Print Email Facebook Twitter Modeling nonlinear moisture diffusion in inhomogeneous media Title Modeling nonlinear moisture diffusion in inhomogeneous media Author Chen, Liangbiao (Lamar University) Zhou, Jiang (Lamar University) Chu, Hsing-wei (Lamar University) Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials) Fan, Xuejun (Lamar University) Date 2017 Abstract While moisture diffusion in microelectronic device and packaging has been studied for decades, the problems involving complex nonlinear moisture diffusion in multi-material assembly have not been fully studied. This paper has developed a general nonlinear diffusion model by adopting water activity, a continuous state variable, as the field variable. The generalized solubility is introduced, which is temperature- and water activity-dependent. The effective diffusivity is defined and derived in terms of generalized solubility and water activity. By comparing the water activity-based model with the existing various normalized models, the present theory can unify and generalize the current approaches. More importantly, the present model can solve both linear and nonlinear moisture diffusion in inhomogeneous material system without normalization. The commercial finite element software has been applied to solve the nonlinear generalized moisture diffusion problem using the analogy of water activity and temperature. A source code of user-defined subroutines in ABAQUS has been provided in the Appendix of the paper. The mathematical formulation and the numerical implementation method presented in this paper can be applied to any nonlinear sorption or diffusion problems in inhomogeneous material system. Subject Electronic packagingMicroelectronicsMoisture diffusionMulti-material systemsNonlinear sorption isothermWater activity To reference this document use: http://resolver.tudelft.nl/uuid:8405475a-3ea1-498f-9d63-6b1d2a089ab5 DOI https://doi.org/10.1016/j.microrel.2017.06.055 Embargo date 2019-08-10 ISSN 0026-2714 Source Microelectronics Reliability, 75, 162-170 Bibliographical note Accepted author manuscript Part of collection Institutional Repository Document type journal article Rights © 2017 Liangbiao Chen, Jiang Zhou, Hsing-wei Chu, Kouchi Zhang, Xuejun Fan Files PDF 44919844_Chen_new_diffusi ... eprint.pdf 1 MB Close viewer /islandora/object/uuid:8405475a-3ea1-498f-9d63-6b1d2a089ab5/datastream/OBJ/view