Today's market offers many heatsink attachment and thermal interface options. Your design decisions usually aim to optimize product performance at minimum cost. Secondary effects, not always sufficiently considered, significantly impact production cost, delivery performance, and reliability. These effects stem from the impact of the heat sink attachment design on the product … [Read more...]
Heat pipe fundamentals
The use of heat pipes in thermal management is increasing rapidly as power densities in electronics continue to rise. Heat pipes are attractive because they can typically carry 100 or more times as much heat as an equivalent piece of solid copper. The basic principle of heat pipe operation is very simple. A small amount of working fluid, typically water, is sealed inside a … [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...]
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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