Opto-Thermal Performances Investigation of Phosphor-in-Glass Based Chip-Scale White LEDs

Chip-scale packaging (CSP) is an important process to achieve high-density white LED and reduce the packaging size. Phosphor-in-glass (PiG) packaged LED can solve some problems, such as the thermal quenching of phosphor particles, and the aging of phosphor layer. Still, the packaging structure greatly affects the quality of LEDs, such as reliability and performance. In this work, the PiG-CSP LEDs with different packaging structures were prepared and their opto-thermal performances were detailedly analyzed. The thermal finite element analysis of LED modules under different structures and currents was carried out by using finite element numerical simulation method, and the temperature distribution of LED modules was obtained. A confirmatory experiment was done with an infrared thermal imager, and comparison studies were carried out. The results show that the LED based on PiG-down-CSP achieves CIE chromaticity coordinates of (0.3265, 0.3566) at 350 mA, a correlated color temperature (CCT) of 5744 K, and a luminous efficiency (LE) of 124.4 lm/W. The relative error of the maximum surface temperature of two LED modules is less than 8.02%. The surface temperature of LEDs with the PiG-up structure is higher than that with the PiG-down structure (63.9 degrees C and 37.1 degrees C, respectively). This research provides practical theoretical support for the structure optimization of PiG-CSP LED.