Nomenclature Q Heat load (W) COP Coefficient of Performance I Electrical current (Amps) T Temperature (°C) R Electrical resistance (Ohms) Z TE Figure of Merit (1/K) where Z = α2 / (ρ λ) Greek Letters Δ Change in value θ Thermal resistance (°C/W) ρ Electrical resistivity (Ohm-cm) α Seebeck coefficient (V/K) λ Thermal conductivity … [Read more...]
High Powered Chip Cooling — Air and Beyond
Introduction Over the past few years many people in the electronics industry have become concerned with the increases in heat density at both the chip and module level of packaging. This trend is not new and has been with us since the days of bipolar chips. As can be seen in Figure 1, the heat flux associated with bipolar circuit technologies steadily increased from the … [Read more...]
A Funny Thing Happened On The Way To The Heatsink
Introduction When faced with the task of calculating the temperature of an IC in a package, which has an external heat sink mounted to it, a thermal engineer usually obtains a values of three thermal resistances: ΘJC , the junction-to-case thermal resistance for the package, ΘCS , the case-to-sink thermal resistance representing the thermal interface material (TIM) between the … [Read more...]
Vibration Analysis For Electronic Equipment
This topic is rather esoteric and usually an afterthought in commercial and industrial applications. In military and defense electronics, it is one of the major drivers for design and product architecture early on in the design cycle with specific targets/budgets. As with junction temperature requirements in a thermal design, there are structural dynamic issues that need to be … [Read more...]
Threatened With a Pipe
I have become a Heel Dragger. When natural convection was all the rage, I was touting fans. Once fan cooling became the status quo, I started dropping hints about heat pipes and thermoelectric coolers. The technology roadmap showed nothing but higher power ahead, and I would soon need those fancier cooling tools. Now everybody senses that this air cooling act is growing stale, … [Read more...]
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