Enhancement of mean-time-to-failure of Sn3.0Ag0.5Cu solder bump joint under current stressing via controlling bump shape
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In this research, two different Sn3.0Ag0.5Cu solder bump joints with barrel shape and hourglass shape respectively were fabricated by controlling solder process, and evolution of intermetallic compounds (IMC) between different solder joint and Cu substrate under 4 × 103 A/cm2 current stressing at 60 °C were investigated. The results indicate that both the decrease of IMC layer thickness in the cathode and the increase of IMC layer thickness in the anode of the hourglass-shaped solder bump joint were obviously slower than that of barrel-shaped solder bump joint, and the formation of the voids at cathode interface was observed in the barrel-shaped solder bump joint after current stressing for 240 h. The mean-time-to-failure (MTTF) of solder joint with hourglass-shaped bump is efficiently improved compared to that with barrel-shaped bump. Compared to that of the solder joint with barrel-shaped bump, enhancement of MTTF of the solder joint with hourglass-shaped bump is attributed to relieve current crowding in entrance and outlet of electric current.
KeywordsSolder Joint Solder Bump Reflow Process Current Crowding Waist Radius
The authors gratefully acknowledge the support received from National Science and Technology Major Project (2011ZX02607).
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