As　an　ideal　modifier,　the　cage-type　polyhedral　oligomeric　silsesquioxane　(POSS)-silanol　creates　a　strong　bonding　with　the　solder　without　agglomeration.　It　has　been　shown　that　the　addition　of　POSS-silanol　improves　both　the　mechanical　performance　and　the　solder＇s　resistance　to　electromigration.　This　study　further　examined　the　effect　of　the　addition　of　POSS-silanol　on　whisker　growth　in　a　Sn3.0Ag0.5Cu　(SAC305)　solder.　The　whisker　growth　was　studied　for　pure　SAC305　and　SAC305　modified　with　POSS-silanol　under　isothermal　aging　and　thermal　cycling　conditions.　The　results　indicate　that　the　added　POSS-silanol　not　only　reinforces　the　solder　joint,　but　also　inhibits　whisker　formation　under　both　thermal　aging　and　thermal　cycling　conditions.　POSS-silanol　can　therefore　be　considered　a　promising　modifier　material　which　enhances　the　reliability　of　solders.　During　the　thermal　aging　process,　the　added　POSS-silanol　was　found　to　inhibit　the　interdiffusion　of　Sn　and　Cu　atoms　at　the　interface　region,　thereby　preventing　the　formation　of　Cu6Sn5　but　promoting　the　conversion　of　Cu6Sn5　into　Cu3Sn.　During　the　thermal　cycling　process,　the　added　POSS-silanol　significantly　inhibited　whisker　formation　and　the　deformation　of　the　interface　by　stiffening　the　solder　matrix　and　decreasing　the　driving　force　for　whisker　formation.　(C)　2015　Elsevier　B.V.　All　rights　reserved.