Manufacturing Transparent Flexible EMI Shields Through OFFSET Printing

H. Cho, S. Somu, A. Busnaina
Center for High-rate Nanomanufacturing, US

Keywords: EMI shield, MWCNTs, OFFSET printing, transparency

Summary:

There is need to protect aircrafts and associated electronics from man-made and naturally occurring external electromagnetic interference (EMI). Currently used EMI shields are heavy and don’t cover the entire frequency spectrum, which ranges from a few MHz to a few hundred GHz. In addition, existing EMI shields are optically opaque and mechanically rigid, which severely limits their use in many applications. We show fabrication of highly organized networks of multi-walled carbon nanotubes (MWCNT) in cross bar architecture with defined dimensions. They are created using an OFFSET printing process on flexible and transparent substrates such as PDMS, PEN and PI. The expected attenuation is in the range of a few tens of db in the desired MHz to GHz frequency range. The dimension of MWCNT cross-bar structure ranges from 100 µm to few microns wide and 10 mm long. The transmittance of transferred MWCNT crossbar structure onto transparent substrate was conducted using UV-vis measurements from the wavelength of 300nm to 1100nm. The transparency for this ordered MWCNT flexible composite is measured to be from 95% to 80% depending on the MWCNTs features, indicating a good optical property and excellent candidate for transparent applications.