Organic solderability preservation evaluation. Topical report

An evaluation was conducted to determine the possible replacement of the hot air solder leveling (HASL) process used in the Allied Signal Federal Manufacturing & Technologies (FM&T) Printed Wiring Board Facility with an organic solderability preservative (OSP). The drivers for replacing HASL include (1) Eliminating lead from PWB fabrication processes; (2) Potential legislation restricting use of lead, (3) Less expensive processing utilizing OSP rather than HASL processing; (4) Avoiding solder dross disposal inherent with HASL processing, (5) OSP provides flat, planar surface required for surface mount technology product, and (6) Trend to thinner PWB designs. A reduction in the cost of nonconformance (CONC) due to HASL defects (exposed copper, solderability, dewetting and non-wetting) would be realized with the incorporation of the OSP process. Several supplier HASL replacement candidates were initially evaluated. One supplier chemistry was chosen for potential use in the FM&T PWB and assembly areas

Mechanical Integrity Issues at MCM-Cs for High Reliability Applications

During the qualification of a new high reliability low-temperature cofired ceramic (LTCC) multichip module (MCM), two issues relating to the electrical and mechanical integrity of the LTCC network were encountered while performing qualification testing. One was electrical opens after aging tests that were caused by cracks in the solder joints. The other was fracturing of the LTCC networks during mechanical testing. Through failure analysis, computer modeling, bend testing, and test samples, changes were identified. Upon implementation of all these changes, the modules passed testing, and the MCM was placed into production