Introduction to LED Thermal Management and Reliability

Some like it hot, others do not. And those others for sure include the designers of products that contain light-emitting diodes (LEDs). This book is about thermal management of LEDs and especially LED applications. The main question to be addressed is: Why do we need thermal management? As Belady put it eloquently in 2001 [Belady and Minichiello, Electronics Cooling Magazine, May issue, 2003]: The ultimate goal of system thermal design is not the prediction of component temperatures, but rather the reduction of thermally associated risk to the product. Hence, the objectives of a designer are not in the first place to calculate or measure temperatures, but to keep the lifetime beyond x years, to keep the color point within margin y, and to raise the efficiency to z %. And indeed, these objectives, determining the quality of LED-based products, are linked to the junction temperature. This is the main reason why a book on LED thermal management starts with an introductory chapter on LED reliability issues. Parts of this chapter have been sourced from a chapter in a book on Solid State Lighting Reliability [Pecht and Chang, Solid state lighting reliability: components to systems, Springer, New York, pp. 43–110, 2013]. 1.