Young’s modulus of (Cu, Ag)–Sn intermetallics measured by nanoindentation

Reflow of Sn-rich solders on a Cu substrate results in the formation of several Cu–Sn and Ag–Sn intermetallics, which control the properties of the solder joint. Bulk measurement of physical properties, such as Young’s modulus, is problematic and may be affected by porosity and undesired phases. In this paper, we report on the accurate and reliable Young’s modulus values of Cu6Sn5, Cu3Sn, and Ag3Sn intermetallics, measured in situ in a solder joint by nanoindentation. The measured values for Cu6Sn5, Cu3Sn, and Ag3Sn, were 112.3±5.0, 134.2±6.7, and 78.9±3.7 GPa, respectively. Comparison of these values with limited data in the literature was also conducted and is discussed.