Synthesis of core–shell structured alumina/Cu microspheres using activation by silver nanoparticles deposited on polydopamine-coated surfaces

A facile approach was developed to synthesize core–shell structured alumina/Cu microspheres by means of activation by silver nanoparticles in situ deposited on the polydopamine-coated alumina microsphere surface. This approach takes advantage of both the sufficient reductive capacity of polydopamine towards silver ions and the high activation of silver nanoparticles towards copper deposition. The chemical compositions of composite microspheres were characterized by energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR). The surface morphologies and crystalline structures of the coated alumina were studied by field-emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD), respectively. The adhesion strength between the copper layer and the substrate was evaluated by ultrasonic exposure and thermal shock test. The results showed that silver nanoparticles effectively catalyzed the copper deposition reaction on the polydopamine-coated surface, which led to a faster and more reliable plating process compared with the process without activation. The compact and continuous copper layer obtained showed strong adhesion on the substrate surface.