| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 546801 | Microelectronics Reliability | 2014 | 7 Pages |
•The stress fields with expansion in volume due to the formation of IMC are given.•The diffusion mechanism is applied to evaluate the whisker growth rate.•The results give an explanation of the experimental observations.•Some suggestions are given to mitigate the whisker growth.
The formation of intermetallic compound Cu6Sn5 gives rise to the internal stress in the lead-free coating, which causes the growth of Sn whiskers. This phenomenon is characterized with the expansion of inclusion in a plate perfectly bonded between two infinite solids. Based on the grain boundary diffusion mechanism, a model is established to evaluate the growth rate of Sn whiskers. The results show that the growth rate of whisker varies with the relative site between whisker and inclusion. When the distance between the whisker and inclusion exceeds a critical value, negative growth rate will appear, and it approaches zero as the distance increases. They explain some phenomena observed in experiments.
