Interfacial diffusion behavior and properties of hot-pressed Kovar/ Cu composites

Kovar/40Cu composites for electronic packaging were prepared by hot pressing at 700-1000 degrees C. The interface diffusion behavior, microstructure, and properties of Kovar/40Cu composites were studied. The results show that the interfacial diffusion of elements from Kovar to Cu matrix occurs when the temperature reaches 800 degrees C, and the diffusion rate of elements from Kovar to Cu matrix is greater than that from Cu matrix to Kovar. The strength of the composite material increases with the temperature, and the strength can reach 547.6 MPa after hot pressing 1000 degrees C/1 h. However, the elongation of composite material increases first and then decreases. After hot pressing at 800 degrees C/0.5 h, the maximum elongation is 20.1 %. Under the influence of solid solution atoms, the thermal conductivity of the composite decreases continuously, and the thermal expansion coefficient increases first and then decreases. The optimal sintering parameter is 800 degrees C/0.5 h.