Sandia computer modeling aids solder reliability in nuclear weapons

Solder isn't the first thing that comes to mind as essential to a nuclear weapon. But since weapons contain hundreds of thousands of solder joints, each potentially a point of failure, Sandia National Laboratories has developed and refined computer models to predict their performance and reliability. "Computational modeling of solder joint fatigue has become critical to Sandia and its role in the current nuclear weapons life extension programs, even before production assembly at the Kansas City National Security Campus," said materials scientist Paul Vianco, who works with material modeler Mike Neilsen. "Sandia uses the computational model to solve manufacturing issues as well as assess the impact of design changes on solder joint reliability. "This is critical as we finalize designs and head into production," he said. Anything with circuit boards requires countless solder joints, and miniaturization of electronics has vastly increased the number in printed wiring assemblies. Vianco lists two examples among a multitude of printed wiring assemblies for weapons: one with more than 900 solder joints, 400 on a single component; the other with about 300 joints.