High power density LED modules with silver sintering die attach on aluminum nitride substrates

Current research studies deal with the investigation of the thermal and optical properties of four LED modules on different substrate materials. The LED modules consist of arrays of 98 blue emitting LEDs with an emission wavelength of 457 nm within an area of 2.11 cm². The modules are based on aluminum oxide or aluminum nitride substrates and the LED chips are attached by using a soldering or a pressureless silver sintering process. The modules are mounted on a high performance microstructured heat exchanger. By using the water driven cooler a maximum optical power density of 106.2 W/cm² at a forward current of 2100 mA and 837.5 W electrical input power is achieved. A saturation of the optical power density over the input current due to thermal degradation is not observed.