Visible Light Communication is an emerging technology in Optical Wireless Communication where the Light Emitting Diodes (LEDs) are utilized for transmission of data. The luminance of the LEDs increases with the forward current; however, for high current levels the heat generated by nonradiative recombination of carriers increases the LED junction temperature, decreasing the efficiency and the lifetime of the devices. Therefore, the design of high power LED driver circuits needs to take into account the unavoidable local heating produced by high power components. In this paper, we performed thermal analysis of an LED driver mounted on Printed Circuit Boards (PCBs) using Thermal Risk Management (TRM) software and studied the heat dissipated by various components on PCBs composed of different dielectric materials such as FR4 and Diamond. Based on TRM simulations, the replacement of FR4 with diamond caused the junction temperature to decrease from 64°C to 45.2°C for a forward current level of 350 mA. The replacement of FR4 with diamond thus effectively improves the thermal management of LEDs and corresponding driver circuits.