In the August 2003 issue, the Technical Data column was devoted to emissivity in practical temperature measurements. But what about the emissivity value that should be entered in your numerical model? Can we use the measured values as discussed in the column mentioned? Let me summarize the main points of it: Emissivity is not only a material property but also a surface … [Read more...]
Integrated Heat Pipe Spreader for Improved FBDIMM Memory Module Thermal Management
Introduction Due to the increasing power density in today's industry standard servers, thermal design and cooling is a significant challenge. In a typical server, the two most challenging elements to cool are the processors and the memory modules. The system level fan speeds are directly dictated (in most cases) by both processor and memory temperatures. Due to the fact that … [Read more...]
Power Map Calculations Using Image Sources and Superposition
Introduction In the past, thermal engineers were content to calculate a single junction temperature in the thermal characterization of an integrated circuit chip in a package. In recent years, as power levels have increased, more attention has been paid to the calculation of local temperature variations on a chip. This is necessary to adequately account for high-heat-flux … [Read more...]
Pushing the Boundaries of Heat Pipe Operation
Introduction Heat pipes are well-established two-phase devices used in the electronics cooling industry to transport heat from the point it is generated to the place where it is extracted from the system. Three wick structures are most commonly used to provide the capillary path for the liquid return to evaporation section; these are sintered powder, screen mesh and grooved … [Read more...]
Heat of Vaporization
Thermal energy transfer associated with a change of phase can be a valuable phenomenon for engineers designing systems for electronics cooling. Solid to liquid phase change materials were described in the May 2005 Technical Data column and the topic for this issue is liquid to vapor phase change. The energy required to change a substance from a liquid state to a vapor state is … [Read more...]
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