The present paper experimentally investigates the heat transfer enhancement of a microchannel heat sink subject to an impinging jet. In order to evaluate the cooling performance of the microchannel heat sink subject to an impinging jet, temperature distributions are measured by using a micro-thermal sensor array manufactured through simple and convenient microfabrication processes. Based on these experimental results, the thermal resistance of the microchannel heat sink subject to an impinging jet is obtained and compared with the thermal resistance as calculated numerically. In order to show the heat transfer enhancement of the microchannel heat sink subject to an impinging jet, its thermal resistance is compared with that of a microchannel heat sink with a parallel flow. Under the condition that the pumping power is 0.072 W, the thermal resistance of the microchannel heat sink subject to an impinging air jet is experimentally obtained to be 6.1 degreesC/W, which is enhanced by about 48.5% compared with that of the microchannel heat sink with a parallel flow. In addition, the microchannel heat sink subject to an impinging jet is shown to be superior to a manifold microchannel heat sink as a cooling device for advanced electronic equipment with high heat generation and compact size. (C) 2003 Elsevier Science B.V. All rights reserved.