电场与热场调控下无模具LED透镜成型技术研究

The lens is very key to high-power light-emitting diodes (LED). And its morphology quality decides the light pattern and efficiency of LED devices. In order to meet requirements of advanced packaging technologies, a novel moldless lens forming technology is proposed based on the regulation of the electric and thermal fields in this study. Centered around the scientific and key issues, which are the regulating mechanism of the electric and thermal fields for flow behavior, and obtaining the optimal process parameters for complex lens forming, the proposal includes the following research contents: 1) A flow model which couples the electric field, thermal field and multiphase flow is built to systematically investigate the rules of encapsulation flow and morphology evolution; 2) The process parameters for complex lens forming are explored and optimized through combining the numerical analysis and experiments; 3) The applying of the new lens forming technology is conducted for the lenses of LED street lamp and backlight. And optical performances of the lenses are tested for evaluating the new lens forming technology. Currently, high-power LED have been widely adopted in vast illumination applications. And with LED developing toward high density, high reliability and high performance, the lens forming technologies with controllable morphology are urgently needed. This study would open the new mentality for LED lens forming technologies. Its achievements would promote the development and application of advanced LED packaging technologies, and provide the power to the semiconductor lighting.

透镜是大功率LED封装的关键部件，透镜成型质量直接决定LED器件光型与光效。本项目利用电场与热场耦合调控原理，提出一种新型无模具LED透镜成型技术，满足大功率LED先进封装需求。围绕理解电场与热场调控封装胶流动行为机制，获得新型透镜成型工艺参数，本项目主要研究内容包括：1）建立电场-热场-多相流耦合流动模型，系统地研究封装胶在电场和热场作用下的流动行为与形貌演变规律；2）采用数值分析与实验相结合的手段进行电场与热场耦合调控下LED透镜成型技术探索与工艺优化；3）新技术在LED路灯与背光模块透镜成型中应用与评估。目前，LED已广泛应用于各种照明领域，随着LED器件朝着高密度、高可靠与高性能发展，迫切需要开发形貌灵活可控的透镜成型技术。项目实施为大功率LED透镜制备技术研发开辟了新思路，有效推动LED封装技术与半导体照明技术发展。

封装胶涂覆与成形是LED封装的关键。传统封装胶涂覆工艺严重依赖于昂贵的封装设备，显著增加了LED封装工艺的成本。发展高性能、低成本LED封装技术对封装胶涂覆工艺创新提出了迫切要求。本项目从封装胶涂覆工艺中流体流动的物理本质出发，探索了基于电场与热场耦合作用封装胶流动行为及调控方法；针对LED封装中透镜成形和荧光粉涂覆提出了新加工方法。具体研究内容包括：. 1）建立基于静电-水平集两相流流体流动的多物理场耦合分析模型，并开展了系统实验研究；揭示了电场作用下，聚合物形貌变化分为微小变形、稳定增长和突变增长三个阶段。电场强度和材料物性参数影响聚合物流动规律，其中电压大小、电极间距、聚合物胶体初始高度、和温度载荷是电场作用下形貌调控的关键影响因素。. 2）针对复杂形貌透镜加工，通过理论优化得到，平板-平板电极实现锥形胶体形貌，圆环-平板电极实现扁平胶体形貌，非对称圆柱-平板电极实现非对称胶体形貌的技术方案，光学实验验证加工透镜具有良好的光学特性。. 3）通过电场与热场作用下调控荧光粉胶表面形貌方法，发展了加工悬链线柱形结构的荧光粉涂覆工艺，实现了模块理想的空间颜色均匀性。. 4）基于电场调控封装胶形貌，提出了一种结合荧光粉导电玻璃和调控透镜表面形貌实现LED光色调节技术，实验验证该技术具有良好的光色调节性能。. 5）发现了离子风作用下聚合物图形化现象，开展了离子风作用下实现聚合物硅胶图形化的实验，揭示了离子沉积是聚合物图形化的作用机制。. 6）基于离子风作用下的聚合物图形化，提出了LED光提取封装胶结构加工和荧光粉保形涂覆新方法。. 通过本项目电场与热场耦合作用下封装胶流动过程及成形工艺研究，为发展LED封装技术提供了新思路，同时电场作用下的流体流动过程的探索，特别是离子风作用下的聚合物图形化机理研究，丰富了电流体领域理论知识。