Abstract: Electromagnetic radiation is an important influencing factor of computer information leakage．The technology to enhance the efficiency of electromagnetic shieding is one of the important technologies to resolve the problem of electromagnetic radiation．In this paper‚according to the theory of shield technology‚the electromagnetic performance of common shielding materials was analyzed‚and the shielding efficiencies of iron and tin were analyzed and calculated． Then‚tinning film with high reflection loss and iron with high absorption loss were selected to make a ferrous case film of electrolytic tinning．The shielding test of the case was carried out in an anechoic room in the EMC authentication center of Guangzhou Testing＆Inspection Institute for Household Electrical Appliance．The results show that the ferrous case with a film thickness of only0．18mm can effectively shield the electromagnetic radiation and avoid the imformation leakage of computers．

Key words: electromagnetic radiation, shield technology, information leakage, electromagnetic shielding, loss