Printed Cu–Ag Phases Using Laser-Induced Forward Transfer

Laser-induced forward transfer (LIFT) is an additive manufacturing technique where short laser pulses are focused through a transparent substrate onto a thin, uniform, metal layer jetting micrometer-scale droplets yielding high-resolution 3D metal structures. Herein, LIFT printing from multilayered metal donors, and from compositional metal mixtures, is explored and presented. A comprehensive study of this sort has been lacking so far. LIFT printing from Cu–Ag structured donors is thoroughly studied. X-ray diffraction (XRD) analysis reveals the formation of a metastable Cu–Ag phase reflecting the high cooling rate of the metal droplets. Tuning properties of the printed metal structures is made possible by controlling the pulse width and the donor layers’ properties. Longer pulses (10 ns) jetting from cosputtered donors yield better homogeneity than shorter pulses (1 ns) from donors made of distinct sputtered layers. These homogenic structures also display better resistance to chemical etching. This study opens the door to designing various phases and structures with different electrical and mechanical properties by using LIFT of multimaterials donors.