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分析了黑瓷封装IC外引线镀锡中出现的封装玻璃发白、表面粗糙、封装玻璃与外引线连锡造成引线极间短路的原因,提出了解决方法。 相似文献
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硫酸盐溶液体系中三价铬镀厚铬工艺及镀层性能研究 总被引:3,自引:0,他引:3
采用硫酸盐溶液体系进行三价铬电镀,获得厚度超过30μm的铬镀层。分别探讨了ρ(Cr3 )、ρ(添加剂)、ρ(H3BO3)、φ(络合剂)和pH对镀液覆盖能力和镀速,电镀时间对镀速和镀层厚度的影响。研究了不同热处理温度下镀层的硬度和表面形貌。通过正交实验获得了最佳工艺条件:144g/LNa2SO4,50g/LK2SO4,60~80g/L硼酸,15g/LCr3 ,10~15mL/L络合剂,1.0~1.5g/L添加剂,适量润湿剂,pH=2.5~3.0,温度40°C,电流密度为10~20A/dm2。在此工艺下,获得了半光亮、银白色的铬镀层,硬度为706HV。通过200°C热处理后,铬镀层的硬度达到最大值,为1401HV。但热处理温度升高,铬镀层表面出现裂纹而影响镀层质量。 相似文献
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列举了紫铜箔碱性镀锡过程中出现的几种常见问题,如:阳极(锡板)表面金黄色钝化膜变淡(或消失)甚至变黑,镀层呈暗灰色海绵状等。分别对产生这些问题的原因进行了简要分析,并给出了相应的解决方法。 相似文献
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稀土催化剂抗酸性镀锡液氧化变质的研究 总被引:4,自引:1,他引:3
酸性镀锡液稳定性差,易氧化变质。探讨了酸性镀锡液产生氧化变质的机理。在镀锡液中加入0.05-0.1g/L稀土催化剂,通过加速氧化试验和空气暴露试验研究镀锡液的稳定性。结果表明:镀液稳定性显著提高。 相似文献
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介绍了一种焦磷酸盐镀铜溶液中铜、总焦磷酸根、磷酸根、柠檬酸铵含量的分析方法和计算方法。分析了正磷酸根产生的原因及其危害,并给出了一种化学处理方法。对正磷酸根含量不同的镀液进行了分析,并测试了相应镀层的性能?采取了不同的措施对镀液进行改进,并对效果进行了讨论。结果表明,正磷酸根的存在是不可避免的,控制槽液温度和pH值、定期过滤溶液、补充新料等措施都可抑制正磷酸根含量的增长。 相似文献
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The present study is performed with an objective to acquire a deeper understanding of the properties of nickel‐plated polyester fabric after conducing low temperature plasma (LTP) treatment. LTP treatment with oxygen and argon gases was employed to render a hydrophilic property of woven polyester fabrics and facilitate the absorption of a palladium catalyst to provide a catalytic surface for electroless nickel plating. The properties of LTP‐induced electroless nickel‐plated polyester fabrics were evaluated by various standard testing methods in terms of both physical and chemical performances. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
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现代移动通信所使用的微波器件,基于微波的传导特性而对器件的表面特性有很高的要求,如表面光亮度和表面金属组织结构。通常都是采用电镀来获得这种表面结构,致密细小的结晶有利于微波的传导。微观观测表明,温度对镀层的结晶大小有明显影响。例如镀银,只有当温度在30℃以下时,才能获得细致的镀层。这也是微波器件镀银工艺需要采用低温控制系统的原因。 相似文献
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Gabriela Silveira da Rosa Sandra Cristina dos Santos Rocha 《Chemical Engineering and Processing: Process Intensification》2010
The aim of this work was to analyze the influences of operational variables on particle growth for urea coating in a conventional spouted bed (CSB). An aqueous polymeric suspension was the coating liquid sprayed on the spouted particles. The effects of inlet air temperature, coating suspension flow rate and atomizing air pressure on particle growth were analyzed by a central composite rotatable design (CCRD) of experiments. The results showed particle growth in the range of 1.1–2.6%, therefore, some results below the expected for a film coating (2–8%). A second-order polynomial model was obtained for estimating particle growth as a function of the statistically significant variables: air temperature, suspension flow rate and atomizing air pressure, with percentage of explained variation R2 = 90.72%. The urea growth kinetics during coating was analyzed for the optimal operating condition and a linear growth coefficient of 1.13 × 10−3 min−1 was obtained. The volatilization analyses showed that the polymer film coating provided a decrease of the nitrogen loss in the range of 3–57%. And, SEM analyses demonstrated a total, uniform and homogeneous covering of the urea particles surface. 相似文献
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Julianna A. Franco Sandra E. Kentish Geoffrey W. Stevens 《Chemical engineering science》2009,64(18):4016-5896
The effect of the presence of monoethanolamine (MEA) degradation products on membrane hollow fibers was investigated using untreated polypropylene (PP) as a model material. Common amine oxidative degradation products were added to MEA to simulate a degraded solution. The effect of these degradation products on the membrane gas absorption process using PP hollow fiber membrane was quantified. When PP membrane which has been exposed to amine degradation products is used in a membrane gas absorption contactor, the mass transfer rate of CO2 is reduced relative to the use of unexposed PP. It was found that the presence of oxalic acid reduced the mass transfer rate of CO2 in MEA most significantly followed by formic acid and then acetic acid. These acids are believed to adsorb into the PP, altering the surface properties and reducing the hydrophobicity of the membrane. This in turn increases the degree of wetting of the membrane pores. The membrane was characterized before and after use in a membrane gas absorption contactor containing degraded MEA solvent and studies showed that membrane pore wetting increased by 22-31% after 69 h of use. SEM images and XPS spectra of exposed PP membrane indicate that wetting may be due to both morphological and chemical changes in the membrane due to contact with the solvent. This study highlights the need to consider reductions in the mass transfer rate of membrane gas absorption processes associated with inevitable changes in the solvent composition that comes with prolonged use. 相似文献
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One major constraint of the agricultural uses of fly ash (FA) is the low availability of different plant nutrients despite their high occurrence in the total amount. However, degrading FA through increased microbial activity can improve the availability of these nutrients substantially. It has been found that intestines of epigeic earthworms contain a high concentration of different microorganisms. Therefore, in the present study we addressed the effects of vermicomposting technology on the solubility of some micronutrient cations (Fe, Mn, Cu, and Zn) and some heavy metals (Pb, Cd, and Cr) in different combinations of fly ash and organic matter, applied in the form of cow dung (CD). Various combinations of FA and CD were treated with and without an epigeic earthworm (Eisenia fetida) and the solubility of different trace elements in the treatments were estimated periodically. The results revealed that the inclusion of epigeic earthworm Eisenia fetida in different combinations of fly ash and cow dung converted a considerable amount of the micronutrients into bio-available forms. On the other hand, the solubility of heavy metals tended to be reduced by the microorganisms, presumably by formation of some organo-metallic complex. Application of these vermicomposted FA and CD combinations to a red lateritic soil was found to improve the soluble Fe, Mn, Cu, and Zn status of the soil. Furthermore, the use of vermicomposted FA and CD (1:1) in potato cultivation demonstrated that use of this mixture at 10 ton per hectare (t ha−1; fresh weight) was able to compensate 80% of the recommended NPK fertiliser, along with farm yard manure application, without compromising the crop yield. 相似文献
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Nisit Tantavichet 《Electrochimica acta》2005,50(9):1849-1861
The influence of plating mode, chloride and thiourea (TU) on morphology of copper deposits has been studied. All experiments were conducted on disc electrodes rotating at 500 rpm and an average current density of 4 A dm−2 to produce 10 μm thick deposits. In additive-free solutions, the use of pulsed current (PC) improved deposit morphology and brightness over DC plating. In the presence of thiourea (no Cl−), the deposits obtained by DC and PC plating were similar under most plating conditions. The presence of thiourea generally improved deposit quality over that obtained in additive-free solutions, but caused the formation of microscopic nodules and the deposits to appear slightly cloudy, resulting in lower reflectances than that of a polished uncoated copper surface. The addition of Cl− to thiourea-containing solutions strongly influenced deposit morphology at both microscopic and macroscopic scales depending on chloride concentration and pulse conditions. It prevented nodule formation and created microscopically bright and reflective deposits, but caused extreme macroscopic roughness. Nevertheless, PC plating at 50 Hz in solutions containing appropriate amounts of thiourea and Cl− was found to yield macroscopically and microscopically smooth deposits with reflectance similar to that of a polished uncoated copper substrate. 相似文献
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研究了N,N?二甲基?二硫代甲酰胺丙磺酸钠(DPS)作为添加剂对以四羟丙基乙二胺(THPED)为单一配位剂的化学镀铜体系的沉积速率、镀层形貌和晶体结构的影响。结果发现,当DPS的质量浓度从0 mg/L增大到1.0 mg/L时,沉积速率从2.91μm/h提高到6.73μm/h,所得镀层结晶均匀、细致。线性扫描伏安测量结果表明,DPS是通过促进甲醛的阳极氧化来加速化学镀过程。本体系的Cu镀层主要呈面心立方多晶取向,DPS的添加会令晶面取向从(220)转变为(111)。 相似文献
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In this study, the effect of air velocity in dehumidification drying environment on one-component waterborne wood top coating drying process is analyzed by drying time and moisture content and surface temperature of coating, in which air temperature is 35°C and relative humidity is 50%, and the air velocity is the only change parameter, varying from 0.2 to 1.2?m/s. It is found that drying time of top coating shortens and moisture content of top coating decreases with increasing air velocity. Surface drying time is about 15?min, hard drying time 21?min, and sanded drying time 37?min. To accelerate the drying speed, the air velocity is increased to more than 0.4?m/s. Moisture content of top coating is 58.2% during surface drying, 31.4% during hard drying, and 21.9% during sanded drying time. An infrared thermometer is used to measure the surface temperature of coating. Surface temperature of top coating is 30.0°C when it is dried to the surface drying degree, 33.5°C when the top coating is dried to the hard drying degree, and 34.6°C when the top coating is dried to the sanded drying degree. The drying degree of coating can be judged from the drying time and surface temperature and moisture content of coating. The drying degree of top coating is better when surface temperature is higher and the moisture content is lower. 相似文献