Experimental investigation and analysis of two-phase flow instability of flow boiling in a mini-channel heat sink

•A comprehensive experimental flow boiling study is conducted on the detailed analysis of flow instability.•Dominant flow patterns showing multi-channel flow instability are classified based on the visualization results.•Effects of heat flux, mass velocity, pressure, and inlet subcooling on flow instability are investigated.•A new flow stability map is developed utilizing a mini-channel heat sink.