How Much Baking Time is Needed for Moisture-Sensitive Packages?

This paper proposes a new method to determine the baking time for moisture-sensitive packages prior to dry pack. The concept is based on consideration of the continuous drying process for a package within moisture barrier bags (MBB), which contain a desiccant. If the moisture is not completely dried out during bake (usually at 125°C), the residual moisture will continue to diffuse out of the package body during storage and shipment in the MBB. In this paper, a 2.5D package is used for a worst-case scenario simulation through finite element modeling. It shows that after a 24hr bake at 125°C, the residual moisture weight gain remains 13% of the total saturated weight gain, and the maximum moisture concentration remains as high as 40% of the saturated moisture concentration; however, after 4 weeks of storage at 30°C in the MBB the residual moisture weight decreases to less than 1%, and the maximum saturated moisture concentration decreases to less than 5% of the saturated moisture concentration. Depending upon package construction, storage conditions and storage time before customer opening of MBB, the modeling results show that consideration of moisture diffusion in the MBB may permit the bake schedule to be shortened.