Corrosion behavior of quenched sac305 solders
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Date
2018-06
Authors
Nor Syafiqah Muhamad
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Abstract
The effect of corrosion behavior of quenched SAC305 solder alloy with different
cooling methods such as furnace cooled and ice quenched were investigated. Typical
phases present in SAC305 solder with different cooling methods were β-Sn, Ag3Sn and
Cu6Sn5. The microstructure of furnace cooled was coarser than microstructure of ice
quenched. The thickness of IMC layer was thicker (4.558 μm) for furnace cooled and
thinner (1.532 μm) for ice quenched. The growth of Sn and eutectic phases were longer
for furnace cooled and has limited time for ice quenched. The corrosion behavior of
different cooling methods was investigated in 3.5 wt% NaCl solution by open circuit
potential (OCP) and potentiodynamic polarization. Based on potentiodynamic
polarization curve, ice quenching exhibit larger passivation range and lower passivation
current density indicates more stable and protective passive layer. Phases, morphologies
and elemental analysis were used to characterize the sample of SAC305 solder at different
cooling rate. In addition, the microstructural and elemental analysis revealed the presence
of oxide on the surface of the corroded sample. The grain size of corrosion product in
furnace cooled sample was larger and the oxide form was large plate-like shape as
compared to ice quenched sample that has a uniform and small plate-like shape. Results
showed that ice quenched sample exhibits better corrosion resistance than furnace cooled
sample due to compact corrosion product layer that can protect the surface of the SAC305
solder alloy.