Major Driving Forces and Growth Mechanisms for Tin Whiskers

This chapter focuses on describing the primary driving forces and mechanisms causing the growth of whiskers and hillocks. It devotes to describing how the growth of intermetallic phase (IMC) leads to stress in the Sn layer. It also discusses the impact of Sn whiskers on reliability and the importance of suppressing their formation. The chapter discusses results from simultaneously measuring the growth of the IMC between the Cu and Sn whiskers, the stress in the Sn layer, and the whisker density to understand how these different processes interact. It describes experimental studies that are designed to identify the other processes that play a role in whiskers forming, for example, plasticity, diffusion‐mediated creep, and prevention of surface diffusion by the Sn oxide. The chapter also describes results from real‐time studies of whisker growth in the scanning electron microscope/focused ion beam milling (SEM/FIB) that show how whiskers and hillocks evolve in time.