Modulus matching strategy of ultra-soft electrically conductive silicone composites for high performance electromagnetic interference shielding

Abstract

Electrically conductive silicone composites have made significant advancements in the field of electromagnetic interference (EMI) shielding due to their excellent conductivity, elasticity, sealability and environmental reliability. Notably, chips and other miniature electronic components with limited pressure-bearing capacity often require composites with both low compressive stress and high EMI shielding performance. Unfortunately, conventional conductive silicone composites often exhibit high compressive stress as a result of the high modulus and high loading contents of fillers, which prevents them from fitting perfectly with the package cavity under low package stress conditions, resulting in inadequate EMI shielding. Herein, the elastic modulus of the silver@polydimethylsiloxane (Ag@PDMS) conductive filler can be adjusted by controlling the crosslinking ratio, which enables the creation-of-Ag@PDMS/Silicone-(APS)-conductive-composites-with-remarkable compressibility, EMI shielding and sealing capabilities. The-APS-composites exhibit a compressive stress of only 0.3 MPa under 50 % compressive strain, which is essential for the packaging-of-precision electronic components. The APS composites show a significant decrease in compressive stress (54 %) and elastic modulus (80 %) under 50 % compressive strain, in comparison to conventional polymer composites with hard fillers. Meanwhile, the APS composites exhibit a-satisfactory-EMI-shielding-effectiveness-(SE)-of-71-dB and demonstrate excellent electromagnetic sealing capabilities in practical electronics. This study provides an effective approach for developing and constructing high-performance ultra-soft composites for precision electronic components packaging.