Development of Tin Whisker Growth Model Using the Faradayic Process

The recent European Union ROHS Directive for the elimination of lead from tin-lead solders in electronics products has lead the industry scrambling for alternatives not affected by tin whisker growth. Tin whiskers spontaneously grow on pure tin and tin-rich alloy surfaces, and may cause reliability and performance issues such as shorting and metal-vapor arcing, which lead to device failure. It is generally acknowledged that a number of factors influence whisker formation/growth: intrinsic stress in the electrodeposit, extrinsic stress resulting from chemical reactions between the tin deposit and substrate, purity of the tin deposit, grain size and crystallographic orientation of the tin deposit, pre-plate chemical treatment of the substrate, tin deposit plating thickness, post-plate heat treatment and storage and operating conditions. A mechanism of how these parameters interact is the key to understanding the formation/growth of whiskers. Faraday Technology proposes to gain fundamental knowledge of how the properties of the electrodeposits influence whiskering propensity with the Faradayic Process, for control of deposit properties and consequent performance of pure tin electrodeposits. This technology enables correlation between deposit properties and whiskering propensity of pure tin deposits in order to establish a tin whisker growth model and accelerated testing regime.