A precision capacitance cell for measurement of thin film out-of-plane expansion. II. Hygrothermal expansion

Abstract

The data reduction techniques necessary for utilizing the capacitance cell described previously by us for thickness measurements [C. R. Snyder and F. I. Mopsik, Rev. Sci. Instrum. 69, 3889 (1998)] in a humid environment are presented. It is demonstrated that our data reduction techniques provide thicknesses that are equivalent to those measured under dry conditions within the expected experimental uncertainty. The utility of this technique is demonstrated by the measurement of the hygrothermal expansion (swelling) of a bisphenol-A based epoxy with novolac hardener and fused silica filler. Our technique is shown to have a higher sensitivity than most current thermomechanical analysis techniques and is readily amenable to humid conditions.