空间行波管输能窗组件贮存失效分析

高频组件是空间行波管的主要部件,是管内传播高频电磁波的重要传输部件,其中陶瓷封接部位一般采用银焊料进行焊接,它一般存放于真空柜中.存放一段时间后,组件表面出现了发黑现象.分析表明真空柜中放置的橡胶制品导致了高频组件银焊料焊接部位发生硫化,导致贮存失效.结合实验结果和理论分析,在大气状态下,橡胶套中的硫是比较稳定的.然而在真空状态下,硫是比较容易从橡胶套中升华进入真空柜中的,从而会在真空柜中弥漫大量硫蒸气,这些硫蒸气与银焊料发生化学反应形成Ag2S,因此含硫的橡胶套不宜放入真空柜.     

真空环境下的共晶焊接

共晶焊接是微电子组装中一种重要的焊接工艺。文章简要介绍了共晶焊接的工作原理以及共晶焊料如何选用和常用共晶焊料的性能特性。然后比较了几种共晶焊接设备的优缺点,得出用真空可控气氛共晶炉在真空环境下完成共晶焊接能有效防止共晶焊接过程中氧化物的产生,大大降低空洞率,从而提高焊接质量。它同样适用于多芯片组件的一次共晶。对真空环境下影响共晶焊接质量的真空度、保护性气氛、焊接过程中的温度曲线、焊接时的压力等条件做了探讨,得出了几种最优的工艺方案,能适用于大部分的共晶焊接工艺。     

TR组件焊接可靠性工艺研究与应用

对毫米波TR(transmitter and receiver)组件焊接过程中线膨胀系数(CTE)失配机理和由于CTE失配导致的热机械应力对组件可靠性的影响进行了分析。根据阶梯焊接温度精确控制和无铅焊料可靠浸润的要求,从实践中总结出了一种真空预镀涂焊接新工艺。实践表明,该新工艺可以精确地进行阶梯焊接温度控制,使无铅焊料有很好的浸润效果,焊透率由70%以下提高到98.3%,延长了CTE不匹配造成的疲劳失效发生时间,提高了TR组件使用可靠性。     

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     

半导体AuSn焊料低温真空封装工艺研究

介绍了半导体金锡(AuSn)焊料焊接封装的影响因素:焊接气氛、镀金层、焊料,在低温真空焊接封装的基础上,重点探讨了AuSn焊料真空钎焊封装的影响因素、AuSn焊料本身的组分比及其浸润性等对焊接封装的影响、AuSn焊料真空焊接封装炉温曲线设置及焊接温度和时间的正交实验、AuSn焊料真空焊接封装中真空度的影响因素、真空度对...     

低银无铅焊料润湿及可靠性能研究

利用润湿测量法研究了低银无铅焊料SAC0307、SAC0507和SAC0807的润湿性能,发现上述低银焊料润湿性能几乎相同.通过波峰焊接实验鉴定了其溶解铜焊盘性能,发现所做短时间溶铜实验中上述低银焊料的低银焊料的溶铜速度几乎相同.温度循环实验后检测了金属间化合物生长及裂纹发生情况,确定低银无铅焊料SAC0807裂纹萌生率最低.所作实验研究中皆采用共晶锡银焊料SAC305作为参照焊料.     

红外探测器锗窗口无助焊剂回流焊接工艺研究

对红外探测器锗窗口无助焊剂回流焊接工艺进行了研究,在还原性气氛下使用铟焊料片对不同镀层体系的锗窗口和可伐合金进行了焊接试验。通过对不同镀层体系下焊接的窗口部件的焊缝形貌、真空漏率分析、X射线无损检测分析以及可靠性试验分析,表明通过对锗窗口和可伐合金焊接面镀金处理,在还原性气氛下回流焊接可以制备出满足密封要求和环境适应性要求的窗口部件。     

感应钎焊技术及其在电连接器焊接中的应用

感应钎焊技术因其具有加热迅速、焊接效率高、焊料氧化少和加热部位局域化的优点,被用来焊接微波组件中的电连接器。针对组件外形不同和待焊电连接器种类不同,设计了与组件结构相匹配的感应线圈,探索优化了感应加热参数设置。焊接获得的电连接器焊缝质量良好、气密性指标优异,满足气密封质量要求。     

Sn-3.0Ag-0.5Cu真空再流焊工艺技术研究

为了获得低热阻和解决不同焊接材料之间的热应力匹配问题,大功率DC-DC模块电源产品广泛采用了载体组件作为功率元器件热沉的散热方法。载体组件由金属基板和陶瓷基板焊接而成,为了得到无空洞的焊接界面,载体组件采用了真空再流焊工艺技术。文中从焊料形态、焊接表面处理、真空度等几个方面介绍了载体组件的Sn-3.0Ag-0.5Cu真...     

混合进行的合金焊接

在2005年，我曾谈到向后兼容的混合合金（SnPb和无铅）回熔焊接问题，重点是球栅阵列（BGA）。我那时说，对于同一个电路板装配线（PCBA），SnPb合金和无铅合金会有一段共存的过渡时期。我不希望出现这种情况，但是，我想这是无法避免的。在多数情况下，使用SnPb焊料来焊接无铅组件不会导致焊接或者可靠性的问题。大多数的无铅表面的处理，能够与SnPb焊料向后兼容——但是，SnPb焊料和无铅BGA是例外，这种组合存在风险。[第一段]     

High-speed photodetectors

This paper is intended as a status report on high-speed detectors for the visible and near-infrared portion of the optical spectrum. Both vacuum and solid-state detectors are discussed, with the emphasis on those devices which can be used as direct (noncoherent) detectors of weak optical signals modulated at microwave frequencies. The best detectors for this application have internal current gain and in this regard the relevant properties and limitations of high-frequency secondary emission multiplication in vacuum tube devices and avalanche multiplication in p-n junctions are summarized.     

无磁蒙乃尔材料漏气原因分析

微波真空电子器件广泛应用于雷达、卫星通信、电子加速器等方面。蒙乃尔材料也称镍一铜合金,其常被应用于微波真空电子器件,其性能好坏将直接影响微波源的可靠性和寿命。但在用银铜焊料对蒙乃尔材料进行钎焊封接时经常会发生漏气现象,直接给应用者造成损失。针对这一现象做了一系列的试验,并结合相关的理论知识对此现象进行了详细的分析,从工艺控制角度来探寻适宜可行的解决方法。介绍了在封接工艺中蒙乃尔材料合金退火的重要性及目的,并分析得出了蒙乃尔材料合金退火的温度及气氛。     

Thermosonic gold wire bonding to laminate substrates with palladiumsurface finishes

As the laminate substrate industry moves from hot air solder level (HASL) finishes, alternate plating finishes are being proposed such as immersion gold/electroless nickel, electroless palladium, and electroless silver. This paper presents results of an evaluation of the thermosonic gold ball wire bondability of electroless palladium. Two palladium thicknesses, with and without a nickel underlayer, were evaluated from two vendors. In each case, a thin gold passivation layer was deposited by immersion plating over the palladium. The initial evaluation criteria included bondability (number of missed bonds and flame off errors), wire pull strength, standard deviation, bond failure mode, and visual inspection. The bonding window was determined by independently varying force (four levels), power (four levels), and time (two levels). The stage temperature was maintained at 150°C, compatible with BT laminate material. Different preconditioning environments such as a solder reflow cycle, high temperature storage (125°C) and humidity storage (85%RH/85°C) on initial bondability were also considered. Rutherford backscattering and Auger analysis were used to examine the surface finishes. The stability of the bonds was investigated by high temperature storage (125°C) with periodic electrical resistance and pull strength testing     

真空开关管用合金钎料与CuCr触头材料的焊接性能研究

用不同牌号的合金钎料和不同的真空钎焊工艺,将不同组分的触头材料和无氧铜零件钎焊成组件.在宏观和微观的条件下,了解钎料的润湿性,测量组件的抗拉强度,分析合金钎料的钎焊特性.     

Phase transformations during the Ag-In plating and bonding of vertical diode elements of multijunction solar cells

The conditions of the bonding of silicon multijunction solar cells with vertical p-n junctions using Ag-In solder are studied. The compositions of electrodeposited indium films on silicon wafers silver plated by screen printing and silver and indium films fabricated by layer-by-layer electrochemical deposition onto the surface of silicon vertical diode cells silver plated in vacuum are studied. Studying the electrochemical-deposition conditions, structure, and surface morphology of the grown layers showed that guaranteed bonding is provided by 8-min heat treatment at 400°C under the pressure of a stack of metallized silicon wafers; however, the ratio of the indium and silver layer thicknesses should not exceed 1: 3. As this condition is satisfied, the solder after wafer bonding has the InAg₃ structure (or InAg₃ with an Ag phase admixture), due to which the junction melting point exceeds 700°C, which guarantees the functioning of such solar cells under concentrated illumination.     

冷阴极触发管在MPM保护电路中的应用

微波功率模块（MPM）是集真空微波管技术与固态微波集成技术优点于一身的一种新兴微波功率源,具有体积小、重量轻、效率高、成本低等优点。研究了冷阴极触发管的特性及工作原理,提出了一种应用于微波功率模块中的自触发撬棒保护电路技术。它以冷阴极触发管为撬棒管,在行波管发生打火故障时,能快速释放高压电源储能电容上的能量,从而保护行波管和集成电源系统。实验结果表明该电路可以取得较好的性能,对系统可起到一定的保护作用。     

Effects of sulfur addition on the wettability and corrosion resistance of Sn-0.7Cu lead-free solder

The effects of sulfur on the wettability of Sn-0.7Cu on Cu and on the corrosion behavior of Sn-0.7Cu in 3.5 wt% NaCl solution were investigated. The results reveal that sulfur considerably improves the wettability of Sn-0.7Cu and the optimal sulfur content is 0.08 wt%. SnS and SnSO₄ phases form on the surface of the sulfur containing Sn-0.7Cu solder alloy after soldering characterized by XPS and XRD analysis. The addition of sulfur decreases the dross formation of the solder melt and the formation of SnO₂ is inhibited. The potentiodynamic polarization tests show that the corrosion resistance of Sn-0.7Cu solder alloy is obviously enhanced by sulfur element. Analyses by SEM and XRD indicate that sulfur promotes the formation of the corrosion product, Sn₃O(OH)₂Cl₂, on the surface of sulfur containing Sn-0.7Cu solder and it keeps the solder alloy from further corrosion.     

A study of large area die bonding materials and their corresponding mechanical and thermal properties

We tested the ability of Au/Sn eutectic, silver paste, and solder paste to bond to a large area as well as the bonding of a high power LED die to a highly conductive submount. The samples ran through several tests including ultrasound image, shear force, and thermal resistance measurement. Finite element analysis (FEA) models were built for comparison and analysis. Au/Sn bonding shows the best thermal and mechanical properties. Silver paste shows lower contact thermal resistance compared with solder paste. Although the thickness of the silver paste bonding layer is greater than the solder paste bonding layer, the average total thermal resistance is noticeably lower than the solder paste bonded samples.     

Effect of silver content on the shear fatigue properties of Sn-Ag-Cu flip-chip interconnects

The mechanical shear fatigue test has been performed to study the effect of silver content on the fatigue properties of Sn-xAg-0.5Cu (x=1, 2, 3, and 4) for flip-chip interconnections. The strength of the solder alloy increases with increasing silver content, preventing shear plastic deformation of the solder bump. The flip-chip joints made using higher silver content solder, such as 3%Ag and 4%Ag, exhibit longer fatigue life for all conditions. The fatigue ductility of the solder decreases with an increase in the silver content. The fatigue endurance of 1%Ag solder is superior to other solders over the plastic strain range of 3%, even though the strength of the solder is the lowest in the solders tested. Based on this study, the 3Ag solder may exhibit good fatigue performance for all conditions, and the 1Ag solder is optimum for severe strain conditions.