In several earlier issues of Electronics Cooling, I discussed the thermal conductivity of air as a function of temperature and pressure. Therein, it was stated that the temperature dependence cannot be neglected, but that the pressure dependence, under 'normal' conditions, is virtually absent. But what is 'normal' these days? In 'normal' electronic systems we, indeed, need … [Read more...]
Thermal Calculations for Multi-chip Modules
Due to the flexible manufacturing processes for producing BGA packages, there has been an explosion of new package designs, many of which contain more than one integrated circuit chip [1]. Existing industry standards for IC package thermal characterization apply only to single-chip packages. This Calculation Corner will present some techniques for calculating the junction … [Read more...]
Effects of electrical noise on thermocouple measurements
Measurements of temperature in electronic equipment and in thermal characterization apparatus are most often made with thermocouples. As with any sensor, the goal is to gather information about the environment in the vicinity of the sensor, in this case the temperature. Unfortunately the environment around the entire instrumentation chain, including the lead wires and the data … [Read more...]
Optical instrumentation for the thermal characterization of electronic devices
What information does light, reflected from a running electronic device, carry? Our research team has been working upon this key question for almost a decade. As this magazine is dedicated to thermal issues, we will focus upon these aspects of optical probing. Figure 1 shows the general principle of our experimental method. Light is shone upon a running device. When the device … [Read more...]
Pyrolytic graphite – thermal performance by structure
Continuing our discussion of different forms of carbon, this column addresses the topic of pyrolytic graphite, a material that opens up many interesting applications not only for cooling but also for scientific measurement equipment. Pyrolytic graphite - the finest forms of which are often called Highly Ordered Pyrolytic Graphite (HOPG) - is manufactured through a pyrolysis … [Read more...]
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