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News Bits and Pieces -
May 26, 2006
A paper written by two Flomerics executives, Márta Rencz and András Poppe, as well as Erno Kollar, Sándor Ress, and Vladimir Székely of the Budapest University of Technology and Economics (BUTE), has been selected as the best of 2005 by the editors of the Institute of Electrical and Electronics Engineers, Inc. (IEEE) Transactions on Components and Packaging Technologies. The paper, entitled “Increasing the Accuracy of Structure Function Based Thermal Material Parameter Measurements” was selected from among nearly 100 manuscripts published in the past year’s volume of the Transactions. The paper appeared in the March 2005 issue (volume 28, issue 1, page 51-57). The Award will be presented on June 1, 2006 at the 56th Electronic Components and Technology Conference in San Diego, California.
The paper explains that structure functions provide a one dimensional representation of the heat flow path of thermal systems and can be obtained by fast and simple thermal transient measurements. The usual way of generating structure functions considers only one heat path. Heat is switched on a point in the structure and the temperature of the point is recorded as a function of time until a steady state is reached. The structure functions are determined by direct mathematical transformations from the measured transient curves. There is always a certain error in these measurements due to parasitic heat flow moving in other directions than the one dimension that is being measured. Parasitic effects can consist of natural convection, radiation losses, and conduction through the fixture itself.
The new method developed by the Flomerics and BUTE researchers improves measurement results by accounting for parasitic heat flow. This method measures the parasitic heat flow path in addition to the thermal transients and then subtracts the thermal impedance of the parasitic branches during the phase of generating the structure functions. The paper presented an application example involving measuring the effective thermal conductivity of a patterned printed circuit board. The paper also included the results of a set of verification experiments in a vacuum chamber that considered the effects of parasitic heat flow paths with single parallel thermal resistances. The authors are currently working on considering parallel heat flow paths with their structure functions.
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