Autocatalytic Laser Activator for Both UV and NIR Lasers: Preparation of Circuits on Polymer Substrates by Selective Metallization

Patternable, high-precision, controllable wettability copper layers for 3D resin-based weather-resistant electronics and 3D liquid manipulation

The realization of 3D patterned metal layers with manipulable surface wettability has significant potential, especially in integrating microelectronics with weather resistance and multifunctional liquid manipulation. However, developing a facile and efficient method to bring it to fruition remains a great challenge. In this work, we proposed a novel 3D selective metallization strategy that combines stereolithography 3D printing with laser-induced selective metallization (LISM). Utilizing 355 nm UV or 1064 nm lasers, this strategy can prepare 3D conductive copper patterns (or circuits) with controlled wettability on various 3D-printed resin parts. The copper layer surface prepared via LISM formed microstructures similar to the papillae on the surface of a lotus leaf, and it spontaneously exhibited superhydrophobicity (156.6°) after aging in the air at room temperature. Superhydrophobic 3D circuits with self-cleaning, corrosion-resistant, and anti-condensation performance were successfully fabricated. By further treating the copper layer with a 355 nm UV laser, we realized the transformation of the superhydrophobic copper layer to a superhydrophilic state, enabling us to prepare high-precision superhydrophilic patterns or channels. A 3D self-driven flow channel was fabricated to successfully realize 3D liquid manipulation and small-scale chemical experiments.

Direct Laser Writing: From Materials Synthesis and Conversion to Electronic Device Processing

Direct Laser Writing (DLW) has been increasingly selected as a microfabrication route for efficient, cost-effective, high-resolution material synthesis and conversion. Concurrently, lasers participate in the patterning and assembly of functional geometries in several fields of application, of which electronics stand out. In this review, recent advances and strategies based on DLW for electronics microfabrication are surveyed and outlined, based on laser material growth strategies. First, the main DLW parameters influencing material synthesis and transformation mechanisms are summarized, aimed at selective, tailored writing of conductive and semiconducting materials. Additive and transformative DLW processing mechanisms are discussed, to open space to explore several categories of materials directly synthesized or transformed for electronics microfabrication. These include metallic conductors, metal oxides, transition metal chalcogenides and carbides, laser-induced graphene, and their mixtures. By accessing a wide range of material types, DLW-based electronic applications are explored, including processing components, energy harvesting and storage, sensing, and bioelectronics. The expanded capability of lasers to participate in multiple fabrication steps at different implementation levels, from material engineering to device processing, indicates their future applicability to next-generation electronics, where more accessible, green microfabrication approaches integrate lasers as comprehensive tools.