Reliability performance assessment and characterization of fine pitch mold array BGA

This paper summarizes evaluations performed to characterize and determine the moisture sensitivity of fine pitch (0.8 mm and 1 mm pitch) mold array process (MAP) BGA packages. The advantages of the MAP BGA over standard PBGA and glob top BGA in terms of cost and package design to meet cellular phone market demand for thinner, smaller and lighter packaging are also discussed. There are multiple issues for both thin (1.3 mm) and thick (1.7 mm) MAP BGAs. The paper addresses the assembly impact of warpage due to thinner substrates, low loop wire bonding and thin molding, and covers the materials used and their advantages, e.g. nonconductive die attach epoxies and molding compounds that decrease strip warpage and wire sweep at mold. Results using an optimized flag design are reported. Solder ball adhesion and joint reliability obtained in 1 mm pitch BGA characterization are discussed. Various studies were made to find the moisture sensitivity level of this new package family, which range in body size from 7/spl times/7 mm to 17/spl times/17 mm for both thick and thin profiles. The reliability test used C-SAM to inspect for package interface delamination after moisture sensitivity level 1, 2 and 3 preconditioning. Studies were also conducted to improve package moisture performance using special flag coatings and pre-bakes on the BT resin substrates. Thermal and electrical characterization data are included to give a baseline comparison between this package and a standard LQFP. Future work and recommendations are provided on package performance improvement and the demand for even lower ball pitch (0.65 or 0.5 mm) and profile BGAs (1 mm) on future products.