Thermal management of electronic equipment is a dynamic process. For example, the anticipated power trends for CMOS technology can be found in the roadmaps of [1 and 2]. They closely follow the rapidly rising power trends seen in the 1980s for the bi-polar circuits [3] but with a time shift by a decade. It is a fortunate circumstance that a tremendous amount of heat transfer … [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...]
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...]
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...]
We still have a headache with Arrhenius
"We have a headache with Arrhenius" was attributed to Takehisa Okada, Senior General Manager of Sony Corporation, when asked about Sony's perspective on reliability prediction methods during a U.S. Japanese Technology Evaluation Center visit.[1] The thermal environment is an important consideration in the design of electronics. Temperatures that arise during the use of … [Read more...]
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