Ag颗粒增强复合钎料钎焊接头蠕变断裂及强化机理研究

测定了不同应力和温度下Ag颗粒增强复合钎料及基体钎料63Sn37Pb钎焊接头蠕变寿命,分析了Ag颗粒增强复合钎料及基体钎料钎焊接头蠕变断裂机理.表明:Ag颗粒增强复合钎料钎焊接头蠕变寿命优于基体钎料;Ag颗粒表面Ag-Sn金属间化合物形成及Ag颗粒对富Pb层阻碍作用是复合钎料钎焊接头蠕变性能提高的主要因素;钎焊接头Cu基板上一薄层富Pb相区形成是蠕变裂纹主要原因.     

Ag颗粒含量对SnCu基复合钎料性能的影响

利用颗粒增强原理研制了新型Ag颗粒增强SnCu基复合钎料,研究了Ag颗粒不同含量对复合钎料性能影响.结果表明:当Ag含量(体积分数)为5%时,复合钎料铺展面积最大,润湿角最小,钎焊接头蠕变寿命最长,比基体钎料提高23倍.     

温度对Cu颗粒增强复合钎料蠕变性能的影响

蠕变性能是影响钎焊接头可靠性的重要指标之一.采用搭接面积为1 mm2的单搭接钎焊接头,在恒定载荷下,测定了Cu颗粒增强锡铅基复合钎料钎焊接头的蠕变寿命,分析并讨论了温度对该复合钎料蠕变寿命的影响.结果表明:Cu颗粒增强的锡铅基复合钎料的蠕变抗力优于传统63Sn37Pb共晶钎料;钎焊接头蠕变寿命随温度的升高而降低,并且温度对复合钎料钎焊接头蠕变寿命的影响较传统63Sn37Pb钎料明显.     

纳米结构强化无铅焊点的力学性能

新型的无铅钎料不仅要具备含铅钎料的工艺性能,更重要的是要有更高的力学性能,特别是焊接接头的抗蠕变能力。将纳米级多面齐聚倍半硅氧烷(Polyhedral oligomeric silsesquioxanes,POSS)颗粒作为增强相添加到基体钎料中,能够有效地改善Sn-3. 5Ag基复合钎料的性能。研究了不同种类POSS增强颗粒对Sn-3. 5Ag钎料显微组织和力学性能的影响,确定出POSS增强颗粒复合钎料的最佳配比,并对最佳配比复合钎料在不同温度不同载荷条件下的蠕变寿命进行了研究。结果表明：POSS颗粒质量分数小于2%时,可以抑制基板界面处初晶金属间化合物的生长;复合钎料的抗剪切强度明显提高;低温时,最大蠕变寿命明显改善。     

新型纳米结构颗粒增强无铅复合钎料性能

为了解决传统复合钎料制备中强化颗粒容易粗化的问题,提高无铅复合钎料的性能,选用共晶Sn-3.5Ag、Sn-3.0Ag-0.5Cu钎料作为基体,3种不同类型具有纳米结构的有机-无机笼型硅氧烷齐聚物(POSS) 颗粒作为增强相而制成复合钎料。研究了复合钎料的铺展性能、钎焊接头的力学性能和抗蠕变性能。结果表明,复合钎料的润湿性能均优于基体钎料的润湿性能,复合钎料钎焊接头的剪切强度和蠕变断裂寿命均明显提高。在相同条件下,Sn-Ag-Cu基复合钎料钎焊接头的性能优于Sn-Ag基复合钎料钎焊接头。      

铝/镁搅拌摩擦焊-钎焊焊接接头微观组织结构

目的研究不同工艺参数下钎料Zn的添加对Al/Mg异种金属搅拌摩擦焊-钎焊焊接接头组织和性能的影响。方法以厚度为0.05 mm的纯Zn作为钎料,对3 mm厚的2A12-T4态铝合金和4 mm厚的AZ31变形镁合金,进行搅拌摩擦焊-钎焊的复合焊接,分析锌夹层的添加对接头微观组织与力学性能的影响。结果当添加Zn中间层时,接头钎焊区缓解了拉伸断裂趋势,在焊接速度为23.5 mm/min,旋转速度为375 r/min时,接头抗拉剪力达到5.5 k N,复合焊接接头的钎焊焊缝由搭接区、固相扩散区、钎焊区组成。结论钎料的添加有效阻止了Al-Mg系金属间化合物的形成。     

耐高温瞬时液相连接无铅钎焊接头的时效稳定性

通过瞬时液相(TLP)连接的互连工艺,采用Sn4.7Ag1.7Cu+Ag复合钎料,制备Sn4.7Ag1.7Cu+Ag复合钎料/Cu接头.采用SEM观察恒温时效过程中接头的组织,结合EDS对比不同工艺下试样接头组织,并对接头性能进行对比分析.结果表明:随着Ag颗粒含量的增加,Sn4.7Ag1.7Cu+Ag/Cu接头耐高温(300℃)服役性能随之提高;Ag含量为25％(质量分数)时接头在高于基体钎料熔点(217℃)83℃下服役15天未断裂,且抗拉强度为25.74 MPa,达到了低温焊接、高温服役的目的;与Sn4.7Ag1.7Cu/Cu接头相比,随着时效的进行,Sn4.7Ag1.7Cu+Ag复合钎料/Cu接头焊缝组织中残余的Ag颗粒不断溶解,并在接头界面附近产生大量Ag3 Sn化合物,而大量的块状Ag3 Sn化合物可以有效抑制焊缝中Sn元素向Cu基板扩散,达到抑制Cu3 Sn层生长的目的;在200℃服役温度条件下,随着时效的进行,Sn4.7Ag1.7Cu+Ag复合钎料/Cu接头力学性能先下降后上升,然后再下降并趋于稳定,且力学性能稳定性比Sn4.7Ag1.7Cu/Cu接头要好.     

镍基钎料钎焊K465高温合金大间隙接头组织与性能研究

K465镍基高温合金为母材,FGH95镍基合金粉为预填粉末,采用预填高熔点粉末的方法对0.5mm大间隙接头进行钎焊,研究不同保温时间对钎缝组织与接头性能的影响。结果表明:1220℃保温0.5h获得的钎缝组织由合金粉颗粒及颗粒间的相构成,颗粒内为γ和γ′两相组织,颗粒间为γ和γ′两相为基体的硼化物、硅化物及γ+γ′共晶组织;随钎焊保温时间延长,合金粉颗粒长大,化合物相及γ+γ′共晶组织合并、总量减少;钎焊保温时间为0.5~16h时,接头平均持久寿命由31.59h提高至54.58h,但不易获得高性能等温凝固接头。     

SiC陶瓷与Ti合金的(Ag-Cu-Ti) -W复合钎焊接头组织结构研究

研究了在Ag,Cu,Ti粉末中加入W粉连接钛合金和SiC陶瓷的接头组织结构和接头状况.结果表明W颗粒均匀分布在钎缝的Ag相中,且未与Ag-Cu-Ti合金基体发生冶金反应,W颗粒的大小和形状基本上与加入前的粉末相当.在较低的钎焊温度和较短的钎焊时间下,能形成组织结构均匀、连接良好的复合接头,钎缝内Cu-Ti相较少,钎缝与钛合金界面形成了多层Ti含量呈梯度变化的Cu-Ti扩散反应层组成的扩散带.W的加入降低了接头热应力.而较高的钎焊温度和较长的钎焊时间,容易在近缝区的陶瓷中产生裂纹.由于扩散进入钎缝Ti量的增多,使得钎缝内形成很多长条形CuTi相组织,提高了与钎缝相邻的Cu-Ti扩散反应层的Ti浓度,并且钎缝内钛合金界面附近形成了没有W相的带状区域.     

定向超合金钎焊接头的冶金研究

本文主要对定向超合金ＤＺ２２采用非晶态镍基、钴基钎料进行了钎焊工艺研究，探讨了钎焊工艺对钎焊接头的组织结构和性能的影响，通过本题研究，取得了接头持久强度达到基体的８０％的结果，这是我所钎焊史上的一个重要突破。     

Creep property of composite solders reinforced by nano-sized particles

In the present work the creep properties of Sn37Pb and Sn0.7Cu based composite solders with nano-sized metallic Cu, Ag and nano-sized oxide Al₂O₃, TiO₂ reinforcement particles have been studied. First, a series of volume percentages of reinforcements were selected for optimizing the content of particles. Then, the composite solder with optimum volume fraction of the reinforcement particles, corresponding to maximum creep rupture life, is selected for investigating the effect of applied stress level and test temperature on creep rupture life of the composite solder joints. In the creep rupture life test, small single-lap tensile-shear joints were adopted. The results indicate that all the composite solders have improved creep resistance, comparing to the eutectic Sn37Pb solder and the Sn0.7Cu lead-free solder. The creep rupture life of the composite solder joints is first increased with the increase in the volume fraction of reinforcement in the composite solders. Then, the creep rupture life is decreased, as the reinforcement content exceeds a certain value. The creep rupture life of the solder joints is decreased with the increase of applied stress and testing temperature. Moreover, the reinforced efficiency of nano-sized Ag particles is the best in all the tested nano-sized reinforcements for the Sn37Pb based and Sn0.7Cu based composite solders, when the particles contents are in their own optimum content.     

Study on creep characterization of nano-sized Ag particle-reinforced Sn–Pb composte solder joints

In the present work, the creep strain of solder joints is measured using a stepped load creep test on a single specimen. Based on the experimental results, the constitutive model on the steady-state creep strain is established by applying a linear curve fitting for the nano-sized Ag particle-reinforced Sn37Pb based composite solder joint and the Sn37Pb solder joint, respectively. It is indicated that the activation energy of the Ag particle-reinforced Sn37Pb based composite solder joints is higher than that of Sn37Pb solder joints. It is expected that the creep resistance of the Ag particle-reinforced Sn37Pb based composite solder joints is superior to that of Sn37Pb solder.     

Investigation of microstructures and tensile properties of a Sn-Cu lead-free solder alloy

In recent years, the pollution of environment from lead (Pb) and Pb-containing compounds in microelectronic devices attracts more and more attentions in academia and industry, the lead-free solder alloys begin to replace the lead-based solders in packaging process of some devices and components. In this work, microstructures and mechanical properties of the lead-free solder alloy Sn99.3Cu0.7(Ni) are investigated. This paper will compare the mechanical properties of the lead-based with lead-free solder alloys (Sn99.3Cu0.7(Ni) and 63Sn37Pb). The tensile tests of lead-based and lead-free solder alloys (Sn99.3Cu0.7(Ni) and Sn63Pb37) were conducted at room and elevated temperature at constant strain rate; the relevant tensile properties of Sn99.3Cu0.7(Ni) and Sn63Pb37 were obtained. Specifically, the tensile strength of this lead-free solder- Sn99.3Cu0.7(Ni) in 25^∘C, 50^∘C, 75^∘C, 100^∘C, 125^∘C was investigated; and it was found that tensile strength of the lead-free solder decreased with the increasing test temperature at constant strain rate, showing strong temperature dependence. The lead-free solder alloy Sn99.3Cu0.7(Ni) was found to have favorable mechanical properties and it may be able to replace the lead-based solder alloy such as Sn63Pb37 in the packaging processes in microelectronic industry.     

Effect of rare earth addition on shear strength of SnAgCu lead-free solder joints

In the present study, the effect of adding trace amount of rare earth (RE) on the shear strength of Sn3.8Ag0.7Cu lead-free solder joints has been investigated. The shear strength of the solder joints as-reflowed and after aging at 150 °C for 168 and 336 h was measured at a constant loading rate of 0.3 mm/min and room temperature. The investigation indicates that the shear strength of Sn3.8Ag0.7Cu0.1RE solder joints is lower than that of Sn3.8Ag0.7Cu solder joints. The shear strength of both Sn3.8Ag0.7Cu solder joints and Sn3.8Ag0.7CuRE solder joints was reduced after aging at elevated temperature. However, the shear strength reduction rate of the Sn3.8Ag0.7Cu solder joints was much faster than that of Sn3.8Ag0.7CuRE solder joints. Moreover, the fracture surfaces were examined by scanning electron microscopy (SEM) and the thickness of intermetallic compounds layer (IML) in the solder joints that join Cu substrate was measured. The results indicated that the addition of rare earth elements suppresses the growth of the thickness of intermetallic compounds layer.     

Effects of Ag particles content on properties of Sn0.7Cu solder

To improve properties of Sn0.7Cu solder, method of particles reinforced was employed. Effects of Ag particle contents (1, 3, 5, 7.5, and 10 vol.%) on spreadability, microstructure, shear strength and creep rupture life of Sn0.7Cu solders have been studied. The experimental results indicate that intermetallic compound (IMC) grows, Shear strength is increased and grains are fined with the increasing of Ag particles. When content of Ag particles is more than 5 vol.%, growth rate of IMC is increased significantly. When the content of Ag is 5 vol.%, the composite solder presents best spreadability and excellent creep rupture property which have maximum spreading area, minimum wetting angle and longest creep rupture life (about 22 times as long as that of Sn0.7Cu solder).     

Effect of addition of TiO2 nanoparticles on the microstructure,microhardness and interfacial reactions of Sn3.5AgXCu solder

In this work, TiO₂ nanoparticles were successfully incorporated into Sn3.5Ag and Sn3.5Ag0.7Cu solder, to synthesize novel lead-free composite solders. Effects of the TiO₂ nanoparticle addition on the microstructure, melting property, microhardness, and the interfacial reactions between Sn3.5AgXCu and Cu have been investigated. Experimental results revealed that the addition of 0.5 wt.% TiO₂ nanoparticles in Sn3.5AgXCu composite solders resulted in a finely dispersed submicro Ag₃Sn phase. This apparently provides classical dispersion strengthening and thereby enhances the shear strength of composite solder joints. After soldering, the interfacial overall intermetallic compounds (IMC) layer of the Sn3.5AgXCu lead-free solder joint was observed to have grown more significantly than that of the Sn3.5AgXCu composite solder joints, indicating that the Sn3.5AgXCu composite solder joints had a lower diffusion coefficient. This signified that the presence of TiO₂ nanoparticles was effective in retarding the growth of the overall IMC layer.     

Effects of rare earths on properties and microstructures of lead-free solder alloys

In order to further enhance the properties of lead-free solder alloys such as SnAgCu, SnAg, SnCu and SnZn, trace amount of rare earths were selected by lots of researchers as alloys addition into these alloys. The enhancement include better wettability, physical properties, creep strength and tensile strength. For Sn3.8Ag0.7Cu bearing rare earths, when the rare earths were La and Ce, the creep-rupture life of solder joints can be remarkably improved, nine times more than that of the original Sn3.8Ag0.7Cu solder joints at room temperature. In addition, creep-rupture lifetime of RE-doped solders increases by over four times for SnAg and seven times for SnCu. This paper summarizes the effects of rare earths on the wettability, mechanical properties, physical behavior and microstructure of a series of lead-free solders.     

Enhancement of creep resistance and thermal behavior of eutectic Sn–Cu lead-free solder alloy by Ag and In-additions

The eutectic Sn–0.7Cu solder alloy is widely used in electronic packaging in which the creep property of the solder joint is essential to meet the global demand for longer operating lifetime in their applications. In this study, the influence of Ag and In additions on tensile creep behavior and thermal properties of bulk eutectic Sn–Cu solder alloy is reported. Results show that addition of Ag and In resulted not only in the formation of new Ag₃Sn and γ-SnIn₄ intermetallic compounds (IMCs), but also in the refinement of grain size of Sn–0.7Cu solder from ∼0.50 to ∼0.15 μm. Accordingly, the creep properties of the Ag or In-containing solder alloys are notably improved. The creep strain rate increases and creep lifetime decreases as the applied stress level and temperature increase. Room and elevated-temperature creep rate of bulk Sn–Cu solder was reduced by 521.0% after Ag addition, but for In addition the reduction was about 200.7%. These differences are attributed to the presence of new Ag₃Sn and γ-SnIn₄ precipitates and their rules in classical dispersion strengthening as a separate phases. Moreover, the eutectic temperature of Sn–0.7Cu is decreased from 227.4 to 217.8 and 224.0 °C with the addition of Ag and In, respectively.