As noted previously in this column, the trend of increasing electronic module power is making it more and more difficult to cool electronic packages with air. As a result there are an increasing number of applications that require the use of forced convection air-cooled heat sinks to control module temperature. An example of a widely used type of heat sink is the parallel plate … [Read more...]
An alternative approach to junction-to-case thermal resistance measurements
As more and more integrated circuits dissipate power at levels once reserved for power discrete devices, junction-to-case thermal resistance (JC or RJC) remains as important as ever. The difficulties in making JC measurements often leads to values that do not accurately indicate true junction temperature (TJ). The measurement difficulties are usually two-fold. First is … [Read more...]
Determining the junction temperature in a semiconductor package, part IV – localized heat generation on the die
In the standard thermal test environment, thermal test chips are designed to dissipate the applied power uniformly over most of the die surface. However, in many situations of practical interest, the power is dissipated over a localized area of the die. This column provides calculation methods to deal with the latter situation. Figure 1 illustrates the situation of interest … [Read more...]
Use of junction-to-board thermal resistance in predictive engineering
The readers of "Electronics Cooling" are familiar with the reasons why the junction to ambient thermal resistance [1], JA or RJA, is an inadequate description of the thermal performance of an integrated circuit. Likewise, you realize that vendors cannot continue to state the integrated circuit will work at a specified ambient temperature (55°C, 70°C, 85°C, or 125°C) as device … [Read more...]
Thermal resistance: an oxymoron?
Introduction Dark light, deafening silence, cruel kindness, living dead, fuzzy logic,honest politics. The adjectives seem to contradict the substantives; such afigure of speech is called an oxymoron. It will be argued within this articlethat 'thermal resistance' is also a serious candidate for this category, atleast if the concept is being applied without realizing the … [Read more...]
