Natural convection heat transfer characteristics of simulated microelectronic chips
01 Feb 1987-Journal of Heat Transfer-transactions of The Asme (American Society of Mechanical Engineers)-Vol. 109, Iss: 1, pp 90-96
TL;DR: In this article, the heat transfer coefficients were obtained with two heater heights (5 mm, 10 mm) and varying width (2 mm, approximately 70 mm) in water and R-113.
Abstract: Microelectronic circuits were simulated with thin foil heaters supplied with d-c power. The heaters were arranged in two configurations: flush mounted on a circuit board substrate or protruding from the substrate about 1 mm. Heat transfer coefficients (midpoint) were obtained with two heater heights (5 mm, 10 mm) and varying width (2 mm {approximately} 70 mm), in water and R-113. The height effect for single flush heaters agrees qualitatively with convectional theory; however, even the widest heaters agrees qualitatively with convectional theory; however, even the widest heaters have coefficients higher than predicted due to leading edge effects. The heat transfer coefficient increases with decreasing width, with the coefficient for 2 mm being about 150% above that for 20 mm {approximately} 70mm. This is attributed to three-dimensional boundary layer effects. The protruding heaters have a coefficient about 15 percent higher. Data were obtained for in-line and staggered arrays of flush heaters with varying distance between heaters. Coefficients for the upper heaters are below those for lower heaters, with the differences diminishing as the vertical or horizontal spacing increases. For the protruding heaters, the upper heaters have higher coefficients than the lower heaters.
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TL;DR: The chapter summarizes analytical, numerical, and experimental work in literature, in order to facilitate the improvement of existing schemes and provide a basis for the development of new ones on the thermal control of semiconductor devices, modules, and total systems.
Abstract: Publisher Summary Thermal control of electronic components has one principal objective, to maintain relatively constant component temperature equal to or below the manufacturer's maximum specified service temperature, typically between 85 and 100°C. It is noted that even a single component operating 10°C beyond this temperature can reduce the reliability of certain systems by as much as 50%. Therefore, it is important for the new thermal control schemes to be capable of eliminating hot spots within the electronic devices, removing heat from these devices and dissipating this heat to the surrounding environment. Several strategies have developed over the years for controlling and removing the heat generated in multichip modules, which include advanced air-cooling schemes, direct cooling, and miniature thermosyphons or free-falling liquid films. The chapter summarizes analytical, numerical, and experimental work in literature, in order to facilitate the improvement of existing schemes and provide a basis for the development of new ones. The chapter focuses on investigations performed over the past decade and includes information on the thermal control of semiconductor devices, modules, and total systems.
285 citations
TL;DR: In this paper, an experimental study of boiling heat transfer from a simulated microelectronic component immersed in a stagnant pool of dielectric Fluorinert (FC-72) is presented.
Abstract: An experimental study of boiling heat transfer from a simulated microelectronic component immersed in a stagnant pool of the dielectric Fluorinert (FC-72) is presented. Various enhancement surfaces were attached to an electrically heated copper calorimeter bar having a vertically oriented heat transfer surface area of 12.7 {times} 12.7 mm{sup 2}. A number of enhancement schemes aimed at a reduction of the incipience temperature overshoot were tested, employing various arrangement of fins, studs, grooves, and vapor-trapping cavities. Atmospheric pressure testing revealed a variation in the magnitude of boiling curve incipience temperature excursion as a function of both macro- and microcharacterization of the surface geometry and initial conditions (pressure and temperature history) prior to boiling. Increased incipience temperatures accompanied prolonged periods of nonboiling. It is assumed that this is due to vapor embryos within surface cavities collapsing to smaller radii. Large artificially created cavities (0.3 mm diameter) were found incapable of maintaining a stable vapor embryo for time periods greater than 10 min. In comparison to flat surfaces, low-profile surface geometries having a structure scale of the order of one bubble departure diameter resulted in significant enhancement of nucleate boiling while drilled surfaces had minimal effectiveness. Surface finish and artificial cavities hadmore » no effect on CHF, but levels of critical heat flux computed on base area were strongly dependent on macrogeometry, due in part to increased surface area.« less
237 citations
Cites background from "Natural convection heat transfer ch..."
...10 Comparison of present natural convection data with the correlation of Park and Bergles (1987) cavities, and horizontal cavities have on natural convection....
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...Ra,? (4) where 5 = 0.184 1 + 2.64 x l 0~ 5 1 - ° 0 3 6 2 (W/Wxf Mi J fT„=70mm developed by Park and Bergles (1987) for natural convection from a small foil heater of height H and width W (typical of electronic chip size) in R-l 13....
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148 citations
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TL;DR: A cooling system employs a cooling liquid and a cooling gas in a combined thermodynamic cycle to overcome the flow resistance of dense assemblies of heat generating components and to improve heat transfer by inducing turbulence, thereby reducing the effects of thermal hysteresis and boundary layer formation as mentioned in this paper.
Abstract: A cooling system employs a cooling liquid and a cooling gas in a combined thermodynamic cycle to overcome the flow resistance of dense assemblies of heat generating components and to improve heat transfer by inducing turbulence, thereby reducing the effects of thermal hysteresis and boundary layer formation. Sensible heat gain to the cooling liquid and gas and latent heat of vaporization of the cooling liquid also occur in channels through and over the components. The flow of cooling gas propels the cooling liquid through the channels. The cooling system is advantageous for cooling electronic components such as integrated circuits which exhibit relatively high degree of energy and physical density, in supercomputers. The cooling system may also be advantageously combined with an immersion cooling system for the power supply components in the computer.
121 citations
TL;DR: In this paper, the authors investigated the heat transfer in a discretely heated enclosure for single and multiple heater configurations and found that the heat source location corresponding to maximum heat transfer is a function of Grashof number.
90 citations