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...]
The increasing importance of thermal test dies
Thermal test dies are among the major tools used in package thermal design qualification. They are usually simple chips, containing heaters and temperature sensors. The sensors measure the temperature on the chip surface as a result of the steady state powering or the time dependence of the temperature increase or decrease in case of transient qualification. From these data, … [Read more...]
The thermal conductivity of fluids
About 10-15 years ago, fluids, either directly (mainly Fluorocarbons), or indirectly (cold plates flushed with water) cooled the majority of mainframe computers. Nowadays, the expected increase in heat flux density causes a renewed interest in either passive or active liquid cooling, because the limits of air cooling come within reach. Other practical applications in which … [Read more...]
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