Effects of Ni-Doping on Microstructures and Properties of Zn-20Sn High-Temperature Lead-Free Solders

In the present work, the effect of Ni doping on the microstructures and properties of Zn-20 Sn high temperature lead-free solder has been investigated. Interestingly,Ni was present as the form of Ni-Zn compounds in the microstructure of Zn-20 Sn-xNi alloy.When the Ni-doping amount was 0.2~0.4 wt.%, the presence of δ phase was found, and when the doping amoun was 0.8 wt.%, the presence of γ phase was observed. With the increase of Ni content, the liquidus temperature increased but the solidus temperature did not change obviously. In addition, the microhardness and electrical resistivities of Zn-20 Sn-xNi solder increased gradually. And the spreading area and shear strength increased firstly but decreased afterwards. When the content of Ni was 0.4 wt.%, the spreading area and shear strength of solder reached to be maximum. After the addition of 0.4 wt.% Ni, the microstructure of the interfacial intermetallic compound(IMC) layer of the interface didn't change, but the total thickness of the IMC layer reduced. The δ-phase was embedded in the grain boundary of ε-Cu Zn5, which hindered the diffusion of atoms. The thickness of IMC layer at the interface reduced, which led to the improvement of the shear strength of the interface.

Low temperature soldering alloy using Sn63 Pb37 implantation of silica ceramics and copper solder assisted by ion and deposition

Copper ion implantation and deposition technique was applied as a pretreatment method for low temperature joining of silica ceramic （ SiO2 ） and copper alloy. The effect of copper ion implantation and deposition parameters on the microstructures and mechanical behavior of the soldering joints was investigated by scanning electron microscope （SEM） , X- ray diffraction （ XRD ） and shearing test. The copper implantation depth was about 90 nm with peak concentration of 70% for the SiO2 sample implanted for 90 rain. If copper film was deposited for 4 rain using magnetron sputtering, copper layer with thickness of 150 nm and peak concentration of 80% was obtained. After pretreatment of ion implantation and deposition, SiO2 and copper were joined successfully at low temperature directly using SnPb solder. The SnPb solder filling ratio along joining seams was up to 100% without defects with smooth soldering toes. With the increase of implantation dose, the shear strength of the Si02/Cu joints increases accordingly. After a special pretreatment on SiO2 （ Cu implantation for 30min, following Cu deposition for 4 rain, then Cu implantation for 60 rain and finally Cu deposition for 120 min） , a maximum soldering strength of 22 MPa was achieved, and the soldering joints fractured at the SiO2 base material.

Exceptional electrostrain with minimal hysteresis and superior temperature stability under low electric field in KNN-based lead-free piezoceramics

Over the past two decades,(K_(0.5)Na_(0.5))NbO_(3)(KNN)-based lead-free piezoelectric ceramics have made significant progress.However,attaining a high electrostrain with remarkable temperature stability and minimal hysteresis under low electric fields has remained a significant challenge.To address this long-standing issue,we have employed a collaborative approach that combines defect engineering,phase engineering,and relaxation engineering.The LKNNS-6BZH ceramic,when sintered at T_(sint)=1170℃,demonstrates an impressive electrostrain with a d_(33) value of 0.276%and 1379 pm·V^(-1)under 20 kV·cm^(-1),which is comparable to or even surpasses that of other lead-free and Pb(Zr,Ti)O_(3)ceramics.Importantly,the electrostrain performance of this ceramic remains stable up to a temperature of 125℃,with the lowest hysteresis observed at 9.73%under 40 kV·cm^(-1).These excellent overall performances are attributed to the presence of defect dipoles involving V′_(A)-V∙∙_(O) and B′_(Nb)-V∙∙O,the coexistence of R-O-T multiphase,and the tuning of the trade-off between long-range ordering and local heterogeneity.This work provides a lead-free alternative for piezoelectric actuators and a paradigm for designing piezoelectric materials with outstanding comprehensive performance under low electric fields.

Wetting Behaviors and Interfacial Reaction between Sn-10Sb-5Cu High Temperature Lead-free Solder and Cu Substrate

Sn-10Sb-5Cu lead-free solder was fabricated for high temperature application in electronic package. Wetting behaviors and interfacial reaction between such a high temperature lead-free solder and Cu substrate were investigated and compared with those of 95Pb-Sn solder. The results showed that the wetting properties of Sn-10Sb-SCu solder are superior to those of 95Pb-Sn solder in maximum wetting force, wetting time and wetting angle in the temperature range of 340-400℃. However, the surface of the Sn-10Sb-5Cu solder sample after wetting balance tests was rougher than that of 95Pb-Sn solder at the temperature lower than 360℃. In static liquid-state interracial reaction, the types and thickness of the intermetallic compounds （IMCs） of both solders were different from each other. The wetting kinetics in the Sn-10Sb-5Cu/Cu system was more rapid than that in 95Pb-Sn/Cu system, and the higher formation rate of IMCs in the former system was considered as the reason.

地铁车辆基地回流系统杂散电流防护措施改进

地铁车辆基地回流系统杂散电流防护工程设计通常采用分区就近回流、设置单向导通装置、设置均流电缆减少回流电阻等措施,针对上述常规防护措施在车辆基地实际应用过程中存在杂散电流的问题,以广州地铁12号线车辆基地为例,提出改进措施:出入线处采用响应式单向导通装置取代传统单向导通装置;回流电缆处与轨连接采用胀钉+铜排冷钎焊方式,其余处采用胀钉连接方式。实践证明上述措施防护效果良好。

Influences of Ag and Au Additions on Structure and Tensile Strength of Sn-5Sb Lead Free Solder Alloy

It is important, for electronic application, to decrease the melting point of Sn-5Sb solder alloy because it is relatively high as compared with the most popular eutectic Pb-Sn solder alloy. Adding Au or Ag can decrease the onset melting temperature （233℃） of this alloy to 203,5℃ and 216℃, respectively. The results indicate that the Sn-5Sb-i.5Au alloy has very good ultimate tensile strength （UTS）, ductility, and fusion heat, which are better than both those of the Sn-5Sb-3.SAg and Sn-5Sb alloys. The formation of intermetallic compounds （IMCs） AuSn4 and Ag3Sn enhanced the SbSn precipitates in the solidification microstructure microstructure stability, while retained the formation of thus significantly improved the strength and ductility For all alloys, both UTS and yield stress （σy） increase with increasing strain rate and decrease with increasing temperature in tensile tests, but changes of ductility are generally small with inconsistent trends.

Characterization of Cu_3P phase in Sn3.0Ag0.5Cu0.5P/Cu solder joints

This article reports the effects of phosphorus addition on the melting behavior, microstructure, and mechanical properties of Sn3.0Ag0.SCu solder. The melting behavior of the solder alloys was determined by differential scanning calorimetry. The interracial micro- structure and phase composition of solder/Cu joints were studied by scanning electron microscopy and energy dispersive spectrometry. Thermodynamics of Cu-P phase formation at the interface between Sn3.0Ag0.5Cu0.5P solder and the Cu substrate was characterized. The results indicate that P addition into Sn3.0Ag0.5Cu solder can change the microstructure and cause the appearance of rod-like CuaP phase which is distributed randomly in the solder bulk. The Sn3.0Ag0.5Cu0.5P joint shows a mixture of ductile and brittle fracture after shear test- ing. Meanwhile, the solidus temperature of Sn3.0Ag0.5Cu solder is slightly enhanced with P addition.

Preliminary Investigation of Copper Joints Soldered with Sn58Bi

In recent years,intensive studies have been carried out to find an alternative for Tin(Sn)⁃Lead(Pb)solder alloys with increasing demand over lower temperature solder alloys in current electronic packaging industry.High temperature operational solder alloys seem to produce drawback to other components on the printed circuit board(PCB).Low melting temperature Sn58Bi substrate as a potential replacement was investigated in this paper based on the melting properties,wettability,and shear strength.The Sn58Bi was soldered at a temperature below 200℃on the Cu substrate,and the shear strength and contact angle were calculated.A peak temperature(melting temperature,T_(M))of 144.83℃was identified.Single lap joint method was performed at a strain rate of 0.1 mm/min and an average shear strength of 23.4 MPa was found from three samples.The contact angle(wettability)was calculated to study the solder joint behaviour at reflow temperature of 170℃.The contact angle of the Sn58Bi was found to be 32.4°and considered to be desired value since the angle is less than 50°.The low temperature soldering provides a preliminary result to allow further application on the real PCB.

“后摩尔时代”芯片互连方法简析

随着半导体制程接近工艺物理极限,半导体工业进入“后摩尔时代”,集成技术成为继续提高电子产品性能的重要途径。现存的实现高度集成的关键技术都对更小尺寸的连接提出了要求。同时随着连接尺寸的减小,封装体在连接工艺中受到的影响导致器件在使用温度下失效的问题越来越严重。封装内的互连部分是芯片热传导、电气连接的重要结构,也是器件失效的重要部位,在互连接头尺寸不断减小的背景下,互连部分的失效在器件整体失效的情况中占据着越来越重要的地位,研究高导热、低工艺影响的微纳连接技术有望解决高功率密度器件的可靠性问题。本文总结了微纳连接技术在新型焊料、能量传递方式两方面的发展,简单介绍了表面活化技术并讨论其应用在电子封装中的可能性,在此基础上讨论了微纳连接技术的发展方向。

双极化天线组件的低温钎焊工艺

一种双极化天线需要同时完成水平极化微带板、垂直极化微带板、双联SMP连接器与金工件支架的低温钎焊。由于连接器的焊料量难以控制,造成钎透率不足,存在成品驻波不稳定、多发驻波超标的问题,需要返修才能提高合格率。通过焊料环的设计定制以及连接器的局部搪锡,优化焊料状态,使一次合格率由40%达到90%。

Sn-Cu-Au低温圆片键合强度偏低原因分析

分析了某MEMS器件Sn-Cu-Au低温圆片键合强度偏低的原因,发现该问题主要由“金脆”现象引起。结合实践经验和相关文献,总结了“金脆”现象发生的一般规律,制定了一个可以避免该现象发生的工艺方案,并开展了针对性的验证试验。试验结果表明,通过优化键合焊料系统的组分配比可以避免“金脆”现象的发生,同时也证实了这一措施是可行有效的。

电子封装低温互连技术研究进展

电子产品作为现代电子行业的产物,已逐渐成为社会发展的主导力量,在电子产品封装过程中,电子器件的封装温度过高会产生较大的热应力,进而降低其可靠性。随着电子器件趋于微型化、高功率化、高集成化,其服役温度越来越高,如何解决电子器件“低温封装、高温服役”这一问题已迫在眉睫。本文就低温电子封装材料及方法,从封装母材、连接材料及连接方法三个方面进行总结,指出只有从母材、焊材及焊接方法同时入手,才能达到最佳技术效果,提出在母材表面制备链长更长的、易去除的临时保护层,采用烧结纳米银、纳米铜或瞬时液相混合焊料,借助与焊缝非直接接触的超声搅拌等材料和方法有望克服低温封装的技术瓶颈,同时提出采用微米级混合焊料并辅以超声振动实现连接的新思想。

红外探测器高精度低温钎焊引线环设计

针对制冷型红外探测器引线环高精度定位的需求,本文设计了一种低温钎焊引线环,研究了引线环的制备工艺。选取具有高强度、低熔点的金锡钎料,在350℃以下焊接引线环的金属件与陶瓷件。通过研究钎焊温度和保温时间对焊缝质量与漏率的影响,成功制备了具有高气密性的高精度引线环。

LTCC基板金锡焊接的返修过程质量控制

低温共烧陶瓷(LTCC)基板与硅铝壳体的一体化烧结在航天T/R组件领域具有成熟而广泛的应用,但在实际生产中不可避免地存在因组件性能不达标而需要返修LTCC基板的情况。本文对LTCC基板的金锡返修焊接进行失效分析,指出在多个基板紧密贴合的组件中,各LTCC基板的间距应大于0.1 mm;对于需返修焊接的硅铝壳体,推荐采用化学镍+电镀镍的工艺制备镍层,并且电镀镍层的厚度应大于2μm。

Sn-Bi基低温无铅焊料的研究进展

作为一种新型低温无铅焊料,Sn-Bi基低温无铅焊料具有较低的熔化温度以及优良的焊接性能,在电子封装领域有着广泛的应用。随着电子元器件向微型化方向的发展,对低温无铅焊料的性能提出了更高的要求。添加微量的合金元素及纳米颗粒可以改善焊料的组织性能,满足电子元器件发展的需求。系统介绍了Sn-Bi基低温无铅焊料的组成、结构以及焊接性能,综述了合金元素和纳米颗粒对Sn-Bi基低温无铅焊料组织性能的影响及作用机理,分析了在研制Sn-Bi基低温无铅焊料过程中存在的不足之处,并提出了相应的改进方法。最后对Sn-Bi基低温无铅焊料在发展中需要关注的问题进行了总结与展望。

芯片共晶模块高钎透率真空回流焊接工艺

芯片共晶模块是微波组件的重要组成部分,芯片共晶模块到壳体封装质量直接影响微波组件的电学性能和可靠性。采用真空回流焊接技术对芯片共晶模块进行低温焊接,通过优化压块材质、温度曲线和真空制程参数等方式,实现芯片共晶模块焊接钎透率达90%以上、单个空洞率低于5%的标准要求。

In对SnBiAg焊料微观结构及力学性能的影响

使用电磁感应加热炉制备Sn-35Bi-0.3Ag-xIn低温无铅焊料,采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、能谱仪(EDS)、万能拉伸试验机、维氏硬度仪,研究添加In元素对焊料的物相、组织结构、机械性能的影响。结果表明,添加In元素固溶到焊料基体中,细化了焊料组织结构。合金焊料的抗拉强度也随着In元素含量的增加而增大。但是其硬度,延展性却随着In元素含量的增加先增加后降低。此外,当添加0.5%含量的In时,析出的Bi相减少,延展性得到提高,焊料的综合力学性能较好。

活性剂对Sn64Bi35Ag1焊锡膏空洞率影响研究

通过对活性剂性能研究,探索助焊剂配方体系中不同活性剂类型及含量变化对焊锡膏空洞率的影响。以PCB测试基板为载体,焊锡膏经印刷、回流焊接后,使用XD7500VR JADE EP型号的X-Ray设备进行焊点空洞率测试,以空洞率的大小为评价指标,按照试验设计对6种不同活性剂进行了助焊剂合成,进一步配制焊锡膏进行焊点空洞率测试。经过对比分析,优选取了4种分解温度呈阶梯状的有机酸进行复配试验。结果表明:有机酸的复配能显著改善焊点的空洞率,己二酸、丙二酸、癸二酸、辛二酸的含量分别为2%、2%、4%、3%复配时,焊锡膏空洞率为6.8%。

电子封装技术的最新进展

现今集成电路的特征线宽即将进入亚0.1 nm时代,根据量子效应这将是半导体集成的极限尺寸,电子产品小型化将更有赖于封装技术的进步。概括总结了SiP三维封装、液晶面板用树脂芯凸点COG封装、低温焊接等技术的最新进展。并对SiP三维封装技术中封装叠层FFCSP技术进行了着重的阐述。指出随着低温焊接、连接部树脂补强以及与Si热膨胀系数相近基板的出现,电子封装构造的精细化才能成为可能,为各种高密度封装、三维封装打下坚实基础。

纳米Ni颗粒增强无铅Sn-Cu-Ag复合钎料搅拌辅助低温钎焊技术

采用搅拌辅助低温(半固态区间)钎焊技术,制备低银无铅钎料和纳米复合钎料钎焊接头。结果表明:240℃时复合钎料的润湿时间较基体的润湿时间缩短了31%,润湿力较基体的提高了3.8%;机械搅拌在破碎树枝晶和加速元素扩散的同时,降低了液相的温度梯度和成分过冷,大大削弱了钎料基体中金属间化合物(IMC)Cu6Sn5的枝晶生长,促使针状Cu6Sn5破碎呈短棒状;在低银无铅钎料中加入纳米Ni颗粒,Ni与Cu6Sn5生成孔洞状化合物(Cux Ni1-x)6Sn5及低温搅拌形成的气孔成为界面原子的扩散通道。搅拌形成的紊流和热流传递加快了原子的溶解与扩散,加速了界面IMC的生长。