Mechanical behavior of lotus-type porous Cu/Al2O3 joints fabricated by direct bonded copper

초록

This study investigates the shear fracture behavior of direct bonded copper (DBC) ceramic substrates bonded with either conventional copper sheet or lotus-type porous copper. Through shear testing, significant differences in fracture mechanisms were observed between the two bonding structures. While copper sheet-bonded samples exhibited higher shear strengths ranging from 70 to 90 MPa, lotus-type porous copper-bonded samples exhibited lower shear strengths ranging from 16 to 32 MPa. The morphology of the porous copper, characterized by porosity and pore diameter, was found to be critical in determining shear strength. Larger pore diameters led to larger local bonding areas between pores, resulting in deeper and more continuous fractures within the alumina substrate. This increased fracture area implied a higher fracture energy requirement and contributed to enhanced shear strength. Additionally, the bonding process caused pore expansion due to molten copper migration, which reduced the actual bonding area, especially in samples with high pore density. These findings highlight the importance of optimizing pore structure to improve the mechanical reliability of porous copper-bonded DBC substrates for advanced electronic applications. Copyright © 2026. Published by Elsevier Ltd.

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