Laser Transfer of Metals and Metal Alloys for Digital Microfabrication of 3D Objects

Abstract

3D copper logos printed on epoxy glass laminates are demonstrated. The structures are printed using laser transfer of molten metal microdroplets. The example in the image shows letters of 50 µm width, with each letter being taller than the last, from a height of 40 µm ('s') to 190 µm ('l'). The scanning microscopy image is taken at a tilt, and the topographic image was taken using interferometric 3D microscopy, to show the effective control of this technique.

Printing Functional 3D Microdevices by Laser‐Induced Forward Transfer

“…LIFT is versatile with respect to material choice since gold, aluminum, copper, and other pure and alloyed metals have been ejected. High‐aspect‐ratio pillars, short inclined pillars, and microstructures with a nearly homogeneous cross section have been fabricated, showing great promise in manufacturing high‐aspect‐ratio microstructures as compared to conventional electrochemistry methods. However, the printed structures have hardly resulted in functional devices, since usually only single materials are printed, whereas thermal and stress sensing, actuation, and induction devices would require various materials or arbitrary 3D shapes.…”

“…Here, a laser pulse is focused onto a thin metal film, which locally melts and ejects a droplet as a result of compressive thermal stresses and local vaporization . LIFT is versatile with respect to material choice since gold, aluminum, copper, and other pure and alloyed metals have been ejected. High‐aspect‐ratio pillars, short inclined pillars, and microstructures with a nearly homogeneous cross section have been fabricated, showing great promise in manufacturing high‐aspect‐ratio microstructures as compared to conventional electrochemistry methods.…”

“…However, the printed structures have hardly resulted in functional devices, since usually only single materials are printed, whereas thermal and stress sensing, actuation, and induction devices would require various materials or arbitrary 3D shapes. Furthermore, picosecond (ps) lasers were used for recent LIFT‐based metal printing, whereas nanosecond (ns) laser sources could widen the process window toward lower cost and increased stability . In particular, ns‐LIFT is known to result in the ejection of highly directed droplet “trains,” which might be suitable for direct‐write.…”

Additive and Photochemical Manufacturing of Copper

“…A handful of metals, such as gold212, silver13, copper2, aluminum14, and chromium1516, have been deposited using this LIFT method. Various types of applications including emerging energy devices and advanced 3D structures have also been utilized using the LIFT techniques17181920212223. Using vacuum deposition methods, such as sputtering24 and thermal evaporation25, pure thin metal films were first grown on transparent carrier substrates.…”

Freestanding 3-D microvascular networks made of alginate hydrogel as a universal tool to create microchannels inside hydrogels

“…[35][36][37][38] To create branched 3-D tubular structures made of hydrogel, we employed a copper template that could be prepared by reported mass-production strategies [39][40][41] or recent 3-D printing strategies. [42][43][44] We immersed the copper template in alginate, a natural polysaccharide derived from brown sea algae, which has been widely used to fabricate bio-scaffolds in biomedical and biological applications; 19,45-49 then we conducted electrolysis, during which the released copper ions from the template quickly cross-linked the alginate in the solution and formed gel. The reaction was so quick that all the generated Cu 2þ ions were consumed before diffusing away, resulting in a uniform thin layer of hydrogel coating covering the copper template.…”