Electromigration study on the interconnects of high density power modules

As the current carrying requirements increase to power the loads within server equipment, the interconnect system throughout the complete power delivery path becomes a very critical element to the overall system reliability. In addition to the electrical attributes of the interconnect, the mechanical and electro-chemical nature of the interconnect system are also key. As the voltage delivered to server microprocessors continue to drop to sub 1 V levels, the high amperage demand increases the current densities on the interconnects including those within power module packages. These high current densities, which can be on the order of 10⁴ A/cm², may create long term reliability concerns due to electromigration phenomenon on the interconnect such as the internal fine-pitch ball grid array (BGA) interconnects used within power modules. This paper presents the results of a study which was performed to understand the possible electromigration impacts to the reliability of the BGA interconnects of high density power modules in real-world server applications.