Effect of temperature and humidity on moisture diffusion in an epoxy moulding compound material

• Published in: Microelectronics and reliability Vol. 107; p. 113596
• Main Authors: Jansen, K.M.B., Zhang, M.F., Ernst, L.J., Vu, D.-K., Weiss, L.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2020
• Subjects: Diffusion; Micro-electronic device; Modelling; Moisture; Moulding compound; Micro-electronic device; Modelling; Moulding compound; Diffusion; Moisture
• ISSN: 0026-2714; 1872-941X
• DOI: 10.1016/j.microrel.2020.113596

In this paper we propose a new multistep characterisation method to be able to map out the dependency of moisture diffusion parameters of a polymeric material over a range of temperature and humidity conditions in a limited amount of time. We do that by (1) using a moisture sorption analyser which can continuously monitor weight changes with microgram accuracy, (2) using thin samples which speeds up the diffusion process and (3) already switch to the next humidity level at 90 or 95% completion of a diffusion step. A multistep diffusion model was developed to account for the overlapping diffusion steps. This model showed to be extremely accurate for fitting experiments consisting of five absorption and one desorption steps. We show that for temperatures up to 85 °C and humidity level between 0 and 85% RH the diffusion of our material was essentially Fickian with a diffusion coefficient ranging from 3.8 × 10−7 mm2/s at 20 °C to 3.6 × 10−6 mm2/s at 85 °C. The moisture saturation concentrations showed a slightly non-linear variation with the applied humidity level. [Display omitted] •The moisture diffusion of an epoxy molding compound is systematically analyzed over a wide temperature and humidity range•A new data analysis method is introduced which largely speeds up the measurement procedure•The saturation concentrations clearly showed a dependency on both humidity and temperature•The moisture absorption and desorption could be modelled with a single temperature dependent diffusion coefficient