LumiBright UV boards, leveraging chip-on-board LED technology with metallic-core printed-circuit-board (PCB) substrates, feature a large emitting area using a closely packed array of UV LED chips to deliver close to 40 W of ultraviolet (UV) optical power. Developed by Innovation in Optics Inc., the boards have standard center wavelengths of 365, 385, 395, and 405 nm. The 1.1-mm-square die can be PCB-mounted as a single chip or in arrays up to 4 by 4 chips to create 19.4 mm2 of source area. Each die can be driven to emit near 2 W/mm2; therefore, a 16-die array can supply nearly 40 W of UV optical power. The boards emit directly into the air with no epoxy or lens encapsulation. Maximized light extraction delivers a Lambertian far-field distribution pattern for greater design flexibility. Low thermal resistance and low junction temperature allow for high current density. UV LED lifetime can exceed 10,000 hours thanks to onboard thermistors. Applications include UV curing, 3D printing, maskless lithography, photodynamic therapy, and fluorescence excitation in life science or machine vision.