Simulation and Experimental Verification of Moisture Diffusion in Embedded Component Packages

This study investigated moisture diffusion and moisture concentration distribution in embedded component packages (ECPs). Three polymeric materials, such as Ajinomoto buildup film (ABF), polyimide (PI), and bismaleimide triazine (BT), used commonly in epoxy molding compound (EMC) were characterized using Fick diffusion and dual Fick diffusion theories, respectively. The samples were subjected to a soaking environment of
$85~^{\circ }$
C/85% relative humidity. All the samples showed non-Fickian diffusion behaviors, particularly the BT sample. The dual-stage models agreed well with experimental data and provide reasonable characterizations of the diffusive properties. Subsequently, a simulation method based on the dual-stage model was proposed to replicate the distribution of moisture concentration within an ECP device. The accuracy of the simulations was verified through a heavy water moisture diffusion experiment that utilized isotope tracing techniques. This article also found that kerf played a role in blocking moisture infiltration. This study presents a more accurate method for characterizing the hygroscopic behavior of polymeric materials and constructing a moisture diffusion model for ECP.