Although the potential for low temperature enhancement of CMOS circuit performance has been recognized for some time, circuit scaling (proportionally reducing the size of the circuit) has been the preferred method of achieving higher performance. But as minimum feature size passed well into the sub-micron and now into the nanometer region, this route to higher performance has … [Read more...]
The Role of Natural Graphite in Electronics Cooling
Graphite is available as a variety of different material forms, the most useful in the electronics cooling market being pyrolytic graphite, graphite fiber reinforced carbon and polymer matrix composites, graphite foams and, the subject of this brief, natural graphite. The basic structure of graphite is shown in Figure 1. Figure 1. Structure of graphite crystal. The … [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...]
Characterizing a package on a populated printed circuit board
This column has emphasized methods of analyzing packages in the JEDEC-standard test environment. A thermal metric that lends itself to analyses of system applications is the junction-to-board thermal characterization parameter, JB. If one knows the board temperature (TB), then the junction temperature (TJ) can be determined by a simple application of the following formula: TJ … [Read more...]
General aspects on fan selection and layout
Introduction and Description of Fan Types Small ventilators are generally called fans. Depending on the geometrical design of the impeller, various constructional types are distinguished to indicate the main direction of the airflow. Here are the descriptions of the most important types of fans: Axial Fans Axial fans are characterized by their typical impeller form, which … [Read more...]
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