Enhanced boiling heat transfer of FC-72 from surfaces with microstructures

For efficiently cooling electronic components, experiments were conducted to study the pool boiling heat transfer performance of FC-72 over silicon chips with surface microstructures. Four different microstructures were studied: a submicron-scale roughness fabricated by chemical vapor deposition of thin SiO₂ film (Chip CVD) or by sputtering of thin SiO₂ film followed by wet etching of the surface (Chip E), micro-reentrant cavities fabricated by a combination of microelectronic fabrication techniques (Chips CAVITY), and micro-pin-fins fabricated by dry etching (Chip PF). All chips with microstructures showed a considerable heat transfer enhancement compared to a smooth surface (Chip S) and the critical heat flux increased in the order of chips S, E, CVD, CAVITY and PF. Chip PF showed a sharp increase in heat flux with increasing wall superheat and the wall temperature at the critical heat flux (CHF) was less than the upper limit for the reliable operation of LSI chips, 85°C, and the maximum CHF can reach 80 W/cm².