Uncertainty analysis is the process of estimating the uncertainty in a result calculated from measurements with known uncertainties. Uncertainty analysis uses the equations by which the result was calculated to estimate the effects of measurement uncertainties on the value of the result. Uncertainty analysis is used in the planning stages of an experiment to judge the … [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...]
Improving productivity in electronic packaging with flow network modeling (fnm)
As the complexity and power density of electronics systems increase, so too does the demand for tools to improve both product quality and designer productivity. This is especially true for thermal designers who use Computational Fluid Dynamics (CFD) tools for thermal designs. Several important factors are driving this trend: System complexity has increased to the point that … [Read more...]
The thermal conductivity of pure metals
As discussed previously in this section, the measurement of the thermal conductivity is notoriously difficult. The consequence is that, while the measurement accuracy by individual researchers is claimed to be of the order of 2%, laboratories participating in round-robin tests produce results differing from each other by 15% or more [1]. Even the measurement of pure metals is … [Read more...]
Use of junction-to-board thermal resistance in predictive engineering
The readers of "Electronics Cooling" are familiar with the reasons why the junction to ambient thermal resistance [1], JA or RJA, is an inadequate description of the thermal performance of an integrated circuit. Likewise, you realize that vendors cannot continue to state the integrated circuit will work at a specified ambient temperature (55°C, 70°C, 85°C, or 125°C) as device … [Read more...]
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