Reducing bonding cycle time of adhesive flip chip process

Abstract

Flip chip assembly using anisotropic conductive adhesives offers an interesting alternative for making high‐density interconnections. The use of conventional organic printed circuit boards makes this technique even more attractive. However, a low‐cost adhesive flip chip bonding process will require a reduced bonding cycle time or the use of multi‐head joining equipment. Adhesive flip chip bonding is characterized by a long bonding cycle time due to the relatively long curing time of adhesives and the need for simultaneous application of pressure during the curing process. In soldered flip chip techniques, the bonding time per assembly is shorter, because all the chips on the substrate can be soldered in a reflow oven at the same time. In this study, the minimum pre‐curing time needed to make a reliable adhesive joint was determined using one commercial anisotropic conductive adhesive film used on FR‐4 substrates. The results are promising, since bonding time reduction from 40 s to 10 s does not reduce the joint reliability.