LD
L. Du
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Sintered metallic interconnects are promising die-attach materials for high-temperature power electronics, yet their mechanical response is strongly influenced by the heterogeneous particle–pore–neck network formed during sintering. This thesis investigates how particle morphology and material composition govern the mechanical behaviour and deformation mechanisms of pressure-assisted sintered Cu-based structures. Nanoindentation, micro-pillar compression and micro-cantilever bending are combined with SEM, TEM/TKD characterization and molecular dynamics (MD) simulations to establish structure–property relationships across multiple length scales and loading modes.
For sintered Cu, monomodal, bimodal and flake-shaped particle assemblies develop distinct packing and load-transfer networks. Nanoindentation reveals that the bimodal structure provides the highest effective stiffness, whereas the monomodal structure exhibits greater plastic resistance; the flake-shaped structure shows substantially weaker through-thickness load-bearing capability. Micro-pillar compression further demonstrates morphology-specific deformation, evolving from distributed compaction in the monomodal structure to coarse-particle-guided extrusion in the bimodal structure and inter-flake shear localization in the flake-shaped structure. In Cu–Ag systems, fracture resistance varies nonmonotonically with composition. Increasing Ag content promotes densification and formation of a continuous Ag-rich network, while heterogeneous Cu–Ag interfaces introduce locally weak regions that reduce fracture resistance at intermediate compositions. MD simulations reproduce the principal experimental trends and clarify the associated particle rearrangement, defect evolution and strain localization mechanisms.
Overall, the results demonstrate that the mechanical performance of sintered Cu-based interconnects is governed by the coupled effects of pore–neck topology, phase connectivity and interfacial integrity. These findings provide a microstructure-based framework for designing sintered metallic interconnects with improved mechanical reliability. ...
For sintered Cu, monomodal, bimodal and flake-shaped particle assemblies develop distinct packing and load-transfer networks. Nanoindentation reveals that the bimodal structure provides the highest effective stiffness, whereas the monomodal structure exhibits greater plastic resistance; the flake-shaped structure shows substantially weaker through-thickness load-bearing capability. Micro-pillar compression further demonstrates morphology-specific deformation, evolving from distributed compaction in the monomodal structure to coarse-particle-guided extrusion in the bimodal structure and inter-flake shear localization in the flake-shaped structure. In Cu–Ag systems, fracture resistance varies nonmonotonically with composition. Increasing Ag content promotes densification and formation of a continuous Ag-rich network, while heterogeneous Cu–Ag interfaces introduce locally weak regions that reduce fracture resistance at intermediate compositions. MD simulations reproduce the principal experimental trends and clarify the associated particle rearrangement, defect evolution and strain localization mechanisms.
Overall, the results demonstrate that the mechanical performance of sintered Cu-based interconnects is governed by the coupled effects of pore–neck topology, phase connectivity and interfacial integrity. These findings provide a microstructure-based framework for designing sintered metallic interconnects with improved mechanical reliability. ...
Sintered metallic interconnects are promising die-attach materials for high-temperature power electronics, yet their mechanical response is strongly influenced by the heterogeneous particle–pore–neck network formed during sintering. This thesis investigates how particle morphology and material composition govern the mechanical behaviour and deformation mechanisms of pressure-assisted sintered Cu-based structures. Nanoindentation, micro-pillar compression and micro-cantilever bending are combined with SEM, TEM/TKD characterization and molecular dynamics (MD) simulations to establish structure–property relationships across multiple length scales and loading modes.
For sintered Cu, monomodal, bimodal and flake-shaped particle assemblies develop distinct packing and load-transfer networks. Nanoindentation reveals that the bimodal structure provides the highest effective stiffness, whereas the monomodal structure exhibits greater plastic resistance; the flake-shaped structure shows substantially weaker through-thickness load-bearing capability. Micro-pillar compression further demonstrates morphology-specific deformation, evolving from distributed compaction in the monomodal structure to coarse-particle-guided extrusion in the bimodal structure and inter-flake shear localization in the flake-shaped structure. In Cu–Ag systems, fracture resistance varies nonmonotonically with composition. Increasing Ag content promotes densification and formation of a continuous Ag-rich network, while heterogeneous Cu–Ag interfaces introduce locally weak regions that reduce fracture resistance at intermediate compositions. MD simulations reproduce the principal experimental trends and clarify the associated particle rearrangement, defect evolution and strain localization mechanisms.
Overall, the results demonstrate that the mechanical performance of sintered Cu-based interconnects is governed by the coupled effects of pore–neck topology, phase connectivity and interfacial integrity. These findings provide a microstructure-based framework for designing sintered metallic interconnects with improved mechanical reliability.
For sintered Cu, monomodal, bimodal and flake-shaped particle assemblies develop distinct packing and load-transfer networks. Nanoindentation reveals that the bimodal structure provides the highest effective stiffness, whereas the monomodal structure exhibits greater plastic resistance; the flake-shaped structure shows substantially weaker through-thickness load-bearing capability. Micro-pillar compression further demonstrates morphology-specific deformation, evolving from distributed compaction in the monomodal structure to coarse-particle-guided extrusion in the bimodal structure and inter-flake shear localization in the flake-shaped structure. In Cu–Ag systems, fracture resistance varies nonmonotonically with composition. Increasing Ag content promotes densification and formation of a continuous Ag-rich network, while heterogeneous Cu–Ag interfaces introduce locally weak regions that reduce fracture resistance at intermediate compositions. MD simulations reproduce the principal experimental trends and clarify the associated particle rearrangement, defect evolution and strain localization mechanisms.
Overall, the results demonstrate that the mechanical performance of sintered Cu-based interconnects is governed by the coupled effects of pore–neck topology, phase connectivity and interfacial integrity. These findings provide a microstructure-based framework for designing sintered metallic interconnects with improved mechanical reliability.