In recent issues, this column has dealt with the use of a number of thermal metrics to calculate the junction temperature of integrated circuits under various conditions. These metrics explored were JA, JC, and JT. To summarize the uses of these metrics: JA represents the junction-to-air thermal resistance for a package tested in an industry-standard test environment. It is … [Read more...]
Determining the junction temperature in a plastic semiconductor package, part II
In the majority of applications involving plastic surface-mount packages, most of the heat generated by integrated circuits will flow to the printed circuit board (PCB) by way of the package leads and then to In higher-power applications it is often necessary to attach a heat sink to the top of the package to keep the junction temperature of the chip within specified limits. … [Read more...]
Determining the junction temperature in a plastic semiconductor package, part 1
One of the primary tasks of the thermal engineer is to determine the temperature of the junction (active circuitry on an integrated circuit) for the various packages in a system. Measurements performed in the industry-standard test environment are often used in this endeavor. The most common thermal metric [1,2] is the junction-to-air thermal resistance, JA (pronounced theta, … [Read more...]
Convection and radiation loss from a fin
In last issue's column, we discussed heat loss by convection and radiation from a printed circuit board in which heat spreads in a 2-D pattern. Here, we look at a slightly simpler situation, namely that of heat transfer by a fin into the ambient air. The situation is illustrated in Figure 1, where, for simplicity, the heat is shown flowing only out of the top surface of the … [Read more...]
Convection and radiation
In last issue's calculation corner,a simple 1-dimensional conduction calculation was described. This time, we look at the other two basic heat transfer processes, namely convection and radiation. In actual applications with multiple heat sources with complicated geometries, the effect of each of these mechanisms on the heat transfer process can be quite difficult to calculate. … [Read more...]
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