The impact of moisture in mold compound preforms on the warpage of PBGA packages

摘要

The moisture in the mold compound preforms influenced the resultant mechanical properties as well as the warpage of IC packages after the molding and post mold curing (PMC) process. Moisture will diffuse into the mold compound preforms (compound pallet) after thawing from cold room and exposing to clean room condition before molding process. The moisture will cause the package to swell, and combine with thermal stress, and finally result in the warpage of molded package after molding process. The main objective of this paper is to address the impact of moisture in the compound preforms on the warpage of the PBGA packages and explain the change in mechanical properties under different moisture conditions, e.g., the variations of the flexural modulus, T_g, and CTE with respect to moisture level. The compound preforms exposure to a clean room condition were simulated by a series of experiments. The warpage of PBGA packages were measured by the moire test. The moisture control during the IC manufacturing process was highlighted in terms of the mechanical properties variation and warpage measurement due to the moisture effects on the mold compound preforms.