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Enhancement of evaporation heat transfer performance is important for cooling of electronic devices. Evaporation heat transfer coefficient of two types of porous surfaces supplied with water liquid film was studied experimentally. First porous surface was multi layers of meshed plates with micro-channel of 0.3 mm width. Thin water liquid film was supplied to the porous surface by bubbles. Evaporation...
Heat pipes are a closed tube or chamber of different shapes whose inner surfaces are lined with a porous capillary wick, containing a saturated working fluid. It is a technology not restricted to aerospace applications, which is frequently used as thermal control devices of satellites and space vehicles. Some other sectors are finding interest on applying heat pipes to promote the thermal control...
Nanofluids are basically made of a base fluid and a volume fraction of dispersed nanoparticles. In order to consider any fluid as a nanofluid, it must contain particle sizes within the range from 1nm up to 100nm. Nanofluids studies and analysis have been both increasing during the last years due to the fact they are able to provide great thermal conductivity enhancements compared to the base fluid...
The present work describes the method by which the thermal resistance of a flat heat pipe spreader can be more accurately computed. The total effectiveness of the heat spreader is dependent on the one-dimensional (R1D) thermal resistance and the thermal spreading resistance (Rs). Recently developed more accurate methods from the literature were used to calculate the spreading resistance by taking...
The demand for increasingly aggressive heat spreading in high power electronics has pushed the limits of existing vapor chamber wick technology. For optimal thermal performance, a vapor chamber wick must be able to provide enough capillary pressure to sustain fluid delivery while still maintaining a low thermal resistance. To minimize thermal resistance and increase capillary forces, small feature...
Micro/nanopillars have attracted increasing attention as wicking structures for applications in passive capillary-driven cooling technologies. Maximizing capillary pressure and thermal conductivity are the most common methods for increasing heat removal in these types of applications. It is well known that closely packed wicking structures produce a higher capillary pressure. However, a smaller spacing...
Fine pitch interconnects combined with 2.5D/3D packaging technology offers enormous potential towards decreasing signal latency and by making it possible to package increased electrical functionality within a given area. However, fine pitch interconnects present their own set of challenges not seen in packages with coarse pitch interconnects. Increased stresses within the Far Back End of Line (FBEOL)...
This study is focused on geometric optimization of a 2.5D interposer based single die flip-chip package. Parametric analyses using the well-established global-local finite element method (FEM) technique have been conducted on the package at both the pre and post encapsulation (or underfill) stages. At the pre and post encapsulation phases, effects of geometric parameters which included variations...
The crystallinity of electroplated copper thin-film interconnections varies drastically depending on its manufacturing process, and thus, their mechanical and electrical properties change significantly depending on their micro texture. These changes should cause the variation of the residual stress in the interconnections, and thus, electronic performance of devices and the lifetime of interconnections...
In stacked-die packages, through-silicon vias (TSVs) are used to connect adjacent dies through tiny solder microbumps. During thermal cycling associated with service, the thermal expansion mismatch between the copper TSVs and the silicon chips results in large residual stresses in the TSVs, along with significant interfacial shear stresses. These shear stresses drive diffusionally assisted interfacial...
In this paper, influence of temperature gradient in interconnects due to Joule heating in 3D packaging on electromigration failure is presented. Black's Mean Time to Failure (MTF) model relates exponentially to the temperature of interconnects which is assumed to be constant hence does not take into account temperature gradient. The developed electromigration model incorporates the driving force due...
This work presents the experimental design, bonding, and testing of a two-phase, embedded FEEDS manifold-microchannel cooler for cooling of high flux electronics. The ultimate goal of this work is to achieve 0.025 cm2-K/W thermal resistance at 1 kW/cm2 heat flux and evaporator exit vapor qualities at or exceeding 90% at less than 10% absolute pressure drop. Unlike previous experiments by the authors...
In this work, we designed, fabricated and characterized a novel hotspot testbed to dissipate ultra-high power density by two-phase convective boiling of refrigerant in a microgap with integrated micropin-fins and isolation air trenches around resistance heaters. The 300 µm long, 200 µm wide, and 10 µm tall microgap with 4 µm diameter micropin-fins was batch micro-fabricated in silicon. The 40 µm wide...
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