Publication: Characterization of sn-3.0ag-0.5cu/cu solder joints by microwave hybrid heating with silicon wafer susceptor
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Date
2022-09-01
Authors
Said, Mardiana
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Abstract
Microwave hybrid heating (MHH) is a new alternative to overcome longer heating utilized by conventional method in soldering process which contributed to excessive intermetallic compound (IMC) growth. This study uses silicon wafer as a susceptor in the MHH system and focuses on MHH parameters, post aging and corrosion characterization in comparison to conventional method. Solder alloy Sn-3.0Ag-0.5Cu (SAC305) was selected and successfully formed solder/substrates joint which are SAC305/Cu and Cu/SAC305/Cu. For comparison, conventional reflow oven was set at reflow temperature of 250°C for 60 s (coded as CR). The best solderability characteristic by MHH was observed at high operating power, 40 s (coded as H40). The H40 shows a more refined Cu6Sn5 IMC structure with smaller grain size and a thinner layer (2.5 µm) compared to CR (3.7 µm). The ultimate tensile strength (UTS) of H40 (44.7 MPa) is 36.7% higher than CR (32.7 MPa) and they decreased consistently at long-term aging for both CR and H40. Pitting characteristics and corrosion products such as SnO, SnO2 and Sn3O(OH)2Cl2 were observed after one dayof immersion in 3.5 wt.% NaCl. They keep expanding until the pitting surface is fully covered with corrosion products and inhibited corrosion activity. Thus, UTS reduction can be reduce from 30-40% to less than 10% after 14 days of immersion. The Si wafer susceptor was successfully form a solder joint by MHH. The solder joint performance by MHH after aging and corrosion showed higher joint strength compared to conventional method. The findings from this research work could introduce a better soldering technique and a remarkable performance in lead free soldering industries.