Thermal analysis and characterization of electronic systems requires a knowledge of fluid velocity. In pursuit of this information, we often resort to measurement or calculation. The issue of measurement becomes a challenge since we are dealing with rather complex flows that tend to be highly nonisothermal. Therefore, it is our intention in this article to highlight the need … [Read more...]
The coefficient of thermal expansion
This is the second technical data feature that deals with the coefficient of thermal expansion (CTE). The first technical data feature, incorporated in the September 1997 issue, covered semiconductor materials, leadframes and solder alloys. This issue will discuss the temperature dependence of the CTE and present data on other materials that are of importance to electronic … [Read more...]
Thermal management of outdoor enclosures using phase change materials
Telephone equipment has traditionally been housed in large buildings, sheds and outdoor cabinets. The cooling of these facilities has been carried out using traditional methods. However, in many of the new systems being developed and deployed such as broadband ISDN, cellular and/or cable, heat dissipation densities will increase substantially [1]. Furthermore, the introduction … [Read more...]
Thermal management of telecommunications cabinets
Figure 1. Thermal analog model of an OSP enclosure Introduction Over the past twenty years, telecommunications electronics have become increasingly decentralized - moving ever furtherfrom the controlled and protected environment of the Central Office intothe Outside Plant (OSP). The OSP environment contains rain and humidity,dust and pollutants, significant daily and annual … [Read more...]
A practical formula for air-cooled boards in ventilated enclosures
Fig. 1 - Ventilated cabinet Introduction Natural air convection is commonly applied as a cooling technique for electronic equipment of moderate power density such as telecommunication boxes. The main advantage of natural convection isits intrinsic reliability, because air movement is generated simply bydensity gradients, if an external body force field exists. However, due … [Read more...]
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