Significant Effect of Temperature and Solders on The Growth Behavior of CU6Sn5 on (110) Cu Single Crystal

Abstract

The package interconnect in integrated electronic components is realized by Interfacial intermetallic compounds (IMC). Meanwhile, the downsizing of µ-bumps to tens of microns in advanced 3D packaging will result in the overgrowth of IMC and the number of grains contained in UBM decreased sharply, which bring new challenge for the reliability of solder joints. For this condition, numerous researches about the growth of IMC generated at the solder/Cu single crystal interface have been reported. For this paper, the growth of IMC at the interface between different solder, i.e., Sn, Sn-2Ag, Sn-3Ag, and (110) Cu single crystal at different temperature, i.e., 230°C, 250°C, 300°C, were investigated. Scanning electron microscope (SEM) and electron backscattered diffraction (EBSD) was used to characterize the morphology and orientation of Cu6Sn5, respectively. Results shows that the CU6Sn5 formed on (110) Cu exhibit worm type at lower temperature and were tends to transform into facet type at higher temperature. Furthermore, the reflow temperature make a difference in the formation of Cu6Sn5 orientation. Besides, the coarsening rate of CU6Sn5 was promoted following the increase of the Ag. The results have a significant meaning in controlling the orientation and improving the reliability of micro solder joints.