Polarity Effect of Electromigration on Solder Reactions
In fiip chip solder joints, electromigration-induced failure is dominated by current crowding at the cathode area of contact. The high current density in the current crowding region enhances the dissolution of UBM at the cathode and transforms Cu to Cu3Sn and to Cu6Sn5 and finally leads to void formation and failure; the interaction between electrical force and chemical force is a key factor in the failure. To understand the interaction and to avoid the complication due to current crowding, straight V-groove samples having Cu wires as electrodes were introduced.
KeywordsSolder Joint Electrical Force Cathode Side Anode Side Interfacial IMCs
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