ALUMINA-COPPER EUTECTIC BOND STRENGTH: CONTRIBUTION OF PREOXIDATION, CUPROUS OXIDES PARTICLES AND PORES

The in uences of cupric oxide layer thickness, cuprous oxide particles and pores on the mechanical properties and microstructure of an alumina-copper eutectic bond have been investigated. The furnace atmosphere in the rst stage was argon gas with 2 10 6 atm oxygen partial pressure. In the second stage, the furnace atmosphere was the same as the rst stage except that the cooling interval was between 900-1000 C and the hydrogen gas was injected into the furnace atmosphere. Finally, in the last stage, a vacuum furnace with 5 10 8 atm pressure was chosen for the bonding procedure. The peel strength of rst stage specimens shows that a cupric oxide layer with 320 25 nm thickness generates maximum peel strength (13:1 0:3 kg/cm) in the joint interface. In the second stage, by using hydrogen gas, a joint interface free from any cuprous oxide particles was formed. In this case, the joint strength has increased to 17:1 0:2 kg/cm. Finally, the bonding process in the vacuum furnace indicates that the furnace gas does not have a considerable e ect on joint interface pores. Furthermore, the bonding process in the vacuum furnace reduces the peel strength of the joint due to the formation of more pores. A thorough study of pore formation is presented.