A heat-transfer device includes a hollow heat-transfer member made of a thermally
conductive material and confining a vacuum sealed chamber therein. The heat-transfer
member includes a base portion that is adapted to be placed in thermal communication
with a heat source. The base portion has an outer wall surface, an inner wall surface
that is opposite to the outer wall surface and that confronts the vacuum sealed
chamber, and at least one coolant groove that extends from the inner wall surface
toward the outer wall surface and that is in fluid communication with the vacuum
sealed chamber. An amount of liquid coolant is contained in the vacuum sealed chamber
and is collected in the coolant groove.
