of the mesh layer 12 a of the core 60 a the mesh 12 b is woven by a plurality of flexible metal wires such as copper wires or stainless steel wires so that the mesh 12 b has an intimate contact with the inner surface of the cavity 26 of the mold 20 alternatively the mesh 12 b may also be woven by a plurality of flexible fiber wires a molten or liquid filling material 14 then is filled into the cavity 26 and the pores of the mesh 12 b via filling tubes 222 defined at the top of the second mold 22 the filling material 14 is selected from such materials that can be easily removed after the heat spreader 100 is formed for example the filling material 14 may be paraffin or some kind of plastic or polymeric material or alloy that is liquefied when heated alternatively the filling material 14 may also be selected from gypsum or ceramic that is frangible after solidified the filling material 14 solidifies in the cavity 26 and binds with the mesh 12 b when it is cooled after the filling material 14 in the cavity 26 is solidified the mold 20 is removed as a result the pores of the mesh 12 b and the cavity 26 of the mold 20 are filled with the filling material 14 and the core 60 a is obtained the columns 16 a of the core 60 a are simultaneously formed by the filling material 14 filled in the columned tubes of the mold 20 thereafter the method as shown in fig3 includes an electrodeposition step in.