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 heat loss from a printed circuit board
In last issue's column, a method for calculating the thermal conductivity of a printed circuit board (PCB) was described. Now, we look at a more complicated heat transfer process, namely the loss of heat from the surface of a PCB to the ambient air. This situation is more challenging to describe mathematically since it involves the simultaneous processes of heat spreading by … [Read more...]
Conduction heat transfer in a printed circuit board
In this issue, we examine heat flow in a printed circuit board (PCB), which typically is a layered composite consisting of copper foil and a glass-reinforced polymer (FR-4). A cross-sectional view of such a laminated structure is illustrated in Figure 1. The Figure indicates the numbering system that will be used for indicating the different layers, numbered 1 through to … [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...]
