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Nanoscale mechanical properties and microstructure of 3D LTCC substrate

With the development of three-dimensional low temperature co-fired ceramic (LTCC) packaging substrate, the internal microscale structures have great effect on the strength, toughness and lifetime of LTCC microsystem, where the study of local or nanoscale mechanical properties and microstructure is critical, especial for the prediction of the local failure behaviors. In this study, the nanoscale mechanical properties and microstructure of 3D LTCC substrate have been investigated. The nanoscale mechanical properties were measured by nanoindentation method on both the top and lateral faces and discussed according to the profile of the residual pit. The Young's modulus and hardness measured by nanoindentation were compared for two faces. The microstructure was studied by using Scanning Electron Microscope and Scanning Probe Microscope. The results show that LTCC can be regarded as a macroscopically homogeneous isotropic material and a particle-reinforced composite at microscopic scales. The properties of the individual particle and matrix were successfully measured and discussed. Moreover, significant effect of the machining process of the embedded channels and cavities on the strength of the substrate and fluid flow in the microchannel are found and discussed according to the microstructures, including the defects found at the corner of the microchannel and impurities found inside the microchannel.