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Purpose -The purpose of this paper is to produce and investigate the interfacial reaction between Sn-3.0Ag-0.5Cu (SAC305) thin films and Cu substrates by solder reflow at various temperatures and times. Design/methodology/approach -SAC305 thin films were deposited on copper substrates using a thermal evaporation technique. The as-deposited SAC305/Cu was then reflowed on a hot plate at temperatures of 230, 240, 250 and 2608C for 30 s. In addition, solder reflow was conducted at a constant temperature of 2308C for 5, 10, 15 and 20 s. The microstructure, phase and thickness of the intermetallic compounds (IMCs) formed were determined after cross-sectional metallographic preparation. Findings -Cu 6 Sn 5 and Cu 3 Sn were observed at the as-reflowed SAC305/Cu interfacial region. The IMC thicknesses increased with the higher reflow temperature and longer reflow times. Originality/value -Up to now, studies on the thin film characteristics of SAC305 lead-free solder have been very limited. Thus, this paper presents the deposition of SAC305 thin film by a thermal evaporation technique and its characteristics after solder reflow.

Purpose – The purpose of this paper is to examine the corrosion behaviors of SAC305 thin film solder alloy in 6 M KOH solution. Design/methodology/approach – The corrosion behavior of bare Cu, as-deposited SAC305/Cu and as-reflowed SAC305/Cu thin films at varying temperatures, was investigated by means of potentiodynamic polarization in a 6 M KOH solution. The microstructure, phase and thickness of the intermetallic compounds formed were determined before and after polarization. Findings – Bare Cu was found to possess the best corrosion resistance, whereas the as-deposited SAC305/Cu had the lowest corrosion resistance. As-reflowed SAC305/Cu with an exposed Cu3Sn layer exhibited better corrosion resistance than did Cu6Sn5. The Ag3Sn phase has the noblest characteristic because it was retained and did not dissolve in the KOH solution. All of the samples contained the corrosion products of oxide. Bare Cu obeys the well-known duplex structure of a Cu2O/CuO, Cu(OH)2 layer. For as-reflowed SAC305/Cu, the corroded surface was also mainly composed of SnO and SnO2. Originality/value – New analysis on the polarization of thin film characteristics of SAC305 lead-free solder in alkaline solution.

Polyethylene oxide (PEO)-potassium hydroxide (KOH)-based alkaline solid polymer electrolyte films have been prepared by using methanol as solvent. The highest room temperature ionic conductivity of (2.1±0.5)×10 −8 S cm −1 was achieved for the composition of 70 wt% PEO:30 wt% KOH. The addition of plasticizer, ethylene carbonate, propylene carbonate, or polyethylene glycol to the highest conductivity of PEO-KOH system helps to increase the ambient ionic conductivity to the order of 10 −6 -10 −4 S cm −1 . The log σ vs 1/T plot of PEO-KOH showed a small conductivity decrease at 50-60°C range. The small decrease and the hysteresis that occur during the heating-cooling cycle was overcome by the presence of the plasticizer. X-ray diffraction observation supports the conductivity results.