Measurement of the Hygroscopic Swelling Coefficient of Thin Film Polymers Used in Semiconductor Packaging

An advanced method based on the digital image correlation technique is implemented for characterization of hygroscopic swelling of thin film polymers. The accuracy of the proposed method is experimentally validated through a comparison with the well-established Moiré interferometry technique. It is applied to various thin film polymers, including polyimide, solder resist, anisotropic conductive film, and thin woven glass/resin composite. The magnitude of hygroscopic swelling coefficients ranges from 0.067 to 0.25%strain/%wt for those films. A practical guideline for specimen preparation and experimental setup is provided for proper implementation of the proposed method.