Digital monitoring for prognostics to defects due to atomic migration

本项目的目的是建立一种原位观察原子输运引起的小缺陷现象的方法学。关键技术是在一定的环境条件下预测缺陷的位置。本文对掺银TiN表面光洁度进行了压力诱导TiN晶须试验。由于掺杂银可以减少锡晶须，因此不适合用于锡晶须的监测。另一方面，在电流作用下的腐蚀样品中观察到了长晶须。TiN晶须的驱动力，即表面光洁度中的应力梯度，是由表面氧化物和扭曲电流产生的。基于锡晶须形成的上述机理，提出了利用微旋转仪和原子力显微镜对锡晶须进行原位观察的实验系统。

The aim of this project is to establish a methodology of in-situ observation for phenomena of small defects due to atomic transportation. Key technology is to predict the site of defects under some environmental conditions. In this study, pressure-induced tin whisker test was conducted for silver doped tin surface finish. Since doped silver can mitigates tin whiskers, it is not suitable for monitoring of tin whisker. On the other hand, long whiskers were observed under corroded samples with electric currents. The driving force of tin whiskers, stress gradient in the surface finish, was generated by surface oxides and distorted electric currents. Based on the above mechanism of tin whiskers, In-situ observation system for tin whiskers were proposed by using micro-manipurator and atomic force microscopy.