电连接器的感应钎焊工艺设计研究

微波组件中的电连接器焊接要求高,感应钎焊技术因其可以实现快速焊接、焊料氧化少、热影响区域小而被用来焊接电连接器。对感应钎焊电连接器的工艺设计进行了研究,针对其工艺设计中的主要因素工件结构形式、工件材料、接触镀层以及焊料种类展开了讨论分析。以上述工艺设计为指导,优化设置了感应钎焊工艺参数,焊接获得了满足相关质量要求和气密性指标的微波电连接器。     

钼的钎焊

正 钼是电真空器件常用的一种金属。但它很难钎焊。我们采用高频碳块焊接法较好地解决了钼与钼,钼与其它金属的钎焊问题。 1.钼与钼的钎焊 钎焊钼要用熔点高,蒸汽压低的焊料。铂是较合适的焊料之一。它的熔点较高,蒸汽压较低,熔点这样高的焊料进行钎焊,用一般氢炉是不行的,因为温度不够高。用高频炉也不理想,因为焊接物体形状不规则时,加热不易均匀,加热温度也较难控     

复杂漏初步探讨

钎焊时,常常在零件上车一条焊料槽,以便放入钎焊焊料。焊料熔化后被吸入焊料槽两边的焊接面A和B,而焊料槽则形成一个小空间。焊接后的情况可能有下列四种(见图1); 一、A面和B面都气密。二、B面气密,A面不气密。三、A面气密,B面不气密,漏气速率为Q_B。     

电子焊料的工艺性能及影响因素

通过分析焊料在钎焊过程中的行为,提出了电子焊料的工艺性能主要包括熔化/固化温度、抗氧化性、润湿性和漫流性。给出了各工艺性能的定义。分析表明:相关的影响因素主要包括合金的组成、纯度和化学均匀性;母材的成分、性质和表面的洁净度;液态焊料的表面张力;钎焊温度、气氛、助焊剂的活性;液态焊料表面膜的组成、结构和性能等。     

表面组装—汽相钎焊

首先介绍表面组装技术的主要特点和存在的问题,接着重点阐述汽相钎焊的热过程及其工作液体、焊料、适用的元器件,并分析了汽相钎焊的特点和用途,详细给出汽相钎焊工艺,最后指出汽相钎焊常见的外观缺陷。     

无焊剂软钎焊技术研究

无焊剂软钎焊技术因其焊接过程中无焊剂残留,被广泛应用于光电器件和芯片倒装焊等方面。首先对无焊剂软钎焊的原理和工艺进行了阐述,并指出气氛保护和等离子处理是无焊剂软钎焊的两个主要技术途径。基于上述分析,采用无焊剂软钎焊工艺开展钎料润湿性研究。结果表明,还原气氛保护和等离子处理后,焊料的润湿铺展性能显著提高。     

微电路封装中的铝钎焊技术

为满足电子系统小型化、轻量化、高性能、高可靠等要求,采用铝合金材料做封装外壳和布线基板已提到议事日程.但铝合金外壳的密封和钎焊存在一系列有待解决的问题,影响了铝合金材料的高导热率和质量轻等性能的充分发挥.文章介绍了一种采用低温铝钎焊料和钎焊技术的铝合金外壳基板钎焊和密封方法.     

Sn-Zn系无铅焊料抗氧化性和润湿性研究现状

Sn-Zn无铅焊料由于熔点接近Sn-Pb,价格低廉、无毒性、力学性能优良等特点,倍受人们的关注。然而由于Zn的表面活性高,在钎焊过程中焊料容易氧化,导致了润湿性能下降。本文综述合金元素对Sn-Zn无铅焊料氧化性能、润湿性的影响。并对Sn-Zn焊料今后的研究方向进行了简要分析。     

一种自动钎焊炉的设计

介绍了一种自动钎焊炉,它包括PLC控制器、温控表和一个带有钎焊焊料的带电回路。PLC控制器把温控表和带电回路联系在一起。通过对PLC控制器和温控表进行一些参数设置后,钎焊炉能自动完成工件的钎焊过程,大大提高了钎焊工艺的一致性和工件的钎焊质量。     

气密性陶瓷管壳

本发明披露了制造气密性陶瓷管壳的方法。这种方法包括如下几个步骤：先在管状陶瓷零件开口端面上涂复由Ｔｉ和／或Ｚｒ组成的活性金属，其涂复的数量为０．１－１０ｍｇ／ｃｍ＾２，这样，就形成了一系列支，然后把钎焊放置于活性金属层上，再放置画住管状陶瓷零件开口部分的金属罩，而金属罩端面圆周应与钎焊料相接触，于是，卞把罩钎焊到了管状陶瓷零件的开口端面上。     

Creep properties of eutectic Sn-3.5Ag solder joints reinforced with mechanically incorporated Ni particles

The creep deformation behavior of eutectic Sn-3.5Ag based Ni particle rein forced composite solder joints was investigated. The Ni particle reinforced composite solder was prepared by mechanically dispersing 15 vol.% of Ni particles into eutectic Sn-3.5Ag solder paste. Static-loading creep tests were carried out on solder joint specimens at 25 C, 65 C, and 105 C, representing homologous temperatures ranging from 0.6 to 0.78. A novel-design, miniature creep-testing frame was utilized in this study. Various creep parameters such as the global and localized creep strain, steady-state creep rate, onset of tertiary creep and the activation energy for creep were quantified by mapping the distorted laser ablation pattern imprinted on the solder joint prior to testing. The Ni-reinforced composite solder joint showed improved creep resistance compared to the results previously reported for eutectic Sn-3.5Ag solder, Sn-4.0Ag-0.5Cu solder alloys, and for eutectic Sn-3.5Ag solder reinforced with Cu or Ag particle reinforcements. The activation energy for creep was ∼0.52 eV for Sn-3.5Ag and Sn-4Ag-0.5Cu solder alloys. The activation energies ranged from 0.55–0.64 eV for Cu, Ag, and Ni reinforced composite solder joints, respectively. Most often, creep fracture occurred closer to one side of the solder joint within the solder matrix.     

Wetting reaction of Sn-Ag based solder systems on Cu substrates plated with Au and/or Pd layer

The wetting behavior of SnAg based Pb-free solders on Cu and Cu substrates plated with Au, Pd, and Au/Pd thin films have been studied. The wetting angle and kinetics of interfacial reaction were measured. The Au-plated substrates exhibit better wetting than the Pd-plated substrates. In the case of SnAg on Pd-plated Cu, SEM observation revealed that the solder cap was surrounded by an innerring of Cu−Sn compound and an outer ring of Pd−Sn compound. This implies that the molten SnAg solder had removed the Pd and wetted the Cu directly in the equilibrium state. The effects of pre-doping Cu in the SnAg solder on wetting behavior were also investigated. We found that wettability decreases with increasing Cu content in the solder. We also observed that the SnAgCu solders have a lower Cu consumption rate than the SnAg solder.     

Processing and aging characteristics of eutectic Sn-3.5Ag solder reinforced with mechanically incorporated Ni particles

Composite solders offer improved properties compared to non-composite solders. Ni reinforced composite solder was prepared by mechanically dispersing 15 vol.% of Ni particles into eutectic Sn-3.5Ag solder paste. The average size of the Ni particle reinforcements was approximately 5 microns. The morphology, size and distribution of the reinforcing phase were characterized metallographically. Solid-state isothermal aging study was performed on small realistic size solder joints to study the formation and growth of the intermetallic (IM) layers at Ni reinforcement/solder and Cu substrate/solder interfaces. Effects of reflow on microstructure and solderability, were studied using Cu substrates. Regarding solderability, the wetting angle of multiple reflowed Ni reinforced composite solder was compared to the solder matrix alloy, eutectic Sn-3.5Ag. General findings of this study revealed that Ni particle reinforced composite solder has comparable wetting characteristics to eutectic Sn-3.5Ag solder. Significant IM layers growth was observed in the Ni composite solder joint under isothermal aging at 150 C. Microstructural evolution was insignificant when aging temperature was lower than 100 C. Multiple reflow did not significantly change the microstructure in Ni composite solder joint.     

抗氧化树脂包覆焊粉的研究

采用有机树脂溶液浸泡焊粉的方法,制备了一种有机树脂包覆焊粉;通过电阻率测试和扫描电镜观察,对焊粉包覆层的质量进行了评价;通过对加速氧化过的焊粉进行铺展和成球试验,研究了树脂包覆层的抗氧化效果。结果表明:本研究所制包覆焊粉,具有均匀的树脂包覆层,且保持了原焊粉的粒度和球形度;包覆焊粉的铺展和成球试验结果均达到了SJ/T11186—1998规定的2级标准,说明包覆焊粉具有比原焊粉更好的抗氧化能力。     

Plastic constraint of large aspect ratio solder joints

The aspect ratio (joint area/joint thickness) of thin (0.001-0.006 in.) surface mount solder (60S-40Pb) joints plays an important role in determining the mechanical properties and fracture behavior of the joints. This study demon-strates that plastic constraint of a large aspect ratio 60Sn-40Pb solder joint can develop triaxial (hydrostatic) stresses several times greater than the average tensile strength of the bulk solder material. A four to sixfold increase in average joint stress and up to a tenfold increase in peak stress was measured on joints with aspect ratios ranging from 400 to 1000. Although a direct relationship of the aspect ratio to the average tensile stress is shown, as the Friction Hill model predicts, the observed stress increase is not nearly as high but proportional to the classical prediction. This is attributed to the existence of internal defects (oxide particles and micro-voids) and transverse grain boundaries which fail producing internal free surfaces. Thus, the actual aspect ratio is thickness/d², where d equals the distance between internal surfaces. The fracture of these constrained joints was brittle, with the separation occurring between a tin-rich copper tin intermetallic at the interface and the solder matrix. Voids within the solder joint are shown to relieve the plastic constraint and lower the average tensile stress of the joint. The Friction Hill model may play an important role in explaining the small percentage of atypical solder joint failures which sometimes occur on electronic assemblies. In particular, the sudden failure of a thin joint in a strain controlled environment may be attributed to the development of a large hydrostatic stress component. Therefore, a flaw free, plastically constrained joint which develops a high stress state will be a high risk candidate for failure.     

Sn-Zn系钎料研究及应用现状

随着钎料无铅化的发展,Sn-Zn钎料以其低廉的成本,与SnPb钎料相近的熔点成为无铅钎料研究的重点.但是Sn-Zn钎料存在易氧化,抗腐蚀性差,润湿性差的问题,通常在SnZn钎料中加入不同元素,改善其性能.主要阐述不同添加元素Bi、Al、In、Re(稀土元素)、Ag、Cu、P和多元合金对SnZn钎料自身性能和钎料与Cu结合性能的影响,概述SnZn系钎料的工业应用现状.     

电子封装用无铅焊料的最新进展

随着WEEE/RoHS法令的颁布,电子封装行业对于无铅焊接提出了更高的要求.根据国际上对无铅焊料的最新研究进展提出了无铅焊料"三大候选"的概念.总结了目前无铅焊料尚存的三大主要弱点,并对国际上推荐使用的几种无铅焊料的优缺点进行了概述.     

The creep and strain rate sensitivity of a high Pb content solder with comparisons to 60Sn/40Pb solder

Creep plays an important role in the mechanical behavior of solder alloys. This paper presents creep and strain rate sensitivity data for a Pb rich solder (92.5Pb, 2.5Ag, 5Sn-Indalloy 151) and compares it to the behavior of near eutectic 60Sn/40Pb solder. The high Pb alloy is used for exposures to higher temperatures than can be withstood by eutectic Sn/Pb solders. The Pb rich solder tested here is less strain rate sensitive than 60Sn/40Pb. There are also differences in the creep behavior.     

Effects of microstructural evolution and intermetallic layer growth on shear strength of ball-grid-array Sn-Cu solder joints

The shear strength of ball-grid-array (BGA) solder joints on Cu bond pads was studied for Sn-Cu solder containing 0, 1.5, and 2.5 wt.% Cu, focusing on the effect of the microstructural changes of the bulk solder and the growth of intermetallic (IMC) layers during soldering at 270°C and aging at 150°C. The Cu additions in Sn solder enhanced both the IMC layer growth and the solder/IMC interface roughness during soldering but had insignificant effects during aging. Rapid Cu dissolution from the pad during reflow soldering resulted in a fine dispersion of Cu₆Sn₅ particles throughout the bulk solder in as-soldered joints even for the case of pure Sn solder, giving rise to a precipitation hardening of the bulk solder. The increased strength of the bulk solder caused the fracture mode of as-soldered joints to shift from the bulk solder to the solder/IMC layer as the IMC layer grew over a critical thickness about 1.2 m for all solders. The bulk solder strength decreased rapidly as the fine Cu₆Sn₅ precipitates coarsened during aging. As a consequence, regardless of the IMC layer thickness and the Cu content of the solders, the shear strength of BGA solder joints degraded significantly after 1 day of aging at 150°C and the shear fracture of aged joints occurred in the bulk solder. This suggests that small additions of Cu in Sn-based solders have an insignificant effect on the shear strength of BGA solderjoints, especially during system use at high temperatures.     

Microstructure Evolution of SnAgCuEr Lead-free Solders Under High Temperature Aging

In this work, we have systematically investigated the evolution of microstructure and of intermetallic compounds (IMCs), in particular, for lead-free SnAgCuEr solders during isothermal aging tests. The effect of trace amounts of the rare earth element Er on this process has also been studied. The results indicate that diffusion and reassembly occur in the solder matrix during the aging process, and the major influence of the rare earth element Er is concentrated on the nucleation sites. ErSn₃ IMCs formed from the molten solder provide heterogeneous nucleation sites for the IMCs in the soldering and aging process. Subsequently, the Cu-Sn IMCs produced during soldering and Ag-Sn IMCs precipitated during the aging process have uniform size and evenly distribute in the solder matrix, and the refinement effect has been achieved in Er-containing solder joints. In addition, some cracks can be seen in Er-free solder joints, and the cracks may nucleate and propagate in the structure along the compound/solder boundaries after long aging times.