Changsoo Jang, Bongtae Han, and Samson Yoon
CALCE, Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, USA
We address moisture diffusion in epoxy molding compounds (EMCs) at temperatures higher than 100 °C. The objectives of this paper are thus: 1) to obtain diffusion properties of EMCs in both absorption and desorption modes at a wide range of temperatures; 2) to establish a non-Fickian correlation for diffusivity; and 3) to assess moisture diffusion behaviours during a solder re-flow process, described by two different Fickian diffusivities of absorption and desorption and the non- Fickian diffusivity. An experimental procedure is established to measure the diffusivity and solubility of selected EMC materials. The results are utilized in a numerical simulation to analyse the effect of the non-Fickian diffusion characteristics on the moisture distribution during the re-flow process.
Index Terms: Diffusion property, moisture diffusion, re-flow process.
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