共查询到18条相似文献,搜索用时 46 毫秒
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随着更加精细的SMT、BGA等表面贴装技术的运用,化学沉镍金(ENIG)作为线路板最终表面处理得到了越来越广泛的应用,同时可怕的“黑盘”现象也随之更广泛地“流行”起来,直接导致贴装后元器件焊接点不规则接触不良。为了贯彻执行最好的流程控制和采取有效的预防措施,了解这种焊接失败的产生机理是非常重要的,及早的观测到可能发生“黑盘”现象的迹象变得同样关键。本文介绍了一种简单的预先探测ENIG镍层“黑盘”现象的测试方法-镍层耐硝酸腐蚀性测试,这种测试可以用于作为一种常规的测试方法监测一般化学沉镍溶液在有效使用寿命范围内新鲜沉积的镍层的质量。利用Weibull概率统计分析在不同的金属置换周期(MTO)下镍层的可靠性能表现。结合试验结果得出了一个镍层耐硝酸腐蚀性的判定标准。 相似文献
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取代化学镍金的新型碱性化学银工艺具有以下特点:(1)镀层是纯银而不是酸性化学银的有机银,它在焊接时不会产生气泡;(2)它的焊接与邦定效果接近于化学镍金;(3)它的成本仅为化学镍金的25%-40%;(4)它易于除去铜和有机杂质,溶液可以长期使用;(5)使用专用的无氰退银和修复液使它易于返工和修复;(6)由于使用了特种的防变色剂,使它不需要除尘室、无硫手套和无硫包装纸。因此,新型的碱性化学银工艺是将来最具潜力替代化学镍金的表面涂(镀)工艺。 相似文献
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为了满足电子行业无铅化的迫切要求,PCB沉银表面处理的优异性能及合理成本,被认为是最佳的选择.但是对PCB制造商普遍认知的沉银工艺的功能性缺陷“贾凡尼效应”(侧蚀现象)却缺乏系统的研究.文章主要研究在沉银置换反应中线路铜被腐蚀而使线路阻值增大或线路开路的侧蚀问题. 相似文献
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Liquid loss occurs at the receding contact line when scanning at high speeds resulting in defects on printed patterns in immersion lithography. To offer intuitive insights into the dynamic effects of the fluid confined between the lens and substrate on critical scan speeds, image processing techniques are explored to develop dynamic models for optimizing future designs of immersion units. Since the distance between the last lens and wafer is less than 1 mm, the dynamic characteristics of the liquid (with free boundary and characteristics of the upper surface of the flow field) play an important role in liquid control, which is concerned in various potential immersion unit designs. A method for characterizing the meniscus dynamics is developed to analyze the liquid behavior and meniscus stability in immersion lithography. A second-order system model is presented to better understand the meniscus development during scanning motion. Experimental results have shown that the meniscus adhering to the hydrophilic surface allows for a higher scanning speed than that adhering to the hydrophobic surface. 相似文献
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We have constructed a theory of polarimetry of illumination used in 193 nm lithography equipments, fabricated a polarimeter mask, and demonstrated it for a hyper-NA (numerical aperture) immersion lithography scanner. The polarimeter mask comprises newly developed thin polarizers and wide-view-angle quarter-wave (λ/4) plates. Although a light traveling through these polarization devices on the polarimeter mask reaches an image detector at the wafer level through a projection optics, Stokes parameters of the illumination light can be measured with no influence from polarization characteristics of the projection optics between the mask and the image detector. 相似文献