Experimental studies to understand the strain distribution on Printed Circuit Board under Thermal Cycling loading using Digital Image Correlation

This paper investigates to detect strain and displacement variations across a Printed Circuit Board Assembly under thermal cycling loading through Digital Image Correlation. Digital image correlation is a relatively new and significantly accurate technique for this kind of application. This is a full-field contactless optical measurement technique, that makes it considerably precise in measuring the strain distribution throughout the board as compared to other conventional techniques. The experimental set up uses a customized chamber made for such specific study wherein nitrogen is infused into the chamber to bring down the chamber temperature towards lower extreme at a faster rate. In this study thermo-mechanical properties of the board material i.e. Coefficient of Thermal Expansion, Glass Transition Temperature and Modulus of Elasticity have been analyzed. In addition, variations in strain in response to stepped temperature variations are also studied. Study concludes that impact on strain response due to thermal variation is significant.