Improvement of high-power-white-LED lamp performance by liquid injection

Performance of a high-power-white-LED lamp is mostly hindered by its poor thermal characteristic. This characteristic is accessed by its thermal resistance. Besides thermal characteristic, light quality of a high-power-white-LED lamp is also an important issue. This parameter is accessed by its luminous efficiency. Both thermal characteristic and light quality need to be optimized in order to develop a high-power-white-LED lamp. In this study we made an attempt to improve the characteristic features (both the thermal resistance and luminous efficiency) of a high-power-white-LED lamp by liquid injection in the lamp package. Experiments were carried out on a high power-white-LED lamp consisting of 5 blue LED chips, 5 phosphor-epoxy layers and 3M Fluorinert FC-43 as an injected liquid. Furthermore, the light extraction with the total internal reflection was simulated to confirm the improvement by liquid injection. It is found from the experimental results that liquid injection has significantly improved the thermal dissipation of the lamp with the decreased thermal resistance by 14 %. It has also improved the lamp´s light quality with the increase in the luminous efficiency by 18 %.