|About this Abstract
||2018 TMS Annual Meeting & Exhibition
||Phase Stability, Phase Transformations, and Reactive Phase Formation in Electronic Materials XVII
||Minor P-doping in the Electroplated Co(P) Layer to Strongly Suppress IMC Formation in Lead-free Solder Joints
||Chao-hong Wang, Che-yang Lin
|On-Site Speaker (Planned)
Co and its alloys are a promising diffusion barrier material due to superior electromigration resistance. Nevertheless, the rapid growth of the Co-Sn intermetallic compounds (IMCs) may degrade the reliability of solder joints. It was found that the microstructure of Co(P) and the IMC formation were greatly influenced by different contents of P. Minor amounts of sodium hypophosphite were added in the electroplating bath to adjust the P contents (from 0.5wt.%P to 3wt.%P) of the deposited Co(P) layer. In the solid-state Sn/Co-0.8wt.%P reactions, the IMC was mainly the CoSn<SUB>3</SUB>, mixed with a small amount of the metastable CoSn<SUB>4</SUB>. Remarkably, the IMC growth was greatly suppressed. In contrast, the growth rate in Sn/Co-3wt.%P/Cu was extremely fast. A series of interfacial reactions were systematically examined. Minor 0.8wt.%P doping was the optimal concentration to effectively suppress the IMC growth.
||Planned: Supplemental Proceedings volume