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.     

AlN陶瓷与无氧铜的活性封接

采用Ag-Cu-Ti活性钎料对AlN陶瓷与无氧铜进行了钎焊。通过对焊接件气密性的测试、陶瓷/金属结合界面的微观分析以及界面化学反应的热力学计算,得出以下结论:Ag-Cu-Ti2.0钎料可以实现AlN与无氧铜的气密封接,漏气速率Q<10×10-8Pa.L/s;钎料与陶瓷界面存在一定厚度的化学反应区,反应产物主要是TiN。     

Sn-Cu、Sn-Ag-Cu系无铅钎料的钎焊特性研究

制备了Sn-0.7Cu、Sn-3.5Ag-0.6Cu钎料,用润湿平衡法测量了钎料对铜的润湿曲线,研究了温度、钎剂活性、钎焊时间对润湿行为的影响,并与Sn-37Pb钎料进行了比较。结果表明:升高温度能显著改善无铅钎料对铜的钎焊性。当温度<270℃时,Sn-0.7Cu的钎焊性明显低于Sn-3.5Ag-0.6Cu钎料;而当温度≥270℃时,两种钎料对铜都会显示较好的润湿性,而Sn-0.7Cu略优于Sn-3.5Ag-0.6Cu钎料。提高钎剂活性能显著增强钎料对铜的润湿性,其卤素离子的最佳质量分数均为0.4%左右。随着浸渍时间的延长,熔融钎料与铜的界面间产生失润现象。无铅钎料的熔点和表面张力较高,是钎焊性较差的根本原因。     

铜颗粒增强对锡铅钎料蠕变寿命的影响

颗粒增强是提高合金性能的重要手段之一.增强体的不同含量对基体的性能会产生不同的影响.主要分析和讨论了铜的不同含量对铜颗粒增强的锡铅基复合钎料蠕变性能的影响.测定6种铜颗粒增强的锡铅基复合钎料的蠕变寿命.试验结果表明:在相同的条件下,复合钎料的蠕变寿命与锡铅钎料相比,均有不同程度的提高.当铜的质量分数约为1%时,复合钎料的蠕变性能最好,约为锡铅钎料的17倍.     

In对Sn9Zn钎料润湿性能的影响

为了提高Sn9Zn共晶钎料的钎焊性能,通过合金化的方法添加了少量元素In,制备了Sn9Zn-xIn钎料。从钎料合金的熔化特性、润湿特性、界面显微结构和母材粗糙度这四个方面评价了不同In含量对Sn9Zn钎料润湿性能的影响。试验结果表明:少量元素In的添加可以降低钎料的熔点;随着In含量的增加,钎料的润湿力增大,润湿时间缩短,润湿性有明显提高;In含量增加,润湿界面层中Cu5Zn8化合物层厚度增加;对母材表面进行毛化处理,通过改变母材表面的微观几何结构,增大钎料与母材的相对接触面积,从而改善钎料的润湿性能。     

镀Ti/Ni膜蓝宝石与无氧铜钎焊的研究

为了可以采用常规的BAg72Cu-V钎料完成蓝宝石与无氧铜的连接,本研究中先将蓝宝石表面镀Ti/Ni复合膜,然后进行高温预扩散处理,最后将镀Ti/Ni膜蓝宝石与无氧铜在真空炉中进行钎焊。本文介绍了蓝宝石镀膜、扩散及焊接工艺,对镀Ti膜蓝宝石及镀Ti/Ni复合膜蓝宝石在高温预扩散前后分别进行了扫描电镜分析和X射线衍射分析,说明蓝宝石镀Ti/Ni膜扩散后的性能优于仅镀Ti膜,并通过对焊接接头的微观分析发现高温预扩散的优势。     

精密连接——真空扩散焊和过渡液相连接的实验研究

针对新型电真空器件研制过程中的精密连接要求,进行了无氧铜真空扩散焊、过渡液相连接工艺实验。并应用氦质谱检漏仪、测量显微镜、金相显微镜、扫描电子显微镜对扩散焊试样进行分析,并进行了不同扩散温度、不同扩散时间的对比实验。实验表明:在相同工艺参数下,无氧铜直接扩散连接能获得可靠的扩散焊接头,内部结构变形量1~12μm,漏率5×10-4 Pa·m3s-1,且在相同扩散压力条件下,不能通过提高扩散温度,延长扩散时间的方法获得气密性接头;过渡液相连接接头可达到气密性要求(QL<5×10-9 Pa·m3s-1),变形量5~15μm,镀银层充分扩散到母材中。     

磁头无铅微焊点液滴飞溅和失效性分析

磁头无铅微焊点可靠性分析主要包括焊点前期液滴飞溅的防护和后期焊点失效性分析,在实际生产中,应用钎料球喷射连接技术时,钎料液滴飞溅时有发生,本文融合激光加热和氮气压力技术,建立了一种新的用于计算磁头内置DFH控制元件连接钎料液滴冲击速度的双液滴模型,同时,采用正交试验法对比了不同激光加热参数和氮气压力条件下磁头内置DFH控制元件连接钎料液滴飞溅的情况,并进一步融合可控扫描式磁场和偏置两种方法,研究了磁头微焊点的失效情况.试验结果表明:下落前,激光脉冲能量是决定液滴温度的主要因素;下落后,对钎料液滴温度影响最大的是钎料液滴的初始温度.磁头无铅微焊点失效是焊点液滴飞溅和金属间化合物共同作用的结果.     

Si3N4陶瓷与钢的真空钎焊研究

本文研究了Cu—Sn—Ti,Cu—In—Ti,Cu—Cr,Cu—Ge—Ti铜基活性钎料钎焊Si_3N_4陶瓷与钢。结果表明,四种铜基无银钎料均可实现Si_3N_4陶瓷与钢的连接,Cu—Sn—Ti,Cu—In—Ti的钎焊接头的剪切强度较高,它们合适的钎焊工艺参数分别为1373K×600s,1323K×600s。钎焊接头的X射线衍射分析,波谱分析表明活性钎料连接陶瓷与金属的机制是钎料中活性元素(Ti、Cu)向陶瓷界面扩散并与之发生化学反应而实现接合。     

新型Sn-Ag-Bi-Cu-In系无铅钎料合金研究

通过正交试验设计形成Sn-Ag-Bi-Cu-In系无铅钎料合金,并对钎料合金的熔化温度、可焊性、密度及剪切强度等进行研究.研究发现,Sn-Ag-Bi-Cu-In系钎料合金熔化温度接近传统的熔化温度,固-液温度差小;钎料密度约为传统Sn63Pb37的87%;试样铺展面积为72.02mm2,与Sn63Pb37焊锡的铺展面积76.85 mm2非常接近;钎料的剪切强度远大于传统Sn63Pb37钎料的剪切强度,其断裂形貌为沿晶脆断.     

The interfacial reaction between Sn-Zn-Ag-Ga-Al solders and metallized Cu substrates

The interfacial interaction between the Sn-8.55Zn-0.5Ag-0.5Ga-0.1Al solder and three kinds of metallized substrates (Cu, Cu/Au, and Cu/Ni-P/Au) does not form the Cu-Sn intermetallic compound (IMC). Continuous Cu-Zn and discontinuous Ag-Zn interfacial IMC layers formed between the Cu and Sn-Zn-Ag-Ga-Al solder, while Cu-Zn and Au-Al-Zn IMCs formed on the Cu/Au substrate. Only the Au-Al-Zn IMC formed at the interface when the electroless Ni-P deposit was the diffusion barrier between Cu and the Au surface layer.     

Mechanism of Reaction Between Nd and Ga in Sn-Zn-0.5Ga-xNd Solder

The mechanism of reaction between Nd and Ga in Sn-Zn-0.5Ga-xNd solder was investigated in order to enhance the reliability of soldered joints. It was found that, after aging treatment at ambient temperature and 125°C for over 3000 h, no Sn whisker growth was observed in Sn-9Zn-0.5Ga-0.08Nd soldered joints. X-ray diffraction (XRD) analysis and thermodynamic calculations indicated that Ga reacted with Nd instead of Sn-Nd intermetallic compound (IMC), eliminating Sn whisker growth. Shear force testing was carried out, and the results indicated that Sn-9Zn-0.5Ga-0.08Nd solder still had excellent mechanical properties after aging treatment. This new discovery can provide a novel approach to develop high-reliability solder without risk of Sn whiskers.     

Solderability testing of 95.5Sn-3.9Ag-0.6Cu solder on oxygen-free high-conductivity copper and Au-Ni-Plated kovar

The solderability of 95.5Sn-3.9Ag-0.6Cu solder on oxygen-free high-conductivity (OFHC) copper and Au-Ni-plated Kovar was examined as a function of flux and process temperature. The three solder fluxes included a rosin-based (R) material, a rosin mildly activated (RMA) flux, and a low-solids (LS) flux. The solderability metric was the contact angle, θ_C, measured by a meniscometer and wetting-balance techniques. The wetting rate and time to maximum force parameters were also documented. In most cases, the contact angles for the 95.5Sn-3.9Ag-0.6Cu solder alloy, regardless of the type of flux or temperature, were higher then those for the 63Sn-37Pb eutectic-solder alloy, indicating a less “solderable” surface.     

银含量对随机振动条件下无铅焊点可靠性的影响

为了探究银含量对无铅焊点在随机振动条件下的可靠性的影响,对Sn-3.0Ag-0.5Cu、Sn-1.0Ag-0.5Cu和Sn-0.3Ag-0.7Cu三种不同Ag含量材料的焊点做窄带范围内的随机振动疲劳实验,并对失效焊点进行分析。结果表明:三种材料焊点的失效位置基本都在靠近PCB侧,最外围焊点最容易失效,失效模式均为脆性断裂,并且随着Ag含量的降低,金属间化合物的厚度逐渐减小,焊点的疲劳寿命逐渐延长。     

三种典型Sn-Ag-Cu无铅钎料的组织和性能研究

对比研究了三种典型标称成分的Sn-Ag-Cu钎料(即日本JEIDA推荐的Sn-3.0Ag-0.5Cu、欧盟IDEALS推荐的Sn-3.8Ag-0.7Cu和美国NEMI推荐的Sn-3.9Ag-0.6Cu)的显微组织特征、熔化特性、润湿性以及钎焊接头微焊点的力学性能等。结果表明,三种钎料的组织和性能非常接近。然而从性价比等方面综合考虑,Sn-3.0Ag-0.5Cu为三种钎料中最具优势的替代传统Sn-Pb钎料(共晶和近共晶钎料)的无铅合金。     

Double-layer no-flow underfill materials and process

The no-flow underfill has been invented and practiced in the industry for a few years. However, due to the interfering of silica fillers with solder joint formation, most no-flow underfills are not filled with silica fillers and hence have a high coefficient of thermal expansion (CTE), which is undesirable for high reliability. In a novel invention, a double-layer no-flow underfill is implemented to the flip-chip process and allows fillers to be incorporated into the no-flow underfill. The effects of bottom layer underfill thickness, bottom layer underfill viscosity, and reflow profile on the solder wetting properties are investigated in a design of experiment (DOE) using quartz chips. It is found that the thickness and viscosity of the bottom layer underfill are essential to the wetting of the solder bumps. Chip scale package (CSP) components are assembled using the double-layer no-flow underfill process. Silica fillers of different sizes and weight percentages are incorporated into the upper layer underfill. With a high viscosity bottom layer underfill, up to 40 wt% fillers can be added into the upper layer underfill and do not interfere with solder joint formation.     

电迁移致SnAgCu微焊点强度退化及尺寸效应研究

在100℃温度下,对直径为300μm、高度为100,200和300μm的Sn-3.0Ag-0.5Cu钎料微焊点施加密度为1×104A/cm2的直流电流。通电48h后,利用DMA对电迁移作用后微焊点拉伸强度的变化进行了研究。结果表明,电迁移作用导致微焊点拉伸强度明显退化,且退化程度随微焊点高度的减小而减弱。其中,高度为300μm的微焊点的平均拉伸强度由初始态的44.4MPa降至27.8MPa,下降了37.4%。电迁移还导致微焊点的断裂由延性变为延性与脆性相结合的模式。     

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。     

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.     

锡铅稀土钎料合金高温蠕变性能试验研究

文中对比分析了Ｓｎ６０Ｐｂ４０和Ｓｎ－Ｐｂ－０．０５Ｒｅ两种钎料合金在多轴应力状态下的蠕变断裂规律,初步探讨了主控两种钎料复合金为断裂的力学因素,并从金属学角度初步探讨了两种钎料合金的蠕变断裂方式,着重分析了混合稀土对锡铅秆料合金蠕变性能的影响。