Composite spreader for cooling computer chip with non-uniform heat dissipation

The performance of a composite spreader, with a 0.4 mm thick top layer of porous graphite (PG), for enhanced cooling with nucleate boiling of FC-72 dielectric liquid, and a 1.6 mm copper (Cu) substrate, for achieving better cooling of underlying 10 x 10 mm computer chip, with a non-uniform surface heat flux, is investigated. This spreader takes an advantage of the enhnaced nucleate boiling heat transfer of FC-72 dielectric liquid on PG and the good beat spreading by Cu. The dissipated thermal power by the chip has a cosine-like distribution with a peak-to-average heat flux, which varied up to 2.467. The spreader surface area, the total thermal power dissipated by the chip, removed from the surface of the spreader, and the total thermal resistance are calculated and compared with those of PG and Cu spreaders of same thickness, 2.0 mm. With Phi(max) = 2.467, 39.48 W and 72.0 W can be removed from the surface of composite spreaders cooled with saturation and 30 K subcooled boiling, compared to 43.0 and 65.3 W for Cu spreaders. The calculated surface areas and total thermal resistances of the composite spreaders, 6.82 cm(2) and 4.90 cm(2) and 0.284 and 0.68 degrees C/W, are smaller than for Cu spreaders, 12.26 cm(2) and 11.92 cm(2), and 0.51 and 0.83 degrees C/W. In addition, the calculated chip maximum surface temperatures of 62.37 degrees C and 72.2 degrees C, are lower than with Cu spreaders (72.67 degrees C and 76.30 degrees C).