SBIR-STTR Award

The impact of metal whisker growth on the reliability of electronics has been exacerbated by environmentally-driven efforts to eliminate lead from tin plating and solders. Even exempt applications, such as military, are affected due to process, logistic and economic supplier realities. It is generally acknowledged in research that the whisker growth mechanism is still not fully understood and that test methods, especially accelerated ones, do not correlate well with field experience. Foresite, Inc., a consultant, laboratory and test equipment development company specializes in the identification, mitigation, removal and prevention of detrimental, process-related residues on electronic assemblies. Foresite research indicates a correlation between ionic residue levels and whisker growth, given prerequisite conditions, such as stress. The Phase I goal is to identify and rank tin whisker nucleation and growth factors by teaming the process residue expertise of Terry Munson, Foresite President, with the whisker research expertise of Prof. Carol Handwerker, Materials Science, Purdue University and the plating process expertise of Dennis Fritz, Senior Engineer, SAIC. An accelerated test for the proclivity of a sample to grow whiskers [using introduced, controlled contamination(?)] will be developed in Phase II. Ultimately, mitigation protocol(s) and, perhaps, whisker test equipment will result.

Keywords:
Tin Whiskers, Ionic Contamination, Residues, Pb-Free, Tin Plating, Solder, Electronic Reliability, Rohs

The impact of metal whiskers on the reliability of electronics has been exacerbated by environmentally-driven efforts to eliminate lead from tin plating and solders. Even exempt applications, such as military, are affected due to COTS. Foresite, Inc., a consultant, laboratory and test equipment development company, has a goal for the subject research, in collaboration with Purdue University, to develop a valid, accelerated test that will measure the susceptibility of a surface to whisker nucleation and growth, particularly through the introduction of known, controlled, surface contamination to act as an accelerant. Foresite research indicates a correlation between ionic residue levels and whisker growth. Phase I produced whisker activity on tin plated, 65°C test samples, in 5 days equal to that activity produced in 42 days of thermal-cycling JEDEC tests. In addition, differentiating whisker results were produced between five plating solutions, aligning with expectations based on previous Purdue research. Whisker samples and accelerated test protocol elements were produced in Phase I. In Phase II these samples will be further analyzed and test elements refined, leading to a final, documented and validated, accelerated, whisker test method. It is planned that a new sensor, based on this technology, will be developed in Phase III.

Keywords:
Tin Whiskers, Pb-Free, High Reliability Electronics, Accelerated Test Method, Process Residues, Ioni