Experiments were performed to measure the incipient boiling heat flux in a heat sink containing 21 rectangular (231 lm wide and 713 lm deep) micro-channels. Tests were performed using deionized water with inlet liquid velocities of 0.13–1.44 m/s, inlet temperatures of 30, 60 and 90 C, and an outlet pressure of 1.2 bar. Using a microscope, boiling incipience was identified when the first bubbles...