基于选冶联合的废印刷线路板铜粉源头除杂的技术路线

废印刷线路板是重要的城市矿产资源,因其成分复杂导致其处理难度大。在详细总结废印刷线路板回收利用方法的基础上,针对主流的废印刷线路板火法冶金处理工艺存在的锡铅锌等杂质金属分散和有机物燃烧释放有害气体的问题,提出一种基于选冶联合的废印刷线路板铜粉源头除杂的技术路线:废印刷线路板铜粉通过碱性加压氧化浸出,使锡铅锌等杂质金属溶解进入浸出液,锡浸出率>98.2%,浸出液经硫化净化脱除杂质,铅和锌的沉淀率>99.5%,净化液经电积产出98.0%的粗锡;浸出渣中废印刷线路板基体和阻焊油等有机物从铜箔表面剥离,采用摇床使之分离,有机物脱除率>50.0%。采用选冶联合的方法脱除了废印刷线路板铜粉中的大部分锡杂质金属和有机物,为后续火法炼铜提供了优质原料,为废印刷线路板铜粉在火法炼铜系统的高效处理提供了新的技术路线。     

Electric discharge in the process for recovering the wastes of printed circuit boards

This paper proposes a new process to separate components at the recovery of waste printed circuit boards and probably other waste of electronic equipment production.     

中性环境中硫氰酸盐浸取废旧线路板中的金

由于贵金属资源稀缺,从二次资源中回收利用金等贵金属成为趋势。研究了一种在中性环境中提取废旧线路板(WPCBs)中金的新方法。将预处理(去除铜等贱金属)后的废旧线路板粉末加入到0.8 mol/L的络合剂硫氰酸铵溶液中,调p H至中性,通过添加氧化剂30%双氧水,在固液比为1:40,双氧水用量为1.5 m L,温度为20℃、振荡速度300 r/min、反应1 h条件下,金浸出率可达96%。     

Recovery of Precious and Base Metals from Waste Printed Circuit Boards Using a Sequential Leaching Procedure

This paper considers the issue of recycling of waste printed circuit boards (WPCBs) containing precious and base metals in appreciable amounts. High-pressure oxidative leaching (HPOL) with dilute sulfuric acid resulted in removal of a significant amount of base metals from a WPCB ash sample obtained by incineration at 800°C. The parameters investigated in the precious metal leaching from WPCB residue after HPOL included the sulfuric acid concentration, thiourea concentration, oxidant concentration, leaching temperature, and leaching time. Recovery of gold, silver, and palladium of 100%, 81%, and 13% from the WPCB residue sample was achieved by thiourea leaching under optimized conditions. The results show that the efficiency of precious metal dissolution from the WPCB sample using thiourea solution depended strongly on the concentration of both thiourea and oxidant.     

Preparation of pure SnO_2 powders from tin slag of printed circuit boards waste

The recycling method and principle of SnO2 from the tin slag of printed circuit boards(PCB) waste were investigated. In this study, pure SnO2 powders were obtained through a multi-step process including ball-milling, roasting, dissolving, precipitating, and pickling. The total recovery rate of tin can be up to 91 %. The SnO2 powders obtained is the single phase, and the content of SnO2 is up to 99.9 %. However, the SnO2 particles are easier to agglomerate during the precipitation process. The agglomerate SnO2 particles are about 7.778 lm in mean particle size(D50). This preparation method presents a viable alternative for the tin slag recycling. The tin is not only recycled, but also reused directly to prepare pure SnO2 powders.     

Pressure leaching of metals from waste printed circuit boards using sulfuric acid

Printed circuit boards (PCBs) are essential components of electronic equipments which contain various metallic values. This paper reports a hydrometallurgical recycling process for waste PCBs, which consists of the novel pretreatment consisting of organic swelling of PCBs followed by sulfuric acid leaching of metals from waste PCBs. To recycle the waste PCBs, experiments were carried out for the recovery of copper from the crushed and organic swelled materials of waste PCBs using sulfuric acid leaching in presence of hydrogen peroxide under atmospheric and pressure condition. The leaching of PCBs at 90°C, pulp density 100 g/L under atmospheric condition, using 6M sulfuric acid resulted in the dissolution of a minor amount of copper due to the presence of plastic coating on the surface of metallic layers. On the other hand, when the liberated metal sheets from organic swelled PCBs were treated with dilute sulfuric acid of concentration 2M along with hydrogen peroxide in an autoclave under oxygen atmosphere, the percentage recovery of copper was found to increase from 59.63% to 97.01% with an increase in hydrogen peroxide concentration from 5 to 15% (v/v) keeping constant pulp density 30 g/L.     

紫色色杆菌从废旧电子线路板中浸出金的研究

紫色色杆菌代谢产生HCN,可浸出废旧电子线路板(WPCB)中的金。考察了预处理、pH值和处理量等重要因素对金浸出率的影响。结果表明,采用硝酸预处理WPCB可以提高金浸出率,每150mL菌液中WPCB物料加入量为0.5g,在pH=10.5条件下浸出8天,WPCB中金的浸出率可达68.14%。     

Application of convection and infrared heat sources for mounting and demounting of electronic modules

The parameters were optimized of convection and infrared heat sources for mounting and demounting of electronic modules on printed circuit boards with surface-mounted electronic components. The modeling of the thermoprofiles of convection and infrared sources allows one to optimize the process duration and the temperature of heating of the electronic components.     

高速高精度印刷电路板表面贴装自动光学检测系统的研究

为满足高精密度、微型化印刷电路板表面贴装要求,实现全自动、可靠性高、速度快的贴装生产,研究了一种新的自动光学检测系统。该装置主要由光路系统、线阵摄像机、量化存储单元、模板库、专用高速图像处理单元、监视单元等模块组成,实现设备标定、缺陷识别、对中校正和位姿补偿等功能。实验证明：该检测系统可以满足高精密度印刷电路板的高速高精度贴装生产的实时检测要求,达到了较好的检测效果。     

Leaching studies for metals recovery from waste printed wiring boards

The leaching behavior of most metals present in printed wiring boards is evaluated, aiming at its recycling by hydrometallurgy. Two leaching reagents (nitric acid and aqua regia) are compared. The effects of acid concentration, particle size of sample, leaching time, and temperature are examined. The results reveal that small particle size and a combination of both nitric acid and aqua regia are capable of dissolving most of the metals content of printed wiring boards.     

Recycling of metal bearing electronic scrap in a plasma furnace

The recycling of electronic waste and the recovery of valuable components are large problems in the modern world economy. This paper presents the effects of melting sorted electronic scrap in a plasma furnace. Printed circuit boards, cables, and windings were processed separately. The characteristics of the obtained products (i.e., alloy metal, slag, dust, and gases) are presented. A method of their further processing in order to obtain commercial products is proposed. Because of the chemical composition and physical properties, the waste slag is environmentally inert and can be used for the production of abrasives. Process dusts containing large amounts of carbon and its compounds have a high calorific value. That makes it possible to use them for energy generation. The gas has a high calorific value, and its afterburning combined with energy recovery is necessary.     

Recycling of lead solder dross,Generated from PCB manufacturing

The main purpose of this work is to analyze lead solder dross, a waste product from manufacturing of printed circuit boards by wave soldering, and to develop an effective and environmentally sound technology for its recycling. A methodology for determination of the content and chemical composition of the metal and oxide phases of the dross is developed. Two methods for recycling of lead solder dross were examined—carbothermal reduction and recycling using boron-containing substances. The influence of various factors on the metal yield was studied and the optimal parameters of the recycling process are defined. The comparison between them under the same parameters-temperature and retention time, showed that recycling of dross with a mixture of borax and boric acid in a 1:2 ratio provides higher metal yield (93%). The recycling of this hazardous waste under developed technology gets glassy slag and solder, which after correction of the chemical composition can be used again for production of PCB.     

The aqueous recovery of gold from electronic scrap

In electronic components, gold is used for electroplating of connectors and contacts because it has excellent corrosion resistance and high electrical conductivity. In addition, gold is used in hybrid links and solders. As the number of electronic products in use increases, so does the need to dispose of defective and obsolete equipment including printed circuit boards. Thus, the gold content from electronic components has become a candidate for recovery. For more information, contact S. Kulandaisamy, CECRI, Karaikudi, 630 006 India; pa_ehm@rediffmail.com.     

Discussions

The paper describes experiments conducted and results obtained when investigating the problem of resist and flux residue removal from printed circuit boards, both before and after assembly.     

Environmentally Safe Plating of Tin-Lead Alloy Coatings

The aim of this experimental study was to minimize the input of lead and tin ions and fluoboric acid into the waste water from the electroplating line, where the printed circuit boards and other parts of electronic devices are plated with tin-lead alloy. For this purpose, after unloading the parts from the plating tank, they were rinsed in the reclaim tank, from which the aforementioned ions were removed with a reclaim immersed electrochemical module (IEM). __________ Translated from Zashchita Metallov, Vol. 41, No. 6, 2005, pp. 637–639. Original Russian Text Copyright ? 2005 by Kruglikov, Turaev, Borodulin.     

A process for extracting precious metals from spent printed circuit boards and automobile catalysts

In this work, a novel process to simultaneously extract precious metals such as gold, palladium, and platinum from spent printed circuit boards (PCBs) and honeycomb-type auto catalysts by smelting without the addition of any collector metals has been developed. The process uses metal components such as copper, tin, and iron contained in spent PCBs as the collector metal and spent auto catalysts as a slag formative. In each experiment, spent PCBs and auto catalysts were crushed, incinerated, and melted after adding fluxes and carbon. Up to 90% of the gold, palladium, and platinum in the raw materials were extracted in a Cu-Sn alloy phase. For more information, contact Jae-chun Lee, Korea Institute of Geoscience & Mineral Resources, Minerals & Materials Processing Division, 30 Gajeong-dong, Yuseong-gu, Daejeon 305-350, Korea; 82-42-868-3020; fax 82-42-861-9727; e-mail jclee@kigam.re.kr.     

Development of Specific Technologies and Assembly Systems for the New Challenge of Electro-Optical Devices

Today's information and communication systems are especially characterized by their capability and reliability of high data rate transmission. An integration of optical wave guides into printed circuit boards allows a hybrid electronics packaging in order to increase the data transmission rate. The success of this technology depends in particular on the availability of efficient production solutions. For this reason, the development of automated assembly systems for electro-optical components has become a main research field at the Institute for Manufacturing Automation and Production Systems. This paper describes the challenges of the placement systems and presents a continuous process chain for the automated assembly of electro-optical components.     

Silvering by Aqueous Reduction

Metal distribution on printed circuit boards exhibits two main problems: over-board thickness variations and through-hole thickness uniformity. A novel electrolyte agitation method involving eductors has been fully characterised using both three dimensional mass transport mapping of agitation patterns within a process tank and by measuring copper thickness distribution on stainless steel panels. Results indicate that improved thickness distribution across boards and enhanced deposition rates are possible using this technology.     

印制板化学镀镍

介绍了采用金属Zn粒子悬浮液活化要镀镍的印制板(PCB)Cu电路表面,使其可以进行化学镀镍的工艺方法,它可以克服Pd-Sn活化的缺点.     

印制电路板表面终饰工艺的研究与发展趋势

热风整平工艺一直是印刷电路板制造中最后的表面处理工艺,但随着印刷电路板的精细化和复杂化以及环境保护的需要,热风整平工艺已被限制应用.由此,产生了一些替代工艺,包括有机焊接保护剂、化学镀影金、化学浸锡以及化学浸银等.本文对热风整平及其主要替代工艺作出评价和探讨,并对未来印刷电路版表面终饰技术的研究和发展提出一些看法.