Abstract

Although the performance of electronic devices in extreme temperature ranges has been extensively studied, the interconnections, which are still mainly Sn-based materials, require thorough observation and assessment to support the mechanical and electrical stability in subzero to cryogenic temperature environments. An in-depth assessment is required because of the nature of Sn, which has a ductile-to-brittle transition temperature of approximately −60°C. Sn-1Ag-0.5Cu (wt.%) (SAC105) solder joints were subjected to shear testing at room temperature and at −196°C at liquid nitrogen temperature. Isothermal aging at 150°C for 50–500 h prior to cryogenic temperature testing indicated further degradation under certain aging conditions. The study presented here investigates the maximum shear strength variations for SAC105 single solder joints with NiAu and Cu-organic solderability preservative (Cu-OSP) pad surface finishes using a multibond tester with a 10-μm shear height and 100-μm/s shear speed. An increase in the maximum shear strength was observed at liquid nitrogen temperature compared to that at room temperature due to an increase in the yield strength and loss in ductility of the solder material in response to the low-temperature environment. The maximum shear strength decreased with isothermal aging due to the crack propagation path variation. Fracture locations were identified between the Ni pad and the (Cu, Ni)6Sn5 interface for the NiAu surface finish components, and Cu-OSP surface finish solder joints revealed transgranular crack through the Cu6Sn5 and crack propagation between the Cu6Sn5 and the solder interface. The shift in the full fracture location is discussed in association with electron backscatter diffraction (EBSD) analysis on partially sheared solder joints at room temperature and at −196°C.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.