The correlated color temperature (CCT) variation of the phosphor-converted light-emitting diodes (LEDs) after curing is a common phenomenon. In the past, it was believed that the phenomenon was caused by the sedimentation of phosphor particles. However, not only sedimentation, but these particles can also flow with the natural convection of silicone because of nonuniform heating during curing. The convective flow of the phosphor particles during curing was studied in detail in this work. The CCT variation and phosphor particles flow in the LED device cup with different depths and wall inclination angles were studied. The results show that the CCT increases after curing when the depth of the device cup is shallow. The case is the opposite when the depth of the device cup is deep. The convective flow behaviors of the silicone were revealed in the simulation. The large-angle inclined wall can increase the silicone flow path length and inhibit the particles flow downward caused by the flow to a certain extent. It is envisioned that the findings will strengthen the understanding of the CCT variation phenomenon and guide the encapsulation structure design of LEDs for better color quality.

中文翻译：

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硅树脂固化过程中荧光粉对流流动行为及其对白色LED光学性能的影响

固化后，荧光粉转换后的发光二极管（LED）的相关色温（CCT）变化是常见现象。过去，认为该现象是由荧光体颗粒的沉降引起的。但是，由于固化过程中加热不均匀，不仅沉淀，而且这些颗粒也可以在有机硅的自然对流下流动。在这项工作中，对荧光粉颗粒在固化过程中的对流进行了详细的研究。研究了不同深度和壁倾角的LED器件杯中的CCT变化和荧光粉颗粒的流动。结果表明，当器件杯的深度较浅时，固化后CCT会增加。当设备杯的深度较深时，情况则相反。在模拟中揭示了有机硅的对流流动行为。大角度的倾斜壁可以在一定程度上增加硅树脂的流路长度，并抑制颗粒向下流动。可以预见，这些发现将加强对CCT变化现象的理解，并指导LED的封装结构设计，以获得更好的色彩质量。