Sn对BiSbCu钎料钎焊工艺性能的影响

在BiSbCu钎料中添加Sn,分析Sn对BiSbCu钎料合金钎焊工艺性能的主要指标——钎料熔点和铺展面积的影响.结果表明:在Bi5Sb2Cu钎料合金中加入Sn可以显著降低钎料的熔点和显著增强钎料合金的铺展性能.当Sn的质量分数为10％时,Bi5Sb2Cu钎料的铺展面积为26.22 mm2,钎焊工艺性能最好.     

Sn对BiSbCu钎料钎焊工艺性能的影响

在BiSbCu钎料中添加Sn,分析Sn对BiSbCu钎料合金钎焊工艺性能的主要指标——钎料熔点和铺展面积的影响。结果表明:在Bi5Sb2Cu钎料合金中加入Sn可以显著降低钎料的熔点和显著增强钎料合金的铺展性能。当Sn的质量分数为10%时,Bi5Sb2Cu钎料的铺展面积为26.22 mm2,钎焊工艺性能最好。     

Sn－Zn－In软钎料合金初步研究

对Ｓｎ－Ｚｎ－Ｉｎ钎料合金的性能进行了研究，钎料铺展性和剪切强度试验结果表明，在Ｓｎ－９Ｚｎ－Ｉｎ软钎料合金中，随Ｉｎ含量增加，铺展面积增大，钎焊接头剪切强度降低。钎料熔点和接头组织等性能的综合分析结果表明Ｓｎ－９Ｚｎ－１０Ｉｎ的性能已接近或超过传统的Ｓｎ－Ｐｂ共晶     

Sn—Zn—In软钎料合金初步研究

对Ｓｎ－Ｚｎ－Ｉｎ钎料合金的性能进行了研究，钎料铺展性和剪切强度试验结果表明，央Ｓｎ－９Ｚｎ－Ｉｎ软钎料合金中，随Ｉｎ含量增加，铺展面积增大，钎焊接头剪切强度降低。钎粒熔点和接头组织等性能的综合分析结果表明Ｓｎ－９Ｚｎ－１０Ｉｎ的性能已接近或超过传统的Ｓｎ－Ｐｂ共晶。     

无铅焊料Sn-Zn-In系列合金的研究

对熔化起始温度和终止温度作线性回归进行合金设计,并对其焊料合金进行了熔点、抗剪切强度及微观组织等研究分析。结果表明:当w(In)(质量分数)为3%~5%,w(Zn)为5%~9%时,焊料的熔化温度在170~200℃,接近于焊料Sn-37Pb的熔化温度183℃;焊料与Cu焊合后形成γ-Cu5Zn8化合物;Sn-Zn-In系焊料的抗剪切强度与焊料Sn-37Pb的剪切强度33.73 MPa相当。     

SnAgCuRE系钎料合金的润湿特性

选择商用水溶性钎剂,以润湿平衡法,研究了SnAgCuRE系钎料合金在表面贴装元器件上的润湿特性。结果表明:当w(RE)为0.1%时,预热15s,255℃钎焊5s,该钎料合金具有最大的润湿力1.510mN和最小的润湿角11.03°,与传统的Sn63Pb37钎料的润湿力相当,可满足表面组装元器件对其润湿性能的要求。     

P对Sn-Cu无铅钎料性能的影响

添加了P到Sn-Cu系无铅钎料中,测定了钎料的熔化温度、抗氧化性能和接头蠕变疲劳寿命。结果表明:在Sn0.7Cu中添加微量的P,提高了无铅钎料的抗氧化性能,对熔化温度基本无影响。Sn0.7Cu0.005P无铅钎料合金熔化温度的峰值为226.7℃,在恒定应力为2MPa的蠕变疲劳试验中,钎料接头蠕变疲劳寿命为337.357min。     

纳米Sn-Ag钎料合金熔化温度及形成焓的研究

考虑表面效应,基于Lindemann熔化准则,利用Miedema模型对Sn-Ag纳米钎料合金的熔化温度及形成焓进行计算.Sn-Ag纳米合金微粒的熔化温度及形成焓均依赖于尺寸和组元成分;对于Sn3.5 Ag纳米钎料合金,当微粒尺寸大小为5nm时,其熔化温度下降约为7％;而合金形成焓随晶粒粒径的减小而增加,合金稳定性降低;对于Sn3.5Ag钎料合金,当粒径尺寸为0.1μm时,合金形成焓完全为正值,对Sn-Ag钎料合金组织形成存在产生很大影响.     

稀土改性的Sn-58Bi低温无铅钎料

研究了微量稀土对Sn-58Bi低温钎料的改性作用.试验添加质量分数为0.1 ?组混合稀土的无铅材料,并对比Sn-58Bi和Sn-58Bi0.5Ag合金.观察了钎料显微组织的变化并做了定量分析,采用DSC测试了钎料的熔化温度,同时测量了钎料的润湿性能、接头强度与硬度.结果表明,微量稀土添加细化了Sn-58Bi钎料合金的显微组织,对钎料的熔化温度几乎没有影响,能显著改善Sn-58Bi钎料的润湿性能和接头剪切强度,而且改善的程度优于添加微量Ag对Sn-58Bi钎料的作用.     

Sn-Zn-Bi-Ag系钎料物理性能研究

通过成分设计形成了Sn-Zn-Bi-Ag系钎料合金。针对微电子产业的应用要求研究了钎料的物理性能,分析了Sn-Zn-Bi-Ag系钎料中合金元素对钎料物理性能的影响。发现:Sn-Zn-Bi-Ag系钎料的合金元素中Bi、Ag含量(质量分数)的增加会使钎料的密度增大,而Zn含量对钎料的密度影响不大。Zn含量5.0%~6.5%,Bi含量1.5%~3.0%,Ag含量0.5%~0.8%范围的Sn-Zn-Bi-Ag钎料具有较好的润湿性能。Sn-Zn-Bi-Ag系钎料中Bi含量不高时,钎料的电阻率均比传统Sn-37Pb钎料小。随着Bi含量的增加,钎料的电阻率有明显增大的趋势。     

The microstructures and mechanical properties of the Sn-Zn-Ag-Al-Ga solder alloys—The effect of Ga

The microstructures and mechanical properties of Sn-8.55Zn-0.5Ag-0.45Al-yGa (wt.%) lead-free solders were investigated. The y content of the solders investigated was 0.5–3.0 wt.%. The results indicate that Ga exhibits prominent influence in the microstructure as well as mechanical properties of the solders. By increasing Ga, the fraction of the Sn/Zn eutectic region decreases and the Sn-matrix region increases. An increase in the Ga content from 0.5 wt.% to 2.0 wt.% enhances the tensile strength while degrading the ductility. The mechanical properties and differential scanning calorimetry (DSC) behavior have been compared with that of the 63Sn-37Pb solder. Gallium lowers the melting point of the Sn-8.55Zn-0.5Ag-0.45Al-yGa solders. The Sn-8.55Zn-0.5Ag-0.45Al-0.5Ga solders exhibit greater tensile strength and better ductility than the 63Sn-37Pb solder.     

Generation of Tin(II) Oxide Crystals on Lead-Free Solder Joints in Deionized Water

The effect of the anode and cathode on the electrochemical corrosion behavior of lead-free Sn-Ag-Cu and Sn-Ag-Cu-Bi solder joints in deionized water was investigated. Corrosion studies indicate that SnO crystals were generated on the surfaces of all lead-free solder joints. The constituents of the lead-free solder alloys, such as Ag, Cu, and Bi, did not affect the corrosion reaction significantly. In contrast to lead-free solders, PbO _x was formed on the surface of the traditional 63Sn-37Pb solder joint in deionized water. A cathode, such as Au or Cu, was necessary for the electrochemical corrosion reaction of solders to occur. The corrosion reaction rate decreased with reduction of the cathode area. The formation mechanism of SnO crystals was essentially a galvanic cell reaction. The anodic reaction of Sn in the lead-free solder joints occurred through solvation by water molecules to form hydrated cations. In the cathodic reaction, oxygen dissolved in the deionized water captures electrons and is deoxidized to hydroxyl at the Au or Cu cathode. By diffusion, the anodic reaction product Sn²⁺ and the cathodic reaction product OH⁻ meet to form Sn(OH)₂, some of which can dehydrate to form more stable SnO·xH₂O crystals on the surface of the solder joints. In addition, thermodynamic analysis confirms that the Sn corrosion reaction could occur spontaneously.     

Mechanical response of solder joints in flip-chip type structures

The mechanical response of PbSn solder joints of two different solder alloys (37 wt.% Pb - 63 wt.% Sn and 95 wt.% Pb - 5 wt.% Sn) used as flip-chip type interconnects is measured through mechanical testing (in tension and in shear). The influence of solder pad composition (Au and Ni) upon the behaviour of the solder joints is examined. Fatigue testing performed upon flipchip samples demonstrates the difference in mechanical comportment between Pb37Sn63 and Pb95Sn5 solders. A model for predicting fatigue life is put forward.     

The microstructures and mechanical properties of the Sn-Zn-Ag-Al-Ga solder alloys—the effect of Ag

The microstructures and mechanical properties of Sn-8.55Zn-xAg-0.45 Al-0.5Ga (wt.%) lead-free solders were investigated. The x content of the solders investigated were 0.5–3.0 wt.%. The results indicate that Ag plays an important role not only in the structure but also in the mechanically properties. The mechanical properties and differential scanning calorimetry (DSC) behavior has been compared with that of 63Sn-37Pb solder. Small additions of Ag decreased the melting point of the Sn-8.55Zn-xAg-0.45Al-0.5Ga solders while maintaining the same strength and ductility as the 63Sn-37Pb solder.     

电子组装用高温无铅钎料的研究进展

分析了国内外电子组装用高温无铅钎料的研究现状。指出目前常用的高温钎料仍然是高Pb焊料或80Au-20Sn钎料,导致焊料含Pb而污染环境,或者含质量分数为80%的Au而使焊料成本奇高。指明了Bi-Ag系钎料具有潜力替代高Pb焊料或80Au-20Sn钎料。未来的研究将在成分设计及可靠性等方面进行探索,以最终找到既经济又可替代传统高铅钎料的高温无铅钎料。     

Microstructural evolution of a lead-free solder alloy Sn-Bi-Ag-Cu prepared by mechanical alloying during thermal shock and aging

In a previous study, a lead-free solder, Sn-6Bi-2Ag-0.5Cu, was developed by mechanical alloying. The alloy shows great potential as a lead-free solder system. In the present work, the microstructural evolution during thermal shock and aging was examined. In the as-soldered joints small bismuth (1 μm to 2 μm) and Ag₃Sn (1 μm) particles were finely dispersed in a nearly pure tin matrix with a small amount of η-Cu₆Sn₅ phase in the bulk of solder. During thermal shock and aging microstructural evolution occurred with Cu-Sn intermetallic compound (IMC) layer growth at interface, bismuth phase coarsening and Ag₃Sn phase coarsening. The microstructure of the solder appeared to be stable at high temperature. The shear strength of the present solder joint is higher than that of Sn-37Pb and Sn-3.5Ag solders. Shear failure occurred Cu-Sn IMC layer-solder interface and in the bulk of solder.     

Metallurgical reactions in composite 90Pb10Sn/lead-free solder joints and their effect on reliability of LTCC/PWB assembly

Use of 90Pb10Sn solder as a noncollapsible sphere material with 95.5Sn 4Ag0.5Cu and SnInAgCu lead-free solders is investigated. Practical reflow conditions led to strong Pb dissolution into liquid solder, resulting in >20 at.% Pb content in the original lead-free solders. The failure mechanism of the test joints is solder cracking due to thermal fatigue, but the characteristic lifetime of 90Pb10Sn/SnInAgCu joints is almost double that of 90Pb10Sn/95.5Sn4Ag0.5Cu in a thermal cycling test (TCT) over the temperature range from −40°C to 125°C. It is predicted that this is mainly a consequence of the better fatigue resistance of the SnPbInAgCu alloy compared with the SnPbAgCu alloy. Indium accelerates the growth of the intermetallic compound (IMC) layer at the low temperature co-fired ceramic (LTCC) metallization/solder interface and causes coarsening of IMC particles during the TCT, but these phenomena do not have a major effect on the creep/fatigue endurance of the test joints.     

Nanoparticles of the Lead-free Solder Alloy Sn-3.0Ag-0.5Cu with Large Melting Temperature Depression

Due to the toxicity of lead (Pb), Pb-containing solder alloys are being phased out from the electronics industry. This has lead to the development and implementation of lead-free solders. Being an environmentally compatible material, the lead-free Sn-3.0Ag-0.5Cu (wt.%) solder alloy is considered to be one of the most promising alternatives to replace the traditionally used Sn-Pb solders. This alloy composition possesses, however, some weaknesses, mainly as a result of its higher melting temperature compared with the Sn-Pb solders. A possible way to decrease the melting temperature of a solder alloy is to decrease the alloy particle size down to the nanometer range. The melting temperature of Sn-3.0Ag-0.5Cu lead-free solder alloy, both as bulk and nanoparticles, was investigated. The nanoparticles were manufactured using the self-developed consumable-electrode direct current arc (CDCA) technique. The melting temperature of the nanoparticles, with an average size of 30 nm, was found to be 213.9°C, which is approximately 10°C lower than that of the bulk alloy. The developed CDCA technique is therefore a promising method to manufacture nanometer-sized solder alloy particles with lower melting temperature compared with the bulk alloy.     

回流次数对Sn3.8Ag0.7Cu-xNi/Ni焊点的影响

研究了复合无铅焊料Sn3.8Ag0.7Cu-xNi(x=0.5,1.0,2.0)与Au/Ni/Cu焊盘在不同回流次数下形成的焊点的性能.结果表明,Ni颗粒增强的复合焊料具有良好的润湿性能,熔点小于222℃;X为0.5的焊料界面IMC由针状(CuNi)6Sn5演化为双层IMC,即多面体状化合物(CuNi)6Sn5和回飞棒...     

高温高铅焊料无铅化的研究进展

微电子封装工业中应用于高温领域的高铅焊料的无铅化是一个国际化难题。对目前高温无铅焊料的研究进展进行了综述,包括80Au-20Sn、Bi基合金、Sn-Sb基合金和Zn-Al基合金。从各种焊料的熔化行为、力学性能、导电导热性能、润湿性、界面反应和可靠性等方面,总结了这些高温无铅焊料的特性以及在应用中各自存在的问题。通过比较,认为Sn-Sb基合金在高温领域取代高铅焊料将有很大的应用前景。