Reliable and Efficient Phosphor-in-Glass-Based Chip-Scale Packaging for High-Power White LEDs

A white light-emitting diode (WLED) with chip-scale packaging (CSP) has wide applications due to its high power density, small size, and high process integration. The phosphor converter of the CSP WLED needs to endure huge heat shock from LED chips and phosphor conversion. In this work, we proposed a phosphor-in-glass (PiG)-based CSP for high-power WLEDs. A wafer PiG was prepared by printing and sintering a phosphor glass film on a glass plate and then cut into a chip-scale PiG for the fabrication of PiG-CSP WLEDs. The optical performances of PiG-CSP WLEDs were optimized by adjusting the film thickness of PiG. Consequently, the PiG-CSP WLED emits a cool white light with optimal light performances at a film thickness of 88
$\mu \text{m}$
. The related luminous efficiency (LE), correlated color temperature (CCT), and chromaticity coordinate are 108.8 lm/W, 5796 K, and (0.3256 and 0.3467), respectively. The down-PiG-CSP structure achieves higher LE and lower CCT than the up-PiG-CSP structure. Compared with the traditional phosphor-in-silicone (PiS)-CSP WLED, the PiG-CSP WLED avoids the carbonization of the converter and displays excellent thermal stability under high input current. The results determine that the PiG-CSP is a reliable and efficient packaging technology for high-power WLEDs.