in-situ growth of whiskers in Sn layer

Whiskers (long single crystal filaments of micro/submicrometer diameter) growth on Sn coating is a major technological threat for electronic/electrical devices. Despite numerous studies during the last 70 years, quantitative modeling is not yet achieved. One major identified driving force for their growth is the presence of compressive stress and/or stress gradients within the coating.By microLaue diffraction, investigation of the signature of strain fields around whiskers which would grow at the time scale of the experiments is proposed. Therefore, we have developed disposable in-situ devices with adjustable load control on model polycristalline Sn coatings. By quick exchange of devices and relocation, we would take strain cartography snapshots of existing whiskers at different times / different applied stress during their effective growth stage . A better understanding of the role of stress and its threshold to nucleate and control the kinetics of whiskers is therefore expected.