Authors: Stephan Meschter, Polina Snugovsky, Jeff Kennedy, Steve McKeown and Eva Kosiba Company: Celestica Inc. and BAE Systems Date Published: 5/4/2011
ICSR (Soldering and Reliability)
Abstract: Driven by legislation resulting from two European Union directives, most commercial electronics manufacturers began delivering lead-free electronic components, assemblies, and equipment in 2006. Although not generally affected directly by the legislation, aerospace and defense equipment manufacturers are being swept along as their electronics supply chain makes the transition which significantly impacts the design, production, and support of aerospace electronic systems. As a result of a global movement away from using lead (Pb), component manufacturers are increasingly applying tin-rich finishes to the leads of their devices. Unfortunately, this can create a risk of tin whisker formation that can result in electrical failures. Because of its unique requirements such as long service lifetimes, rugged operating environments, and high consequences of failure, the aerospace and defense industries must mitigate the detrimental effects that tin whiskers. The present paper describes a multi-year testing and modeling program that aims to assess tin whisker growth on lead-free manufactured assemblies and utilizes whisker short circuit statistical modeling to enable improved reliability assessments. Details of the test configuration, environmental selection, whisker measurement statistics and modeling framework will be provided.
Key words: Tin Whiskers, Lead Free, Assembly, Risk Modeling, Monte Carlo