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

The moisture in the mold compound preforms influenced the resultant mechanical properties as well as the warpage of IC packages after molding and post mold curing (PMC) process. The moisture will diffuse into the mold compound preforms (compound pallet) after thawing from cold room and exposing to the clean room condition before molding process. The moisture will swell the package 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 resultant mechanical properties changes under the different moisture conditions, e.g., the variations of the flexural modulus, Tg, and CTE with respect to the moisture level. The actual compound preforms exposure to a clean room condition, were simulated by a series of experiments. The warpage of PBGA packages were measured in terms of 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 performs.