Electromigration　(EM)　has　become　one　of　the　reliability　concerns　to　the　electronic　solder　joint　due　to　its　increasing　capacity　to　bear　the　high　current　density　(10(4)　A/cm(2)).　Although　the　failure　induced　by　EM　can　trigger　a　large　void　across　the　entire　cathode　interface,　no　effective　solutions　are　presented　throughout　years　of　effort　on　this　problem.　Here,　the　composite　solder　joints　are　addressed　to　demonstrate　their　potential　roles　on　solving　the　EM　issue　in　the　eutectic　SnBi　solder　joints.　Micro-sized　Ni　particles　were　selected　to　intentionally　add　into　the　solder　matrix　due　to　their　extensive　application　as　a　barrier　layer　in　the　under-bump-metallization　(UBM)　of　flip　chip　solder　joints.　The　ultimate　results　illustrated　that　the　Ni　particles　can　react　with　Sn　to　form　the　cluster-type　Sn-Ni　intermetallic　compounds　(IMCs)　inside　the　solder　matrix　after　the　first　reflow.　Accordingly,　the　phase　segregation　of　Sn　and　Bi　was　significantly　inhibited　during　the　current　stressing,　demonstrating　the　Sn-Ni　IMCs　can　act　as　the　obstacles　to　obstruct　the　movement　of　dominant　diffusion　entity　(Bi　atoms/ions)　along　the　phase　boundaries.　(C)　2010　Elsevier　B.V.　All　rights　reserved.