Models for Color Point Stability of LEDs
Wednesday, March 01, 2017: 4:00 PM - 4:30 PM
According to conventional wisdom the issue of projecting the color point stability of LED packages requires detailed knowledge of the construction materials and package architecture. This information along with extensive testing would allow development of an accurate model for predicting color point stability for the specific package from given manufacturer. Any change of the materials whether it be phosphors, encapsulants or packaging materials would require additional testing and a new model. Development of an industry standard method for projecting color point stability requires a model with minimal to no variables based on materials or supplier. As a result there is no currently accepted method for projecting color point stability. Recently a model called Differential Chromaticity has been developed to address these needs. The model was developed by evaluation of LED test sets that extend from 12,000 - 20,000 hours and includes multiple types of packages from multiple suppliers. To date the model has proven robust and is able to model multiple color shift mechanisms without adjustable parameters. Different types of color shift mechanisms will be discussed along with the principles of Differential Chromaticity. Utility of the model in predicting different color shift mechanisms will also be discussed.