55 research outputs found

    Mechanical and electrical characterisation of anisotropic conductive adhesive particles

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    This thesis presents research into the mechanical and electrical characterisation of Anisotropic Conductive Adhesive (ACA) particles and their behaviour within typical joints. A new technique has been developed for study of individual ACA particle mechanical and electrical performance when undergoing deformation. A study of the effects of planarity variations on individual electrical joints in real ACA assemblies is presented firstly, followed by the research on the mechanical deformation and electrical tests of individual ACA particles undergoing deformation. In the co-planarity research, experiments introducing deliberate rotation between a chip and substrate were designed and carried out to simulate planarity variations in ACA assemblies. There are two outputs from this part of the research. One is the planarity variation effects on individual electrical joints in ACA assemblies, and the other is the effect of bond thickness on the resistance of a real joint. [Continues.

    Novel fine pitch interconnection methods using metallised polymer spheres

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    There is an ongoing demand for electronics devices with more functionality while reducing size and cost, for example smart phones and tablet personal computers. This requirement has led to significantly higher integrated circuit input/output densities and therefore the need for off-chip interconnection pitch reduction. Flip-chip processes utilising anisotropic conductive adhesives anisotropic conductive films (ACAs/ACFs) have been successfully applied in liquid crystal display (LCD) interconnection for more than two decades. However the conflict between the need for a high particle density, to ensure sufficient the conductivity, without increasing the probability of short circuits has remained an issue since the initial utilization of ACAs/ACFs for interconnection. But this issue has become even more severe with the challenge of ultra-fine pitch interconnection. This thesis advances a potential solution to this challenge where the conductive particles typically used in ACAs are selectively deposited onto the connections ensuring conductivity without bridging. The research presented in this thesis work has been undertaken to advance the fundamental understanding of the mechanical characteristics of micro-sized metal coated polymer particles (MCPs) and their application in fine or ultra-fine pitch interconnections. This included use of a new technique based on an in-situ nanomechanical system within SEM which was utilised to study MCP fracture and failure when undergoing deformation. Different loading conditions were applied to both uncoated polymer particles and MCPs, and the in-situ system enables their observation throughout compression. The results showed that both the polymer particles and MCP display viscoelastic characteristics with clear strain-rate hardening behaviour, and that the rate of compression therefore influences the initiation of cracks and their propagation direction. Selective particle deposition using electrophoretic deposition (EPD) and magnetic deposition (MD) of Ni/Au-MCPs have been evaluated and a fine or ultra-fine pitch deposition has been demonstrated, followed by a subsequent assembly process. The MCPs were successfully positively charged using metal cations and this charging mechanism was analysed. A new theory has been proposed to explain the assembly mechanism of EPD of Ni/Au coated particles using this metal cation based charging method. The magnetic deposition experiments showed that sufficient magnetostatic interaction force between the magnetized particles and pads enables a highly selective dense deposition of particles. Successful bonding to form conductive interconnections with pre-deposited particles have been demonstrated using a thermocompression flip-chip bonder, which illustrates the applicable capability of EPD of MCPs for fine or ultra-fine pitch interconnection

    Nanowires for 3d silicon interconnection – low temperature compliant nanowire-polymer film for z-axis interconnect

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    Semiconductor chip packaging has evolved from single chip packaging to 3D heterogeneous system integration using multichip stacking in a single module. One of the key challenges in 3D integration is the high density interconnects that need to be formed between the chips with through-silicon-vias (TSVs) and inter-chip interconnects. Anisotropic Conductive Film (ACF) technology is one of the low-temperature, fine-pitch interconnect method, which has been considered as a potential replacement for solder interconnects in line with continuous scaling of the interconnects in the IC industry. However, the conventional ACF materials are facing challenges to accommodate the reduced pad and pitch size due to the micro-size particles and the particle agglomeration issue. A new interconnect material - Nanowire Anisotropic Conductive Film (NW-ACF), composed of high density copper nanowires of ~ 200 nm diameter and 10-30 µm length that are vertically distributed in a polymeric template, is developed in this work to tackle the constrains of the conventional ACFs and serves as an inter-chip interconnect solution for potential three-dimensional (3D) applications

    Trends and Techniques for Space Base Electronics

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    Simulations of various phosphorus and boron diffusions in SOS were completed and a sputtering system, furnaces, and photolithography related equipment were set up. Double layer metal experiments initially utilized wet chemistry techniques. By incorporating ultrasonic etching of the vias, premetal cleaning a modified buffered HF, phosphorus doped vapox, and extended sintering, yields of 98% were obtained using the standard test pattern. A two dimensional modeling program was written for simulating short channel MOSFETs with nonuniform substrate doping. A key simplifying assumption used is that the majority carriers can be represented by a sheet charge at the silicon dioxide silicon interface. Although the program is incomplete, the two dimensional Poisson equation for the potential distribution was achieved. The status of other Z-D MOSFET simulation programs is summarized

    Shuttle mission simulator baseline definition report, volume 1

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    A baseline definition of the space shuttle mission simulator is presented. The subjects discussed are: (1) physical arrangement of the complete simulator system in the appropriate facility, with a definition of the required facility modifications, (2) functional descriptions of all hardware units, including the operational features, data demands, and facility interfaces, (3) hardware features necessary to integrate the items into a baseline simulator system to include the rationale for selecting the chosen implementation, and (4) operating, maintenance, and configuration updating characteristics of the simulator hardware

    NASA Tech Briefs, March 1995

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    This issue contains articles with a special focus on Computer-Aided design and engineering amd a research report on the Ames Research Center. Other subjects in this issue are: Electronic Components and Circuits, Electronic Systems, Physical Sciences, Materials, Computer Programs, Mechanics, Machinery, Manufacturing/Fabrication, Mathematics and Information Sciences and Life Science

    Aeronautical engineering: A cumulative index to a continuing bibliography (supplement 248)

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    This publication is a cumulative index to the abstracts contained in Supplements 236 through 247 of Aeronautical Engineering: A Continuing Bibliography. The bibliographic series is compiled through the cooperative efforts of the American Institute of Aeronautics and Astronautics (AIAA) and the National Aeronautics and Space Administration (NASA). Seven indexes are included -- subject, personal author, corporate source, foreign technology, contract number, report number and accession number

    Microgravity Science and Applications: Program Tasks and Bibliography for Fiscal Year 1996

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    NASA's Microgravity Science and Applications Division (MSAD) sponsors a program that expands the use of space as a laboratory for the study of important physical, chemical, and biochemical processes. The primary objective of the program is to broaden the value and capabilities of human presence in space by exploiting the unique characteristics of the space environment for research. However, since flight opportunities are rare and flight research development is expensive, a vigorous ground-based research program, from which only the best experiments evolve, is critical to the continuing strength of the program. The microgravity environment affords unique characteristics that allow the investigation of phenomena and processes that are difficult or impossible to study an Earth. The ability to control gravitational effects such as buoyancy driven convection, sedimentation, and hydrostatic pressures make it possible to isolate phenomena and make measurements that have significantly greater accuracy than can be achieved in normal gravity. Space flight gives scientists the opportunity to study the fundamental states of physical matter-solids, liquids and gasses-and the forces that affect those states. Because the orbital environment allows the treatment of gravity as a variable, research in microgravity leads to a greater fundamental understanding of the influence of gravity on the world around us. With appropriate emphasis, the results of space experiments lead to both knowledge and technological advances that have direct applications on Earth. Microgravity research also provides the practical knowledge essential to the development of future space systems. The Office of Life and Microgravity Sciences and Applications (OLMSA) is responsible for planning and executing research stimulated by the Agency's broad scientific goals. OLMSA's Microgravity Science and Applications Division (MSAD) is responsible for guiding and focusing a comprehensive program, and currently manages its research and development tasks through five major scientific areas: biotechnology, combustion science, fluid physics, fundamental physics, and materials science. FY 1996 was an important year for MSAD. NASA continued to build a solid research community for the coming space station era. During FY 1996, the NASA Microgravity Research Program continued investigations selected from the 1994 combustion science, fluid physics, and materials science NRAS. MSAD also released a NASA Research Announcement in microgravity biotechnology, with more than 130 proposals received in response. Selection of research for funding is expected in early 1997. The principal investigators chosen from these NRAs will form the core of the MSAD research program at the beginning of the space station era. The third United States Microgravity Payload (USMP-3) and the Life and Microgravity Spacelab (LMS) missions yielded a wealth of microgravity data in FY 1996. The USMP-3 mission included a fluids facility and three solidification furnaces, each designed to examine a different type of crystal growth

    Proceedings of the Fifth Parabolic Dish Solar Thermal Power Program

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    The proceedings of the Fifth Parabolic Dish Solar Thermal Power Program Annual Review are presented. The results of activities within the Parabolic Dish Technology and Module/Systems Development element of the Department of Energy's Solar Thermal Energy Systems Program were emphasized. Among the topics discussed were: overall Project and Program aspects, Stirling and Brayton module development, concentrator and engine/receiver development along with associated hardware and test results; distributed systems operating experience; international parabolic dish development activities; and non-DOE-sponsored domestic dish activities. Solar electric generation was also addressed

    2000-2001 Graduate Catalog

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