Tin Whisker Mitigation by Photonic Sintering for Sn-based Surface Finishes

For decades Sn/Pb components and circuit assemblies have been used for high reliability, high performance military and Air Force applications. With new legislation intended to eliminate lead from electronics manufacturing and packaging, the next generation of high performance devices will need to use only lead free technology. Unfortunately, lead free tin surfaces may form whiskers that may grow in length to cause electrical short circuits between adjacent components and devices. ANI has worked extensively on metallic conductive inks, successfully developing a copper conductive ink using copper metallic nanoparticles for inkjet printed electronic applications. This extraordinary success was achieved using a proprietary sintering process whereby a very short flash of photonic energy transforms the dried copper ink to metallic copper traces with conductivities close to levels expected for bulk Cu. We have demonstrated that this sintering process can totally flatten and eliminate copper nanowires and whiskers. We propose to extend this success, utilizing the sintering process as a post-deposition step to eliminate tin whiskers that may develop during the electrodeposition process. The systems are inexpensive, are commercially available, require less than one second process time, and can be integrated easily with current electrodeposition systems.