无铅转移工艺问题研究

针对无铅钎焊工艺在实际生产中出现的问题进行了分析和研究,找出影响其钎焊质量如表面粗糙、虚焊等主要问题,从钎焊温度、钎焊环境以及钎料膏质量等几个方面着手,经过反复试验验证,提出了解决工艺问题的方法,试验证明该方法对提高无铅钎焊质量具有较好的效果,可用于指导生产实践。     

Sn2.5Ag0.7CuxRE钎料对表面贴装元件的最佳润湿工艺参数试验研究

采用润湿平衡法研究了新型无铅钎料Sn2.5Ag0.7CuxRE对表面贴装元件的润湿性能。通过正交试验分析表明,钎焊温度对润湿力起显著作用,当采用水基免清洗助焊剂时,Sn2.5Ag0.7CuxRE无铅钎料合金钎焊的最佳工艺参数分别为:预热时间15 s、钎焊温度250℃和钎焊时间3 s。与两种商业应用的无铅钎料的润湿性能的比较表明,在该工艺条件下,Sn2.5Ag0.7CuxRE无铅钎料合金的润湿性能可略优于商用钎料,表明该钎料在选择合适的钎焊参数和钎剂后,可以满足表面组装行业对无铅钎料润湿性能的要求。     

基于QC的无铅手工钎焊工艺

分析了影响无铅手工钎焊质量的各种因素,绘制了满足无铅钎焊质量要求的亲和图,并设计了无铅手工钎焊新工艺的正交试验方案,寻求钎焊工艺参数的最佳组合,并对最佳组合进行分析,验证其合理性。     

激光软钎焊技术在高密度封装器件无铅连接中的应用

介绍了激光软钎焊技术的原理及特点，分析了激光软钎焊技术在高密度封装器件无铅连接中的应用优势。由于激光软钎焊技术具有局部加热、快速加热、快速冷却的特点，在高密度封装器件的无铅钎焊时，能够显著改善无铅钎料的润湿性能，细化无铅焊点的微观组织，提高无铅焊点的力学性能，因此激光软钎焊技术在高密度封装器件（如四边扁平封装器件以及球栅阵列封装器件）的无铅连接中有着广阔的应用前景。     

球化温度对BGA钎焊球质量的影响

钎焊球是BGA及μBGA等高密封装技术中凸点制作关键材料。球化温度是影响钎焊球质量关键因素。本文采用切丝重熔法制作钎焊球,研究了球化温度对63Sn37Pb钎焊球真球度和外观质量的影响。结果表明：在一定球化温度范围内,钎焊球的真球度和表面质量均随着球化温度的升高而变好,但温度接近球化剂沸点时,真球度有所下降。     

球化剂种类对BGA焊球质量的影响

钎焊球是BGA及μBGA等高密封装技术中凸点制作的关键材料,球化剂种类是影响钎焊球质量的关键因素.在预热温度为500℃和球化温度为280℃,球化剂分别采用机油、重油、硅油和花生油时,采用切丝重熔法制作高密封装用钎焊球.研究了不同球化剂种类对63Sn37Pb钎焊球的球形度和外观形貌的影响.结果表明,花生油作为球化剂时,63Sn37Pb钎焊球的真球度系数值最小,钎焊球越接近真球形状,球形度越好,外观形貌也最好,球化效果最好.重油、硅油次之,机油最差.     

矩形片式电阻半导体激光钎焊无铅焊点的热循环试验

选用Sn-Ag-Cu无铅钎料,采用半导体激光软钎焊和红外再流焊两种方法对0805型矩形片式电阻元件进行钎焊,并对采用不同方法得到的钎焊焊点进行热循环试验.结果表明,激光软钎焊矩形片式电阻焊点的力学性能优于传统红外再流焊工艺所获得的电阻焊点的力学性能;片式电阻焊点的剪切力随热循环次数的增加呈现下降趋势,在热循环次数相同时,激光软钎焊焊点的力学性能优于红外再流焊焊点.随着热循环次数的增加,片式电阻焊点的剪切断裂的方式由明显的韧性断裂逐渐向脆性断裂转变.     

球化温度对BGA钎焊球真球度及表面质量的影响

钎焊球是BGA及μBGA等高密封装技术中凸点制作的关键材料,球化温度是影响钎焊球质量的关键因素之一.本文采用自制切丝重熔法装置,以花生油为球化剂,研究了球化温度对63Sn37Pb钎焊球真球度和表面质量的影响.结果表明:在其他条件相同情况下,随着球化温度升高,钎焊球球化效果及表面质量越好,但球化温度过高(超过300℃),球化剂易产生浓烟,钎焊球易氧化.实验条件下,球化温度以300℃为宜.     

微波元件铝波导的钎焊

铝波导的形状复杂,有的是由几十个厚薄相差很大的(0.5～30毫米)元件钎焊而成。铝波导钎焊的技术关键有以下几点:①波导元件精度要求高;②严格地控制钎缝上钎料的流量和谨慎地处理好密集钎缝;③提高钎缝的致密性和抗腐蚀性。为保证产品的尺寸精度,必须正确地控制和减小元件钎焊时的变形。引起元件钎焊后变形的原因有以下几点: ①钎焊时加热不均匀。②钎焊时元件的放置或支撑不合理。这一点,在炉中钎焊时尤为明显。     

矩形片状元件无铅焊点断裂机制

采用微焊点强度测试仪测试了Sn-Ag-Cu钎料和Sn-Pb钎料钎焊的矩形片状元件钎焊接头的抗剪强度,并对焊点断口进行了扫描电镜分析.结果表明,Sn-Ag-Cu无铅钎料焊点的抗剪力明显大于Sn-Pb钎料焊点的抗剪力,但是两种焊点的剪切力变化曲线相似,表明焊点在剪切失效前都有明显的塑性应变过程.断口SEM分析发现,两种焊点的断裂位置都位于钎料与元件底面焊盘的界面处和钎料与元件侧面焊盘的界面处,且Sn-Ag-Cu钎料焊点的性能都比Sn-Pb钎料焊点的性能优异,说明Sn-Ag-Cu钎料完全可以替代Sn-Pb钎料钎焊矩形片状元件.     

铝的无铅软钎焊试验研究

研究了Sn-0.7cu,Sn-Ag-Cu,Sn-3.5Ag等软钎料合金对1060 Al的润湿性,结果表明钎料中Ag含量在1.5%～2.5%(质量分数)之间润湿性最好.SEM观察发现,钎料合金/Al界面处Ag2 Al金属问化合物并不是从基体AJ向外生长,而是与Al之间隔了一层富Sn相.最后结合Ag-Al扩散模型与键参数函数理论对Ag-Al化合物相的生长过程及润湿性的影响作出了解释.     

Lift-off phenomenon in wave soldering

The mechanism of lift-off, which is the serious defect formation that the solder fillet is peeled off from a Cu land pad on a printed wiring board in wave soldering, has been examined primarily by using basic Sn–Bi alloys (Sn at 2–5 wt%) and solidification simulation. The probability of lift-off increases with increasing Bi content. Lift-off results from the segregation of Bi, which diffuses in a short distance, in the interfacial region between a Sn–Bi alloy and a Cu land pad during dendritic structure formation. A higher fillet results in a more severe lift-off—the top side of a printed wiring board, where the fillet is low, seldom shows lift-off. The solidification simulation indicates that the solidification of the solder fillet rapidly propagates from a lead wire to a fillet edge. A Cu land acts as a heat sink, with heat flowing from the inner through-hole to the land pad. Both rapid cooling and annealing at high temperature can effectively prevent lift-off.     

钎焊材料行业发展与标准化需求

概述了中国钎焊材料行业发展现状,综述了ISO,EN,GB,AWS等标准化组织及其钎焊材料标准化研究现状,并对钎焊材料标准中的关键指标进行了分析。针对自动化、智能化钎焊制造需求,提出了未来国内钎焊材料标准化发展方向。     

Selection of soldering temperature for ultrasonic-assisted soldering of 5056 aluminum alloy using Zn-Al system solders

The conditions for sound butt-joints of 5056 aluminum alloy containing 4.6 mass% Mg using Zn-xAl (x = 5, 13, and 38 mass%) solder at the relevant temperatures were investigated. Each solder foil was inserted between faying surfaces of 5056 aluminum rods. Ultrasonic vibration at a frequency of 19 kHz was applied to the faying surfaces through an aluminum substrate at soldering temperatures for 4 s in air. The strength of obtained solder joints was measured by tensile tests. The microstructure in the solder layer after the soldering process was evaluated with an SEM-EDX. The results of tensile tests revealed that joints soldered under the liquidus temperature of Zn-Al solders showed higher strength than joints soldered over the liquidus temperature. In the joints soldered over the solder liquidus temperature, the joint strength decreased with an increase in soldering temperature. It was caused by the formation of MgZn₂ in the solder layer due to dissolution of 5056-Al into the solder liquid during the soldering process. On the other hand, ultrasonic-assisted soldering under the solder liquidus temperature suppressed dissolution of 5056-Al and improved the joint strength by reducing the formation of MgZn₂.     

有机金属型铝用无铅低温软钎剂的试验

首次将有机金属盐辛酸亚锡作为活性组分替代现有技术中一般采用的无机金属氟硼酸盐,研发出新型铝用无铅低温软钎剂,并通过对照试验和扩展性能、XRD、SEM及EDS等测试.研究其对铝钎焊的助焊性能.结果表明:所得钎剂能很好地实现铝的无铅低温软钎焊.并在节能、环保、吸潮、稳定以及润湿铺展等性能方面显著地优于传统的有机型铝用软钎剂.同时,辛酸亚锡中的Sn2+被Al置换后能达到铝板200μm左右深处,从而有望解决因Sn-Al之间几乎不发生相反应而造成的接头强度不够、焊点易脱落问题,为铝的无铅低温软钎焊和铝在电子产品中的应用提供了新思路.     

A new reduced-oxide soldering activation method

This article describes a new reduced-oxide soldering activation (ROSA?) process that removes oxides from tin, tin-lead, and copper surfaces without the use of a flux. In this process, surface oxides are electrolessly reduced back to the metallic state by a highly reducing vanadous ion solution that is non-corrosive to most metals and is regenerated electrochemically. The electroless reduction and redox regeneration cycles form a closed loop such that oxygen gas is the only effluent. Wetting time and surface analysis data show that a ten-second exposure to the vanadous ROSA solution completely reduces all tin-lead oxides that would normally be encountered on production components. The ROSA treatment has a wide operating window, provides soldering performance comparable to that attainable with a fully-activated rosin flux, and offers the promise of providing low soldering defect rates without the use of CFC solvents.     

波峰焊工艺参数优化

波峰焊主要用于传统通孔插装印制电路板电装工艺以及表面组装与通孔插装元器件的混装工艺。与手工焊接相比较,波峰焊具有生产效率高、焊接质量好、可靠性高等优点。波峰焊接工艺是一个复杂而系统的工程,在实际生产过程中必须严格控制焊剂涂覆量、印制板预热温度、焊接温度和时间、印制板爬坡角度和波峰高度;综合调整其工艺参数,才能获得较好的焊接质量。     

Diffusion soldering for stable high-temperature thin-film bonds

Diffusion soldering is a special bonding technique to produce joints at a moderate temperature that are subsequently stable at higher temperatures. The search for material systems extending the upper-temperature limit of stability requires information from the pertinent phase diagrams and the reaction kinetics. Combining experimental studies on phase equilibration in powder samples with bulk and thin-film diffusion couples is a useful approach for a systematic search. Promising candidates for dsoldering are Pt-In or Pd-In, and molybdenum is also an effective diffusion barrier against the attack of liquid tin.