The Technical Data column of the previous issue discussed the concept of thermal diffusivity. It makes sense to discuss in this issue a related topic: thermal effusivity. While thermal diffusivity, a, is defined as the ratio between the thermal conductivity, k, and the volumetric thermal capacity, ρcp, the effusivity, e, is related to their product, as follows: It is … [Read more...]
Thermal Strain in Semiconductor Packages, Part II
Introduction This Calculation Corner continues Part I, published in the previous issue [1]. Part I described the construction of a typical flip-chip package configuration for high-power chips, consisting of a laminate assembly of materials adhesively bonded together and having different Coefficients of Thermal Expansion (CTE). The process of bonding these different materials … [Read more...]
A Practical Implementation Of Silicon Microchannel Coolers
Introduction More than twenty-five years ago, Tuckerman and Pease first described the use of silicon microchannel cooling for very high power densities [1]. However, the coolers could not be fabricated easily and pressure drops were very high. As chip power densities are now increasing beyond air cooling limits, a variety of liquid cooling methods are being investigated. Due to … [Read more...]
Air-Cooled, Pin Fin Coldwall Design For Operation At Altitude
Introduction Numerous thermal management techniques exist depending on the system, application, and power level. For airborne electronic systems, the most direct approach to thermal management would be to use ambient air or chilled air, provided by the aircraft, routed to and blown across the electronics. However, in some applications potential contaminants in the cooling air, … [Read more...]
Comparison Of Heat Transfer Rates Of Different Nanofluids On The Basis Of The Mouromtseff Number
Nanofluids are dispersions of nanometer-sized particles in a base fluid such as water, ethylene glycol or propylene glycol. In the last decade, nanofluids have attracted more attention as a new generation of coolants for various industrial and automotive applications. Use of high thermal conductivity metallic nanoparticles (e.g., copper, aluminum, silver, gold, etc.) … [Read more...]
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