Thermal and Optical Performance of LEDs Mounted on Substrates With Converging–Diverging and Diverging–Converging Channels

Abstract

Though light-emitting diodes (LEDs) are gaining attention for implementation in various applications, thermal management remains a major concern in solid-state lighting devices. Thermal resistance and junction temperature are the critical parameters of LEDs, which should be maintained at nominal levels for its reliable and robust operation. In this paper, novel substrates were proposed to enhance the thermal performance of LEDs. Aluminum substrates with converging–diverging (CD) and diverging–converging (DC) geometries were fabricated using high-precision milling machine. Three different converge–diverge angles such as 45°, 60°, and 90° were used in CD and DC substrates. Numerical simulations were done using computational fluid dynamics software to gain more insights on heat distribution and flow dynamics in the proposed substrates. Thermal characterization was done using thermal transient method by mounting the LED on CD and DC substrates. The thermal performances of the proposed substrates were compared with bare aluminum substrate by measuring the thermal resistance and junction temperature of LED. Optical analysis on LED was done by utilizing still air chamber and spectrometer. From the analysis, DC substrates showed lower thermal resistance and junction temperature compared to the other two substrates due to the conjugate heat transfer effect. Precisely, DC substrate with 90° showed higher thermal and optical performance than any other substrates considered.