Flip chip bonding using isotropically conductive adhesives

In this paper results of investigations concerning the reliability of adhesive bumps are presented. These bumps interconnect test flip chips with different sizes to both Al/sub 2/O/sub 3/ and FR4 substrates. The samples have been exposed to thermal cycling. The transition resistance of the bumps [TRR], and the resistance of daisy chains as criteria of the interconnection's quality, have been measured at different time instances of the environmental stress. Ag migration investigations were also carried out. This study shows that there is no reliable adhesive bump interconnection without the use of underfill material.