In the Technical Data column of ElectronicsCooling Magazine, September 1998, the thermal conductivity of gases in general has been discussed. A few sentences were devoted to the temperature and pressure dependence of the most common gases. For example, it was stated that above 0.001 bar, the increase in thermal conductivity is of the order of magnitude of 1% per bar increase of … [Read more...]
The treacherous streams
During the development of a telecommunications product, an unpredictable phenomenon of air streams within the maze of cards and module was encountered. It could only be compared to suddenly confronting powerful inner streams in a calm ocean. Unlike the ocean, however, these streams appeared in a man-made machine. It seemed as if someone had rewritten the laws of physics. It was … [Read more...]
Thermal characterization of power ICs using virtual junction temperature
Thermal experts generally view thermal resistance as a measurable property of a semiconductor device. A system designer, who designs an appliance, is usually not a thermal expert. The system designer just needs a way to determine the size of the external heat sink. At high heat sink temperatures, less power dissipation is allowed in the device. The ratio at which case … [Read more...]
We still have a headache with Arrhenius
"We have a headache with Arrhenius" was attributed to Takehisa Okada, Senior General Manager of Sony Corporation, when asked about Sony's perspective on reliability prediction methods during a U.S. Japanese Technology Evaluation Center visit.[1] The thermal environment is an important consideration in the design of electronics. Temperatures that arise during the use of … [Read more...]
CFD: One measly letter away from CAD
"The stuff you engineers design is too good," the guy from Marketing said, "I need shoddier! Can you make them less efficient and cheaper?" I was working for a small company that made electric power conditioning equipment. Our devices protected against spikes, sags and brownouts in the AC power for mission-critical equipment like air traffic control radar and the computer … [Read more...]
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