Mechanism of a catalytic silver(I)-complex: assisted electroless deposition of inductance coil on poly(ethylene terephthalate) film

In this work, silver nitrate, thiourea, bisphenol A diglycidyl ether (BADGE), and propylene glycol methyl ether (PM) were selected for designing a silver(I)-complex to trigger the deposition of inductance coil on PET film through electroless copper plating. The most stable silver(I)-complex structure is formed when the ratio of thiourea molecules and silver ions is 3 to 1 by quantum chemical calculations based on density functional theory (DFT). Meanwhile, XRD test demonstrates that the white precipitate crystallized from PM solution of thiourea and silver nitrate is [Ag(SC(NH2)2)3]NO3, which is consistent with theoretical calculations. The cross section of PET film with copper patterns and interconnection holes characterized by metallurgical microscope proves that the silver(I)-complex is able to initiate copper deposition on the surface and through hole wall of PET film. The measured inductance values at operating frequency from 1 to 50 MHz indicate that the fabricated flexible inductor is capable of being integrated into flexible electronics when the bending angles are within 45°. Additionally, the inductor can also be utilized as an angel sensor when the bending angles are in the range of 60° to 180° at 10 MHz.