Novel Silver Solid-State Bonding Designs Between Two Copper Structures.

Both copper (Cu) and silver (Ag) have been studied extensively for electrical conductor applications. To expand the applications, two bonding designs were implemented in this paper. For the first design, a 50- \mu \textm Ag layer was annealed at 400 °C to increase Ag grain size, thereby making it more ductile. For the second design, a 5- \mu \textm Ag layer with cavities was created to release the thermal induced stress and allow easier plastic deformation for the bonding medium. For both designs, the resulting Cu substrates were bonded to Cu chips by the solid-state bonding process. The cross sections of bonded samples show no visible voids or gaps on Cu/Ag and Ag/Cu interfaces. The breaking forces of ten samples tested far exceed the requirement specified in the military standards MIL-STD-883J Method 2019.9. The successful demonstrations of solid-state bonding between Ag and Cu should open the possibility of bringing alternatives for bonding methods in the field of electronic packaging. [ABSTRACT FROM PUBLISHER]