Thermal Testing of LEDs

Abstract

In this chapter, after a generic discussion of thermal testing techniques used to characterize packaged semiconductor devices; the latest practical test methods widespread in thermal testing of LED components and SSL luminaires are discussed. Thus, the focus is on the latest, power semiconductor and LED-specific test procedures, environments and thermal metrics-all derived from the classical JEDEC JESD51 family of testing standards. Detailed discussion is devoted to the transient extension of the so-called static test method and the differential measurement principle in its practical realization. Different representations of the thermal impedance are presented starting from the classical Z(th)(t) functions ending with the so-called structure functions. These are discussed in depth because they became the de facto standard in laboratory testing of thermal properties of LED components, in reliability analysis and in quality assurance at leading LED manufacturers. The basic concepts are introduced through practical examples.