Thermal spreading resistance characteristics of a high power light emitting diode module

• Published in: Applied thermal engineering Vol. 70; no. 1; pp. 361 - 368
• Main Authors: Yang, Kai-Shing, Chung, Chi-Hung, Tu, Cheng-Wei, Wong, Cheng-Chou, Yang, Tsung-Yi, Lee, Ming-Tsang
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 05.09.2014; Elsevier
• Subjects: Applied sciences; Computer simulation; Electronic package heat transfer; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Heat transfer; LED; Light-emitting diodes; Mathematical models; Modules; Spreading; Spreading resistance; Theoretical studies. Data and constants. Metering; Thermal conductivity; Thermal resistance measurement; Thermal resistance measurement; LED; Electronic package heat transfer; Spreading resistance; High power; Thermal resistance; Heat transfer
• ISSN: 1359-4311
• DOI: 10.1016/j.applthermaleng.2014.05.028

In this study, effects of the dimensions and the thermal conductivity of the substrate on the heat transfer characteristics of a LED module are investigated. The total thermal resistance corresponding to a LED module operating at different power levels is measured using a method following JESD51-1 and JESD51-14 standards. In addition, a finite element method (FEM) numerical simulation is carried out to analyze the heat transfer phenomena in the LED module. It is found that, for the current experimental conditions, the importance of the thermal spreading resistance effect increases with decreasing substrate thickness and/or increasing input power of the LED module, which corresponds to an increase in the total thermal resistance and correspondingly a higher chip temperature. Experimental and numerical results show that the thermal spreading resistance and thus the chip temperature can be reduced by increasing the substrate thickness or by utilizing materials with high lateral thermal conductivities (directionally-dependent) for the substrate. In consequence, for LED modules with the same substrate thickness, using graphite composite to replace aluminum as the substrate material reduces the spreading resistance by nearly 14% in the current study. •We performed an experimental and numerical study for heat transfer in a LED.•The thermal spreading resistance effect is significant in the LED module.•Lateral thermal conductivity of the substrate is critical to the spreading resistance.•The thermal spreading resistance effect increases with increasing of LED power.