This study investigates the shear fracture behavior of direct bonded copper (DBC) ceramic substrates with conventional copper sheet and 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 demonstrated lower values between 16 and 32 MPa. The morphology of the porous copper, characterized by porosity and pore diameter, was found to be critical in determining shear performance. 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 a higher energy requirement for fracture and 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.
Choi et al. (Sun,) studied this question.
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