Determination of an effective coefficient of thermal expansion of electronic packaging components: a whole-field approach

Abstract

Moire interferometry is proposed as a tool for the coefficient of thermal expansion (CTE) measurement of electronic packaging components. The method is a whole-field displacement measurement technique with a sub-micron sensitivity, which can produce the overall CTE and the local CTE across the entire component with high accuracy. The large dynamic range of the method makes it compatible with CTE evaluation of a broad range of components. Two experimental procedures are suggested for 1) CTE over a fixed temperature range and 2) CTE as a function of temperature. The procedures are implemented for various thin small outline packages (TSOPs) a plastic ball grid array (PBGA) package, and a stacked memory cube. The results emphasize the importance of a whole-field measurement technique. A supplementary thermo-mechanical analyzer (TMA) test on an aluminum alloy is conducted and the results are compared with a Moire measurement to discuss the accuracy of the proposed measurement procedure.