Magzor Corporation — Department of Defense SBIR Phase I: Traditionally, highly flexible EMI shielding fabrics have failed to block EMI in LF (30 1

Description

Traditionally, highly flexible EMI shielding fabrics have failed to block EMI in LF (30 150 kHz) range. This proposal will demonstrate a flexible polyester cloth with a copper and NiFe layer (best suited as an inner liner) that provides effective broad-spectrum EMI shielding that includes the LF frequency range for minimal added cost, weight, and technological risk. To accomplish this feat, we will first use existing technology to electrolessly deposit a 300-nm-thick copper layer onto a polyester cloth without significant reduction in tensile yield strength to provide a seed layer and high frequency (f>300 MHz) shielding, and then electroplate an additional layer of 200-nm-thick high permeability NiFe 80/20 (80% Ni, 20% Fe) to absorb LF EMI (essentially near-field magnetic fields). Magzor Corp. engineers will use thier expertise in electroplating extremely high permeability (r=8500) NiFe (also known as Permalloy) to ensure that the shielding has substantially better attenuation at LF than a conductive non-magnetic material such as Cu or carbon nanotubes technologies that are typically not even tested in the 30 150 kHz range. The permeability of the Permalloy (r=8500) alloy is much higher than that of other electroplated metals such as Ni (r=12) (10), which greatly improves the magnetic shielding capability. However, the permeability of our material is not high enough to be saturated by the earth"s magnetic field. This technique provides a minimum electromagnetic interference shielding effectiveness (EMISE) of 50 dB at 30 kHz, while only adding 11.5 g (0.41 oz) in weight and $1.5 in added cost for a square yard of material. This technique can also be used to metalize hook and loop connections (Velcro) to provide a quick and easy method of electrically connecting seams to minimize the maximum opening of the shield.