Volume 21, Issue 5 (September 1993)
Metallized Microballoon Filled Composite EMI Shielding Materials
The need for lightweight, formable materials that can conduct elasticity and shield against electromagnetic interference (EMI) is widespread. Applications ranging from modeled cases for terrestrial electronics to shielding systems for metallize can benefit from such tailorable, lightweight conductive materials. This paper explores the possibility of creating a new family of ultra-lightweight conductive shield materials using metallized microballoons as a conductive filler material. The conductive costings investigated include gold, silver, and aluminum on ceramic microballoons in an epoxy matrix. Factors influencing the electrical conductivity are discussed, and the shielding performance is tested using X-band microwave transmission measurements and anechoic shielding effectiveness testing. Variables available that have the potential to allow application specific tailoring of the shielding material are described. Initial findings are discussed and performance is related to the microballoon volume fraction and costing materials. Results indicate that shield densities significantly below 1.0 g/cm2 are possible, with electrical surface resistivities approaching these of common metals.