陶瓷与金属的活性封接

对陶瓷与金属Ti-Ag-Cu活性法出现的Ti-Ag-Cu活性合金焊料在不同金属表面的流散性进行了分析，解释了用Ti-Ag-Cu活性合金焊料焊接陶瓷和金属时不能达到真空气密的原因；同时，在实验基础上对溅射镀膜金属化焊接工艺进行了分析。     

微波功率器件中AuGe合金焊接界面特征

在微观尺度上,焊点的可靠性取决于焊料同焊盘之间界面反应生成的界面金属间化合物(IMC)的结构。通过金锗合金焊点的界面反应及微观结构随环境的变化表征了焊点的可靠性,研究了AuGe合金焊料与不同金层厚度的Ni/Au焊盘共晶焊接后其界面特征,同时总结了AuGe合金焊料在Cu和Ni等常见焊盘上的焊接润湿性及其焊接界面特征。切片分析结果显示,在共晶焊接后,厚金样品焊接界面冷却时焊料层析出富Au相形成不规则焊接结合层,Au层厚度减薄50%～60%;薄金样品的Au层全部消失,并在界面处形成很薄的一层富Ni的NiGe化合物。实验结果显示,厚Au层样品未出现Ni向焊接层扩散的现象和NiGe化合物的生成,厚Au层起到了阻挡层作用;薄金样品时,Ni通过互扩散缓慢与Ge形成NiGe化合物,在长期使用中焊接层会通过元素扩散等形式演变,使整个焊接层转变为含氧化层、富P层、NiGe层和AuCuGe合金层等多层结构的IMC,降低了焊点强度,严重影响焊接层可靠性。这说明IMC在焊接过程中主要以界面化学反应方式形成,服役过程中主要以元素扩散方式演变。     

矩形光斑钛/铝异种合金激光熔钎焊

为提高焊接过程的稳定性,拓展最佳的工艺参数范围,采用能量均匀分布的矩形光斑对V形及Y形坡口的钛/铝异种合金进行激光熔钎焊(LWB),获得了在不同线能量条件下的界面微观组织及接头的力学性能.采用扫描电镜(SEM)及金相显微镜对接头界面的微观组织进行观察,结果发现,界面反应层厚度依赖于焊接线能量大小,并且从接头的上部到下部逐渐变薄;界面反应层厚度的不均匀分布对接头的力学性能有很大影响.根据抗拉强度测试的结果发现Y形坡口的焊接接头存在着混合型断裂、焊缝处断裂和界面处断裂三种断裂模式,而V形坡口的焊接接头存在着焊缝处断裂和界面处断裂两种断裂模式;接头的最高抗拉强度为290 MPa,可达铝母材的80%以上.     

钛合金电子束焊缝金属微观结构的TEM观察

本文对不同电子束扫描频率的ＴＣ４钛合金焊缝金属微观结构进行了透射电镜观察。研究结果表明,电子束扫描频率对钛合金焊缝金属微观结构有很大影响。电子束扫描作用在焊接凝固前沿的动压力以及焊接凝固过程的稳定性的综合作用,直接影响ＴＣ４钛合金焊缝金属微观结构及位错分布。     

Sn-3Ag-3Bi焊点剪切强度的研究

提出一种可有效降低测试误差的剪切强度测试方法。用该方法对Sn-Ag-Bi无铅焊料分别在Cu基板和Ni-P基板上的焊点,经不同的热时效后的剪切强度,进行了测量并对断裂面的微观结构进行了研究。结果显示,焊点的剪切强度及断裂位置与焊接界面金属间化合物(IMC)的组成和厚度有关。     

金刚石锯片激光焊接的微观组织与性能研究

从金刚石锯片的激光焊接接头的微观结构,分析了焊接接头的各区域的显微组织分布、基板组织状态及后处理对焊接性能的影响,研究了提高焊接性能的主要途径。     

CCGA焊柱加固工艺技术研究

针对陶瓷柱栅阵列(CCGA)封装的焊接界面在热冲击试验中出现的断裂失效问题,探讨了如何通过加固CCGA焊接界面来提高器件可靠性的工艺技术.该工艺通过在焊接区域涂覆适量的环氧胶来对焊接界面进行加固保护,对于提高焊柱的抗热冲击能力具有明显的作用,并且能够有效地提高焊柱的可靠性.此外,为了进一步地提高CCGA器件的组装可靠性,对新型结构焊柱进行了相关的试验验证.     

C/SiC与TC4钛合金异质连接过渡层的研究

分别用A95钨合金、A80钨合金、C103铌合金及三者的焊接组合作为C/SiC与TC4钛合金异质连接的过渡层,采用扫描电子显微镜、X射线衍射对过渡层与C/SiC的界面进行微观组织及结构分析,并对相应的封接件进行气密性及拉伸性能测试。结果表明,采用A95,A80钨合金作过渡层时,钨合金与C/SiC界面为冶金结合,界面产物为TiC,TiSi,Cu4Ti和Cu3Ti等;而采用三者的焊接组合作过渡层时,过渡层的热膨胀系数呈梯度变化且界面均为冶金结合,使C/SiC与TC4钛合金封接件具有高的气密性和抗拉强度（62.21 MPa）,实现良好异质连接。     

超音速喷涂界面的微结构与界面结合强度

超音速火焰喷涂界面结构强度因喷涂材料和衬底材料的变化而异，本文通过对几种不同材料的ＨＶＯＦ喷涂界面微结构的研究揭示了影响喷涂界面结构强度的微观结构本质 。     

基于铜合金中间层的钛合金与不锈钢激光-电弧复合热源焊接研究

运用激光-电弧复合热源焊接方法,通过添加Cu-Zn中间层实现了TC4钛合金与304不锈钢的良好焊接,并对搭接接头横截面形貌、微观组织、相成分、力学性能及断裂位置进行了分析。结果表明,钛合金与不锈钢复合焊接接头过渡区组织成分主要包括Ti-Cu金属间化合物、铜基固溶体及Fe-Cu共析混合物。随着激光功率的增加,在钛-铜界面一侧,生成的Ti-Cu金属间化合物厚度逐渐增大,对接头性能产生不良影响,激光功率较大时断裂发生在钛-铜界面处。在铜-不锈钢界面一侧,Cu和Fe元素互扩散的深度和密度随激光功率的增大逐渐增加,有利于提高接头性能,激光功率较小时断裂发生在铜-不锈钢界面处。实现钛合金与不锈钢的良好焊接的关键在于Ti-Cu金属间化合物与Fe-Cu共析混合物的协调控制。     

氮化硼陶瓷和金属的接合技术

用Ｔｉ－Ａｇ－Ｃｕ活性法，对俄罗斯生产的气密ＢＮ陶瓷进行了陶瓷－金属接合技术的研究。研究表明，只要采取适当的结构和合理的工艺，即可获得高强度的接合和良好的气密性。对接合机理进行了各种分析并且进行了热力学计算，计算结果和分析数据一致，从而认为ＢＮ陶瓷和金属的高强度、气密接合是以化学反应为基础的。     

A reliability study of the lead-free solder connections of miniature chip components on hybrid circuits

The results of the influence of lead-free solder paste, design and process parameters on the attachment reliability of chip surface-mounted components (SMCs) on thick-film conductor pads are presented. The purpose of the investigation was to compare the quality of the soldered joints made with new solder pastes that do not contain lead with joints soldered with standard SnPb solders. The miniature zero-ohm chip resistors were soldered with selected lead-free solder pastes. The visual appearance of the solder joint according to the standards of lead-free soldered components was compared with components soldered with SnPb solders. On the test sample with soldered chip resistors connected in series, the solder-joint resistance was measured before and after temperature cycling. On the same test sample the solder-joint resistance changes were measured with impedance spectroscopy. After temperature cycling the damaged samples were analysed with SEM and EDS. The reliability test results after temperature cycling indicate two lead-free solder pastes that are the most convenient for chip-component soldering on thick-film conductor pads with the reliability of the joints being equal or better than solder joints with Pb-containing solder paste.     

Interfacial Reaction between Zn-Al-Based High-Temperature Solders and Ni Substrate

The Zn-Al(-Cu) eutectic alloys (melting point 381°C) are candidates for use as Pb-free high-temperature solders as a substitute for Pb-based solders, which are suitable for severe working environments such as the engine room of hybrid vehicles equipped with an inverter system as well as a heat engine. In this study, the interfacial reaction between Zn-Al(-Cu) alloys and the Ni substrate during soldering, aging, and thermal cycling was investigated. Semiconductor chips and Ni substrates were soldered with Zn-Al(-Cu) alloys at various temperatures under a nitrogen atmosphere. The soldered assemblies were then heat-treated at 200°C and 300°C to examine the microstructural evolution at the soldered interface. The effect of severe thermal cycles between −40°C and 250°C in air on the microstructure and fracture behavior at the solder joint was investigated. Even after a 1000-cycle test, the thickness of the Al₃Ni₂ layer formed at the interface between the Zn-Al-based solder and the Ni substrate, which is responsible for the damage of the soldered assemblies, was quite small.     

Reliability study of Sn–Ag–Cu–Ce soldered joints in quad flat packages

The reliability of Sn–Ag–Cu–Ce lead-free soldered joints in quad flat packages under thermal cycling was investigated based on finite element simulation and experiments. The stress and strain response of fine pitch QFP device lead-free soldered joints were analyzed using finite element method based on Garofalo–Arrhenius model. The simulated results indicate that the creep distribution is not uniform, the heel of joints is the maximum creep strain concentrated sites. And comparisons were then made with experimental results of the cracks observed in the Sn–Ag–Cu–Ce soldered joints subjected to the temperature cycled experiment. In addition, the relative mechanical and metallurgical factors, which dominate the failure of soldered joints, were utilized to analyze the phenomena. The fracture surfaces indicate that crack initiate and propagate along the interface among bulk Cu₆Sn₅ phases in Sn–Ag–Cu–Ce soldered joints.     

BGA植球工艺技术

BGA(ball grid array)球栅阵列封装技术是20世纪90年代以后发展起来的一种先进的高性能封装技术,是一种用于多引脚器件与电路的封装技术。BGA最大的特点就是采用焊球作为引脚,这不仅提高了封装密度,也提高了封装性能。而植球工艺作为BGA封装中的关键工艺将会直接影响器件与电路的性能及可靠性。影响BGA植球工艺的主要因素有:植球材料、植球工艺及回流焊工艺。文章通过对BGA植球的基板、焊膏/助焊剂、焊球等材料的详细介绍,详实阐述了植球工艺过程,并对BGA后处理的回流焊工艺进行了详细描述,提供了BGA植球工艺的检测方法,对植球工艺的可靠性进行了探讨。     

Reliability of soldered joints in CSPs of various designs andmounting conditions

The chip size package (CSP) is being used in various portable electronic products recently. Further evaluation of the reliability of its soldered joints is required all the more now because those soldered joints are invisible. This study focused on the thermal fatigue life of soldered joints in the CSP. CSPs were mounted on printed circuit boards (PCBs) in various configurations and mounting conditions, and underwent thermal cycle testing. Then, the fatigue lives of their soldered joints were compared. As a result, the following two facts became apparent. First, reflowing at a 210°C peak tends to result in failures that may be derived from poor wetting between solder and pad, in cases where the CSP is mounted on a nickel and gold plated pad. And second, the size of the soldered joint has a great influence on its fatigue life. The larger the soldered joints that we made, the longer fatigue life they indicated. A finite element method (FEM) analysis of those mounted structures was also executed. Viscoplastic (creep and plastic) property of solder was evaluated to compute equivalent inelastic strain occurring in the joints. A parameter in the Coffin-Manson equation is obtained from the computed inelastic strain amplitudes and the experimented actual fatigue lives. This result will enable estimation of the fatigue life of soldered joints of the CSP without actual tests     

SMT工艺中BGA焊接不良原因分析

介绍了SMT工艺中最常见的一种BGA焊接不良的原因分析。以一款客诉PCB BGA焊接不良为例对其产生的原因进行分析和讲解,最终寻找到导致该款PCB BGA焊接不良的真正原因,并针对焊接不良问题提出了相应的改善措施,突出了SMT过程中的具体控制技巧。为同行业进行SMT工艺提供一定的参考依据。     

陶瓷-金属封接用钛银铜合金焊料含钛量及其封接工艺的研究

正 (一) 前言 几十年来电真空器件一直采用钼锰金属化或涂钛粉的陶瓷金属封接工艺。该工艺比较复杂,同时封接质量又不易保证。我们研究了用钛银铜(Ti-Ag-Cu)活性合金焊料直接封接的工艺;试验了合金焊料中活性元素钛含量和封接温度等参量对封接质量的影响;给出了合金焊料的合适合钛量和封接的工艺规范。实验表明,钛银铜合金焊料直接封接工艺,方法简单,质量稳定,是值得推广应用的     

热循环条件下无铅焊点可靠性的有限元分析

通过有限元数值模拟对Sn3.5Ag0.75Cu无铅焊料焊点的可靠性问题进行了分析。采用统一粘塑性Anand本构方程对焊料焊点结构进行有限元分析,研究焊点在热循环加载过程中的应力应变等力学行为。研究结果表明,在焊点内部焊点与基板结合处的应力较大,而焊点中央的应力较小;焊点在低温阶段的应力最大,在高温阶段应变最大;在升降温阶段的应力应变变化较大,而在保温阶段的应力应变变化较小。