Abstract: A heat sink is provided for that eliminates inefficient coolant bypass channels. The heat sink comprises a coolant cavity that is defined by a cover and a body portion. The thermally conductive cover includes a first plurality of substantially uniformly dispersed pin fins that extend at an angle from the inside surface of the cover towards a section of the body portion that is opposite the cover. The body portion opposite the cover includes a second plurality of pin fins that extend in the opposite direction from the first plurality. The coolant cavity also includes thermal bosses that protrude from an inside surface of the body portion. The bosses run parallel to the first and second plurality of pin fins and extend from a point near the thermally conductive cover to the section of the thermally conductive body portion that is opposite to the thermally conductive cover.