Recent development in High Power LED (HPL) is poised to replace traditional lighting sources such as Fluorescent, HID, Halogen and conventional incandescent bulbs in many applications. Due to the solid state compact nature of the light source it is inherently rugged and reliable and has been the favored lighting source for most indoor and outdoor applications including many hazardous locations that impact, and safety environments including mining, bridge, aerospace, and automotive . In order to accelerate this transition many enhancements and advances are taking place to improve on the reliability, and thermal performance of these devices.
With the use of large LED arrays, it is possible to generate large heat loads at the system level which can cause challenges for overall heat dissipation, especially when cooling requirements call for passive methods. These two challenges work together to cause elevated LED die temperatures, which have been linked to lower quantum efficiencies, shorter lifetimes, emission wavelength shifts and catastrophic device failure. It has been predicted previously that the lifetime of a device decays exponentially as the temperature increases. This can result in a lifetime decrease from 42,000 hours to 18,000 hours when the device temperature increases from 40°C to 50°C.
This paper explores the various improvements and advances made in the micro-packaging of LEDs to enhance their performance.