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Thermal Analyses of LED Light Bars and Backlight Modules

  • M.-Y. Tsai (a1), C.-Y. Tang (a1), C.-E. Zheng (a1), Y.-Y. Tsai (a2) and C.-H. Chen (a2)...


The effects of various parameters, such as thermal properties of substrates, thermal interface materials (TIMs) and heat sinks on the thermal performance of the light emitting diode (LED) light bars and backlight module are investigated experimentally and numerically in terms of junction temperature (Tj ) and thermal resistances from junction to air (Rj-a ). The results show that the measured Rj-a of the light bars by powering-on five LEDs in the test is different from one by powering-on only one LED, resulting from the extra heat coming from the adjacent LED packages affecting the Tj for the case of powering-on five LEDs. For the modules, Rj-a is significantly reduced by using the heat sinks for all backlight modules, and aluminum and iron heat sinks do not show any obvious difference in heat dissipation along with any substrates and TIMs. Furthermore, both experimental and simulation results show that the thermal conductivity of the substrates are more important and dominant than TIM and heat sink for the Rj-a of the backlight modules concerned, and also demonstrate that the thermal field for the local model can represent the one in full-scale backlight module.


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1. Steranka, F. M. et al., “High Power LEDs Technology Status and Market Applications,” Physica Status Solidi (a), 94, pp. 380388 (2002).
2. Arik, M., Petroski, J. and Weaver, S., “Thermal Challenges for the Future Generation Solid State Lighting Applications: Light Emitting Diode,” Proceedings of International Society Conference on Thermal Phenomena, pp. 113120 (2002).
3. Schubert, E. F. and Kim, J. K., “Solid-State Light Sources Getting Smart,” Science, 308, pp. 12741278 (2005).
4. Chang, M. H., Das, D., Varde, P.V. and Pecht, M., “Light Emitting Diodes Reliability Review,” Microelectronics Reliability, 52, pp. 762782 (2012).
5. Narendran, N., Gu, Y., Freyssinier, J., Yu, P. H. and Deng, L., “Solid-state Lighting: Failure Analysis of White LEDs,” Journal of Crystal Growth, pp. 449456 (2004).
6. Narendran, N. and Gu, Y., “Life of LED-based White Light Sources,” IEEE/OSA Journal of Display Technology, 1, pp. 167170 (2005).
7. Arik, M., Becker, C., Weaver, S. and Petroski, J., “Thermal Management of LEDs: Package to System,” Proceedings of SPIE, 5187, doi: 10.1117/12.512731 (2004).
8. Cheng, H. H., Huang, D. S. and Lin, M. T., “Heat Dissipation Design and Analysis of High Power LED Array Using the Finite Element Method,” Microelectronics Reliability, 52, pp. 905911 (2012).
9. Juntunen, E., Sitomaniemi, A., Tapaninen, O., Persons, R., Challingsworth, M. and Heikkinen, V., “Thermal Performance Comparison of Thick-Film Insulated Aluminum Substrates With Metal Core PCBs for High-Power LED Modules,” IEEE Trans. on Components, Packaging and Manufacturing Technology, 2, pp. 19571964 (2012).
10. Juntunen, E., et al., “Copper-Core MCPCB With Thermal Vias for High-Power COB LED Modules,” IEEE Transactions on Power Electronics, 29, pp. 14101417 (2014).
11. Yung, K. C., Liem, H., Choy, H.S. and Cai, Z.X., “Thermal Investigation of a High Brightness LED Array Package Assembly for Various Placement Algorithms,” Applied Thermal Engineering, 63, pp. 105118 (2014).
12. Ye, H., et al., “Electrical-thermal-luminous-chromatic Model of Phos-phor-converted White Light-emitting Diodes,” Applied Thermal Engineering, 63, pp. 588597 (2014).
13. Wang, C. P., et al., “Analysis of Thermal Resistance Characteristics of Power LED Module,” IEEE Transactions on Electron Devices, 61, pp. 105109 (2014).
14. Jeong, M. W., Jeon, S. W., Lee, S. H. and Kim, Y., “Effective Heat Dissipation and Geometric Optimization in an LED Module with Aluminum Nitride (AlN) Insulation Plate,” Applied Thermal Engineering, 76, pp. 212219 (2015).
15. Frank, R., “Semiconductor Junction Thermometers,” The Measurement Instrumentation and Sensor Handbook, Webster, J. G. ed., CRC/IEEE Press, Boca Raton (1999).
16. Siegal, B., “Measurement of Junction Temperature Confirms Package Thermal Design,” LaserFocus-World, (2003).
17. Tsai, M. Y., Chen, C. H. and Tsai, W. L., “Thermal Resistance and Reliability of High-Power LED Packages under WHTOL and Thermal Shock Tests,” IEEE Transactions on Components and Packaging Technologies, 33, pp. 738746 (2010).
18. JEDEC Standard EIA/JESD51-2, “Integrated Circuits Thermal Test Method Environmental Conditions Natural Convection (Still Air),” (1995)
19. Tsai, M. Y., Chen, C. H. and Kang, C. S., “Thermal Measurements and Analyses of Low-Cost High-Power LED Package,” Microelectronics Reliability, 52, p. 845854 (2012).
20. Fu, Y. F., Yang, S. Y., Hung, T. Y., Lee, C. C. and Chiang, K. N., “Light Degradation Test and Design of Thermal Performance for High-power Light-emitting Diodes,” Microelectronics Reliability, 52, pp. 794803 (2012).
21. Anderson, J. D., Computational Fluid Dynamics, McGraw-Hill International Editions, New York (1995).



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