La对Sn3.5Ag0.5Cu钎料界面组织和性能的影响

通过SEM和EDAX等,研究了La添加量对Sn3.5Ag0.5Cu钎料与Cu基体焊合界面IMC微观组织及性能的影响。结果表明:添加不同量的La均对Sn3.5Ag0.5Cu与Cu基体焊合后的组织有细化作用并增强其力学性能。其中以w(La)达到0.05%时最优,剪切强度可提高10.7%。材料热力学理论计算结果表明,La具有"亲Sn"倾向,添加少量La到Sn3.5Ag0.5Cu钎料中,可减小Cu6Sn5/Cu界面Sn的活度,降低IMC的长大驱动力。     

镧对Sn3.5Ag0.5Cu钎料组织性能影响

运用莱卡显微镜、扫描电镜和能谱分析等手段,研究了稀土元素La的添加量对Sn3.5Ag0.5Cu钎料及其与Cu基体焊接后微观组织及性能的影响。结果表明:添加不同含量的稀土La均能使钎料及其与Cu基体焊接后组织与性能得到改善,其中以w(La)达到0.05%时为最优,显微硬度及剪切强度分别提高14%和10.7%。键参数函数计算结果表明La具有"亲Sn"倾向,可细化钎料组织,降低IMC(界面金属间化合物)的长大驱动力。     

Ag对Sn-Pb电子钎料合金性能的影响

研究了Ag的合金化对Sn-Pb钎料合金材料性能的影响。并从钎料的润湿性能，机械性能及抗腐蚀性能等方面讨论了Ag的有利作用，研究表明，在一些特定条件下的电子元件的焊接，Sn-Pb-Ag钎料可部分地或全部地替代昂贵的遗金属钎料合金。     

热循环条件下Sn基钎料接头电迁移行为研究

通过电迁移和热疲劳循环实验,研究了热循环和高电流密度耦合作用下Sn58Bi和Sn3.0Ag0.5Cu钎料焊接接头的失效形式。实验结果表明,在通电和高低温冲击的耦合作用下,两种钎料接头的失效都发生在升温阶段。热循环导致接头内部裂纹的萌生和扩展,导致局部电流密度持续增大,加速了电迁移的发生,最终导致焊点失效。在热电耦合作用下,Sn58Bi钎料接头的使用寿命要长于Sn3.0Ag0.5Cu钎料接头的使用寿命。     

时效温度下钎料的稀土相CeSn3表面Sn晶须生长

于Sn3.8Ag0.7Cu钎料中添加过量的稀土Ce会在其内部形成大尺寸的稀土相CeSn3,将稀土相CeSn3暴露于空气中,研究在时效处理过程中时效温度对其表面Sn晶须生长的影响规律.结果表明:时效温度对稀土相CeSn3表面Sn晶须的生长产生显著影响.室温时效20 min后,其表面会形成少量的白色Sn颗粒:75℃时效20...     

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。     

SnAgCuRE系钎料的钎焊接头组织与力学性能

以Sn2.5Ag0.7Cu为基础,添加微量的稀土(RE)r(Ce︰La)为4︰1,研究了钎焊接头的显微组织与力学性能。结果表明:添加微量的RE后,钎料与Cu试样间的界面层厚度明显减小,且界面处的组织更加平滑,相应地其剪切强度随微量RE的添加而增大,并在RE含量(质量分数)为0.1%时达到最大值36MPa。     

Sn-Ag系电子无铅软钎料的超电势研究

随着微电子表面组装技术（SMT）的迅速发展和公众环境意识的增强，无铅软钎料成为近年来研究的焦点。主要研究了Sn-Ag系合金钎料的超电势电化学性能，并且与传统的Sn-Pb近共晶合金进行了对比。试验证明在酸、碱两种不同的溶液环境中，无铅软钎料在Sn-Pb合金的超电势有明显的差异。并指出含铋的钎料的超电势随着铋的含量的增加而降低，从而提出了在无铅软钎料研究中应当考虑因超电势变化而引起的问题。     

稀土对Zn20Sn高温无铅钎料组织与性能的影响

向Zn20Sn高温无铅钎料中添加微量铈镧混合稀土（RE）,研究了RE的添加量对该钎料合金显微组织及性能的影响。结果表明,添加微量RE的合金显微组织中出现含RE的金属间化合物（IMC）。随着RE的添加,形状各异的IMC的数量显著增加。RE质量分数为0.5%~1.0%的合金的固相线温度不变,而液相线温度略有降低。当RE质量分数为0.5%时,钎料在Cu基板上的铺展面积最大,比Zn20Sn钎料提高了57.6%。但随着RE的继续添加,钎料的润湿性降低。当RE质量分数超过0.1%时,钎料的显微硬度和电阻率随着RE含量的增加而增大。综合考虑,合适的RE添加量为质量分数0.5%。     

BiAgSbCu系高温无铅钎料制备及焊接性能研究

研制开发熔点在260 ℃以上的高温无铅钎料来代替传统的高铅钎料运用于电子封装一直是钎焊领域的一大难题。熔点约为272 ℃的Bi-2.6 Ag-5 Sb钎料合金因润湿性和焊接可靠性不良在运用上受到限制。文中通过在Bi-2.6 Ag-5 Sb钎料合金中添加微量元素Cu来改善B-i2.6 Ag-5 Sb合金的润湿性及焊接可靠性。研究结果表明,Cu含量对BiAgSbCu系钎料合金熔点影响较小,当Cu含量为2 %时,润湿性及焊接可靠性最佳。     

稀土元素对无铅钎料微观结构及性能的影响

添加适量的稀土元素可以有效提高无铅钎料(如SnAgCu,SnZn)的性能,尤其是添加稀土的SnAgCu钎料的蠕变断裂寿命是未添加时的7倍.针对添加微量稀土元素对无铅钎料润湿性、力学性能、蠕变性能以及电迁移行为的影响,特别是对钎料微观结构的变化规律进行了综述,并指出了新型钎料的应用及发展前景.     

Effects of reflow on wettability, microstructure and mechanical properties in lead-free solders

Solder joints used in electronic applications undergo reflow operations. Such operations can affect the solderability, interface intermetallic layer formation and the resultant solder joint microstructure. These in turn can affect the overall mechanical behavior of such joints. In this study the effects of reflow on solderability and mechanical properties were studied. Nanoindentation testing (NIT) was used to obtain mechanical properties from the non-reflow (as-melted) and multiple reflowed solder materials. These studies were carried out with eutectic Sn-3.5Ag solders, with or without mechanically added Cu or Ag reinforcements, using Cu substrates. Microstructural analysis was carried out on solder joints made with the same solders using copper substrate.     

Effect of alloying elements on properties and microstructures of SnAgCu solders

Recent years, the SnAgCu family of alloys has been found a widely application as a replacement for the conventional SnPb solders in electronic industry. In order to further enhance the properties of SnAgCu solder alloys, alloying elements such as rare earth, Bi, Sb, Fe, Co, Mn, Ti, In, Ni, Ge and nano-particles were selected by lots of researchers as alloys addition into these alloys. Rare earth (RE) elements have been called the ‘‘vitamin” of metals, which means that a small amount of RE elements can greatly enhance the properties of metals, such as microstructure refinement, alloying and purification of materials and metamorphosis of inclusions. In addition, a small amount of Zn addition has the ability to reduce undercooling efficiently and suppress the formation of massive primary Ag₃Sn plates, and Bi/Ga has the ability to enhance the wettability of SnAgCu alloys as well as Ni. Moreover, adding Co/Fe/Ge can effectively refine microstructure, modify interfacial Cu-Sn compounds and increase the shear strength of joints with Cu. This paper summarizes the effects of alloying elements on the wettability, mechanical properties, creep behavior and microstructures of SnAgCu lead-free solder alloys.     

Effects of mechanical deformation and annealing on the microstructure and hardness of Pb-free solders

The microstructure property relations of several Pb-free solders are investigated to understand the microstructural changes during thermal and mechanical processes of Pb-free solders. The Pb-free solder alloys investigated include pure Sn, Sn-0.7% Cu, Sn-3.5% Ag, and Sn-3.8% Ag-0.7% Cu (in weight percent). To reproduce a typical microstructure observed in solder joints, the cooling rate, ingot size, and reflow conditions of cast alloys were carefully controlled. The cast-alloy pellets are subjected to compressive deformation up to 50% and annealing at 150°C for 48 h. The microstructure of Pb-free solders is evaluated as a function of alloy composition, plastic deformation, and annealing. The changes in mechanical property are measured by a microhardness test. The work hardening in Sn-based alloys is found to increase as the amount of alloying elements and/or deformation increases. The changes in microhardness upon deformation and annealing are correlated with the microstructural changes, such as recrystallization or grain growth, in Pb-free solder alloys.     

Effects of solid-state annealing on the interfacial intermetallics between tin-lead solders and copper

The interfacial intermetallics between Cu and solder were studied for four Sn-Pb compositions at the annealing temperatures of 125°C, 150°C, and 175°C for up to 30 days. The η-phase (Cu₆Sn₅) layer formed during reflow continues to grow during annealing. An additional layer of ɛ-phase (Cu₃Sn) forms at the η/Cu interface after an incubation annealing time. The thickness results fit a power-law relationship against time with average exponents 0.69 and 0.44 for the η phase and the ɛ phase, respectively. On prolonged annealing, the proportions of the individual phases in the total layer reach a steady state.     

Sn基钎料与Cu和Al基板的润湿性比较研究

采用润湿平衡法测量了四种Sn基钎料(Sn-37Pb、Sn-3.OAg-0.5Cu、Sn-0.7Cu与Sn-9Zn)分别在250,260和270℃与Cu、Al两种基板的润湿性能.结果表明:钎料与Al基板的润湿时间均比Cu基板长,除Sn-9Zn外,其他三种钎料与Cu基板的润湿力比Al基板大,并且随着温度升高,润湿性能提高,...     

Microstructure and mechanical properties predicted by indentation testing of lead-free solders

Microstructure and mechanical properties were investigated for ten systems of lead-free solders compared with the eutectic Sn-Pb solder. Mechanical properties including elastic, plastic, and creep deformations were predicted by indentation testing. This method was established based on the elastic-plastic-creep finite-element method (FEM). The predicted mechanical properties were obtained for the temperatures ranging between −20°C and 160°C.     

颗粒增强Sn-Ag基无铅复合钎料显微组织与性能

通过外加法向Sn-3.5Ag焊料中加入体积分数为10%的微米级Cu、Ni颗粒制备了无铅复合钎料,对钎料的显微组织、拉剪及润湿性能进行了研究。结果表明,颗粒周围以及基板界面处的显微组织中生成了金属间化合物,其形态及大小因加入颗粒而不同。颗粒的加入提高了钎料钎焊接头的剪切强度,其中Cu颗粒增强的接头的剪切强度提高了33%,Ni颗粒的提高了20%。两种复合钎料的铺展面积均下降了约15%,其中Cu颗粒增强复合钎料润湿角由11°增加到18°。     

Influence of rotating magnetic field on solidification microstructure and tensile properties of Sn-Bi lead-free solders

The solidification microstructures and corresponding mechanical properties of Sn-20Bi and Sn-20Bi-0.4Cu alloys were studied with and without rotating magnetic field (RMF). Without RMF, the microstructures of both solders exhibit great numbers of undesirable columnar structure of dendrite primary β-Sn phase and large Cu₆Sn₅ phase. The RMF-driven flow has induced columnar-to-equiaxed transition (CET) of dendrite primary β-Sn phase, which simultaneously results in dendrite fragmentation, and provokes distinct grain and intermetallic compound (IMC) refinement effects due to Lorentz force acting on the melt. The individual contributions of RMF on the lattice strain, crystallite size, stress and energy density were evaluated from X-ray peak broadening using various Williamson-Hall models. RMF can also reduce effectively the lattice strain and crystallite size of both solders, which are likely vital prerequisite for property control on metallic materials. Tensile tests showed that the tensile strength of Sn-20Bi solder was enhanced and ductility of Sn-20Bi-0.4Cu alloy was improved. These effects could increase the elastic compliance and develop the drop impact reliability of bulk solders.     

三种典型Sn-Ag-Cu无铅钎料的组织和性能研究

对比研究了三种典型标称成分的Sn-Ag-Cu钎料(即日本JEIDA推荐的Sn-3.0Ag-0.5Cu、欧盟IDEALS推荐的Sn-3.8Ag-0.7Cu和美国NEMI推荐的Sn-3.9Ag-0.6Cu)的显微组织特征、熔化特性、润湿性以及钎焊接头微焊点的力学性能等。结果表明,三种钎料的组织和性能非常接近。然而从性价比等方面综合考虑,Sn-3.0Ag-0.5Cu为三种钎料中最具优势的替代传统Sn-Pb钎料(共晶和近共晶钎料)的无铅合金。