Study on Optical and Thermal Uniformity of LED Filament Based on Flip Chip1

Abstract

The LED filament has become a research hotspot in industrial and academic fields. The filament was fabricated by the flip LED chip, and its optical and thermal uniformity was tested and analyzed in detail. The color temperature (CT), brightness and surface temperature (ST) of LED filament at different positions was measured by BM-7 aiming point luminance meter and Ti-32 infrared thermal imager respectively. The experimental results show that the brightness and ST of the filament conformed to the Lambert distribution. The filament was simulated by lightTools optical software and FLOEFD thermal software respectively, and the simulated illumination and temperature distribution were the same as the test results. Experimental results show that the CT and brightness of LED filament on both sides was 4.23% and 9.27% lower than that of the middle position, respectively. The ST difference of the whole device was 9.80 C. The thermal parameters of LED filament were simulated by FLOEFD software. The simulated results indicated that the ST was distributed with high level in the middle and low level at both sides, the results of simulation and experiment are consistent. Therefore, it was reveled that the LED filament prepared based on the LED flip chip has good optical and thermal uniformity and be feasible as a new type of LED light source.