接触表面电阻率及其对屏蔽效能的影响

为了减少来自机壳缝隙的潜在EMI泄漏,工程师通常在缝隙位置增加衬垫来加以密封.如果要这些衬垫完全地起作用,必须有可利用的导电区域.然而,常见的问题是暴露的金属因为氧化和/或腐蚀以及物理外观等因素,很难达到预期的效果.因此,很多情况下要增加一层导电的镀层来保护裸露的金属.增加的电镀处理的确能够影响机壳的屏蔽效能,尤其是当工作频率还在持续升高的时候.

Contact Surface Resistivity Its Effect on Shielding Effectiveness

In order to reduce potential EMI leakage from seams of enclosures, gasketing is usually added to the seams in an attempt to seal them up. Conductive areas must be available for these gaskets to function properly. However, the problem is that normally exposed metal is not desirable due to problems with oxidation and/or corrosion and sometimesphysical appearance. Therefore, many times a layer of conductive plating that covers the bare metal is added. It is the effect of this added plating finish that can and does impact the shielding effectiveness of the enclosure especially as operating frequencies continue to go higher.