Mechanical testing of thin polymer films

Package designers need reliable mechanical data of packaging materials at a variety of temperatures in order to predict stress distribution and to make long term predictions on package reliability. It is generally assumed that coefficients of thermal expansion and modulus data of metals and ceramics do not depend on the film thickness of these materials. The same, however, does not hold true for polymers. This poses several questions: How strong is the dependence of thermo-mechanical properties on film thickness? How well can these properties be measured? Do all polymers behave similarly? This paper explores some of these issues.