共查询到17条相似文献,搜索用时 140 毫秒
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无铅波峰焊设备的特点 总被引:1,自引:0,他引:1
相对于传统的Sn-Pb焊料,无铅焊料需要较高的焊接温度,而且润湿性差,另外免清洗助焊剂和水溶性助焊剂的固体含量低,活性温度高和活性区间窄。无铅焊料和助焊剂的特性决定了无铅波峰焊设备在结构和材料选用上有很大不同。通过对无铅波峰焊设备的各个部分的特点进行分析,为传统的旧波峰焊设备的改造提供参考。 相似文献
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相对于传统的Sn—Pb焊料,无铅焊料需要较高的焊接温度,而且润湿性差,另外免清洗助焊剂和水溶性助焊剂的固体含量低,活性温度高和活性区间窄。无铅焊料和助焊剂的特性决定了无铅波峰焊设备在结构和材料选用上有很大不同。本文通过对无铅波峰焊设备的各个部分的特点进行分析,为传统的旧波峰焊设备的改造提供参考。 相似文献
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免清洗液态助焊剂标准的技术要点 总被引:3,自引:0,他引:3
本文介绍了我国免清洗液态助焊剂电子行业标准的技术要点和标准制定的基本依据及其它有关情况,对免清洗液态助焊剂的颜色、不挥发物含量、卤化物、离子污染、扩展率、铜镜腐蚀、表面绝缘电阻、电迁移和残留有机污染物等标准的技术要点进行了详细的说明。 相似文献
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Arra M. Shangguan D. Yi S. Thalhammer R. Fockenberger H. 《Electronics Packaging Manufacturing, IEEE Transactions on》2002,25(4):289-299
Lead-free wave soldering was studied in this work using a 95.5Sn/3.8Ag/0.7Cu alloy. A process DOE was developed, with three variables (solder bath temperature, conveyor speed, and soldering atmosphere), using a dual wave system. Four no-clean flux systems, including alcohol- and water-based types, were included in the evaluation. A specially designed "Lead-Free Solder Test Vehicle", which has various types of components, was used in the experiments. Both organic solderability preservative (OSP) and electroless nickel/immersion gold (Ni/Au, or ENIG) surface finishes were studied. Soldering performance (bridging, wetting and hole filling) was used as the responses for the DOE. In addition, dross formation was measured at different solder bath temperatures and atmospheres. Dross formation with Sn/Ag/Cu bath was compared to that with eutectic Sn/Pb bath. Regarding the connector-type component, a pad design giving the best soldering performance was evaluated based on the DOE results. Finally, a confirmation run with the optimum flux and process parameters was carried out using the Sn/Ag/Cu solder, and a comparative run was made with the Sn/Pb solder alloy and a no-clean flux used in production. The soldering results between the two runs indicate that with optimum flux and process parameters, it is possible to achieve acceptable process performance with the Sn/Ag/Cu alloy. 相似文献
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无VOC免清洗助焊剂焊后残留物的可靠性评价 总被引:1,自引:0,他引:1
为了研究焊后残留物的腐蚀性以及可能对PCB的电气绝缘性能造成的影响,通过表面绝缘电阻(Rs)试验和电化学迁移试验评价了三种不同固体含量的无VOC(挥发性有机物)免清洗助焊剂焊后残留物的可靠性。结果表明,使用w(固体含量)为3.6%的助焊剂,湿热试验后试件的Rs大幅下降,并且PCB表面腐蚀严重;而w(固体含量)为2.3%的助焊剂,则试件具有较高的Rs(6.4×109Ω),并且对PCB腐蚀性小。使用放大30倍的显微镜观察电化学迁移测试后的试件,均没有发现枝晶。 相似文献
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焊膏用免清洗助焊剂的制备与研究 总被引:20,自引:7,他引:13
根据免清洗助焊剂各组份的特点,分别对其活性剂、溶剂、成膜剂以及添加物进行筛选和处理.在一定温度下对各组份进行均匀化处理并制备出助焊剂,依据标准对所制备的焊剂进行性能测试.以自制的锡银铜系焊粉为基础制备焊膏并做焊接模拟.结果表明:采用有机酸和有机胺复配制备的活性物质满足预期要求;复配溶剂满足沸点、黏度和极性基团三大原则;所制备的免清洗焊剂多项性能满足规范要求,达到了免清洗的要求,解决了助焊性与腐蚀性的矛盾;所制备的焊膏焊接性能良好,无腐蚀,固体残留量低,存储寿命较长. 相似文献
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免清洗技术在印制板装联中的实用性和经济性及今后发展趋势 总被引:3,自引:0,他引:3
主要介绍了免清洗技术应用的现状及今后发展趋势。着重论述了中小企业如何大力开展免清洗工艺技术,并在重点考虑成本效益的同时,要积极配合国家环保局尽早实现逐步在2006年淘汰ODS物质的战略。此外,还谈到了免洗助焊剂使用注意事项。 相似文献
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TomForsythe 《洗净技术》2004,(4):5-10
本文介绍一种为环保而设计的新一代电子线路板清洗剂,这项技术设计用于批量水洗或在线喷洗。该清洗剂能清除掉表面贴装的组件和先进的封装件上的松香基助焊剂、免洗技术的少量残余助焊剂、水溶性助焊剂,未固化的焊糊及组件的残余物。 相似文献
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《Electronics Packaging Manufacturing, IEEE Transactions on》2006,29(3):217-223
Printed circuit board (PCB) specimens containing three different IPC-B-25 test structures were exposed to temperature/humidity/bias conditions in order to evaluate the effects of conformal coating, conductor spacing, voltage bias, flux chemistry, and test environment on surface insulation resistance (SIR). Results indicate that conformal coatings improve reliability, provided that sources of contamination on the PCB and within the coating are minimized. The presence of fibrous contaminants within the coating represented a preferential medium for moisture adsorption and ion transport, leading to accelerated reduction of SIR. In the absence of contamination, PCBs with conformal coatings were found to be less susceptible to SIR degradation than uncoated PCBs, with silicone providing better protection than urethane, and acrylic providing the least protection of the three coating materials evaluated. Conductor spacing was observed to represent a factor in the electrochemical migration (ECM) process independent of electric field, indicating that updated test structures are required to predict reliability of today's high-density assemblies. The SIR failure rate with rosin-based no-clean flux was observed to be greater than that with aqueous-based no-clean flux. A higher failure rate was also observed for tests conducted at 40$^circ$ C/93% RH than for 85$^circ$ C/85% RH. Due to the more rapid evaporation of weak organic acids in the flux residues at higher temperatures, test results obtained at 85$^circ$ C/85% RH will not accurately predict reliability at lower temperatures for PCBs processed using no-clean flux. PCB specimens were exposed to temperature/humidity/bias conditions in order to evaluate the effects of conformal coating, conductor spacing, voltage bias, flux chemistry, and test environment on reduction of surface insulation resistance. Results indicate that, in the absence of contamination, conformal coatings improve reliability. 相似文献