The beneficial effect of underfilling on the reliability offlip-chip joints

摘要

Recently, several low cost alternatives for flip-chipinterconnection technology have been investigated. The scope of thispaper is a reliability study of flip-chip assemblies on varioussubstrates (mainly FR4). The deterioration (characterised by theelectrical resistance) of isotropically conductive adhesive and ofsolder (63Sn37Pb, 96.5Sn3.5Ag) bumps caused by both thermal cycling andthermal shocks are described. These investigations confirm that in lowcost flip-chip technology, there is practically no reliable bumpinterconnection without using underfill material