利用機構方式解決EMI之研究

SOLVING EMI BY MECHANICAL DESIGN

王志中(Chih-Chung Wang)

指導教授 ： 李碩仁

元智大學/工程學院/機械工程學系/碩士(2006年)

摘要

本實驗採用一般常用的材料如導電漆、電鍍、鍍鋅板、不鏽鋼、鎂鋰合金等等，使用後加工方式製作成試片並與複合材料做屏蔽效率做分析比較，並且將複合材料運用在公司產品進行分析比較。在此我們所使用的是導電不鏽鋼絲與塑膠材料混合在一起的複合材料，一般而言導電不鏽鋼絲比例越高，其屏蔽效果越好，但是因導電不鏽鋼絲之成本高於工程塑膠約八倍左右，且導電不鏽鋼絲加的越多，會導致塑膠材料縮減，會提高屏蔽效果但反之對材料可塑性及強度會跟著降低，失去塑膠易加工、重量輕、低成本的優點。
由實驗的結果，當導電漆在ASTM D4935-99規範的頻率範圍（30MHz∼1.8GHz）內，30 MHz時屏蔽效果可達到50dB左右，但到了200 MHz ~1800 MHz時，屏蔽效果只能20dB左右，其他材料經過量測，屏蔽效果都可達到40∼55dB，這些已經符合一般業界的應用所需。使用複合材料運用在公司產品進行電磁波分析，當複合材料在無線干擾特性 EN 55022規範的頻率範圍（30MHz∼1GHz）內，結果顯示，使用複合材料確實屏蔽許多輻射傳導，可降低產品成本，使得產品能順利上市。

關鍵字

複合材料 ； 屏蔽效能

並列摘要

The purpose of this research is to compare the shielding effectiveness between composites and common materials, such as conductive coating plastics, electroplating, electron galvanized steel plate, stainless steels, Mg-Li alloy, and etc. Besides experimenting with different test pieces, the composites were also implemented into the products for analysis. The composite used is composed of conductive stainless wire and plastics. In general, the higher percentage of conductive stainless wire, the better shielding effectiveness it will be. Since the price of conductive stainless wire is around eight times of engineer plastics, larger percentage of conductive stainless wire will result in worse plasticity and higher cost. The advantages of plastic materials: easy-processing, light weight, and low cost, will be diminished.

According to the experimental results of conductive coating material, in the frequency ranges specified by ASTM D4935-99 (30MHz~1.8GHz), the shielding effectiveness is about 50dB in low frequency ranges and 20dB in high frequency ranges. The shielding effectiveness is around 40~55dB for all the other testing materials. It’s good enough to meet the EMI requirements in normal applications. As for the products made of composite shielding , the reduction in radiated emission energy meets the specification of EN55022 (30MHz~1GHz). With composite materials, the advantages are lower cost and shorter time to market.

並列關鍵字

EMC ； EMI ； EMS

參考文獻

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