It is often necessary to generate in-house pressure-drop and base-to-ambient thermal resistance data for ducted fan/heat sink assemblies. For reliable applicability of the performance data, the configuration of the test article should closely match the intended application so that the test article coolant flow characteristics (turbulence level, 3-dimensionality, etc.) match … [Read more...]
Simplified Transient Model for IC Packages
Previous installments of this column have all dealt with situations in which the die temperature was assumed to be at a constant temperature after the system had achieved the steady state. However, there are many times in which it is useful to know how rapidly the temperature of the chip changes when the applied power changes abruptly. This month's column presents a simple … [Read more...]
Thermal joint conductance for graphite materials
The heat flow across a metal/interstitial elastic-layer/metal joint is a very important problem in many microelectronic applications. It is generally known that when two surfaces are brought together, intimate solid-to-solid contact occurs only at discrete parts of the interface. Therefore, the actual contact area of pressed surfaces represents a very small fraction of the … [Read more...]
Thermal Design Challenges in Automotive Alternator Power Electronics
Ever since the advent of the automotive alternator, or claw-pole alternating current generator, in the 1960's, there has been an ever-increasing thermal design challenge to cool the power electronics in these machines. Figure 1 depicts a typical cutaway section of a modern day alternator. At first glance one may think that cooling the diodes in a rectifier bridge of an … [Read more...]
Understanding Phase Change Materials
Although phase change materials (PCM) were introduced nearly twenty years ago, it was not until the development of the high-powered Pentium processor that this class of interface material gained widespread acceptance. The large quantities of heat produced by these processors necessitated a carefully designed thermal path where all of the thermal resistances were minimized. For … [Read more...]
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