Tin Whisker Mitigation Technologies for Sn-based Surface Finishes on Electronic Assemblies and Microelectronic Devices

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, 65oC 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.