Environmentally compliant alloys for aerospace electronics

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Human beings are not the only entities that age. All materials age by the atomic movement of atoms and molecules that make up their microstructure, or by chemical reaction with the surrounding environment. Over time, these tiny movements and reactions end up changing the material structure, often weakening the materials. The aging of the solder alloy materials used to hold electronic components together in engineered devices is of major concern, particularly since the environmentally legislated solders that must be used do not age well - they weaken over time and can cause failures more quickly than the lead (Pb)-based materials industry has incorporated into historical risk models and system redundancies. New environmentally compliant solder formulations have been developed which are cost effective and mechanically robust in the short term. In order to use these materials to assemble high reliability long life products, where the cost of failure is high and the risk of failure are catastrophic, such as for airplane control systems, the long term properties must be understood. This proposal realizes the creation of the scientific knowledge on the material properties of the industrially-relevant Sn-Cu-Bi (tin copper bismuth) solder alloys and how and why they change with age. We will then bring this knowledge to aerospace electronics product companies, so that they can manufacture higher reliability products using the optimum materials when they need to complete the transition to lead-free electronics in the near future.