无铅焊膏中松香含量对焊点剪切强度的影响

对不同松香含量的助焊剂进行了润湿力性能测试和黏度测试。用这些助焊剂配制成焊膏,并对焊后的焊点进行了剪切试验,以此来测定不同的松香含量下焊点的剪切强度。结果表明:焊膏的黏度随着松香含量的增加而增加,而其润湿力逐渐降低。当松香的质量分数为42.69%时,焊点的剪切强度可达48.36MPa,焊膏焊接性能良好,焊点饱满光亮。     

Sn58Bi-xW复合钎料焊点微观组织及性能的研究

采用SEM、EDX等手段,研究了Sn58Bi-x W钎料润湿性能、组织形貌及焊点接头力学性能。结果表明:适量W颗粒可以提高Sn58Bi润湿性,随着W颗粒含量的增加,钎料的润湿性呈现先上升后下降的趋势,W质量分数为0.05%时润湿性最好,其铺展面积为132.73 mm~2。W颗粒可以有效细化Sn58Bi钎料合金的微观组织,减小焊点界面IMC厚度,当W添加量为质量分数0.1%,Sn-58B钎料的微观组织最为细小,界面IMC的厚度为0.71μm,焊点的抗拉强度最高,达101.6 MPa。     

回流焊对SnAgCuBi/Cu焊点IMC及剪切强度的影响

利用金相显微镜和扫描电镜对多次回流焊后的Sn-0.3Ag-0.7Cu-xBi/Cu焊点IMC和剪切断口形貌进行了观察和分析。结果表明:Bi的加入提高了接头剪切强度,且随着Bi含量的增加而增加,当w(Bi)为4.5%时达最大值45.07MPa,同时Bi的加入有效抑制了焊点IMC的增长。经过5次回流焊后,未加入Bi的焊点剪切强度由24.55MPa下降到20.82MPa,而加入w(Bi)为3.0%的焊点剪切强度由35.95MPa下降到32.46MPa。     

氮气保护对无铅再流焊QFP焊点拉伸强度的影响

无铅钎料差的润湿性给传统电子组装工艺带来了巨大的挑战,氮气保护有利于改善无铅钎料的润湿性,提高焊点质量.主要研究了不同氧含量对QFP引脚焊点拉伸强度的影响,得到一个最佳的氧含量范围.     

已二酸含量对导电胶性能的影响

通过在导电胶中直接添加短链二元羧酸已二酸对导电胶进行改性,研究了不同含量的已二酸对导电胶性能的影响规律。通过同步热分析仪对不同已二酸含量的导电胶的固化过程和固化后的热稳定性能分析表明,已二酸的添加会和环氧树脂进行反应,并且会促进导电胶的固化放热峰向低温方向偏移;同时已二酸的添加还会部分提高导电胶的热稳定性能。通过电子万能试验机对不同已二酸含量的导电胶的粘接强度进行分析表明,当已二酸质量分数低于0.5%时,随着已二酸含量的增加,导电胶的剪切强度逐步下降,当已二酸质量分数达到0.5%后,导电胶的剪切强度出现上升现象。通过四点探针测试仪对各不同导电胶的体积电阻率的测试,发现随着已二酸含量的增加,导电胶的体积电阻率逐渐减小。     

松香树脂对SnAgCu焊膏性能的影响

通过焊膏回流焊接铺展性能及其抗塌落能力测试分析.研究了助焊剂中氢化松香和聚合松香的总含量以及它们的复配比例对SnAgCu焊膏性能的影响.结果表明:当助焊剂中松香质量分数在20%～60%的范围时,增加松香含量可提高焊膏的铺展性能,改善焊点形貌,并显著增强抗塌落能力.当助焊剂中松香总质量分数为40%时,不同松香复配比例的焊膏铺展试验均表现出焊点饱满、表面光亮、周边规则的特征,铺展率基本相当,约为82%,而焊膏的抗塌落性能随聚合松香比例提高而提高.元件试焊表明焊膏具有良好的焊接性能,可用于一般电子产品的焊接.     

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。     

Sn95Sb5焊料与ENIG/ENEPIG镀层焊点界面可靠性研究

研究了Sn95Sb5焊料在化学镍金(ENIG)镀层、化学镍钯浸金(ENEPIG)镀层表面形成的焊点界面微观组织形貌与剪切强度。使用Sn95Sb5焊料在FR4印制板上焊接0805片式电容,焊点在高温时效测试和温度循环过程中均表现出较高的剪切强度,焊点界面连续且完整,剪切强度下降的最大幅度不超过19.2%。Sn95Sb5焊料在ENIG镀层表面形成的焊点(Sn95Sb5/ENIG焊点)强度更高。Sn95Sb5焊料在ENEPIG镀层表面形成的焊点(Sn95Sb5/ENEPIG焊点)界面反应更为复杂,在焊点界面附近可观察到条块状的(Pd,Ni,Au) Sn₄。Sn95Sb5/ENEPIG焊点界面的金属间化合物层平均厚度约为Sn95Sb5/ENIG焊点界面的2倍。     

添加SAC微粒对SnBi锡膏焊后性能的影响

采用机械混合的方法,向Sn58Bi(Sn Bi)共晶锡膏中添加不等量的Sn-3.0Ag-0.5Cu(SAC)微粒,制备Sn Bi-SAC复合锡膏。在不改变Sn Bi锡膏低温焊接工艺的前提下,改善Sn Bi锡膏焊后合金硬脆缺陷。实验结果表明:Sn Bi-SAC复合锡膏中SAC微粒含量分别为质量分数0,3%,5%,8%时,采用180℃低温焊接均可获得良好的钎焊效果。与Sn Bi共晶锡膏焊后合金相比较,Sn Bi-SAC复合锡膏中SAC微粒含量的增加促使焊后合金微观组织中的β-Sn相含量与晶粒尺寸增大,改善了Sn Bi焊后合金中富Bi相的致密网状结构。当锡膏中SAC微粒含量由0增大至质量分数8%时,合金硬度从213.9 m Pa下降到117 m Pa,对Sn Bi锡膏焊后合金硬脆缺陷起到改善效果。     

氮气保护在无铅化电子组装中的应用

无铅钎料的高熔点、差润湿性给SMT传统的焊接工艺带来了很大冲击,并且对焊点质量也产生了很大的影响。为了防止氧化,改善钎料与焊盘、元件引脚之间的润湿性,提高产品合格率,目前在电子纽装中普遍采用氮气保护。针对几种常用无铅钎料进行了氮气气氛中润湿性和焊点组织的分析,并初步研究了氮气保护对焊点质量和氧化渣的影响。结果表明：氮气保护可以改善无铅钎料润湿性,细化焊点组织,减少氧化渣量,而且对焊点外观和成品率也有一定的影响。     

Mechanical Properties and Electrochemical Corrosion Behavior of Al/Sn-9Zn-<Emphasis Type="Italic">x</Emphasis>Ag/Cu Joints

The effect of Ag content on the wetting behavior of Sn-9Zn-xAg on aluminum and copper substrates during soldering, as well as the mechanical properties and electrochemical corrosion behavior of Al/Sn-9Zn-xAg/Cu solder joints, were investigated in the present work. Tiny Zn and coarsened dendritic AgZn₃ regions were distributed in the Sn matrix in the bulk Sn-9Zn-xAg solders, and the amount of Zn decreased while that of AgZn₃ increased with increasing Ag content. The wettability of Sn-9Zn-1.5Ag solder on Cu substrate was better than those of the other Sn-9Zn-xAg solders but worse than that of Sn-9Zn solder. The wettability of Sn-9Zn-1.5Ag on the Al substrate was also better than those of the other Sn-9Zn-xAg solders, and even better than that of Sn-9Zn solder. The Al/Sn-9Zn/Cu joint had the highest shear strength, and the shear strength of the Al/Sn-9Zn-xAg/Cu (x = 0 wt.% to 3 wt.%) joints gradually decreased with increasing Ag content. The corrosion resistance of the Sn-9Zn-xAg solders in Al/Sn-9Zn-xAg/Cu joints in 5% NaCl solution was improved compared with that of Sn-9Zn. The corrosion potential of Sn-9Zn-xAg solders continuously increased with increasing Ag content from 0 wt.% to 2 wt.% but then decreased for Sn-9Zn-3Ag. The addition of Ag resulted in the formation of the AgZn₃ phase and in a reduction of the amount of the eutectic Zn phase in the solder matrix; therefore, the corrosion resistance of the Al/Sn-9Zn-xAg/Cu joints was improved.     

The effect of soldering process variables on the microstructure and mechanical properties of eutectic Sn-Ag/Cu solder joints

Fundamental understanding of the relationship among process, microstructure, and mechanical properties is essential to solder alloy design, soldering process development, and joint reliability prediction and optimization. This research focused on the process-structure-property relationship in eutectic Sn-Ag/Cu solder joints. As a Pb-free alternative, eutectic Sn-Ag solder offers enhanced mechanical properties, good wettability on Cu and Cu alloys, and the potential for a broader range of application compared to eutectic Sn-Pb solder. The relationship between soldering process parameters (soldering temperature, reflow time, and cooling rate) and joint microstructure was studied systemati-cally. Microhardness, tensile shear strength, and shear creep strength were measured and the relationship between the joint microstructures and mechani-cal properties was determined. Based on these results, low soldering tempera-tures, fast cooling rates, and short reflow times are suggested for producing joints with the best shear strength, ductility, and creep resistance.     

Characterization of eutectic Sn-Bi solder joints

This report presents experimental results on 58Bi-42Sn solder joints, optical and SEM microstructures of their matrix and of their interface with copper, solidification behavior studied by differential scanning calorimetry, wettability to copper, creep, and low cycle fatigue. These results are discussed in comparison with 60Sn-40Pb solder, and with three low temperature solders, 52In-48Sn, 43Sn-43Pb-14Bi, and 40In-40Sn-20Pb. The 58Bi-42Sn solder paste with RMA flux wets Cu matrix with a wetting angle of 35° and had a 15° C undercooling during solidification. The constitutive equation of the steady state shear strain rate, and the Coffin-Manson relation constants for the low cycle shear fatigue life at 65° C have been determined. The test results show that this solder has the best creep resistance but the poorest fatigue strength compared with the other four solders.     

Constitutive modeling on creep deformation for a SnPb-based composite solder reinforced with microsized Cu particles

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 creep strain tests, the constitutive modeling on the steady-state creep rate is determined for the Cu particle-reinforced Sn37Pb-based composite solder joint and the Sn37Pb solder joint, respectively. It is indicated that the activation energy of the Cu particle-reinforced Sn37Pb-based composite solder joint is higher than that of Sn37Pb solder joint. In addition, the stress exponent of the Cu particle-reinforced Sn37Pb-based composite solder joint is higher than that of the Sn37Pb solder joint. It is expected that the creep resistance of the Cu particle-reinforced Sn37Pb-based composite solder joint is superior to that of the Sn37Pb solder. Finally, the creep deformation mechanisms of the solder joint are discussed.     

SnAgCu系钎料的合金组织和力学性能

研究了Cu含量对SnAgCu系钎料合金显微组织及其与化学镀Ni基板钎焊接头力学性能的影响。结果表明:高Cu含量SnAgCu合金会产生较多的(CuxNi1-x)6Sn5金属间化合物,从而减少镀Ni层的消耗,进一步提高钎焊接头的剪切强度。与Sn-3.0Ag-0.3Cu相比,Sn-3.0Ag-1.0Cu钎焊接头剪切强度提高了6.78%。经过150℃时效1000h后,界面Ni3(P,Sn)层的增长率从Sn-3.0Ag-0.3Cu合金的约66%降低到Sn-3.0Ag-1.0Cu合金的约40%。     

不同加载速率对SAC/Cu焊点剪切强度的影响

通过对Sn0.3Ag0.7Cu/Cu和Sn3.0Ag0.5Cu/Cu焊点进行剪切测试结果表明:两种钎料焊点的剪切强度与加载速率有着明显的相关性,即焊点的剪切强度都随着加载速率的增加而增加。当加载速率为0.01 mm/s时,断裂模式为韧脆混合断裂,随着加载速率的增加,两种钎料焊点断口的韧窝数量不断增加,呈现韧性断裂特征,断口以韧窝为主。另外在相同加载速率下,Sn3.0Ag0.5Cu/Cu焊点断口的韧窝数量和分布情况都优于Sn0.3Ag0.7Cu/Cu焊点,即其韧性断裂的趋势更加明显,剪切强度更大。     

Sn-9Zn合金无铅钎料用助焊剂研究

通过测量润湿面积和润湿角,研究不同助焊剂对Sn-9Zn焊料润湿性的影响。结果表明:助焊剂对Sn-9Zn焊料润湿性影响很大,由乳酸、聚乙二醇和SnCl2所构成的助焊剂与Sn-9Zn焊料有很好适应性;同时扫描电镜和能谱分析也表明焊料与Cu基体界面的IMC为Cu5Zn8相,比Sn-37Pb焊料具有更高的剪切强度。     

Creep Properties of Composite Solders Reinforced with Nano- and Microsized Particles

In the present work the creep properties of Sn37Pb- and Sn0.7Cu-based composite solders reinforced with metallic nano- and microsized Cu and Ag particles have been studied. First, a series of volume percentages of reinforcements were selected to optimize the content of reinforcing particles. Then, the composite solder with optimum volume fraction of reinforcement particles, corresponding to the maximum creep rupture lifetime, was selected to investigate the effect of applied stress and temperature on the creep rupture lifetime of the composite solder joints. In the creep rupture lifetime test, small single-lap tensile-shear joints were adopted. The results indicate that composite solders reinforced with microsized particles exhibit better creep strengthening than composite solders reinforced with nanosized particles, although the mechanical tensile shear strength of composite solder joints reinforced with nanosized particles may be higher than those reinforced with microsized particles. Moreover, the creep strengthening action of the reinforcement particles is more obvious under conditions of lower applied stress or lower test temperature. Strengthening by metallic Cu or Ag reinforcement particles decreases with increasing temperature or applied stress. The Sn0.7Cu-based composite solder reinforced with microsized Ag particles is a low-cost lead-free solder that is easy to process and may have good market potential.     

Sn-8Zn无铅钎料性能的研究

研究了不同微量合金元素(Bi、Ag)对Sn-8Zn无铅钎料高温抗氧化性能及接头剪切强度的影响,采用氧化质量增加△m值的方法,在高温下观察钎料表面氧化膜形状和颜色的变化并对氧化膜进行X射线衍射分析,探讨了钎料的高温抗氧化性能的机理,通过对钎料的金相显微组织观察和对热处理后钎焊接头的剪切强度试验,分析了提高接头剪切强度的原因.试验结果表明:在Sn-8Zn钎料中加入适量的合金元素(Bi、Ag)均可以改善和提高钎料的高温抗氧化性能和接头的剪切强度.     

Sn-9Zn/Cu焊点剪切强度及断口形貌分析

研究了BGA直径分别为750μm、1 000μm、1 300μm的Sn-9Zn/Cu焊点剪切强度及其变化规律。采用SEM和EDX对剪切断口进行观察和元素成分分析。试验结果表明,随着焊球直径的增大,焊点剪切强度先减小后增大。剪切断裂位置大部分位于钎料内部,局部位于界面化合物Cu5Zn8处。在相同的剪切高度与剪切速率下,随...