Non-migration conductive adhesives

Ag filled isotropic conductive adhesives (ICAs) have been investigated as promising alternatives to lead-containing solders in surface mount technology (SMT) applications. However, one serious concern is the electromigration of silver filled ICAs, especially when used in high density interconnection assembly. This paper investigates electromigration resistance of ICAs using Ag-Sn alloys as conductive fillers. It was found that electromigration resistance depends on Ag:Sn ratios and that Ag-Sn alloys containing 25/spl sim/75 mol% of Sn have excellent resistance. These new ICAs and conventional ICAs (as reference) were evaluated for SMT, using chip components with several kinds of terminations for their stability of contact resistance and adhesion strength during reliability tests. From the test results, it can be concluded that the new ICAs are suitable potential materials for SMT application.