environment changes, the package thermal resistance does not change, what changes is the board resistance. Thermal enhancement can be achieved in board and system level in additional to package level. The board and system act as the system heat sink. The thermal resistance of this heat sink is represented by the board to ambient thermal resistance. In this study, the sensitivity of the board thermal resistance to different parameters is examined by simulation. These parameters include: package size and placement, board construction and mounting, and the component interaction. It is suggested that by carefully designing the board and system, the optimal thermal performance can be reached