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...]
Uncertainty analysis
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...]
Thermal characterization of active components
In the European project SEED (Supplier Evaluation and Exploitation of DELPHI), the methods for thermal characterization of active components developed in the predecessor DELPHI (Development of Libraries of PHysical models for an Integrated design environment) were evaluated by component suppliers. The methods were improved for practical application and extended to a large … [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...]
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...]
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