Introduction Thermal management of servers and communications equipment has become significantly more challenging over the past several years. As is well known, processor powers have increased to 150 W or more and are projected to continue to rise, despite the move to multi-core designs (and the huge investment in software that this entails) [1]. Rack-level functional density … [Read more...]
Electronics Cooling At Higher Pressures … a Positive Displacement Pump Solution
Introduction Many liquid cooling solutions in use today employ cooling system devices that result in system pressure drops limited to <0.5 bar (7.25 psi), which allows these systems to fit within the limits of centrifugal pumps. The evolution of alternative cooling devices has brought about pressure drop requirements >1.0 bar (14.50 psi) in some cases [1]. These higher … [Read more...]
Reliability Testing Of Thermal Greases
Introduction Thermal Interface Materials (TIMs) play a key role in the thermal management of electronic systems by providing a path of low thermal resistance between the heat generating devices and the heat spreader/sink. Typical TIM solutions include adhesives, greases, gels, phase change materials, pads, and solder alloys. Most TIMs consist of a polymer matrix, such as an … [Read more...]
Thermal Effusivity
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...]
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