Unraveling the Processing Parameters for Selective Positioning of Multi-materials Using Laser Decal Transfer

Abstract

3D printing or additive manufacturing has gained popularity due to its high innovation potential, process improvement, and design freedom in industries such as aerospace, dental, medical, and automotive. A detailed investigation into thin film as a feedstock for printing maskless MEMS structures is an important area of current research. In this work, we explore the selective positioning of ZnO ceramic over a NiTi interdigitated structure on an ITO-coated glass substrate using the laser decal transfer technique. A CO2 laser (λ = 10.6 µm) is employed, and the effects of laser processing parameters—including laser fluence, laser pulse overlaps, and stand-off distance—are systematically analyzed. Key experimental findings indicate that a laser fluence of 75 J/cm2 optimally facilitates ZnO transfer while avoiding material burning. A stand-off distance of 12.5 cm allows effective material transfer, whereas off-focus conditions hinder ZnO deposition. Additionally, an optimal laser pulse overlaps of 65% achieves a balance between continuous material transfer and minimal heat-affected zone. The transferred ZnO seed layer, approximately 5 µm thick, is further hydrothermally grown into well-structured ZnO nano-rods, confirmed through SEM and XRD analysis, which identifies a hexagonal wurtzite crystal structure. Finally, using optimized parameters, the feasibility of multi-material transfer is demonstrated, with successful ZnO deposition on a NiTi interdigitated structure (600 µm feature size), forming a layered structure. The proposed laser micro-3D printing via laser decal transfer offers significant advantages for fabricating complex sensors with controlled gradient-based properties. © ASM International 2025.