Silicon device pad design considerations for solder flip chip applications

As the use of solder flip chip devices increases, it is important to ensure that the design and materials used in the die to solder bump structure are compatible with one another and provide a robust system that will meet reliability requirements. The key elements of this system are the final metal pad design, die passivation, and under bump metallization. This paper examines the interactions of these elements and offers some recommendations based on experimental observations.