Thermal design engineers working in defense electronics are facing many challenges, some of which have been around for a long time and some that are more recent. Worldwide climatic extreme temperatures are reasonably constant and there are many military electronic systems that function in these extremes. As a result, there is significant design history available for … [Read more...]
A Few Design Techniques On How To Reduce The Power
There will always be the need to get heat out of high power circuitry, but with a little extra design effort up front, we may be able to reduce overall power needs. Here are two techniques that can help do that. Turn Idle Circuits Off A circuit that is not always used can be turned off until needed. This is a technique widely used in battery powered electronics, but it can be … [Read more...]
Thermal Calculations for Multi-chip Modules
Due to the flexible manufacturing processes for producing BGA packages, there has been an explosion of new package designs, many of which contain more than one integrated circuit chip [1]. Existing industry standards for IC package thermal characterization apply only to single-chip packages. This Calculation Corner will present some techniques for calculating the junction … [Read more...]
The Thermal Conductivity of Air at Reduced Pressures and Length Scales
In several earlier issues of Electronics Cooling, I discussed the thermal conductivity of air as a function of temperature and pressure. Therein, it was stated that the temperature dependence cannot be neglected, but that the pressure dependence, under 'normal' conditions, is virtually absent. But what is 'normal' these days? In 'normal' electronic systems we, indeed, need … [Read more...]
Selective Surfaces
"Who's that guy with the gigantic novelty scissors?" I asked. "That's Percy," Herbie said, "VP of the Biological Intercommunications Group, BIG for short. The Lost Pet Tracking System has been his baby since Day One." There was a festive air at the Prairieton Police Station, kids holding dogs on leashes, colorful balloons tied to squad cars, even the high school marching … [Read more...]
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