Advanced CSP and fine pitch ball grid array assembly reliability

The Arrival of fine pitch ball grid array shifts the focus of Semiconductor packaging improvement. In general the most significant marginality for prior package types was for moisture sensitivity, or the Popcorn phenomenon. Significant advances in mold compound formulation have improved performance in this area. In some types of fine pitch ball grid array packaging, the safety factor for solder joint reliability is significantly reduced as compared to traditional package types. It is now the most marginal element of packaging design in many applications. Shared responsibility for the solder interconnect between the component supplier and the board assembler greatly complicates failure analysis and the remediation of failures. A paradigm shift is underway, away from a model in which component solder joint reliability was assumed by the customer to be guaranteed by design, to one in which at a minimum some evidence of assembly reliability potential and recommendations for appropriate use are required as part of qualification. Area array interconnect reliability, which for typical wirebonded 50 mil pitch Plastic Ball Grid Array (PBGA) packages was in the range of the requirement needed for outside applications, 10 year life, is with FBGA a critical parameter in some cases for applications in an office environment, 5 years life. This paper reports data on assembly reliability studies for a number of component types, and compares results to the requirements of typical applications.