LED manufacturers sort LEDs into 'bins' based on the forward voltage to give their customers the most consistent light color possible. Manufacturing tolerances can cause a range of colors even in the same batch of LEDs, so this binning process gives their customers higher consistency in the color produced. Despite the tight grouping of forward voltages in these bins, inherent LED characteristics can still result in non-homogeneous current draw, luminous flux, heat dissipation and junction temperature.
This highly interconnected process was investigated using STAR-CCM+ and SPICE to simulate the coupled thermal and electrical problems. STAR-CCM+ was used to solve the thermal field while SPICE solved the electrical problem and a JAVA interface managed the communication between the two programs.