Gregory Czap, Kyungju Noh, et al.
APS Global Physics Summit 2025
The undercooling of flip-chip Pb-free solder bumps was investigated by differential scanning calorimetry (DSC) to understand the effects of solder composition and volume, with and without the presence of an under bump metallurgy (UBM). A large amount of the undercooling (as large as 90 °C) was observed with Sn-rich, flip-chip size solder bumps sitting in a glass mold, while the corresponding undercooling was significantly reduced in the presence of a wettable UBM surface. In addition, the solidification of an array of individual solder bumps was monitored in situ by a video imaging technique during both heating-up and cooling-down cycles. Data obtained by the optical imaging method were used to complement the DSC thermal measurements. A random solidification of the array of bumps was demonstrated during cooling, which also spans a wide temperature range of 40-80 °C. In contrast, an almost simultaneous melting of the bumps was observed during heating. © 2007 Materials Research Society.
Gregory Czap, Kyungju Noh, et al.
APS Global Physics Summit 2025
Mark W. Dowley
Solid State Communications
Eloisa Bentivegna
Big Data 2022
M. Hargrove, S.W. Crowder, et al.
IEDM 1998