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...]
One-dimensional heat flow
The simplest heat flow situation is that described as “one-dimensional heat flow”. The Figure illustrates a one-dimensional heat flow situation. It shows heat flowing in one face of an object and out the opposite face. Each face is at a uniform temperature. There is no heat flow out of the sides of the object. The cross- sectional area of the object in the direction of heat … [Read more...]
Standardizing heat sink characterization for forced convection
Figure 1. Wind tunnel configuration Introduction While there has been a flurry of activity inliterature addressing the behavior of heat sinks in computer electronics,the reusability of the data presented in these papers has been somewhatlimited for two reasons: 1) The data presented is application specific. 2) There has never been a standard method for characterizing … [Read more...]
A simple method to estimate heat sink air flow bypass
Introduction After selecting or designing a heat sink based upon a given air velocity orvolumetric flow rate through the fins, the thermal designer needs to determinethe total amount of flow which must be delivered in the duct or card passagecontaining the module w with heat sink. As shown in Figure 1, some of the flowwill go around or bypass the heat sink. In fact, depending … [Read more...]
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