CARD-LOKS AND THERMAL RESISTANCE
Testingperformed by numerous users of Calmark's Series 225 and similar size Card-Loks(approx .25 high) has shown that the thermal resistance across the interface ofa card which is clamped to a cold plate will usually fall within the range of2° to 4°C inch/watt. Three piece Card-Loks of shorter lengthswill usually provide results close to the 2, while longer Card-Loks (over 6inches) may fall closed to the 4. These thermal resistance numbers applywhen testing is performed at or near sea level. When the same testing isperformed at high altitude or near vacuum conditions the results can besignificantly affected. Increases of from 10 to 40 percent would not beunusual, especially with longer three piece Card-Loks Five piece Card-Loks,such as Series 260 or 265, with their greater and more evenly distributedclamping forces, will greatly reduce these potential gradients.
The following chart provides an easy method of estimating the temperature riseacross the interface (junction) of the card and cold plate when thermalconductivity is the only means of heat transfer considered (heat loss due toradiation and convection minimized).
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