Coefficient of thermal expansion of encapsulants-is it always a constant?

The mismatch between encapsulants and the printed-circuit board, the components, and even the potting shell or can due to thermal expansion and contraction, particularly if the encapsulant expansion rate is not constant, is treated. The coefficient of thermal expansion (CTE) and glass transition temperature are defined. Problems that arise because not all CTE values are reported the same way or the wrong temperature was used are discussed. The more basic problems that occur because of a lack of understanding of what CTE is and what effects it are examined.<>