專利摘要：
The present invention mainly provides a novel microchannel structure comprising a plurality of first fluid-guiding channels, a plurality of micro fluid-guiding channels and a plurality of second fluid-guiding channels. Particularly, the first fluid-guiding channel has an arc-shaped fluid-guiding end corner communicating with a first channel opening of the micro fluid-guiding channel, and the second fluid-guiding channel has an arc-shaped fluid-guiding start corner communicating with a second channel opening of the micro fluid-guiding channel. Therefore, when a refrigerant fluid flows in the heat sink, the flow speed of the refrigerant fluid would be changed because the cross sectional area of an U-shaped fluid-guiding channel constructed by the arc-shaped fluid-guiding end corner, the micro fluid-guiding channel and the arc-shaped fluid-guiding start corner varies along the flow direction of the refrigerant fluid, such that the heat dissipating ability of the heat sink is enhanced without increasing the power of circulation pump.