Formation of micromoulds via UV lithography of SU8 photoresist and nickel electrodeposition

Abstract: Current lithography methods for creating micromoulds, other than LIGA, often use glass or silicon wafer as substrates. Since they are nonconductive, a metallic seed layer is required to be deposited over the substrate for electrodeposition to take place. This paper demonstrates a new method of creating a micromould directly onto a metal substrate, which can then be immediately utilized for microinjection moulding after nickel electrodeposition. The selected metal brass substrate is machined by a single-point diamond turning process to achieve a nanosurface of 12 nm. Standard UV lithography using SU8 photoresist was then employed to create a microgear onto the brass. At approximately 20 mm depth, nickel microcavity gear of 1 mm diameter was successfully created directly onto the brass substrate, after electrodeposited in nickel solution. A pulse current deposition method at a current density of 400 A/m2 was used for the deposition process