Research On Packaging Of White High-Brightness LEDs

With the increasing luminous efficacy of Light emitting diode(LED) and the successful fabrication of power high brightness LED chip (HB-LED), solid state lighting using white HB-LED becomes feasible. Especially with the integrating energy-saving electrical power such as solar energy batteries in the future, white HB-LED will be a promising candidate as one of the green solid state illuminating sources. Due to the outstanding benefits of LED compared with the traditional light sources, as well as the huge promising exist and potential for gaining markets share in the general illumination and vehicle forward lighting, and etc., international governments and global industries put huge investments into the R&D of white LED illumination source, inevitably, which will result in the further progress of optoelectronics, material, energy, semiconductor chip fabrication and packaging technology fields and etc. Our research focused on the packaging technology of white HB LED, designed one practicable and reliable high-power packaging structure with single HB-LED chip and investigated the whole HB-LED packaging process. Furthermore, we proposed the innovative notion of chip scale and system scale packaging such as chip-on-board technology, which found its great use in multi-chips array packaging module, and presented efficiency integrating cooling mechanism to solve thermal management. This thesis was organized as follows: Firstly, we briefly introduced lighting mechanism, electrodes patterns, and the fabrication process of high power LED chip. The evolution of LED packaging progress and the international main-stream technologies of white HB-LED chip packaging were also presented. Secondly, according to property of LED light source, we discussed the geometry optical phenomenon during the photons generated and emitted from the active layer of the semiconductor chip. A simplified geometrical optical model of point source assumption was illustrated. Thereof, we obtained mathematical model of luminance distribution on the specific spatial planar of the multi-chip array module. Thirdly, we introduced fundamentals of heat transfer theory, presented the prevailing chip-cooling technologies with high efficiency. A thermal modeling and parameters analysis of multi-chips array package integrated with an innovative micro-channel cooling module was fully investigated. Finally, we deeply studied the whole process of packaging white HB LED device, and fabricated some samples of single-chip and multi-chip HB-LED device. We also made related thermal dissipation and lighting tests and analyses, under some cooling conditions. As the packaging had a great impact on the performance of LED devices, our research is of practical value for the packaging R&D of white HB-LED device.