The SPIE Photonics West in San Francisco, the world’s largest event for photonic technologies, will start on Saturday with three conferences and two trade fairs.
On Monday, 04.02.19, the CiS Research Institute will participate in the session SPIE Conference 10940: Light-Emitting Devices, Materials, and Applications with two lectures on the topics “Discussion on reliability issues for UVB and UVC LEDs” and “An innovative Si package for high-performance UV LEDs”. Two scientific poster contributions will be shown on Wednesday evening.
Contribution 1: Discussion on reliability issues for UVB and UVC LEDs
For safe assembly and long component life of UVB and UVC LEDs, fundamentally different technologies are required than with established VIS/NIR LED components. At the CiS Research Institute, various processes have therefore been tested for several years and evaluated in terms of reliability and service life. The losses and failures in the production of significant batch sizes of such UV-LED assemblies are presented and discussed – starting with the yield of the LED wafer, various mounting options, the baking behaviour of the first operating hours and the long-term service life. The influences of different operating conditions as well as typical error patterns are shown. With the developed technology, yields of more than 80% can be achieved, which are significantly limited by the LED yield from the wafer composite at present.
Contribution 2: An innovative Si package for high-performance UV LEDs
Due to the low efficiency and component lifetime of available UVB and UVC LEDs, established assembly technologies and component housings achieve only unsatisfactory results – both in terms of luminous efficacy and the urgently required heat dissipation. The silicon submount developed at the CiS Research Institute eliminates these disadvantages. The structure, which can be stacked on three levels at wafer level, consists of a silicon carrier wafer with an integrated Z diode and through-holes on the back of the carrier, enabling simple and space-saving flip-chip assembly. An UV-stabilized aluminum reflector, also manufactured on a silicon substrate, is mounted on top of the flip chip. A hermetically sealed housing and parallelisation of the LED radiation is achieved by a Fresnel quartz optic mounted on it. All in all, the design achieves a light yield increased by a factor of 3 with excellent heat dissipation and a minimum size for high packing densities.