Indium　is　acknowledged　as　a　preferred　material　for　micro-light-emitting　diodes　(micro-LEDs)　flip-chip　bonding　within　the　industry,　due　to　its　favorable　economic　characteristics　and　low　melting　point.　However,　indium　bumps　fabricated　via　photolithography　and　thermal　evaporation　often　exhibit　irregular　shapes　and　varying　heights,　and　they　readily　oxidize　in　air　to　form　a　tightly　adhered　oxide　layer　(In2O3),　leading　to　flip-chip　bonding　failures　and　blind　pixels.　The　reflow　process　can　not　only　remove　the　oxide　layer　but　also　enhance　bump　uniformity.　Nevertheless,　literature　on　indium　reflow　predominantly　focuses　on　planar　substrates,　with　limited　studies　on　high-resolution　micro-LED　chips　for　flip-chip　bonding.　This　paper　details　the　preparation　of　micro-LED　chips　with　a　pixel　density　(pixel　per　inch,　PPI)　of　3175.　An　indium　bump　array　with　a　diameter　of　approximately　5　μm　was　prepared　on　the　micro-LED　chips　using　thermal　evaporation　technology.　The　influence　of　reflow　time　and　temperature　on　indium　bumps　was　thoroughly　investigated　by　the　formic　acid　reflow　process,　revealing　that　under　the　conditions　of　270　°C　and　180　s,　the　indium　bumps　with　a　narrower　size　distribution　could　be　reflowed　into　spherical　shapes　on　the　micro-LED　structure.　Furthermore,　an　inversely　proportional　relationship　was　discovered　between　mesa/metal　layer　height　and　indium　bump　growth,　which　influenced　the　reflow　effect.　Ultimately,　micro-LED　chips　were　integrated　with　si　complementary　metal–oxide–semiconductor　(CMOS)　driver　chips　through　flip-chip　bonding　technology,　resulting　in　the　successful　functioning　of　the　devices.　©　2024　Elsevier　B.V.