Corrosion Failure Modes in a TAB200 Test Vehicle

Temperature-humidity bias (THB) tests were carried out for tape automated bonded (TAB) samples, consisting of Au/Cu/Cr metal bump structures and AI/Si interconnecting metallization tracks, passivated with P-doped glass. Three predominant failure modes were identified: 1) type A failure: corrosion of positive and negative metallization tracks; 2) type B failure: corrosion at the bond pad-bump interfaces; and 3) type C failure: debonding of the Cu/Sn inner leads from the bumps. While type C failure was mainly due to improper bonding parameters and thus not directly related to the corrosion process, the other two types were caused by specific ionic impurities. Adhesion between the various metalpassivation interfaces and the quality of the passivation both had a major influence on the corrosion characteristics.