Reliability Research On The Package Of High Power LED

Based on the demand of the energy saving in the world-around and the excellent characteristics of the semiconductor illumination, high power light emitting diodes(HP-LED), which improves quickly in recent years as the representative of semiconductor illumination is a strong candidate for the next generation general illumination. The quality of LED including stability,illuminant efficiency and lifetime will be seriously affected while the high power LED run up to a ultra-high temperature. The research of LED reliability plays an important role in its prevalence and the complete realization of green illumination.Because of problems caused by the thermal stress on the structure of the high power LED, which due to the CTE of the packaging materials, many kinds of reliability issues of the high power LED packaging are discussed and analyzed. The temperature distribution of the phosphor particles of different phosphor coating methods are simulated by the FEA. The method is a pre-estimating one, which can help to make an effective instruction for the choice of packaging materials and methods. It not only reduces the period of design and manufacture but also enhances the economic benefits.There is a description on the technical processes and failure mode of one high power LED. Furthermore, FEA is used to research the variety of thermal stress on the gold-tin eutectic solder layer between the normal power dissipation and the high temperature reflow process. It shows that different packaging materials have different effects on the eutectic solder layer of the high power LED. More practical experiments prove that Au80Sn solder layer as the die bonding material have the excellent reliability after acceleration aging.Finally, experiments are exerted on the technique of phosphor coating and the phosphor layer is molded successfully. Idealized numerical models are created to evaluate the temperature of phosphor particles and layers. Synthetic regarding, the layer of phosphor coating may be the most excellent phosphor technique at current technical level.