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...]
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...]
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...]
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...]
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...]
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