Research On Anti-EMI Metal Thin Films On Plastic Shell

Nowadays electromagnetic pollution is becoming worse and worse, and the abroad application of the plastic in the package of electronic products also aggravates the pollution. With the electromagnetic compatibility standards and regulations of electronic equipments being promulgated by most countries, it's becoming a trend to do the design of electromagnetic shielding. And the electromagnetic shielding of plastic package has become internationally popular research topics.In this paper, we researched on the electromagnetic shielding films of plastic package from both theoretical and experimental aspects. We successfully designed and deposited various kinds of metal films for shielding on the plastic PET by magnetron sputtering. The major works and innovation in this paper are as follows:(1) We deduced the formula for shielding effectiveness using the classic transmission line theory, which complies with the S.A.Schelkunoff theory of electromagnetic shielding. And we simulated and designed shielding films with multi-layers and sandwich structure from the formula.(2) We deposited various kinds of metal films for shielding with an adhesion of more than 500 kPa and a shielding effectiveness of more than 60 dB between 2 GHz and 4 GHz on the plastic PET by magnetron sputtering; we put forward optimal anti-EMI metal films of 400 nm Cu/160 nm 1Cr18Ni9Ti through experiments, which can meet the needs of practical use; it was proved that shielding films with sandwich structure with the same total thickness can greatly improve the shielding effectiveness by about 10 dB. The experiment results complied with the theory design very well, which indicated that the deduced formula for shielding effectiveness had very important practical value.(3) We increased the plastic surface roughness and activity with a riveting effect by means of sandblasting or plasma processing-cleaning. As a result, the adhesion of Cu film and plastic had reached more than 500 kPa and been greatly enhanced by 37%. And this technology has important practical applications in the process of industrialization.(4) We put forward the waveguide to measure the shielding effectiveness by measuring the parameter S₂₁ of Anti-EMI metal films, which was fast, exact and practical. And this method has not been reported domestically.