Fundamentals and Development Trends of High Power LED Packaging

Abstract

In this chapter, with the belief that LED packaging shares many similar points to electronic packaging and with the hope that the cost breakdown will continue in LED packaging, we first presented the fundamentals of electronic packaging from the conventional leadframe based plastic packaging, to chip scale packaging, to wafer level integration, and to the system in packaging (SiP) which is based on more than Moore. The last concept is important, as solid state lighting, more than lighting, will generate more opportunities for the LED due to their unique features. Then, we discussed the LED chips in terms of current spreading efficiency, internal quantum efficiency, and high light extraction efficiency. Types and functions of LED packaging are described in details in terms of conventional low power packaging, and high power packaging. Factors and system design of high power packaging are discussed in detail, with particular focus on the cross-disciplinary co-design approach to the design of LED packaging. As a complicated system, packaging design cannot focus on one issue and should address these issues simultaneously and provide an integrated system with balanced performance. Reliability issues are briefly discussed. Finally, development trends and a roadmap are provided, with particular interest in the integration from a simple application specific LED packaging (ASLP), to more advanced level wafer level integration. It is believed that silicon based packaging will be rapidly used in LED packaging.