The　paper　is　focused　on　the　investigation　of　the　laminar　flow　and　heat　transfer　characteristics　in　the　interrupted　microchannel　heat　sink　with　ribs　in　the　transverse　microchambers.　A　three-dimensional　model　based　on　finite　volume　approach　and　SIMPLEC　algorithm　is　performed　considering　entrance　effect,　conjugate　heat　transfer,　viscous　heating　and　temperature-dependent　thermo-physical　properties.　Five　different　rib　configurations　are　considered,　including　rectangular,　backward　triangular,　diamond,　forward　triangular　and　ellipsoidal.　The　present　study　firstly　examines　the　effect　of　such　ribs　on　velocity　contour,　pressure　distribution　and　temperature　distribution,　further　the　local　pressure　drop　and　heat　transfer　characteristics　in　such　microchannel　heat　sinks.　Result　shows　that　the　ribs　in　the　transverse　microchambers　can　effectively　prevent　the　decline　of　local　heat　transfer　coefficient　along　the　flow　direction.　Secondly,　the　average　friction　factor　and　Nusselt　number　for　such　microchannel　heat　sinks　have　been　studied.　Results　show　that　for　Reynolds　number　ranging　from　187　to　715,　there　is　a　24-57%　increase　in　the　Nusselt　number　for　the　interrupted　microchannel　heat　sinks　with　ribs,　while　the　friction　factor　increased　by　3-70%,　comparing　with　the　straight　microchannel　heat　sink.　Finally,　based　on　the　performance　evaluation　criteria,　the　performance　of　such　microchannel　heat　sink　has　been　comprehensively　evaluated.　Results　shows　that　for　the　studied　Reynolds　number　range　and　microchannel　geometries　in　this　paper,　the　interrupted　microchannel　heat　sink　with　ellipsoidal　ribs　in　the　transverse　microchambers　shows　the　best　heat　transfer　performance,　with　maximum　1.39　of　performance　evaluation　criteria.　(C)　2016　Elsevier　Masson　SAS.　All　rights　reserved.