Process of vacuum vapor phase soldering for micro-spring pins and their high-speed impact failure behavior

Objective This research addresses the requirements for high-reliability packaging by investigating high-precision assembly, soldering process, and high-speed impact reliability of micro-spring pins in ceramic column grid array packaging. Methods By designing assembly tooling, rapid collective assembly of 1 156 micro-spring pins was achieved and bonded with vacuum vapor phase soldering process. Results Metallurgical bond was achieved with the formation of an approximately 1 μm thick Cu-Ni-Sn intermetallic compound at the interface. Post-soldering pin spacing accuracy reached ±10 μm and void rate in soldered joints was reduced to below 5%. Shear tests demonstrated consistent strength (approximately 9.3163 N) under both high-speed and low-speed loading, with fractures occurring at the root of micro-springs. High-speed impact tests along X, Y, Z three axis using daisy-chain samples revealed no failure in soldered joints under low-level impacts, while failures under high-level impacts occurred within micro-spring bodies (exhibiting brittle fracture), with soldered joints remaining intact. Conclusion The results indicate that the developed micro-spring pin connection process is reliable and suitable for high-impact-resistant electronic packaging applications.