Surface mount technology in high-reliability applications; military airborne applications

Summary form only given. The efforts taken to date as part of the USAF Manufacturing Technology for Advanced Data and Signal Processing program to enhance significantly solder-joint reliability are described. The proposed critical factors which affect solder-joint reliability and the methodology taken to demonstrate reliability enhancements are detailed. In order to produce solder joints meeting the desired solder-joint geometry, new methods of solder deposition were developed. Conventional surface-mount applications use solder paste as a vehicle for applying solder to form the electrical interconnection; however, solder paste was not a viable method of achieving the desired joint geometries. Instead, a novel process was developed using noneutectic solder preforms and a vapor-phase reflow process. This process also offered other significant advantages over the use of solder paste. Improvements in solder joint-to-joint uniformity were also observed, and an improved solder-joint repair process was developed.>