Optimization of Copper Thermocompression Diffusion Bonding under Vacuum: Microstructural and Mechanical Characteristics
2. Materials and Methods
2.1. Cu-Cu Thermocompression Bonding
2.2. Diffusion Bonding Characterization
3. Results and Discussion
3.1. Microstructural Investigation
3.2. Mechanical Properties
- Cu-Cu bonds with advanced mechanical properties were successfully formatted through a thermocompression process under vacuum. Commercial copper foils with 200 μm thickness were used for the bonding tests, while a pressure of 10 MPa was applied.
- The increase of the bonding temperature, from 750 to 1000 °C, and the duration, from 20 to 90 min, significantly improved the bonding strength of the copper bonds. The highest ultimate BS (180 MPa) approached the respective value of the base material, and was achieved at 1000 °C for 90 min. The transverse microhardness of the bond reached 55 HV, slightly higher in comparison to the respective value of the base material.
- Electron backscatter diffraction (EBSD) investigation, of the optimum bonded specimen, reveals a satisfactory interdiffusion growth in regions with finer grains. Transmission electron microscopy revealed the formation of small equiaxed recrystallized twin crystals in the bonding zone with a size ranging from 200 to 400 nm.
- The above mechanical and microstructural data indicated that the developed copper-bonded structure could be successfully used in devices that are submitted to intense mechanical stress (i.e., bar-wound stators in vehicles).
Conflicts of Interest
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Samouhos, M.; Peppas, A.; Angelopoulos, P.; Taxiarchou, M.; Tsakiridis, P. Optimization of Copper Thermocompression Diffusion Bonding under Vacuum: Microstructural and Mechanical Characteristics. Metals 2019, 9, 1044. https://doi.org/10.3390/met9101044
Samouhos M, Peppas A, Angelopoulos P, Taxiarchou M, Tsakiridis P. Optimization of Copper Thermocompression Diffusion Bonding under Vacuum: Microstructural and Mechanical Characteristics. Metals. 2019; 9(10):1044. https://doi.org/10.3390/met9101044Chicago/Turabian Style
Samouhos, Michail, Antonis Peppas, Panagiotis Angelopoulos, Maria Taxiarchou, and Petros Tsakiridis. 2019. "Optimization of Copper Thermocompression Diffusion Bonding under Vacuum: Microstructural and Mechanical Characteristics" Metals 9, no. 10: 1044. https://doi.org/10.3390/met9101044