Assembly issues in three flip chip processes Available to Purchase

Discusses three simple and low‐cost flip chip assembly processes. First, flip chip on board using non‐conductive adhesive is evaluated. This process can give reasonable reliability and high assembly yield, when the parameters for epoxy placement and bonding are optimised. Second, the flip chip assembly process using reflowable no‐flow underfill is discussed. Because the underfill epoxy is already placed in the gap between the IC chip and the substrate before reflow, it is not easy to control the solder joints’ collapse and obtain the desired solder‐joint shapes and stand‐off distance during reflow. Finally, the stud bump bonding process is also discussed. It is not easy although possible to maintain the optimal dipping of the conductive adhesive, when the average height of the gold bumps is small. Some solutions for overcoming the above‐mentioned difficulties are presented in this paper.