A time‐lapse study of thermomechanical fatigue damage has been undertaken using three‐dimensional X‐ray computer tomography. Morphologies were extracted from tomography data and integrated with data from microscopy modalities at different resolution levels. This enables contextualization of some of the fine‐scale properties which underpin the large‐scale damage observed via tomography. Lateral views of crack development are presented, which show networks analogous to mud‐cracks. Crack fronts which develop in the most porous regions within the sintered attachment layer travel across the boundary into the copper substrate. The propagation characteristics of these cracks within the substrate are analysed. Evidence is provided of heterogeneous densification within the sintered joint under power cycling, and this is shown to play a major role in driving the initiation and propagation of the cracks. Examination of the texture (differing levels of X‐ray absorption) of virtual cross‐sectional images reveals the origins of the nonuniformity of densification. Finally, cracks within the sintered joint are shown to have a negligible impact on the conduction pathway of the joint due to their aspect ratio and orientation with respect to the assembly.

中文翻译：

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用于电力电子模块的热机械变形烧结纳米银芯片附件的三维损伤形态

已经使用三维 X 射线计算机断层扫描对热机械疲劳损伤进行了延时研究。从断层扫描数据中提取形态，并与来自不同分辨率级别的显微镜模式的数据相结合。这使得一些精细尺度特性的背景成为可能，这些特性支持通过断层扫描观察到的大规模损伤。提供了裂缝发展的横向视图，其中显示了类似于泥浆裂缝的网络。在烧结附着层内最多孔区域中形成的裂纹前沿穿过边界进入铜基板。分析这些裂纹在基板内的传播特性。提供了在功率循环下烧结接头内的异质致密化的证据，这被证明在驱动裂纹的萌生和扩展方面起着重要作用。检查虚拟横截面图像的纹理（不同水平的 X 射线吸收）揭示了致密化不均匀性的起源。最后，烧结接头内的裂纹由于其相对于组件的纵横比和方向而对接头的传导路径的影响可以忽略不计。