An examination on the direct concentration approach to simulating moisture diffusion in a multi-material system

摘要: Abstract In 2009, Xie et al. proposed a diffusion simulation method called direct concentration approach (DCA), which aimed at solving moisture problems in electronic packages under transient temperature environment such as reflow process (“Direct Concentration Approach of Moisture Diffusion and Whole Field Vapor Pressure Modeling for Reflow Process: Part I — Theory Numerical Implementation,” ASME J. Electron. Packag., 131, p. 031,010). However, our study shows that although the DCA may give reasonably accurate results several circumstances, its relative error result can be high 10% one test cases. More importantly, generally leads to discontinuity flux bi-material interface, means violate law mass conservation. A theoretical derivation based on one-dimensional (1-D) case is presented demonstrate flaw using finite element formulation.