Simultaneous laser sintering and embedding of silver nanoparticles for highly flexible embedded electrodes

Abstract

In manufacturing electronic devices embedded in flexible substrates, persistent technical challenges include process complexity, substrate damage, high surface roughness, and low mechanical flexibility. To address these challenges, this study proposes a method that involves simultaneously sintering silver nanoparticles (Ag NPs) and embedding them in polyethylene terephthalate (PET) substrates to fabricate flexible embedded electrodes. The proposed technique uses laser-generated high-intensity shock waves to compress Ag NPs coated on a PET substrate heated to its glass-transition temperature. The mechanical impact of the shock wave embeds the Ag NPs into the substrate while simultaneously sintering the particles. The thin-film Ag electrode fabricated using the proposed method exhibited outstanding electrical and mechanical properties. The electrical resistivity measured as low as 7.8 μΩ·cm, with a minimal increase of approximately 5 % after 2000 bending cycles at a bending radius of 1 mm. Furthermore, the fracture strength of the fully embedded electrode, as assessed through adhesive tape-peel tests, significantly surpassed that produced through conventional sintering methods. The proposed method has the potential to revolutionize conventional sintering methods in flexible substrate applications, offering a more efficient and reliable method for fabricating flexible embedded electrodes.