Thermal Performance of LED Filament in Flip-Chip Packaging Manufactured for Different Correlated Color Temperature

He Jiang,Xiaofeng Su,Hanwen Gu,Xuezhou Yang,Jiming Sa,Cong Fan,Yiwen Zhou,Zhushanying Zhang

doi:10.3390/app11198844

Abstract

The effect of correlated color temperature (CCT) on the thermal performance of light emitting diode (LED) filament in flip-chip packaging was investigated in detail. Two filaments with different lengths were selected as the research object, and the thermal resistance of filaments under three CCT (2200 K, 2400 K, 2700 K) were studied. The optical properties and thermal parameters of the two groups of filaments were measured, and the results were analyzed combined with the color coordinate. The experimental results show that thermal properties of LED filaments is closely related to CCT. Under constant current condition, junction temperature decreases with the increase of color difference. With the change of phosphor glue and phosphorus powder ratio, the color temperature of LED filament also changes. In the filaments with the same chip structure and packaging mechanism, the higher the proportion of red phosphorescent powder, the worse the heat dissipation performance of the filament. These results show that in the design and manufacture of LED filament, it is helpful to control the CCT of LED filament under the premise of meeting the use requirements.

Highlights

The color of the light emitted by the Light-emitting diodes (LED) filament is not exactly the same as the color of the light emitted by the black body at various temperatures, so the concept of “correlated color temperature” is used in LED
The purpose of this paper is to study the influence of color temperature on the thermal properties of LED filaments
Because different phosphor powder ratios lead to different color temperatures, the chromatic coordinate values of the two groups of filaments are further measured

Summary

Introduction

Light-emitting diodes (LED), an ultramodern cold light source, have the advantages of energy saving, environmental protection, long life and stable performance. It is widely used in daily lighting, animal and plant culture and even liquid crystal display [1,2,3,4]. When using LEDs as everyday lighting materials, there are many aspects to pay attention to. Efficiency and color characteristics must be considered when designing LED light sources [5,6]. The color of the light emitted by the LED filament is not exactly the same as the color of the light emitted by the black body at various temperatures, so the concept of “correlated color temperature” is used in LED.

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Conclusion