Qualification challenges and results on flip-chip process

A series of reliability qualification tests have been performed on GaAs MMICs with SnAg solder bumps assembled onto laminate substrates. Qualification vehicles included both MMIC die and daisy chain structures; the former to assess any reliability issues related to the GaAs wafer process, and the latter to focus directly on reliability concerns related to the bumps. We have observed that significant attention must be paid in designing the board substrate, as this element of the assembly appears to have greater influence on the success or failure of the part than the die itself. Qualification tests performed on properly designed substrates have been successfully completed.