Pressure-assisted direct bonding of copper to silicon nitride for high thermal conductivity and strong interfacial bonding strength.

To achieve superior thermal and mechanical properties of copper-bonded (Cu-bonded) Si₃N₄ substrate, a pressure-assisted direct bonded Cu (DBC) technique was applied to bond Cu foil with Si₃N₄ plate. The effects of oxide layer (SiO₂) thickness of Si₃N₄ plate on the microstructure, thermal and mechanical properties of the Si₃N₄-DBC samples were investigated. The successful bonding of Cu foil to Si₃N₄ plate was confirmed by the presence of the interfacial products of Cu₂MgSiO₄ and CuYO₂. Additionally, it was demonstrated that a thin SiO₂ layer can result in a discontinuous distribution of interfacial products while a thick one can lead to the formation of pores in SiO₂ layer. Notably, the sample prepared by Si₃N₄ plate with 5-μm-thickness SiO₂ layer and Cu foil with 5.9-μm-thickness oxide layer (Cu₂O) exhibited the optimally comprehensive properties with thermal conductivity of 92 W·m⁻¹·K⁻¹ and shearing strength of 102 MPa, which demonstrates significant promise for application in power electronic modules. [ABSTRACT FROM AUTHOR]