Ultrafast laser nanostructuring and its application in electrochemical deposition of metal microstructures with high density and robust bonding strength

Ultrafast laser direct writing technology, with its capacity to efficiently and conveniently induce micro-nano structures on material surfaces, has opened up new avenues for precision material processing and the preparation of functional devices. In this study, we investigate the potential application of laser nanostructuring for surface functionalization and therefore localized electrochemical deposition. The surface skin-layer nano-relief structures induced by ultrafast laser are demonstrated to provide localized field enhancement and create attachment sites for electrochemical reactions, thereby enabling equivalent parallel localized electrochemical deposition under standard plating conditions. Furthermore, these nano-relief structures form a unique interdigitating junction structure between the depositor and the substrate, significantly enhancing the bond strength between the depositor and the substrate. The shear test results indicating the bond strengths can be up to 100 MPa, significantly exceeding that of conventional localized electrochemical deposition techniques. With the incorporation of electrochemical additives, crystalline growth during electrochemical deposition is regulated, realizing efficient and controllable deposition of high-density copper microstructures. The hardness and elastic modulus of the deposited copper were tested to be 0.95 GPa and 67.99 GPa, respectively, approaching those of forged copper. For microstructure arrays on a centimeter scale, the electrodeposition time can be reduced from hundreds of hours to tens of minutes. This method is not only applicable to metallic conductive substrates but can also be extended to localized electrochemical deposition on semiconductor materials, offering promising prospects for the high-efficiency, high-performance, and practical manufacturing of metallic complex structured devices.