Surface flatness is an important issue for thermal designers as it is directly related to thermal contact resistance between surfaces. In this column, the definitions of surface flatness related parameters are discussed. These definitions are presented here as in the ASME B46.1-1995 standard [1]. Surfaces are characterized by three main parameters: roughness, waviness, and … [Read more...]
Simple Formulas for Estimating Thermal Spreading Resistance
A problem commonly encountered in the thermal analysis of electronic packages is that of thermal spreading resistance. Thermal spreading resistance occurs as heat flows by conduction between a source and a sink with different cross-sectional areas. Examples of two situations involving spreading heat flow are shown in Figure 1. One example is that of a chip mounted on the bottom … [Read more...]
Nostradamitech
The big electronics design show was in town. Gino suggested we blow off work for the day and check it out. I was a little short on promotional pens and key chains, so I fell in with him. Gino is OK, even if he's one of those Reliability Engineers. The cavernous convention center was packed with flashy booths of the usual component, CAD-tool and test equipment vendors. It's … [Read more...]
Air Cooled Compact Heat Exchanger Design For Electronics Cooling
Introduction This article will discuss air-cooled compact heat exchanger design using published data. Kays & London's Compact Heat Exchangers [1] contains measured heat transfer and pressure drop data on a variety of circular and rectangular passages including circular tubes, tube banks, straight fins, louvered fins, strip or lanced offset fins, wavy fins and pin fins. … [Read more...]
Thermal Interface Materials: A Brief Review of Design Characteristics and Materials
Introduction In the past few decades, as microprocessors have continued to evolve along Moore's law, providing increased functionality and performance, there has been an associated increase in cooling demand driven both by the increase in raw power and in local power densities on the die, commonly referred to as "hot spots"[1, 2]. Considerable attention has therefore been given … [Read more...]
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