电镀可焊性锡合金工艺的发展现状

1 引言 可焊性镀层是一种功能性镀层,可焊性锡合金(锡铅、锡银、锡铋和锡铜等)镀层由于其优良的抗蚀性和可焊性被广泛应用于电子工业中,作为电子器件、线材、印制线路板和集成电路块的保护性和可焊性镀层.本文就电镀可焊性锡合金工艺的特点、应用及发展现状作一综述.     

锡-铜-铋合金电镀液

概述了含有亚锡盐、铜盐、铋盐、酸和表面活性剂等组成的锡—铜—铋合金电镀液,可以获得镀层外观、抗裂性和可焊性等性能良好的锡—铜—铋合金镀层,适用于电子部件用的无铅可焊性镀层。     

甲基磺酸盐在锡及锡基合金镀层中的应用现状

介绍了甲基磺酸(MSA)盐镀液体系的特点。分析了电镀锡及可焊性锡合金镀液的主要成分及特点,介绍了MSA体系在电镀锡钢板中的应用。对比了电镀无铅镀层和Sn–Pb合金镀层的性能,给出了电镀及化学镀锡及锡基合金的工艺配方及操作条件。     

甲基磺酸盐电镀锡银合金工艺的研究

随着电子电镀工业的飞速发展,镀层质量的要求也越来越高,尤其是在可焊性方面更为突出.研究了一种环保型的电镀工艺,获得的锡银合金镀层具有很好的可焊性,而且该镀液的稳定性相当好,为可焊性镀层的发展提供了一个新的方向.     

电镀铜锡合金工艺研究进展

电镀铜锡合金具有装饰性好、可焊性优良、成本低、无毒、不使人体过敏等优点,而得到广泛的应用.介绍了电镀铜锡合金工艺的研究进展和应用、电镀铜锡合金镀液配方和工艺条件.     

锡及锡合金可焊性镀层电镀工艺

介绍了目前常用于电子元器件电镀纯锡液的主要技术要求。阐述了酸性硫酸盐镀锡、酸性氟硼酸盐镀锡或锡-铅合金、烷基磺酸盐镀锡或锡-铅合金、中性或弱酸性镀锡或锡-铅合金的工艺特点、镀液镀层性能及性价比。还介绍了Sn—Bi、Sn—Ag、Sn—Cu无氟无铅可焊性电镀锡基二元合金的特点、性能及典型的工艺配方。     

引脚可焊性镀层无铅纯锡高速电镀添加剂的开发

介绍了引脚可焊性镀层高速电镀工艺流程、高速电镀添加剂各组分的作用及其选择要求。通过Hull槽实验、10L电镀实验和高速模拟实验确定了甲基磺酸、二价锡离子、温度、电流密度和自制的添加剂——可焊性镀层锡铅高速电镀添加剂SYT845和无铅纯锡高速电镀添加剂SYT843H等各工艺条件对高速电镀过程的影响。可焊性实验和扫描电镜照片表明,采用SYT845型和SYT843H型添加剂所得的高速电镀镀层具有良好的可焊性,且结晶规整、细致,晶粒尺寸为1～3μm;SYT843H无铅纯锡高速电镀样品经TCT试验1000个循环（-60～150℃）后在500倍的SEM照片中没有发现锡须。该自制的添加剂应用于生产中已有2年。     

电镀Sn-Pb-In合金研究

电子元件锡铅可焊性镀层易于老化,合金元素铟的添加能大大提高镀层的焊接性能和抗性能。本文提出锡－铅－铟合金电镀工艺,探讨了铟含量的变化对锡－铅－铟合金镀层抗老化性、可焊性和光洁度的影响。     

可焊性多层电镀

随着电子工业的发展,对电子元器件的可焊性提出了越来越高的要求。因为基本元器件可焊性差,就将严重影响到整机工作的可靠性和使用时间,可焊性已成为衡量电子元器件好坏的一个重要指标。为了适应电子工业的发展,前人对可焊性镀层的电镀曾做过大量的研究。金、银、铅锡、镍锡 锡、锌锡     

电镀锡和可焊性锡合金发展概况

锡及其合金由于优良的耐蚀性和可焊性而广泛应用于电子工业中。总结了电镀锡、锡铅合金和锡铋合金的分类、特点及应用情况。     

BNT系无铅压电陶瓷的研究进展

(Bi1/2Na1/2)TiO3基无铅压电陶瓷是目前研究最广泛,最具吸引力的无铅压电陶瓷体系.本文主要综述了近几年国内外专家重点研究的以BNT为基的4类无铅压电陶瓷,并指出目前国内外学者对钛酸铋钠粉体合成的关注.     

铅-3%锑合金电化学磷化工艺及影响因素研究

提出了一种以锌钙系磷化液为主体的铅-3%锑合金电化学磷化新工艺。电化学测试结果表明:合金经过磷化后,表面形成的磷化膜能有效阻止其在3%NaCl溶液中的腐蚀,使合金的稳定性得到提高。该工艺所用试剂不含有害促进剂,磷化过程无污染,技术环保,具有工业推广价值。     

HYDRODYNAMICAL STUDY OF A STAGEWISE CONTROLLED CYCLING EXTRACTION COLUMN

In order to decrease center segregation together with center porosity, electromagnetic stirring has been applied to continuous casting of billets, blooms and slabs. As well known, however, the violent agitation in the pool is powerful to prevent center segregation, but promotes the formation of white band

To tackle this problem, the turbulent electromagnetically driven flows in the pool are theoretically analyzed. Especially focusing on the effect of the electromagnetically driven reverse-turn flows on the structure, the solidification experiments were conducted by use of the Sn-10% Pb alloy

Theoretical equation of the maximum velocity appearing at every half period for the reverse-turn flow is given as follows

where, B = k3 yfr^/\(aw/ti)l/4B}.     

氧化锌和铅硼玻璃料对MgTiO3微波介质陶瓷的影响

研究了氧化锌和铅硼玻璃料的加入对MgTiO3微波介质陶瓷的烧结和微波介电特性的影响。结果表明：氧化锌和铅硼玻璃料均可以使MgTiO3微波介质陶瓷的烧结温度降低，在等量添加的条件下，铅硼玻璃料降低烧结温度的效果更佳，可使烧结温度降至1200℃，且器件在2－6GHz的频率范围内具有良好的介电性能。     

Lead(II) adsorption onto the graphene layer of carbonaceous materials in aqueous solution

Lead(II) adsorption from an aqueous solution onto a graphene layer (Cπ electrons) was investigated using activated carbon and charcoal. The carbonaceous materials were treated by several steps to prepare ash free and acidic oxygen free graphite surface by washing with HCl and H₂F₂ solution followed by out gassing at 1273 K. Changes in Pb(II) adsorption capacity were checked at each step to maximize the area of the graphene layer. As received activated carbon and charcoal and their HNO₃ oxidized counterparts were also used for the adsorption experiments for comparison with the ash free and the acidic oxygen free carbons. Boehm titration and Langmuir isotherms were used to evaluate the Pb(II) adsorption onto the adsorbents. The experimental results indicate that an acidic oxygen free graphene layer exhibits a basic character caused by Cπ electrons. When only a small amount of acidic oxygen groups was present, the Pb(II) adsorption strength onto the graphene layer (Cπ electrons) significantly diminished, and the Pb(II) adsorption sites were switched from the graphene layer to carboxylic and lactonic groups on the carbons in the results.     

Reciprocal effect of Pb(II) and surfactant onto their sorption in weak acid polyacrylic cation exchanger

The decrease in the equilibrium sorption of Pb(II) and nonionic surfactants (oxyethylated alcohols OS-20 and alkylmonoethers ALM-10) in H-form of Purolite C 106 cation exchanger was observed due to their presence in the same solution. The sorption of Pb(II) both in the form of free cations and in the form of Pb(II) bonded with surfactant takes place. The sorption of Pb(II) bonded with OS-20 is higher compared with that of Pb(II) bonded with ALM-10. In the presence of ALM-10 the sorption of Pb(II) free cations prevails. Increasing the acidity from pH 5 to pH 3, increases the rate of the sorption of surfactant. Due to the presence of surfactant the rate of Pb(II) sorption also increases, while without surfactant it decreases with an increase in acidity. © 1998 SCI     

Tin-Lead flake poly (ether sulfone) composite formed by in-situ melt processing of tin-lead particles

Tin-lead (60Sn-40Pb) flake poly(ether sulfone) (PES) composites in which the flakes were partially interconnected and of average thickness 2 μm were prepared by hot pressing molten Sn-Pb particles in a matrix of PES at a temperature above the melting temperature of Sn-Pb and above the glass transition temperature of PES. Hot pressing at 240°C and 6.51 Mpa resulted in a 15 vol% Sn-Pb composite of lower electrical resistivity and higher electromagnetic interference shielding effectiveness than a PES composite containing 15 vol% aluminum flakes that were not formed in-situ. The electrical properties of the in-situ PES/Sn-Pb flake composites were much better than those of PES/Sn-Pb flake composites were fabricated by hot pressing at 310°C (the manufacturer-suggested fabrication temperature), though the mechanical properties were not as good.     

Adsorption characterization of lead(II) and cadmium(II) on crosslinked carboxymethyl starch

The adsorption of Pb(II) and Cd(II) ions with crosslinked carboxymethyl starch (CCS) was investigated as function of the solution pH, contact time, initial metal‐ion concentration, and temperature. Isotherm studies revealed that the adsorption of metal ions onto CCS better followed the Langmuir isotherm and the Dubinin–Radushkevich isotherm with adsorption maximum capacities of about 80.0 and 47.0 mg/g for Pb(II) and Cd(II) ions, respectively. The mean free energies of adsorption were found to be between 8 and 16 kJ/mol for Pb(II) and Cd(II) ions; this suggested that the adsorption of Pb(II) and Cd(II) ions onto CCS occurred with an ion‐exchange process. For two‐target heavy‐metal ion adsorption, a pseudo‐second‐order model and intraparticle diffusion seem significant in the rate‐controlling step, but the pseudo‐second‐order chemical reaction kinetics provide the best correlation for the experimental data. The enthalpy change for the process was found to be exothermic, and the ΔS^θ values were calculated to be negative for the adsorption of Pb(II) and Cd(II) ions onto CCS. Negative free enthalpy change values indicated that the adsorption process was feasible. The studies of the kinetics, isotherm, and thermodynamics indicated that the adsorption of CCS was more effective for Pb(II) ions than for Cd(II) ions. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Microstructural development in a rapidly cooled eutectic Sn-3.5% Ag solder reinforced with copper powder

Experiments using eutectic Sn-3.5% Ag solder paste were conducted with the objective of examining the conjoint influence of copper particles addition and rapid cooling on microstructural development. The composite solder mixture was made by thoroughly mixing a pre-weighed amount of copper particles with a commercial Sn-3.5% Ag solder paste. The experiments were quite similar to the heating and cooling cycle of an industrial reflow soldering process. Heating of the samples was conducted in a furnace whose temperature was carefully controlled. The cooling process was conducted on a chilled aluminum block through which coolant was circulated at 0.5 °C. When the solder temperature reached 250 °C, the circulating system would turn on automatically and the sample, which is still molten, is forced to cool rapidly. Temperature records of the solder samples revealed that addition of copper particles to the eutectic Sn-3.5% Ag did not appreciably affect the heating and melting properties when compared to the unreinforced Sn-3.5% Ag counterpart. However, copper particles did change the solidification temperature of the composite solder. Detailed observations for varying amounts of copper particle addition revealed that copper particles less than 1.0 wt.% lowered the solidification temperature of the composite solder. For copper particles greater than 1.0 wt.%, the solidification temperature increased a few degrees Celsius, indicating that some of the copper particles did not completely dissolve in the Sn-dominant solder during the melting process. Results reveal that as-solidified microstructures of the eutectic Sn-3.5% Ag solder contain columnar type dendrites of the Sn-rich phase and a eutectic mixture of the Sn₃Ag and Sn-rich phase located between the dendrite columns. The addition of copper particles to the eutectic Sn-3.5% Ag solder does refine the morphology of the primary phase, which is attributed to the presence and distribution of the Cu₆Sn₅ intermetallic in the solder matrix.     

The effects of Cu and Al on dry sliding wear properties of eutectic Sn-9Zn lead-free solder alloy

The present study investigates the influence of Cu and Al on microstructure and wear behavior of a eutectic Sn-9Zn solder alloy. The Sn-9Zn–X alloy was produced by adding various amounts of Cu and Al through investment casting method. The produced Sn-9Zn–X alloys were characterized by a scanning electron microscope, X-ray diffraction, and hardness measurements. In wear tests at 1 ms^?1 sliding speed, 10 N load and 5 different sliding distances (400–2000 m) were used. The results show that as the amount of Cu and Al increased within Sn-9Zn alloy, the hardness of the alloy increased as well. Depending on the increase in hardness of the alloys produced by investment casting, it was observed that weight loss decreased during wear tests. Furthermore, the same proportion of added Al alloys’ hardness and weight loss were observed to be higher than the added Cu alloys. Furthermore, the Cu-added alloy exhibited higher hardness and lower weight loss than the Al-added alloy did.