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PCB板内表面涂覆为"电金+化金"是比较新颖的工艺,但在生产过程中发现有镀金焊盘缺损的问题。本文通过分析不同金镍厚组合的镀金焊盘在酸蚀中的抗蚀能力,得出金厚达到一定厚度时,致密的金层会成为阴极性镀层,加速蚀刻作为阳极性镀层的镍层,其速度至少加快2倍。利用这一规律,重新定义了合理的金厚范围,优化了酸蚀中保护镀金盘的干膜尺寸。 相似文献
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第八讲──影响镀层厚度分布均匀性的因素 总被引:1,自引:0,他引:1
1 使镀层厚度分布均匀的重要性 电沉积时总希望镀层厚度在工件上的分布越均匀越好.当工件上沉积的总金属量相同时,若厚度分布不均匀,则会带来很多坏处: 相似文献
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半导体器件所使用的金属管壳零件,一般是先电镀镍再电镀金。对于挂镀工艺可采取通用公式计算即 对于滚镀工艺要考虑到多量管座交叉混合和滚动扩散的影响,推导出如下理论公式即经过实测验证和工艺应用对电镀镍层的某些滚镀工艺公式简化为: 对电镀金层某些滚镀工艺公式简化为: 对某些电镀银镉挂镀工艺公式简化为: 以上公式与实测值相比,误差范围为1-5%。在工艺应用中易于监控和测算电镀层平均厚度。 相似文献
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Model for the outer cavity of a dual‐cavity die with parameters determined by two‐dimensional finite‐element analysis 下载免费PDF全文
A coating die forms liquid layers of uniform thickness for application to a substrate. In a dual‐cavity coating die an outer cavity and slot improves flow distribution from an inner cavity and slot. A model for axial flow in the outer cavity must consider the ever‐present cross flow. A 1‐D equation for the pressure gradient for a power‐law liquid is obtained as a small departure from a uniform flow distribution and no axial flow. The equation contains a shape factor dependent on cavity shape, Reynolds number, and power‐law index. The shape factor for five triangular cavity shapes is obtained by finite‐element analysis and correlated for application to die design up to the onset of flow recirculation which arises at the junction of the cavity and outer slot. The performance of the combined cavity and slot is considered and the most effective design determined. © 2017 American Institute of Chemical Engineers AIChE J, 64: 708–716, 2018 相似文献
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Copper electroplating was used to improve the thermo-mechanical properties of carbon foam. As the coating time increased, the pore size, foam porosity and specific surface area were altered. This dynamic process kept changing as a function of carbon microstructure and geometry. However, the final physical properties of the coated foam seem to depend mainly on the coating thickness. A numerical model was developed to determine the coating thickness and its distribution. The coating thickness was measured using light microscopy and scanning electron microscopy. A comparison of the mathematical model to the experimental measurements reveals that the model is capable of predicting the coating thickness inside carbon foam fairly well. 相似文献
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