Conductive water-based graphene suspension for electromagnetic interference shielding via spray coating on SiP module

Abstract

Conductive inks have been widely used to develop electronic devices, such as sensors, RFID antennas, and transistors. Electronic utilization is a coating that forms conductive films for electromagnetic interference shielding (EMI Shielding). This process also can be employed to cover electronic modules called System in Package (SiP). A technology known as conformal shielding utilizes spray coating with metallic inks to form a conductive layer over the SiP. Traditionally, copper or silver inks have been the primary materials employed due to their high electrical conductivity. Conversely, these metallic inks are associated with significant costs, environmental impacts, and complex production methods. In this context, water-based graphene dispersion could be an alternative to EMI Shielding for electronic chips. Graphene is attractive due to its excellent electrical and thermal properties, reduced cost, and being an environmentally friendly material. In this study, a water-based graphene suspension was developed and applied via spray coating to form films for electromagnetic shielding. The graphene dispersion in water utilized Carboxymethyl cellulose (CMC). Characterizations of the graphene suspension, including morphology, particle size distribution, and chemical analysis, were conducted. The resistivity of the resulting films and their shielding effectiveness (SE) were measured. Electronic chip modules were painted to assess coverage. The study demonstrated the successful formulation of a stable water-graphene suspension exhibiting favorable electrical resistivity (2.8 × 10−2 Ω.cm) after drying at 300 °C for 1 h. The resulting film achieved a shielding effectiveness of −9 dB at 1.0 GHz. Graphene film completely covered the electronic chips, indicating an alternative conformal shielding.