A Measurement Method Base on FWHM for Determining Junction Temperature of LED
JIANG Fu-chun1, HE Si-yu1, LIU Yuan-hai1, LIU Wen1*, CHAI Guang-yue1, 2, LI Bai-kui1, PENG Dong-sheng1
1. College of Physics and Photoelectric Engineering，Shenzhen University, Shenzhen 518000, China
2. College of New Energy and New Materials，Shenzhen Technology University, Shenzhen 518000, China
Abstract：In this paper, a measurement system based on the FWHM (Full Width Half Maximum) method for junction temperature of LED is designed, which uses ordinary spectrometer. First, the relative spectral distribution of various color LEDs under different ambient temperatures and driving currents are measured by a general spectrometer. Since the spectral data collected by the spectrometer are discrete, in order to obtain a more accurate FWHM, it is necessary to fit the discrete spectral data into a continuous peak near the half of the strongest peak value Imax, i. e. 0.5Imax. So, the more accurate FWHM at different temperatures can be calculated and then the functional relationship between junction temperature Tj and FWHM can be obtained by fitting a certain function. Experiments show that the linear relationship between Tj-FWHM function of white and blue LED is higher than that of other color LED, and its linear index R2 is very close to 1. It shows that the two parameters of Tj and FWHM have strong linear function relationship. Using the functional relationship between Tj and FWHM, the junction temperature corresponding to any measured value FWHM can be calculated. Because this method uses the normal driving current, the self-heating effect can not be neglected. In order to reduce the junction temperature rise of LED devices caused by self-heating effect in fixed reaction time and the measurement error caused by the temperature deviation introduced by temperature control system, Tj and FWHM in a certain state are selected as the reference state, and the corresponding Tj and FWHM are obtained by point-by-point difference method, and then the corresponding ΔTj and ΔFWHM are obtained. ΔTj and ΔFWHM are fitted into corresponding linear functions to obtain the calibration function, which can greatly reduce the deviation caused by the self-heating effect and temperature control system. Finally, the results obtained by this method are compared with those obtained by T3Ster instrument of Mentor Graphics. It is found that the deviation is 2.5%, which is within the acceptable error range. The results show that the proposed method of measuring the junction temperature of LED by the FWHM method is feasible. This method overcomes the shortcomings of small peak wavelength drift of spectroscopy, which brings great errors to the test results, and has the advantages of not destroying the original packaging structure and not requiring expensive instruments.
蒋福春，何思宇，刘远海，刘 文，柴广跃，李百奎，彭冬生. 基于半峰宽的发光二极管结温测量方法[J]. 光谱学与光谱分析, 2020, 40(07): 2087-2091.
JIANG Fu-chun, HE Si-yu, LIU Yuan-hai, LIU Wen, CHAI Guang-yue, LI Bai-kui, PENG Dong-sheng. A Measurement Method Base on FWHM for Determining Junction Temperature of LED. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2020, 40(07): 2087-2091.
[1] CHEN Ying-cong, WEN Shang-sheng, WU Yu-xiang(陈颖聪，文尚胜，吴玉香). Acta Optica Sinica(光学学报), 2013, 33(8): 0823005.
[2] Senawiratne J, Chatterjee A, Detchprohm T, et al. Thin Solid Films, 2010, 518(6): 1732.
[3] DENG Hui, LÜ Yi-jun, GAO Yu-lin, et al（邓 辉，吕毅军，高玉琳，等）. Acta Optica Sinica, 2012, 32(6): 0623001.
[4] CHEN Huan-ting, LÜ Yi-jun, CHEN Zhong, et al（陈焕庭，吕毅军，陈 忠，等）. Acta Optica Sinica, 2009, 29(3): 805.
[5] Hong E, Narendran N. Proceedings of SPIE, 2004, 5187: 93.
[6] Xi Y，Schubert E F. Applied Physics Letters, 2004, 85：2163.
[7] XU Yu-zhen, LIN Wei-ming（徐玉珍，林维明）. Acta Optica Sinica, 2013, 33(5): 0523001.
[8] Gu Y, Narendran N. Proceedings of SPIE, 2004, 5187: 107.
[9] Fan H Y. Physical Review, 1951, 82(6): 900.
[10] ZHAO Wei-qiang，LIU Hui，CAI Qian, et al(赵伟强，刘 慧，蔡 骞，等). China Measurement & Test(中国测试)，2010，36(6): 17.
[11] Pan Y, Wu M, Su Q. J. Phys. Chem. Solids, 2004, 65: 845.
[12] Lin Y, Gao Y L, Lu Y J, et al. Applied Physics Letters, 2012, 100(20): 202108.
