Effect of temperature on interface diffusion in micro solder joint under current stressing
(School of Materials Science and Engineering, Harbin University of Science and Technology, Harbin 150040, China)
Abstract: The effects of temperature on Cu pad consumption and intermetallic compound (IMC) growth were investigated under current stressing. The Cu/Sn-3.0Ag-0.5Cu (SAC305)/Cu solder joints were used, with a certain current density of 0.76×104A/cm2 at 100, 140, 160 and 180 °C. The constitutive equations of cathode Cu pad consumption and anode interface IMC growth are established, respectively, based on the loading time and sample temperature. The cathode Cu pad consumption (δ) increases linearly with the loading time and the consumption rate shows parabolic curve relationships with sample temperature. The anode interface IMC thickness (δ1) increased is linearly with the square root of loading time and the interface IMC growth coefficient shows parabolic curve relationship with sample temperature. The δ and δ1 have different variation laws under current stressing, due to the current facilitating larger amount of IMC formation in the bulk solder.
Key words: electromigration; element diffusion; intermetallic compounds; Cu pad consumption