Immersion Cooling of a Simulated Microelectronic Chip with Artificial Re-entrant Cavities

Abstract

Pool boiling heat transfer results for a 10 mm×10 mm rectangular chip immersed in subcooled FC-72 were reported. Three kinds of surfaces were tested : an untreated silicon wafer surface, an etched surface of a thin SiO₂ film that was sputtered on a silicon wafer, and the same kind of SiO₂ surface with artificial cavities. The cavities were a re-entrant type with mouth diameters ranging from 0.7 to 1.4μm. These artificial cavities were effective in reducing the boiling incipience superheat. For degassed FC-72, the boiling incipience temperature agreed fairly well with the theoretical prediction of the heterogeneous nucleation theory. When the dissolved air content of the test liquid was sufficiently high, the chip temperatures at boiling incipience and at fully developed nucleate boiling were significantly decreased.