Abstract
This study examines factor(s) behind the formation of primary Cu6Sn5 (in the bulk, rather than at the interface) in solder joints, even though solder alloys are hypoeutectic. To understand the contribution from copper (Cu) dissolution from the substrate a Cu-free alloy, tin-3.5 silver (Sn-3.5Ag), was used as a soldered-on copper organic solderability preservative (Cu-OSP) and electroless nickel immersion gold (ENIG) surface finish substrates. Microstructure observations including in situ synchrotron were used to observe microstructure development real-time and confirm the time and location for nucleation of primary Cu6Sn5. High-speed shear tests were performed to determine the solder joint’s strengths. The results confirm that Cu dissolution during soldering is responsible for the formation of primary Cu6Sn5. The ENIG finish prevented Cu dissolution and the formation of Cu6Sn5 resulting in higher solder joint strength for the Sn-3.5Ag/ENIG solder joints. The findings can be used to understand the evolution of primary Cu6Sn5 and how it can be suppressed to improve joint strength.
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 callDisclaimer: 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.
