Maximum bubble pressure, dilatometric, and meniscographic methods were used in the investigations of the surface tension, density. wetting time, wetting force, contact angle, and interfacial tension of liquid alloys of Sn-Ag-Cu eutectic composition with various additions of Bi. Density and surface tension measurements were conducted in the temperature range 250-900°C. Surface tensions at 250°C measured under a protective atmosphere of Ar-H 2 were combined with data from meniscographic studies done under air or with a protective flux. The meniscographic data with a nonwetted teflon substrate provided data on interfacial tension (solder-flux), surface tension in air, and meniscographic data with a Cu substrate allowed determinations of wetting time, wetting force, and calculation of contact angle. The calculated wetting angles from meniscographic studies for binary Sn-Ag eutectic and two ternary Sn-Ag-Cu alloys were verified by separate measurements by the sessile drop method under a protective atmosphere with a Cu substrate. Additions of Bi to both ternary alloys improve the wettability and move the parameters somewhat closer to those of traditional Sn-Pb solders.

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.

Users who downloaded this article also downloaded: (2011),"Silver nanoparticles effect on the wettability of Sn-Ag-Cu solder pastes and solder joints microstructure on copper", Soldering & Surface Mount Technology, Vol. 23 Iss 3 pp. 150-160 http://dx.doi.org/10.1108/09540911111146908 (2012),"Computational fluid dynamic and thermal analysis for BGA assembly during forced convection reflow soldering process", Soldering & Surface Mount Technology, Vol. 24 Iss 2 pp. 77-91 http://dx.If you would like to write for this, or any other Emerald publication, then please use our Emerald for Authors service information about how to choose which publication to write for and submission guidelines are available for all. Please visit www.emeraldinsight.com/authors for more information. About Emerald www.emeraldinsight.comEmerald is a global publisher linking research and practice to the benefit of society. The company manages a portfolio of more than 290 journals and over 2,350 books and book series volumes, as well as providing an extensive range of online products and additional customer resources and services.Emerald is both COUNTER 4 and TRANSFER compliant. The organization is a partner of the Committee on Publication Ethics (COPE) and also works with Portico and the LOCKSS initiative for digital archive preservation. AbstractPurpose -The purpose of this paper is to study the effect of copper concentration in near-eutectic liquid SAC solders on their thermophysical properties: viscosity, surface tension, density; as well as wetting behavior on copper substrates at 523 K. Design/methodology/approach -Viscosity, surface tension, and density were studied over a broad range of temperatures with the recently developed Roach-Henein method. The obtained results were compared with the data from modified capillary, maximum bubble pressure, wetting balance and dilatometric measurements. Wetting angles measured with wetting balance method were compared with the results of sessile drop measurements. Findings -The results obtained indicate that increasing concentration of copper in the alloy results in higher density, surface tension and viscosity, but differences resulting from copper concentration on wettability are relatively small. At 523 K, the density is: 7.097, 7.186, 7.232 g cm 2 3 , the surface tension is: 538.1, 553.5, 556.7 m Nm 2 1 , the viscosity is: 2.173, 2.227, 2.467 mPas, respectively, for alloys containing 0.41, 1.01 and 1.61 wt% of Cu. Wetting angles on copper substrates are similar within a margin of error for all compositions. The results of present study are compared with the available literature data and a relatively good agreement is observed. Originality/value -This paper provides the data of thermophysical properties of widely-used SAC solders including viscosity, of which there is little data in the literature. It is confirmed that the increased copper concentration increases viscosity, yet this effect is small and does not correlate with the wetting behavior.

Purpose -The purpose of this paper is to investigate the influence of In additions on the wetting properties of the Sn2.86Ag0.40Cu (in wt%) eutecticbased alloys, on a copper substrate, in the presence of a flux. The main goal was to find correlations between the results of the wetting balance (WB) and the sessile drop (SD) method, in relation to the contact angles. Design/methodology/approach -The WB method was applied for the wetting measurements, at 2508C, in an air atmosphere and in the presence of a flux. The SD measurements were conducted at the same temperature, in the presence of the same flux, but in an Ar atmosphere, while the maximum bubble pressure (MBP) and dilatometric measurements were conducted in an Ar þ H 2 atmosphere. The density data from the dilatometric method were used for the determination of the surface tension by means of MBP, and the WB method was used to determine the surface and interfacial tension. Next, the surface tension data from these two methods were compared. The WB data were used to calculate the contact angles and the obtained indirect data were compared with the results of the direct SD measurements of the contact angle. Findings -A higher In content in the alloy resulted in a lower contact angle on the copper, and the WB results agreed well with the results of the SD experiments. It was confirmed that, in liquid In-Sn and the alloys containing In and Sn (Ag-In-Sn, Sn-Ag-Cu-In, Sn-Zn-In), the improvement of the wettability was indicated only by the increase of the contact angle with the increasing In content. Research limitations/implications -Further studies are necessary for the confirmation of practical application, but they should be directed to the soldering of high indium alloys on printed circuit boards, with different finishes and qualities of the solder joint performance. Practical implications -Taking into account the contact angle data from the WB and SD methods, the best results of the SAC-In alloy on copper were obtained for the alloy of the highest In content. It was found that the contact angles from SD after 4 s were higher (non-equilibrium conditions) than the values calculated from WB after 3 s. In contrast, the contact angles from SD after 10 min (equilibrium conditions) were lower than those from WB after 3 s. The comparison suggests that the contact angles from WB are situated within the data from SD, showing the same lowering tendency with the increasing content of In, and they may be well accepted for practical purposes. On the other hand, the sample of the solder in the SD method, after a prolonged time -in order to get the equilibrium contact angle -may be used to study the interfacial phenomena with the Cu substrate. The differential thermal analysis results indicate that the melting temperature decreases with increasing tin concentration. Taking into account the results of this study and the available literature data, alloys containing 8-10 wt% of In can be recommended for practical application. Originality/value -The WB and SD methods were used fo...

Purpose -The purpose of this paper is to investigate the influence of silver nanoparticle additions on the wetting properties of Sn-Ag-Cu (SAC) solder paste. In this investigation, the basic solder paste contained 85 wt.% of commercial Sn 96.5 Ag 3 Cu 0.5 powder (with the particle sizes in the range of 20-38 mm) and 15 wt.% of self-prepared middle activated rosin flux. To this paste was added 0.5, 1, 2 and 4 wt.% of self-prepared silver nano-powders of different grain sizes (from 9 to 138 nm). After the pastes had stabilized, their wetting properties were tested. The main goal of these investigations was to improve the wetting properties of SAC solder paste and to find correlations between the results of the wetting of solder paste with nanoparticles on the copper substrate with the microstructure of the solder joints. Design/methodology/approach -The following methods were applied for the wetting solder paste investigation: spreading on the copper substrate, contact angle measurement on the copper and wetting on a FR-4 laminate double sided with an 18-mm thick copper foil. The investigations were performed at temperatures of 220, 230, 240 and 2508C. Cross-sectioning was performed on the solder paste after reflow on the copper substrate. For the microstructural analysis of the "nano" modified solder joints obtained at 2508C, standard metallographic procedures were applied. Changes in the microstructure, the thickness of the inter-metallic compounds (IMCs) and their chemical compositions were observed by means of scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). Findings -As expected, a higher silver nanoparticle addition to the SAC solder paste resulted in better wetting properties on copper. The results indicated the possibility of an improvement of the reflow soldering process by using SAC solder paste with silver nanoparticles and by lowering its soldering temperature. An improvement was also observed in the wettability with a decrease in the silver nanoparticle grain size. Also, the wettability proceeded at a lower temperature (208C lower) than that for the SAC paste, without the nano-additives. For the 4 per cent silver nanoparticle addition, Ag 3 Sn star-like IMCs were also found, which grew with the lowering of the silver nanoparticle grain size. Research limitations/implications -Further studies are necessary for confirmation of the practical application, especially of the mechanical properties, as well as the reliability properties of the solder joints, for the chosen solder paste with silver nanoparticles. Practical implications -Taking into account the wetting data, the best results of the "nano" SAC solder pastes were obtained for the highest addition of the silver nanoparticles. It was found that the spreading on copper was higher and the contact angles were lower for the SAC solder paste with 4 per cent (by wt.) of 138-nm grain size silver nanoparticles. A comparison of SAC solder pastes with a 4 per cent silver nanoparticle addition but of a different grain size (138-9 nm...