Young's modulus of moulding compounds measured with a resonance method

Knowledge of Young's modulus is very important for understanding the mechanical behaviour of complex microelectronic devices. Polymeric materials like moulding compounds for device encapsulation are often changed in the production process and their Young's modulus depends strongly on the production and storage or ambient conditions. The Young's modulus is measured with the three-point bending test. This is very time and cost consuming and the change of Young's modulus due to environmental stress cannot be investigated on the same sample if progression of degradation is to be assessed. Therefore, a faster method would be of great interest. In this paper, we describe the applicability of the impulse excitation technique to measure the Young's modulus of moulding compounds non-destructively. This method has the advantage of being fast and having high accuracy and repeatability such that it could be applied to measure the change of Young's modulus during temperature and moisture storage in stress tests typical for semiconductor technology.