Thermal performance enhancement of packaging substrates with integrated vapor chamber

The first part of this research investigates the effects of copper structures, such as copper through-package-vias (TPVs), and copper traces in redistribution layer (RDL), on the thermal performance of glass interposers through numerical and experimental approaches. Numerical parametric study on 2.5D interposers shows that as more copper structures are incorporated in glass interposers, the performance of silicon and glass interposers becomes closer, showing 31% difference in thermal resistance, compared to 53% difference without any copper structures in both interposers. In the second part of this study, a thermal model of glass interposer mounted on the vapor chamber integrated PCB is developed using multi-scale modeling scheme. The comparison of thermal performance between silicon and glass interposers shows that integration of vapor chamber with PCB makes thermal performance of both interposers almost identical, overcoming the limitation posed by low thermal conductivity of glass. The third part of this thesis focuses on design, fabrication, and performance measurement of PCB integrated with vapor chamber. Copper micropillar wick structure is fabricated on PCB with electroplating process, and its wettability is enhanced by silica nanoparticle coating. Design of the wick for the vapor chamber is determined based on the capillary performance and permeability test results. Fabricated device with ultra-thin thickness (~800 µm) shows higher thermal performance than copper plated PCB with the same thickness. Finally, 3D computational fluid dynamics/heat transfer model of the vapor chamber is developed, and modeling result is compared with test result.Ph.D

Electronics Thermal Management in Information and Communications Technologies: Challenges and Future Directions

This paper reviews thermal management challenges encountered in a wide range of electronics cooling applications from large-scale (data center and telecommunication) to smallscale systems (personal, portable/wearable, and automotive). This paper identifies drivers for progress and immediate and future challenges based on discussions at the 3rd Workshop on Thermal Management in Telecommunication Systems and Data Centers held in Redwood City, CA, USA, on November 4–5, 2015. Participants in this workshop represented industry and academia, with backgrounds ranging from data center thermal management and energy efficiency to high-performance computing and liquid cooling, thermal management in wearable and mobile devices, and acoustic noise management. By considering a wide range of electronics cooling applications with different lengths and time scales, this paper identifies both common themes and diverging views in the thermal management community

A review of metal foam and metal matrix composites for heat exchangers and heat Sinks

Recent advances in manufacturing methods open the possibility for broader use of metal foams and metal matrix composites (MMCs) for heat exchangers, and these materials can have tailored material properties. Metal foams in particular combine a number of interesting properties from a heat exchanger's point of view. In this paper, the material properties of metal foams and MMCs are surveyed, and the current state of the art is reviewed for heat exchanger applications. Four different applications are considered: liquid-liquid, liquid-gas, and gas-gas heat exchangers and heat sinks. Manufacturing and implementation issues are identified and discussed, and it is concluded that these materials hold promise both for heat exchangers and heat sinks, but that some key issues still need to be solved before broad-scale application is possible

NASA SBIR abstracts of 1990 phase 1 projects

The research objectives of the 280 projects placed under contract in the National Aeronautics and Space Administration (NASA) 1990 Small Business Innovation Research (SBIR) Phase 1 program are described. The basic document consists of edited, non-proprietary abstracts of the winning proposals submitted by small businesses in response to NASA's 1990 SBIR Phase 1 Program Solicitation. The abstracts are presented under the 15 technical topics within which Phase 1 proposals were solicited. Each project was assigned a sequential identifying number from 001 to 280, in order of its appearance in the body of the report. The document also includes Appendixes to provide additional information about the SBIR program and permit cross-reference in the 1990 Phase 1 projects by company name, location by state, principal investigator, NASA field center responsible for management of each project, and NASA contract number

Heat Exchangers

The demand for energy to satisfy the basic needs and services of the population worldwide is increasing as are the economic costs associated with energy production. As such, it is essential to emphasize energy recovery systems to improve heat transfer in thermal processes. Currently, significant research efforts are being conducted to expose criteria and analysis techniques for the design of heat exchange equipment. This book discusses optimization of heat exchangers, heat transfer in novel working fluids, and the experimental and numerical analysis of heat transfer applications

Index to NASA Tech Briefs, 1975

This index contains abstracts and four indexes--subject, personal author, originating Center, and Tech Brief number--for 1975 Tech Briefs

High-Performance Integrated Window and Façade Solutions for California

The researchers developed a new generation of high-performance façade systems and supporting design and management tools to support industry in meeting California’s greenhouse gas reduction targets, reduce energy consumption, and enable an adaptable response to minimize real-time demands on the electricity grid. The project resulted in five outcomes: (1) The research team developed an R-5, 1-inch thick, triplepane, insulating glass unit with a novel low-conductance aluminum frame. This technology can help significantly reduce residential cooling and heating loads, particularly during the evening. (2) The team developed a prototype of a windowintegrated local ventilation and energy recovery device that provides clean, dry fresh air through the façade with minimal energy requirements. (3) A daylight-redirecting louver system was prototyped to redirect sunlight 15–40 feet from the window. Simulations estimated that lighting energy use could be reduced by 35–54 percent without glare. (4) A control system incorporating physics-based equations and a mathematical solver was prototyped and field tested to demonstrate feasibility. Simulations estimated that total electricity costs could be reduced by 9-28 percent on sunny summer days through adaptive control of operable shading and daylighting components and the thermostat compared to state-of-the-art automatic façade controls in commercial building perimeter zones. (5) Supporting models and tools needed by industry for technology R&D and market transformation activities were validated. Attaining California’s clean energy goals require making a fundamental shift from today’s ad-hoc assemblages of static components to turnkey, intelligent, responsive, integrated building façade systems. These systems offered significant reductions in energy use, peak demand, and operating cost in California

Complex fluid flow in microchannels and heat pipes with enhanced surfaces for advanced heat conversion and recovery systems

This paper addresses a multiscale approach for heat recovery systems, used in two distinct applications. In both applications, a microscale approach is used (microchannel heat sinks and heat pipes) for macroscale applications (cooling of a photovoltaic—PV cell), and the thermal energy of exhaust gases of an internal combustion engine is used for thermoelectric generators with variable conductance heat pipes. Several experimental techniques are combined such as visualization, thermography with high spatial and temporal resolution, and the characterization of the flow hydrodynamics, such as the friction losses. The analysis performed evidences the relevance of looking at the physics of the observed phenomena to optimize the heat sink geometry. For instance, the results based on the dissipated heat flux and the convective heat transfer coefficients obtained in the tests of the microchannel-based heat sinks for cooling applications in PV cells show an improvement in the dissipated power at the expense of controlled pumping power, for the best performing geometries. Simple geometries based on these results were then used as inputs in a genetic algorithm to produce the optimized geometries. In both applications, the analysis performed evidences the potential of using two-phase flows. However, instabilities at the microscale must be accurately addressed to take advantage of liquid phase change. In this context, the use of enhanced interfaces may significantly contribute to the resolution of the instability issues as they are able to control bubble dynamics. Such an approach is also addressed here.Authors acknowledge to Fundação para a Ciência e a Tecnologia¸ FCT and PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund, for partially financing this project through projects PTDC/EME-TED/7801/2020, JICAM/0003/2017, UIDB/00481/2020, UIDP/00481/2020, and CENTRO-01-0145-FEDER-022083 (Centro2020) and for funding the scholarship of Pedro Pontes, ref. SFRH/BD/149286/2019

Enhanced microchannel evaporator with integrated nanostructures in space application

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Elektronik cihazların işletim kapasitesinin artması ve elektronik ekipmanların boyutunun değişimi ile birlikte elektronik sanayinde ısıl yönetim önemli bir faktör haline gelmiştir. Elektronik ekipmanların gelecekte ısı yükünün artması ve elektronik ekipmanların boyutların küçülmesi ile birlikte günümüzde kullanılan ticari ısıl yönetim sistemlerinden hava ile soğutma sistemleri yeterli olmayacaktır. Yüksek ısı akılı elektronik ekipmanların performansının artırılması için ve elektronik ekipmanların güvenilir sıcaklık aralığında çalışabilmesi için ısının transfer edilmesi gerekmektedir. Isı tranferinde iyileştirme ekipman boyutlarının küçülmesine ve veriminin artmasına sebep olacaktır. Diğer ısı transfer yöntemleri ile karşılaştırıldığında havuz kaynamanın yüksek ısı akısını düşük duvar sıcaklığı ile transferi nedeni ile en iyi seçenek olmuştur. Buharlaştırıcılar buhar odası ve ısı boru tasarımlarında önemli rol oynamaktadır. Buharlaşma sırasında sıcaklık farkının azaltılması ve ısı akısının artırılması ısı transfer sistemlerine etki eden iki önemli alandır. Bu yüzden havuz kaynama kullanılarak ısı transferini artırmak için özel yüzeyler geliştirilmiştir. Bu özel yüzeyler mikrokanal, sinterlenmiş yüzey ve pin finlerdir. Bu çalışma ile ısı transferinin geliştirilmesi için mikrokanallar üzerinde birden fazla pasif teknik olarak kullanılan nanoyapılar, sinterlenmiş yüzeyler ve pin fin ile sağlanmıştır. Yedi yapı bireysel olarak incelenmiştir. Deneyler bakır malzeme ve gazı alınmış su kullanılarak mikrokanal, sinterlenmiş yüzey ve pin fin (mikro sütunlar) yapıların etkilerini incelemek için yapılmıştır. Kaynama performansı kritik ısı akısı ve ısı transferi katsayısı cinsinden ölçülmüştür. Kritik ısı akısı ve ısı transfer katsayısının bütün değiştirilmiş yüzeyler için düz bakır yüzeye oranla geliştiği görülmüştür.Increasing processing capacity within the size of electronic device has made thermal management a key factor to electronic industries. Commercialized thermal management such as conventional air cooling system will not suffice the future requirements due to effects of increasing heat dissipation and miniaturization. In order to increase performance of electronic devices with high heat flux needs to be dissipated and electronic devices must operate reliably within safe temperature ranges. Heat transfer improvement will result in lower size of equipment and increased efficency. Compared to other conventional methods of heat transfer, pool boiling offers a much attractive option, as it is able to dissipate large amount of heat at low wall superheats. Evaporators play a crucial role in the design of vapor chambers and heat pipes. Reducing the temperature difference during evaporation and increasing heat flux are two important areas that directly affect the performance of the heat transfer systems. Therefore, special surfaces have been developed to further enhance the heat transfer using pool boiling. These special surfaces are microchannel, sintered and pin-fins. The present study deals with enhancement of heat transfer using combination of multiple passive techniques, namely nanostructures and microporous sintered surfaces over open microchannel surfaces and microchannels with pin-fins. Seven structures were studied as individual. Experiments were conducted to study the effects of microchannel, sintered, and pin fins ( micropillar) on the boiling heat transfer from a copper chip in a pool of degassed water. Boiling performance was measured in terms of critical heat flux (CHF) and heat transfer coefficient (HTC). Both HTC and CHF have been greatly improved on all modified surfaces compared to the plain copper chip baseline

Patterning the Condenser-Side Wick in Ultra-Thin Vapor Chamber Heat Spreaders to Improve Skin Temperature Uniformity of Mobile Devices

Vapor chamber technologies offer an attractive approach for passive heat spreading in mobile electronic devices, in which meeting the demand for increased functionality and performance is hampered by a reliance on conventional conductive heat spreaders. However, market trends in device thickness mandate that vapor chambers be designed to operate effectively at ultra-thin (sub-millimeter) thicknesses. At these form factors, the lateral thermal resistance of vapor chambers is governed by the saturation temperature/ pressure gradient in the confined vapor core. In addition, thermal management requirements of mobile electronic devices are increasingly governed by user comfort; heat spreading technologies must be designed specifically to mitigate hot spots on the device skin. The current work considers these unique transport limitations and thermal requirements encountered in mobile applications, and develops a methodology for the design of vapor chambers to yield improved condenser-side temperature uniformity at ultra-thin form factors. Unlike previous approaches that have focused on designing evaporator-side wicks for reduced thermal resistance and delayed dryout at higher operating powers, the current work focuses on manipulating the condenser-side wick to improve lateral heat spreading. The proposed condenser-side wick designs are evaluated using a 3D numerical vapor chamber transport model that accurately captures conjugate heat transport, phase change at the liquid–vapor interface, and pressurization of the vapor core due to evaporation. A biporous condenser-side wick design is proposed that facilitates a thicker vapor core, and thereby reduces the condenser surface peak-to-mean temperature difference by 37% relative to a monolithic wick structure