Local thermomechanical stress can cause failures in semiconductor packages during long‐time operation under harsh environmental conditions. This study helps to explain the packaging‐induced stress in blue GaN‐LEDs soldered onto copper substrates using AuSn alloy as lead‐free interconnect material. Based on the finite element method, a virtual prototype is developed to simulate the thermomechanical behavior and stress in the LED and in the complete LED/AuSn/Cu assembly considering plastic and viscoplastic strain. The investigations were performed by varying the temperature between −50°C and 180°C. To validate the model, the simulation results are compared to experimental data collected with Raman spectroscopy. Studies of the phonon mode of GaN semiconductor are elaborated to understand the induced thermomechanical stress. The model enables evaluation of the stress in the interfaces of the assembly, which otherwise cannot be accessed by measurements. It serves to predict how assemblies would perform, before committing resources to build a physical prototype.

中文翻译：

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使用有限元方法和拉曼光谱研究了焊接在Cu衬底上的GaN-LED中的热机械应力

在恶劣的环境条件下长时间运行期间，局部热机械应力会导致半导体封装失效。这项研究有助于解释使用AuSn合金作为无铅互连材料焊接到铜基板上的蓝色GaN-LED中封装引起的应力。基于有限元方法，开发了一个虚拟原型来模拟考虑塑性和粘塑性应变的LED以及整个LED / AuSn / Cu组件中的热机械行为和应力。通过在-50°C至180°C之间变化温度来进行研究。为了验证模型，将模拟结果与拉曼光谱法收集的实验数据进行比较。研究详细阐述了GaN半导体的声子模式，以了解感应的热机械应力。该模型可以评估组件界面中的应力，否则无法通过测量访问。它可用来在提交资源以构建物理原型之前预测程序集的性能。