MEASUREMENT OF THE HYGROSCOPIC SWELLING COEFFICIENT IN MOLD COMPOUNDS USING MOIRE INTERFEROMETRY

An experimental method is proposed to characterize the hygroscopic swelling of mold compounds. The method utilizes moire interferometry, which measures in-plane displacements over a relatively large gage length with submicron measurement sensitivity. Deformations caused by the absorption of moisture in mold compounds are analyzed to determine the coefficient of hygroscopic swelling (CHS). The large gage length nullifies the pointto-point variation within the sample, and the high sensitivity provides the measurement accuracy required for the small hygroscopic deformation. Representative results obtained from a commercially available mold compound are presented.