(Sn-Ag)eut+Cu soldering materials, part I: Wettability studies

Abstract

The maximum bubble pressure, dilatometric, and meniscographic methods were used in investigations of the surface tension, density, wetting time, wetting force, contact angles, and interfacial tension of liquid (Sn-Ag)eut and two (Sn-Ag)eut+Cu alloys (Cu at.%=0.46 and 0.74). The density and surface tension measurements were conducted in the temperature range from 230 to 950 °C, and the meniscographic investigations were carried out at 252 °C. The resultant values of surface tension were compared with those calculated from Butler’s model based on optimized thermodynamic parameters and our data from earlier investigations. In an earlier study, experimental data for all investigated compositions (Cu at. %=1.08 to 6.5) exhibit an increase in the surface tension with interesting temperature, while both ternary alloys of this study show a slight lowering tendency in comparison to (Sn-Ag)eut. A more evident decreasing tendency of surface tension and interfacial tension was noted in meniscographic measurements, noting that data of interfacial tension are always lower than surface tension due to the role of the flux. Eight different fluxes were tested to select the lowest interfacial tension for the (Sn-Ag)eut. ROLI (3% solids), which is the alcoholic solution of organic compounds and rosin activated by halogens, was recommended. In (Sn-Ag)eut+Cu Soldering Materials, Part II: Electrical and Mechanical Studies, for the same (Sn-Ag)eut and (Sn-Ag)eut+Cu alloys (Cu at. %=0.46 and 0.74), the electrical resistance and strength measurements will be presented in parallel with printed-circuit boards in wave soldering at 260 °C.