Experimental Verification of Thermal Structure Function Distortion for LEDs with Silicone Domes

Light emitting diodes (LEDs) are highly efficient light sources with a long lifetime. LEDs are widely used in modern lighting applications. Reliable thermal modelling of LEDs and lighting solutions based on LEDs is a key aspect for achieving high reliability, desired light properties and lifetime of lighting systems. Though the LEDs are significantly more efficient than convenient incandescent bulbs, still they dissipate a great part of electrical power applied as heat. Lacking such efficient way of cooling as energy radiation LEDs have to rely on other means of heat transfer which complicates their thermal design. Thermal transient testing is a common way to evaluate thermal properties of LEDs. Nevertheless, due to the intrinsic limitations of the method and peculiar architecture of LEDs the data extracted with the method may contain error. This paper quantifies the transient characterization error for LEDs with silicone and phosphor/silicone composite domes and experimentally determines the sources of it.