3-Dimensional Lattice Boltzmann Simulation of Phosphor Jel Dispensing Process in Light Emitting Diodes
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摘要: 为实现蓝光LED(light emitting diode)芯片向白光LED照明的转化,大功率LED封装工艺流程中存在一个关键的环节——荧光粉涂覆,即通过点涂方式将荧光粉硅胶涂覆于LED芯片周围.荧光粉硅胶涂覆工艺是一个两相流动过程,它直接决定了荧光粉硅胶层的几何形貌及物理特性,并影响LED最终的光学和热学性能;因此对其中流动过程物理机制的理解有利于提升荧光粉涂覆质量,实现高性能LED产品.基于格子Boltzmann方法,建立荧光粉硅胶流动模型,并应用该模型研究了在平坦表面和方形凸起结构两种封装形式上的荧光粉硅胶点涂成形流动过程.结果表明:格子Boltzmann方法能够准确地模拟荧光粉点涂流动过程;在平坦表面上荧光粉硅胶液滴接触线与液滴直径之比(dL/D)和相对时间(t/T)成幂函数关系.
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关键词:
- 荧光粉硅胶点涂工艺 /
- 流动模拟 /
- 格子Boltzmann方法
Abstract: To get white light emission, it’s common to use a blue LED (light emitting diode) chip to be coated with yellow emitting phosphor jel via a dispensing process. The phosphor jel dispensing process is of two-phase flow, which decides the morphology and properties of the phosphor gel, thus strongly influences both optical and thermal performances of the resulting LEDs. It is important to describe the dispensing process accurately and improve the coating quality. Based on the lattice Boltzmann method (LBM), a flow model of phosphor gel was established to simulate the dispensing process. The dispensing and shaping processes of phosphor gel on flat surface and square projection were analyzed respectively. Results show that LBM simulates the dispensing process of phosphor gel accurately and predicts the morphology well. The droplet contact line length changes as a power function of the droplet diameter on flat surface. The simulation results provide a theoretical basis for the optimization of the phosphor gel dispensing process. -
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