A thermal spreader comprises: a casing having a first side contacted with a heat source and a second side secured with a heat sink, and having a vapor chamber defined in an interior in the casing; and a crosslinking capillary lattice retained in the casing and occupying the vapor chamber in the casing, whereby upon evacuation to form vacuum in the vapor chamber and filling of a vaporizable working fluid in the vapor chamber, the working fluid will be repeatedly vaporized and condensed through the crosslinking capillary lattice to absorb and remove heat from the first side of the casing and to dissipate heat outwardly from the second side of the casing.
