Laser-Assisted Electrochemical Deposition of Bilateral Au Coatings on Ni Foils: Mechanism and Experimental Study

Bilateral localized Au coatings are of great importance for high-density interconnection and double-sided functionalization in microelectronic devices. Conventional bilateral electrochemical deposition (ECD) typically requires cathode reversal or masking, which makes the process cumbersome and limits precision. Herein, a maskless laser-assisted electrochemical deposition (LECD) technology is proposed to achieve simultaneous bilateral deposition under single-side laser irradiation. Comparative experiments were conducted to elucidate the bilateral deposition mechanism under the synergistic effects of thermomechanical enhancement and laser cleaning, and single-factor experiments were performed to investigate the influence of the effective accumulated energy density (E_eff) on surface morphology and thickness symmetry. The comparative results show that the local temperature rise induced by front-side laser irradiation is conducted to the back side through the substrate, thereby increasing the cathodic overpotential and reaction kinetics at both interfaces and inducing electrochemical deposition to form coatings. Compared with the back-side coating, the front-side coating benefits from the coupled cleaning-deposition process and exhibits a denser and more uniform structure. The single-factor experiments reveal that, with increasing E_eff, the coatings on both sides undergo a characteristic matte-gold-bright-gold-rematte-gold morphological evolution. Under the optimized parameters (single-pulse energy of 12-14 μJ and scanning speed of 100-140 mm/s), high-quality bilateral coatings with an interfacial symmetry index (ISI) of 0.7 were obtained. In addition, the LECD coatings were superior to or comparable to conventional ECD coatings in corrosion resistance, interfacial bonding strength, and electrical performance. This study provides an efficient strategy for fabricating high-precision bilateral functional coatings for microelectronic applications.