电路板激光钎焊系统

采用激光作为热源对电路板端子进行焊接,在激光聚焦头与电路板之间添加自动送丝机构,对电路板焊盘处进行自动送丝处理。阐述了设备总体结构、自动送丝机构、钎焊工艺流程及实际焊接效果。其中,钎焊工艺流程包括电路板预热处理、自动送丝、锡丝形成液滴、锡滴冷却和形成钎焊接头的过程;重点比较研究了预热和非预热处理的钎焊效果。结果表明,经预热处理焊锡液滴刚好覆盖焊盘,焊点圆滑饱满,无明显缺口,无脱落现象,效果更好。     

Sn-Zn-Ag-Bi无铅钎料的成分设计

为了改善Sn-Zn钎料的性能,在Sn-Zn钎料中添加Ag、Bi两种合金元素.使用正交试验法,研究钎料成分变化时钎料润湿面积、剪切强度及腐蚀率的变化规律.3个影响因子分别为Ag的质量分数、Bi的质量分数和Zn的质量分数,每个影响因子设定3个水平,进行3因素3水平正交试验.以钎料的润湿面积、剪切强度及腐蚀率作为评价指标,分析试验结果,优化最佳的工艺参数,确定Sn-Zn-Ag-Bi钎料的最优成分是alB2C2,即质量分数Sn为91.5%、Zn为5%、Bi为3%、Ag为0.5%.结果表明,在该成分下,最优钎料各项指标与Sn-9Zn相比有较大的提高.     

Sn-Zn-Cu无铅钎料的组织、润湿性和力学性能

研究了(Sn-9Zn)-xCu无铅钎料的微观组织、润湿性能和力学性能.Cu的加入使得Sn-9Zn钎料中针状富Zn相逐渐转变为Cu-Zn化合物,当Cu含量为8%时,Cu6Sn5相生成.Sn-Zn-Cu合金熔点随着Cu含量增加而升高,同时润湿性随Cu的加入得到显著改善.使用中性活性松香钎剂,钎料与Cu箔钎焊时的润湿角显著减小.Sn-9Zn的润湿角为120°,而(Sn-9Zn)-10Cu的润湿角为54°.这是由于Cu的加入降低了Zn的活性,减少了Zn在钎料表面氧化,降低了液态钎料表面张力,使得钎料能获得较好的润湿性.合金在2%Cu时获得较高的强度,随着Cu含量的增加,Cu-Zn化合物相对增多,抗拉强度有所下降;而合金的塑性随着Cu的加入迅速下降.     

导电游丝激光锡膏微焊接

导电游丝人工焊接存在效率低一致性差的问题。为了实现其自动化焊接,设计了一套能够进行锡膏微量分液、焊点视觉定位、激光加热、红外测温的焊接平台。首先,进行了红外测温仪的发射率标定与精度测量,激光能量中心与相机视野中心的同轴度的补偿。然后,在镀金的焊盘上进行微小焊点焊接试验。最后,测量了30 μm游丝焊点的导电性。试验结果表明激光锡膏微焊接中存在虚焊假焊、多锡珠产生、焊点与基底接触面积的多态性以及助焊剂残留的问题,通过优化激光加热功率曲线与焊接工艺过程,得到了直径为0.2 mm左右的导电性良好的焊点。导电游丝激光锡膏微焊接自动化设计具备可行性。     

Acceleration of galvanic lead solder corrosion due to phosphate

Although orthophosphate is often effective in reducing lead corrosion, bench-scale tests revealed cases in which even high doses of orthophosphate (1–3 mg/L P) in potable water increased lead and tin release from simulated soldered copper joints. Phosphate increased the galvanic current between tin and copper plumbing materials, especially in water with less than 10 mg/L and when the percentage of the anodic current carried by ion was less than 30%. Tin release was increased more than lead release from 50:50 Pb–Sn solder in these circumstances.     

Nitrate accelerated corrosion of lead solder in potable water systems

Although nitrate is generally believed to have little effect on lead corrosion, bench-scale tests in this work revealed that increasing nitrate in the range of occurrence in potable water (0–10 mg/L N) can dramatically increase lead leaching from simulated soldered pipe joints. Lead in water created slightly increased galvanic currents between solder and copper pipe, but nitrate also altered the nature of the attack in a manner that caused solder particles to detach into the water. Chloramine decay and the associated conversion of ammonia to nitrate could create much higher lead contamination of potable water from solder in some cases.     

元器件镀金引脚焊点开裂失效分析与控制

宇航元器件镀金引脚钎焊前,需对焊接位置进行去金搪铅锡处理,避免焊接界面生成脆性金锡化合物,防止在使用时受外力作用而发生焊点“金脆”开裂.文中针对某宇航型号所用霍尔元件镀金引脚的焊点经历环境试验后脱落的问题,对相关镀金引脚焊点的形貌、金相与界面结构进行分析. 结果表明,元件引脚焊接位置已进行去金处理,但其焊接位置末端局部去金不彻底,焊点界面局部区域生成脆性金锡化合物,导致焊点前端生成裂纹源;经历宇航级温度循环或外力冲击考核试验时,因裂纹前端存在应力集中,导致裂纹持续扩展并发生焊点开裂脱落失效.确保镀金引线焊接位置去金质量并严控钎焊位置,避免在焊点内局部区域生成脆性金锡化合物,对提升镀金引脚焊点可靠应用具有重要意义.     

A pyrometallurgical alternative: The refining electrolysis of lead and solder

Conclusions  In refining electrolysis in hexafluorosilic acid with current densities of 100 A/m², it is possible to separate bismuth and antimony from prerefined lead bullion. Pure lead with less than 50 ppm bismuth and less than 100 ppm antimony was deposited at the cathode. The current efficiency was 99%, and the specific energy consumption was 30–40 kWh/t. Under the same conditions, a lead-tin alloy with less than 300 ppm antimony can be produced by refining a Pb−Sn−Sb alloy with 30% tin and up to 5% antimony. In this case, antimony remains in the anode sludge. Because of the high amount of anode sludge, the strong adhesion of the sludge on the anode surface, and its physical properties in the case of high antimony contents (i.e., more than 5% antimony in the anodes), some differences in the usual electrolysis technology are necessary to guarantee a long-term, stable, and trouble-free electrolysis. The tendency of anode passivation can be reduced by using a periodic current reversal technique. This technique results in a smaller amount of anode sludge, a reduced loss of lead in the anode sludge, and lower anodic polarization values.     

New Method for Destroying Organic Contaminants and Recycling Wastewater from PCB and MF Manufacturing Process Effluent Streams

This paper was recently published in the January edition of Industrial Environmental Management and is a modified version of an article published previously in Circuit World Vol.9 No. 4, 2003. The work was carried out as a CRAFT Project (ROCWAT-Thematic Priority F5 (Project number EEVK1-2001-30014). Part of the process involves dissemination to as wide an audience as possible through appropriate journals.     

Investigation of reactions between lead/tin solder and palladium surface finishes

The role of palladium as a surface finish for the electronics industry was investigated. Of particular interest were the metallurgical phases that form during and following soldering operations of palladium thin films. The formation of PdSn₄ intermetallics on composite substrates (gold/palladium/nickel) with varying palladium chemistry and layer thickness were soldered at 220 °C and observed using scanning electron microscope combined with energy dispersive X-ray (SEM/EDX) analysis. Thin layers of palladium approximately 1 μm thick, combined with a fast dissolution rate also resulted in the formation of Ni₃Sn₄ intermetallics. The role of phosphorus in palladium thin films was also investigated. Its presence was found to increase the solubility of palladium in molten solder producing intermetallic crystals that are confined to the bulk. A thin gold layer, used to protect the palladium was found to dissolve rapidly into the solder and to redeposit, forming a thin layer just outside the PdSn₄ intermetallic structure.     

POSS在无铅焊点中界面反应能的分子动力学模拟

运用分子动力学模拟研究了环己烯POSS在无铅焊点锡(β-Sn)晶体的(100)、(110)、(001)面以及在Sn-Ag-Cu合金表面的界面反应,得到了各自的界面反应能大小.结果表明,环己烯POSS易与β-Sn的各主要晶面相结合,但在(110)面上具有最低的界面反应能,结合性能最好.在锡中加入银(Ag)和铜(Cu)提高了环己烯POSS在其表面的界面反应能,表明对结合性能产生了不利影响,但仍然具有较好的结合性能.此外,还计算了环己烯POSS的溶解度参数.对于理解POSS对于无铅焊点的增强作用以及应用POSS来开发焊料增强剂具有重要而实际的意义     

稀土Ce元素对Sn-Zn-Bi-Ag-Al无铅钎料性能的影响

为了改善Sn-9Zn-4Bi-0.5Ag-0.05Al无铅钎料的综合性能,文中通过添加稀土元素Ce,研究了Ce元素对无铅钎料的润湿性能、抗剪强度以及熔点的影响.结果表明,稀土Ce元素的加入明显改善了钎料的润湿性能.当Ce的添加量为0.05wt%时,润湿性能最佳,钎焊接头的抗剪切强度也有明显提高,但随着稀土Ce元素的加入...     

稀土元素Ce对锡银铜无铅钎料润湿性及钎缝力学性能的影响

采用STA-5100型可焊性测试仪和STR-1000微焊点强度测试仪，对添加了稀土元素Ce的Sn-3．8Ag-0．7Cu无铅钎料的润湿性及钎缝的力学性能进行了研究。试验结果表明，Ce的加入，可以改善钎料的润湿性，质量百分含量为0．03％～0．05％时效果最好，温度升高以及通人氮气均可以明显地提高Sn-3．8Ag-0．7Cu—Ce无铅钎料的润湿性；当Sn-3．8Ag-0．7Cu钎料中稀土元素Ce的质量百分含量为0．03％时，钎缝的力学性能最佳。     

氯化铅渣中铜、银和铅的分步浸出回收

采用分步浸出工艺回收铋精炼过程中产生的氯化铅渣中的铜、银和铅,先在低酸条件下浸出铜,与铅银分离,然后通过氨浸分银的方式实现铅与银的分离,用优化方案进行了流程试验。结果表明,在铜浸出阶段,控制反应初始pH为3,加入量为理论耗量1.1倍的硫酸钠,液固比为5:1,75 ℃浸出1.5 h,氯化铅渣浸出渣中铜含量降至0.1%,浸出液中银含量不超过2 mg/L;在银浸出阶段,控制氨水浓度为7%,50 ℃浸出1.5 h,浸出渣中银含量降低至100 g/t;流程试验结果表明工艺具有良好的综合回收效果。     

引线框架铜合金材料与SnAg3.0Cu0.5的界面组织

采用扫描电镜和能谱分析等手段研究了3种不同引线框架用铜合金材料与SnAgCu钎料的界面结构,3种铜合金引线框架材料与SnAg3.0Cu0.5焊膏焊后未经时效的界面组织相似.焊点在160℃恒温时效300 h后,Cu-0.1Fe-0.03P合金、Cu-0.36Cr-0.03Zr合金、Cu-0.38Cr-0.17Sn-0.16Zn合金与SnAg3.0Cu0.5焊膏的界面金属间化合物厚度分别为8.7、7.4、6.2μm,其成分主要为Cu6Sn5,靠近铜合金一侧均有少量Cu,Sn生成.结果表明,Cu-0.38Cr-0.17Sn-0.16Zn合金比Cu-0.1Fe-0.03P合金和Cu-0.36Cr-0.03Zr合金具有更好的焊接可靠性能,Cu-0.38Cr-0.17Sn-0.16Zn合金中的Zn元素在焊点界面的富集有效减缓了界面处原子的相互扩散,使金属同化合物的增长速度降低.     

Selective recovery of Sn from copper alloy dross and its heat-treatment for synthesis of SnO2

Preliminary study on concentration and separation of tin (Sn) from copper alloy dross by selective dissolution method was conducted. The tin in the copper alloy dross did not dissolve in an aqueous nitric acid solution which could allow separation of tin from the copper alloy dross. The tin as H₂SnO₃ (metastannic acid) phase was precipitated in the solution with centrifuging process and transformed to tin dioxide (SnO₂) after drying process. The dried sample was heat-treated at low temperature and its phase characteristics, surface morphology and chemical composition were investigated.     

Recycling of gold from electronics: Cost-effective use through ‘Design for Recycling’

With over 300 tonnes of gold used in electronics each year, end-of-life electronic equipment offers an important recycling potential for the secondary supply of gold. With gold concentrations reaching 300-350 g/t for mobile phone handsets and 200-250 g/t for computer circuit boards, this “urban mine” is significantly richer than what is available in primary ores.     

酸、碱性蚀刻液再生循环利用及铜回收设备

一、酸、碱性蚀刻液再生循环利用及铜回收设备简介 针对目前线路板生产过程的主要污染物之一酸、碱性蚀刻废液,在总结前人研究成果利弊的基础上,结合印制板生产中酸、碱性蚀刻过程的特点,自行开发了高效提取酸、碱蚀刻废液中的有价金属铜,同时循环使用保留在废液中的有用成分,及对提铜后的酸、碱性废液进行再生的全套工艺：整个工艺由提取铜、电解成紫铜板（纯度〉99．8％）、酸、碱性蚀废液再生。     

Ni/P/Ce对SnAgCu抗氧化性能和结晶裂纹的影响

通过向Sn3.0Ag0.5Cu(SAC305)合金中添加微量的Ni,P和Ce元素,研究了各添加元素对合金钎料高温抗氧化性能和结晶裂纹的影响.结果表明,Ni元素的添加对钎料合金抗氧化性能没有很明显的改善,但明显地减少了合金表面结晶裂纹的总长度,抑制其产生;微量P元素的添加由于在合金钎料表面形成了复杂的致密新相,可以防止熔化钎料的表面直接与空气接触,明显改善了合金的抗氧化性能,但P元素的添加却增加了合金表面结晶裂纹的产生;Ce元素的添加恶化了钎料合金的抗氧化性,对合金表面的结晶裂纹抑制作用较小.     

循环经济理念下的再生资源产业

一、发展再生资源产业是建设循环经济的重要内容 循环经济是相对于传统的线性经济发展模式而言的.在传统的线性经济发展模式中,社会经济运行体系主要由生产系统和消费系统构成,自然资源通过生产系统转变为产品,产品又通过消费系统变成为废物,废物最终被抛弃进入环境中,造成对自然环境的污染和破坏.这种线性的经济运行模式导致的最终结果必然是自然资源的枯竭和自然环境的破坏,是一种不可持续的发展模式.