电感耦合等离子体原子发射光谱(ICP-AES)法测定锡铅焊料中11种微量元素

根据目前市场上常见锡铅焊料中主元素的特性(锡含量范围0.X%~95%,铅含量范围X%~99%),合理选择了有效的样品前处理方法。参考铸造锡铅焊料牌号及化学成分和仪器工作条件,确定了待测元素的测定范围。应用电感耦合等离子体原子发射光谱法同时测定锡铅焊料中锑、铋、铁、砷、铜、银、锌、铝、镉、磷、金11种元素的含量,方法操作简单。选择了合适的分析谱线,进行了基体元素对待测元素以及各待测元素之间的干扰研究,基体效应小,各待测元素之间基本无干扰,11次独立的测定数据相对标准偏差为1.0%~11.3%,方法的加标回收率为90.2%~105%。完全能满足现实生产中对锡铅焊料杂质元素的测定要求。     

Surface properties of liquid In-Zn alloys

The measurements of surface tension and density of zinc, indium and liquid In-Zn alloys containing 0.9, 0.85, 0.75, 0.70, 0.60, 0.40, 0.25 and 0.10 mole fraction of In were carried out using the method of maximum pressure in gaseous bubbles (MBP) as well as dilatometric technique. The technique of sessile drop was additionally applied in the measurements of surface tension for pure indium and zinc. The measurements were performed at temperature range 474-1151 K. The isotherms of surface tension calculated based on Butler's equation at 700 and 1100 K corresponded well with the experimental values for zinc content lower than 0.6 mole fraction. The surface tension calculated for alloys of higher zinc concentrations (0.6 < X_Zn < 0.95) had a positive value of the surface tension temperature coefficient (dσ/dT), which did not coincide with the experimental results. The density as well as molar volume of liquid In-Zn alloys showed almost identical behaviour like the ideal solutions. The observed little deviations were contained within assessed experimental errors.     

New lead-free solder alloy

As the electronics industry is moving towards lead-free manufacturing processes, a new lead-free solder alloy based on Sn–9Zn–1Bi–2Cu–In is described. The quaternary alloy with indium additions exhibits melting, wetting, and mechanical properties superior to those in binary, ternary, and quaternary alloys. Indium as a penternary addition decreases the melting point of this alloy to 181 ^°C which it is a lower value when compared with the eutectic Sn–Pb solder (183 ^°C), it decreases the contact angle to 23^° which is very close to that for Sn–Pb solder alloy, it increases the Young’s modulus to higher values, and it increases its hardness to 19 kgf/mm² when compared with 12.9 kgf/mm² for the Sn–Pb solder alloy.     

Effect of Al on the electrochemical corrosion behaviour of Pb free Sn-8.5 Zn-0.5 Ag-XAl-0.5 Ga solder in 3.5% NaCl solution

The effect of Al on the electrochemical corrosion behaviour of Pb-free Sn-8.5 Zn-0.5 Ag-XAl-0.5 Ga solder in 3.5% NaCl solution was investigated by using potentiodynamic polarization techniques. The X content in the solder varied from 0.1 to 3 wt.%. Polarization studies revealed that an increase in Al content upto 1.5 wt.% decreased the corrosion current density (I_corr), corrosion rate of the solder and shifted the corrosion potential (E_corr) towards more noble values. However, higher content of Al, i.e. 3 (wt.%) in the five-element solder enhanced the corrosion rate and resulted in a significant increase in the E_corr towards more negative values. Passivation behaviour was noticed in all the solders having varying Al content, but the passive film formed at 1.5 wt.% Al was most stable due to its low passivation current density (i_p) and low critical current density (i_cc) value in comparison to the other solders. XPS and Auger depth profile results revealed that the passive film consisted of oxides/hydroxides of Al and Zn formed on the surface of the solder with Sn being formed in the subsequent layer. Considerable aluminium segregation occurred towards the surface principally as Al₂O₃/Al(OH)₃ with increase in Al content to 1.5 wt.% in the five element solder. The formation of Al₂O₃ seemed to prevent the oxidation of zinc on the surface of the solder.     

The Surface Tension and Density of Liquid Ag–Bi, Ag–Sn, and Bi–Sn Alloys

Summary. The sessile drop method has been used to measure density and surface tension for pure Ag, Bi, Sn, and their mixtures. For pure metals and Bi–Sn alloys negative temperature coefficients of surface tension have been obtained. In case of Ag–Bi and Ag–Sn alloys the temperature coefficients of surface tension take negative or positive values depending on composition. Experimental values of the surface tension for Ag–Bi, Ag–Sn, and Bi–Sn are compared with those computed from Butler’s model. A relatively good agreement is observed.     

水杨酸的添加对全无机锡铅混合钙钛矿太阳能电池的影响

全无机钙钛矿太阳能电池(PSCs)因其优异的光电转换效率和高的环境稳定性而被广大学者关注,但Pb元素的使用对环境危害较大限制了其进一步应用。尽管科研人员目前在努力寻找一种危害较小的元素替代铅,但无铅钙钛矿仍然比含铅钙钛矿更易分解,性能也更低。本文采用Sn部分取代Pb制备得到全无机锡铅混合钙钛矿薄膜,并通过添加一定量的水杨酸从而抑制Sn²⁺氧化为Sn⁴⁺,达到稳定相态提升电池光电转换效率的目的。结果表明随着水杨酸的添加量由2 mg·mL^-1增加至6 mg·mL^-1,器件的光电转换效率先增大后降低。通过SEM、XRD、XPS等测试结果发现,当添加量为4 mg·mL^-1时,薄膜相稳定性最好,与不添加水杨酸的器件相比,其短路电流密度(J_sc)从14.7 mA·cm^-2显著提高至15.1 mA·cm^-2,光电转换效率由5.8%提高至6.5%。此外,最优器件在空气环境中存放5 d后,初始光电转换效率仍可保持原有效率的50％,进一步表明水杨酸的添加对锡铅混合钙钛矿相稳定性的提升具有一定的促进作用。     

Second Generation Lead-free Solder Alloys – A Challenge to Thermodynamics

Summary. For environmental reasons, lead has to be removed from solder alloys used for interconnection purposes in electronics equipment. A new series of alloys, mainly based upon tin, and often containing copper and silver, has been evolved by empirical reasoning. A more theoretical approach is now being pursued, using thermodynamic principles, to produce the second generation of solder alloys. The paper outlines the soldering process, the requirements of solder alloys, and the various mechanisms (such as overload, fatigue, creep, and thermomechanical fatigue) that are potential causes of failure in service. It also describes from the manufacturing and the performance perspectives, the physical and mechanical properties necessary for reliable solder joints. These include conductivity, melting point, strength, ductility, and thermal stability of microstructure. The challenging question is posed as to how can thermodynamics contribute to prescribing and developing an improved series of alloys?     

The surface tension and density of the Cu-Ag-In alloys

The surface tension and the densities of the Cu-Ag-In alloys have been measured by means of the sessile drop method. The density of these alloys depends linearly on temperature in the case of all the investigated compositions. The surface tension shows a linear dependence on temperature except for the lowest temperatures. For most of the alloys, the surface tension at the lowest temperature is lower than that predicted by the straight line. The experimental values of the surface tension of the Cu-Ag-In alloys are compared with those computed from the model, and quite good agreement is observed.     

Comments and reconciliation of the Ni–Bi‐system thermodynamic reassessments

The binary Ni‐Bi alloys as well as multicomponent materials comprising systems like Ni‐Bi‐Sn, Ni‐Bi‐Sb etc. are recently considered as prospective for design of lead‐free solders. For that reason various authors focused their attention to the Ni‐Bi system thermodynamics. The studies identified five phases in the above system. Two of them (i.e., (Ni) and liquid), were treated as disordered substitutional solutions. The phase NiBi₃ is stoichiometric and a standard two‐sublattice model was repeatedly applied to describe its Gibbs free energy, while for the nonstoichiometric NiBi phase, a three‐sublattice model was retained. The pure bismuth phase ((Bi)) is stoichiometric as well. The results are discussed and compared to literature thermochemical and topological data. In liquid state, strong repulsions between nickel and bismuth atoms are anticipated in the nickel rich‐side, but no data about a liquid phase miscibility gap is available yet. Therefore, the stability of the liquid phase has to be reassured, in spite of positive deviations from ideal behaviour. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Comparative thermodynamic study and characterization of ternary Ag-In-Sn alloys

The results of thermodynamics and characterization of alloys in ternary Ag-In-Sn system is presented in this paper. Thermodynamic properties, in three investigated sections with molar ratio In:Sn=1:1, 1:2 and 1:4, have been calculated at the temperature of 1423 K using different predicting methods (general solution model, Toop, Hillert, Muggianu, Kohler, Redlich-Kister), compared mutually and with literature experimental data. The alloys in investigated sections have been characterized using DTA, XRD, SEM and optic microscopy.