Structural optimization and numerical thermal analysis of ultraviolet light-emitting diodes with high-power multi-chip arrays

In this paper, the finite element method and experiment were used to systematically study the influence of different factors on the heat dissipation of high-power ultraviolet light-emitting diode (UV LED) module, including chip spacing and structure, sub-mount, adhesive materials, the packaging area and void ratio of adhesive. The package structure was optimized by introducing Al barrier plate and changing the spacing between adjacent chips. Considering the balance of junction temperature and irradiance, the appropriate chip spacing (∼ 2.5 mm) should be chose. The simulations analysis demonstrated that both sub-mount and adhesive materials play an important role in the thermal performance of the UV LED module. The area ratio (∼0.9) between the adhesive area and the chip area can not only realize the excellent heat dissipation but also minimize the use of adhesive materials. During reflow soldering, the lager coalesced voids should be decreased as soon as possible, which have worse heat dissipation performance than the distributed voids. Furthermore, the reliability and validity of the numerical simulation were verified by the experiment data. The present conclusions provide significant insight on designing and optimizing high-power UV LED devices.