Ningbo Materials Institute breaks through the key preparation technology of high-power LED light-transparent transparent ceramic sheets

Solid-state lighting is known as the fourth-generation electric light source after incandescent lamps, fluorescent lamps and high-intensity discharge lamps. Compared with 5% of incandescent lamps and 20% of energy conversion efficiency of fluorescent lamps, LED energy conversion efficiency exceeds 50%. The power consumption of LEDs is only 1/10 of that of incandescent lamps, and 2/5 of fluorescent lamps, especially blue-light chips combined with yellow phosphors. White light illumination is an important direction for next-generation lighting.

In recent years, LEDs mainly use blue chip excitation/composite yellow phosphor to synthesize high quality white light. However, the silica gel and epoxy resin mixed ceramic phosphors currently used have large heat dissipation and stability problems, which greatly limits the limitation. LED applications in high power (such as roads, car headlights, marine fisheries, stage lighting, etc.).

After four years of hard work, the researchers of the Special Fiber and Nuclear Energy Materials Engineering Laboratory of the Institute of Materials Technology and Engineering, Chinese Academy of Sciences, recently solved the problem of interface compatibility between two-phase composite ceramics by cooperating with Jaehyung Lee, Department of Materials and Engineering, Lingnan University, Korea. The high transparent ceramic preparation technology with low light scattering loss successfully inserts the ceramic phosphor into the aluminum-based transparent ceramic matrix with matching thermal expansion coefficient. The transparent ceramic sheet has a thermal conductivity of 14 W/m. K (silicone and epoxy at 0.4 W/m.K) increases the thermal conductivity of passive light modules in conventional packages by two orders of magnitude. By adjusting the color and content of the phosphors, the research team obtained a light-transparent transparent ceramic sheet with different illumination requirements.

Researchers from Ningbo Materials Institute cooperated with related packaging companies to package the transparent ceramic sheets onto commercial blue chips to obtain all-ceramic LED lamps. Through the test of related performance, the color temperature of the lamp bead reached 4500K, and the luminous efficiency reached 107lm/W, which reached the mainstream LED light effect level in the market. Fluorescent transparent ceramic packaging technology will greatly simplify the mixing and tinting process in traditional LED packaging , and is expected to fully standardize fluorescent ceramics of different colors and reduce manual errors.

The work was awarded the National Natural Science Foundation of China (a study on the dielectric loss mechanism of microwave segment transparent ceramics for ADS and multi-scale analysis of micro-defects, 51172248), Zhejiang Outstanding Youth Fund (microwave-synthesized nitride phosphor for semiconductor lighting ) Chemical reaction kinetics, microstructure evolution and luminescence properties, R12E020005) and Ningbo International Cooperation Project (Key Technology Development for Nitride-based Fluorescent Ceramics for LEDs, 2014A610006). At present, around the light-transparent transparent ceramic technology, the team has an authorized invention patent, a utility model patent and three invention patents.

(a) fluorescent ceramic sheet, (b) light-transmissive transparent ceramic package schematic, (c) transparent ceramic LED lamp bead, (d) demonstration of transparent ceramic LED lamp white light conversion effect.