In-situ moisture desorption characterization of epoxy mold compound

Moisture desorption characteristics of an epoxy mold compound (EMC) at 100°C, 120°C, 140°C, 160°C, 180°C, 200°C, 220°C, 240°C, and 260°C, respectively, is studied in this paper. A high resolution moisture analyzer is used to measure in-situ moisture weight loss as a function of time at different temperatures. The specimens are preconditioned (e.g. 85°C /85%RH) before they are placed in the analyzer for desorption process. The material can be heated to the desired temperature in a contained septum bottle that connects to a dry air flow system and a moisture sensor. The moisture sensor detects water in the gas stream to generate an accurate measurement of the moisture content released from the specimen. Manual moisture weight gain tests at 85°C/85% RH and 60°C/85% RH are also performed for comparison analysis. It is found that while dual stage model describes the anomalous moisture absorption and desorption well at temperatures below 100°C, a single-phase Fickian diffusion model fit the desorption curves reasonably above 100°C. This means that the initial moisture content, which includes both free and bound water, can be released completely at higher temperatures in reflow process. Arrhenius constants, i.e. pre-factor and activation energy, are obtained for an entire temperature range both below and above the glass transition temperature.