David Copeland

Bio: David Copeland is an academic researcher from Fujitsu. The author has contributed to research in topics: Fin & Leakage (electronics). The author has an hindex of 2, co-authored 3 publications receiving 25 citations.

Fundamental Performance Limits of Heatsinks

Abstract: Dedicated fan-duct-heatsink combinations have become a standard means of cooling computer processors. Most previous studies have considered optimizaton of fin geometry (pitch and thickness) with overall heatsink dimensions (length, width, height) fixed. The present study considers size requirements for the constraints of fixed air volume flow rate and pressure drop, fixed fan/blower power, and fixed thermal conductance. First, an ideal heatsink with infinite fin thermal conductivity is considered, providing simple power-law prediction of performance. Next, fins of finite thermal conductivity and thickness are included in the analysis, permitting prediction and minimization of weight. Finally, effects of developing flow are incorporated, resulting in variations from the ideal predictions. Models of each of the three levels of complexity can be used, previous to more detailed numerical and/or experimental studies, to design optimized heatsinks.

Total Power Requirements for Near-Future Refrigerated Systems

Abstract: As feature dimensions of processors shrink to 100 nanometers and smaller, leakage current becomes a significant part of total power dissipation. The magnitude of power dissipated as leakage current can approach half that of the active current at higher junction temperatures. Leakage current exhibits a strong exponential relationship with temperature. Reduction of junction temperatures from a traditional value of 85 C to a near-ambient value of 25 C can reduce leakage current to a fraction of its usual value, and total power by nearly one-third. To date, refrigeration has been used to increase operating frequency and improve reliability, at the cost of considerable power consumption. At finer feature dimensions, the energy saved by reduction of junction temperature is comparable to that used by the refrigeration system. Realistic values of refrigeration performance, representative of current equipment and refrigerants, are used to perform a case study of a typical near-future processor. Leakage, active and refrigeration power requirements over a junction temperature range from 85 to 25 C are quantified.Copyright © 2003 by ASME

Fundamental performance limits of heatsinks

Abstract: Dedicated fan-duct-heatsink combinations have become a standard means of cooling computer processors. Most previous studies have considered optimizaton of fin geometry (pitch and thickness) with overall heatsink dimensions (length, width, height) fixed. The present study considers size requirements for the constraints of fixed air volume flow rate and pressure drop, fixed fan/blower power, and fixed thermal conductance. First, an ideal heatsink with infinite fin thermal conductivity is considered, providing simple power-law prediction of performance. Next, fins of finite thermal conductivity and thickness are included in the analysis, permitting prediction and minimization of weight. Finally, effects of developing flow are incorporated, resulting in variations from the ideal predictions. Models of each of the three levels of complexity can be used, previous to more detailed numerical and/or experimental studies, to design optimized heatsinks.

Thermal issues in next-generation integrated circuits

Abstract: The drive for higher performance has led to greater integration and higher clock frequency of microprocessor chips. This translates into higher heat dissipation and, therefore, effective cooling of electronic chips is becoming increasingly important for their reliable performance. We systematically explore the limits for heat removal from a model chip in various configurations. First, the heat removal from a bare chip by pure heat conduction and convection is studied to establish the theoretical limit of heat removal from a bare die bound by an infinite medium. This is followed by an analysis of heat removal from a packaged chip by evaluating the thermal resistance due to individual packaging elements. The analysis results allow us to identify the bottlenecks in the thermal performance of current generation packages, and to motivate lowering of thermal resistance through the board-side for efficient heat removal to meet ever increasing reliability and performance requirements.

Energy Efficient Heat Sink Design: Natural Versus Forced Convection Cooling

Abstract: In highly efficient converter systems, the power consumption of the cooling system (fans) significantly influences the total system efficiency as well as the power density. This paper investigates the potential of free convection cooled heat sinks and compares their performance to forced convection cooled heat sinks on the basis of their volume and power consumption. Underlying theoretical concepts for both types of cooling systems are summarized and their application in an optimization procedure is presented. The theoretical concepts are validated with prototype heat sinks. Finally, at an example of a half-bridge converter, it is shown that by free convection cooling, not only the efficiency but also the power density can be increased. In this case, by paralleling semiconductor devices the losses decrease approximately by a factor of three while simultaneously the heat sink volume can be reduced by approximately 50%.