Direct Integration of Functional Structures on 3-D Microscale Surfaces by Laser Dynamic Forming

This paper demonstrates the scalable and fast-shaping top-down integration capability of laser dynamic forming (LDF), transferring functional structures conformal to three-dimensional (3-D) micro-to-mesoscale curvilinear features on various substrates by the laser-induced shockwave. The functional materials preserve their electrical resistance and temperature coefficient of resistance after the laser shock induced transfer. The ductile interconnections inherit 3-D microscale structures on various substrates without excessive necking and fracture. This process is realized by the lamination of functional materials with cushion layers and the shockwave controlled by laser pulse intensity. The ability of direct transfer is affected by the laser intensity, cushion layer thickness, and geometry of the 3-D substrates. The experiments and numerical study reveal that the cushion layer absorbs most of shockwave energy by large thickness reduction and extends the formability of ductile interconnections. Eventually, the thickness of ductile functional materials is distributed uniformly along the 3-D surfaces. The ranges of the processing conditions for direct integration of functional materials without property degradation are also investigated.