Solderability of Sn-9Zn-0.5Ag-lIn lead-free solder on Cu substrate. Part 1. Thermal properties, microstructure, corrosion and oxidation resistance

摘要

The thermal properties, microstructure corrosion and oxidation resistance of the Sn-9Zn-0.5Ag-lIn lead-free solder have been investigated by differential scanning calorimetry, X-ray diffractometry, scanning electron microscopy, energy dispersive spectrometry, potentiostat and ther-mogravimetry. The Sn-9Zn-0.5Ag-lIn solder alloy has a near-eutectic composition, it melts at 187.6 deg C and the heat of fusion is determined as 71.3 J/g. The Sn-9Zn-0.5Ag-lIn solder alloy with a corrosion potential of - 1.09 V_(SCE) and a current density of 9.90 X 10~(-2) A/cm~2, shows a better corrosion resistance than that of the Sn-9Zn solder alloy. From the thermogravimetry analysis, the weight gain ratio of the Sn-9Zn solder alloy appears a parabolic relationship at 150 deg C. The initial oxidation behavior of the Sn-9Zn-0.5Ag and Sn-9Zn-0.5Ag-lIn solder alloys also shows a parabolic relationship but the weight gain ratio of them appears a negative linear one after aging at 150 deg C for 2.5 and 5 h, respectively.