柔性微型无机发光二极管的瞬态传热分析

A transient thermal analysis of microscale inorganic light-emitting diodes

集成在柔性衬底上的微型无机发光二极管(microscale inorganic light-emitting diodes,μ-ILED)能够承受拉、弯、扭等载荷,可以实现与人体组织直接集成,可作为一种新型光学探测器应用于人体健康监测和临床医学诊断.但这种电子器件在工作时会发出大量的热,器件的传热特性成为应用的重要问题.本文采用分离变量方法针对具有轴对称形状柔性μ-ILED瞬态传热过程建立了理论和有限元仿真模型,得到了系统温升随时间和空间坐标的变化规律,理论预测结果得到了有限元仿真的验证.通过理论模型,讨论了μ-ILED与封装层/衬底材料面内尺寸之间比值对正常工作下柔性μ-ILED温升的影响关系,这些结果能够预测基于柔性μ-ILED的微小体征探测器的发热过程,对其热管理及相应的散热设计具有一定的指导意义.

Microscale inorganic light-emitting diodes（μ-ILEDs） that are integrated in flexible substrates are able to be deformed like a rubber band.Such flexible μ-ILEDs can be integrated with human tissue directly as a novel optical detector applied to human health monitoring and clinical diagnosis.However,large amounts of heat will be emitted when such devices are operating,and the heat-transfer characteristics of the device are critical for its applications.In this paper,an axial symmetry analytical model,validated by 3 D finite-element analysis,is developed to describe the transient heat transfer process based on the separation variable method.Both the time and space variations of the temperature increase are obtained theoretically.According to the analytical model,the influence of the in-plane dimension ratio R0/R on the steady-state temperature increase of the μ-ILED is discussed.These results are able to predict the heating process of flexible μ-ILEDs and also pave the basis for thermal management and relevant thermal design of flexible μ-ILEDs.