Effect of Surface Modification of Multi-walled Carbon Nanotubes on Thermal Conductivity of Underfill for Microelectronic Packaging PDF Download

Author:
Publisher:
ISBN:
Category : Carbon nanotubes
Languages : en
Pages : 252

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Author: Aisyah Borhan
Publisher:
ISBN:
Category : Metallic composites
Languages : en
Pages : 51

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Author: Nor Syazwani Abu Bakar
Publisher:
ISBN:
Category :
Languages : en
Pages : 31

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Author: Wei Lin
Publisher:
ISBN:
Category : Microelectronic packaging
Languages : en
Pages :

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As the integration scale of transistors/devices in a chip/system keeps increasing, effective cooling has become more and more important in microelectronics. To address the thermal dissipation issue, one important solution is to develop thermal interface materials with higher performance. Carbon nanotubes, given their high intrinsic thermal and mechanical properties, and their high thermal and chemical stabilities, have received extensive attention from both academia and industry as a candidate for high-performance thermal interface materials.\r : The thesis is devoted to addressing some challenges related to the potential application of carbon nanotubes as thermal interface materials in microelectronics. These challenges include: 1) controlled synthesis of vertically aligned carbon nanotubes on various bulk substrates via chemical vapor deposition and the fundamental understanding involved; 2) development of a scalable annealing process to improve the intrinsic properties of synthesized carbon nanotubes; 3) development of a state-of-art assembling process to effectively implement high-quality vertically aligned carbon nanotubes into a flip-chip assembly; 4) a reliable thermal measurement of intrinsic thermal transport property of vertically aligned carbon nanotube films; 5) improvement of interfacial thermal transport between carbon nanotubes and other materials.\r : The major achievements are summarized.\r : 1. Based on the fundamental understanding of catalytic chemical vapor deposition processes and the growth mechanism of carbon nanotube, fast synthesis of high-quality vertically aligned carbon nanotubes on various bulk substrates (e.g., copper, quartz, silicon, aluminum oxide, etc.) has been successfully achieved. The synthesis of vertically aligned carbon nanotubes on the bulk copper substrate by the thermal chemical vapor deposition process has set a world record. In order to functionalize the synthesized carbon nanotubes while maintaining their good vertical alignment, an in situ functionalization process has for the first time been demonstrated. The in situ functionalization renders the vertically aligned carbon nanotubes a proper chemical reactivity for forming chemical bonding with other substrate materials such as gold and silicon.\r : 2. An ultrafast microwave annealing process has been developed to reduce the defect density in vertically aligned carbon nanotubes. Raman and thermogravimetric analyses have shown a distinct defect reduction in the CNTs annealed in microwave for 3 min. Fibers spun from the as-annealed CNTs, in comparison with those from the pristine CNTs, show increases of ~35% and ~65%, respectively, in tensile strength (~0.8 GPa) and modulus (~90 GPa) during tensile testing; an ~20% improvement in electrical conductivity (~80000 S m−1) was also reported. The mechanism of the microwave response of CNTs was discussed. Such an microwave annealing process has been extended to the preparation of reduced graphene oxide.\r : 3. Based on the fundamental understanding of interfacial thermal transport and surface chemistry of metals and carbon nanotubes, two major transfer/assembling processes have been developed: molecular bonding and metal bonding. Effective improvement of the interfacial thermal transport has been achieved by the interfacial bonding.\r : 4. The thermal diffusivity of vertically aligned carbon nanotube (VACNT, multi-walled) films was measured by a laser flash technique, and shown to be ~30 mm2 s−1 along the tube-alignment direction. The calculated thermal conductivities of the VACNT film and the individual CNTs are ~27 and ~540 W m−1 K−1, respectively. The technique was verified to be reliable although a proper sampling procedure is critical. A systematic parametric study of the effects of defects, buckling, tip-to-tip contacts, packing density, and tube-tube interaction on the thermal diffusivity was carried out. Defects and buckling decreased the thermal diffusivity dramatically. An increased packing density was beneficial in increasing the collective thermal conductivity of the VACNT film; however, the increased tube-tube interaction in dense VACNT films decreased the thermal conductivity of the individual CNTs. The tip-to-tip contact resistance was shown to be ~1×10−7 m2 K W−1. The study will shed light on the potential application of VACNTs as thermal interface materials in microelectronic packaging.\r : 5. A combined process of in situ functionalization and microwave curing has been developed to effective enhance the interface between carbon nanotubes and the epoxy matrix. Effective medium theory has been used to analyze the interfacial thermal resistance between carbon nanotubes and polymer matrix, and that between graphite nanoplatlets and polymer matrix.

Author: Nur Anis Mohammad Sabri
Publisher:
ISBN:
Category : Nanotubes
Languages : en
Pages : 77

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Author: Xingyou Tian
Publisher: John Wiley & Sons
ISBN: 3527352422
Category : Technology & Engineering
Languages : en
Pages : 373

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Book Description
Thermal Management Materials for Electronic Packaging Practical resource exploring the theoretical and experimental basis as well as solutions for the development of new thermal management materials for electronic packaging Thermal Management Materials for Electronic Packaging: Preparation, Characterization, and Devices provides in-depth and systematic summaries on cutting-edge thermal management materials for high-power density electronic devices, introducing the preparation methods and application scenarios of thermal management materials for electronic packing, covering refinements of thermal conductivity theory and performance prediction models for multiphase composites, and overall focusing on key scientific issues related to the subject, such as the internal interface of new high thermal conductive substrate materials and the mechanism of spatial topology on performance. The text also discusses key issues on the design and preparation of thermal conductive substrate materials with high thermal conductive properties, including their characterization, properties, and manipulation, as well as the latest methods, techniques, and applications in this rapidly developing area. Sample topics covered in Thermal Management Materials for Electronic Packaging include: Basic concepts and laws of thermal conduction, heat conduction differential equation and finite solution, and thermal conductivity of solids Definition and classification of electronic packaging, thermal management in electronic equipment, and requirements of electronic packaging materials Synthesis and surface modification of high thermal conductive filler and the synthesis of substrates and preparation of thermal conductive composites with inorganic ceramic skeleton structure Assembly of thermal conductive materials in different dimensions and preparation of composite materials, and reliability analysis and environmental performance evaluation Thermal Management Materials for Electronic Packaging serves as an ideal reference for researchers and workers in related fields to significantly improve the mechanical and thermal management properties of materials, expand the material selection and design margin of substrates, and develop substrates that meet the application needs of different gradients.

Author: Stephen S. Furkay
Publisher:
ISBN:
Category : Electronic apparatus and appliances
Languages : en
Pages : 396

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Author: Nathan J. Victor
Publisher:
ISBN:
Category : Carbon
Languages : en
Pages : 310

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Author: Paritosh Garg
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Through past research, it is known that carbon nanotubes have the potential of enhancing the thermal performance of heat transfer fluids. The research is of importance in electronics cooling, defense, space, transportation applications and any other area where small and highly efficient heat transfer systems are needed. However, most of the past work discusses the experimental results by focusing on the effect of varying concentration of carbon nanotubes (CNTs) on the thermal performance of CNT nanofluids. Not much work has been done on studying the effect of processing variables. In the current experimental work, accurate measurements were carried out in an effort to understand the impact of several key variables on laminar flow convective heat transfer. The impact of ultrasonication energy on CNT nanofluids processing, and the corresponding effects on flow and thermal properties were studied in detail. The properties measured were viscosity, thermal conductivity and the convective heat transfer under laminar conditions. Four samples of 1 wt % multi walled carbon nanotubes (MWCNT) aqueous suspensions with different ultrasonication times were prepared for the study. Direct imaging was done using a newly developed wet-TEM technique to assess the dispersion characteristics of CNT nanofluid samples. The results obtained were discussed in the context of the CNT nanofluid preparation by ultrasonication and its indirect effect on each of the properties. It was found that the changes in viscosity and enhancements in thermal conductivity and convective heat transfer are affected by ultrasonication time. The maximum enhancements in thermal conductivity and convective heat transfer were found to be 20 % and 32 %, respectively, in the sample processed for 40 minutes. The thermal conductivity enhancement increased considerably at temperatures greater than 24 [degrees] C. The percentage enhancement in convective heat transfer was found to increase with the axial distance in the heat transfer section. Additionally, the suspensions were found to exhibit a shear thinning behavior, which followed the Power Law viscosity model.

Author: Vasudevan Raghavan
Publisher:
ISBN:
Category :
Languages : en
Pages : 88

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With technological advancements and ever-growing competition, the need for Carbon Nanotubes (CNTs) is now greater than ever. Some engineering applications for CNTs are sensors, field emission devices, energy storage, composite materials, and heat dissipation sinks. Heat transfer applications like the heat dissipation in computers remain a challenge. It has been theoretically proven that the thermal conductivity of Multiwalled Carbon Nanotubes (MWCNTs) can reach 3000 W/mK. Experimental measurements, however, have shown much lower values, although higher than those of carbon micro fibers and polymeric matrices. For polymeric composite materials, in-plane thermal conductivity is governed by the carbon fibers but the out of plane conductivity is dominated by the polymeric matrix. Using aligned CNT arrays in the transverse direction is expected to substantially increase the thermal conductivity. In this thesis a study was conducted to better understand heat conduction in CNT arrays and quantify their thermal conductivity. A method was devised to measure the thermal conductivity of carbon nanotube arrays based on Fourier's law. The method relied on using a strain gage as a heater and maintaining a steady state one dimensional flow. Heat was provided with a power source and thermocouples were placed at various points on the sample and connected to a thermocouple reader. Various parameters that affect the thermal conductivity of CNTs are the alignment, density, chirality, functionalization, and interface resistance. Interface resistance is one of the major parameters that affects the thermal conductivity. This thesis presents the results of a study on the effect of interface materials, array density and height on the thermal conductivity of CNT arrays.