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  • 1.
    Berglund, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    Optical measuring system using a camera and laser fan-out for narrow mounting on a miniaturized submarine2009Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim was to develop, manufacture and evaluate diffractive lenses, or diffractive optical elements (DOE), for use in correlation with a camera to add perspective in pictures. The application is a miniaturized submarine developed in order to perform distant exploration and analysis in harsh and narrow environments. The idea is to project a laser pattern upon the observed structure and thereby add geometrical information to pictures acquired with an onboard CMOS camera. The design of the DOE-structures was simulated using the optimal rotational angle method (ORA). A set of prototype DOEs were realized using a series of microelectromechanical system (MEMS) processes, including photolithography, deposition and deep reactive-ion etching (DRIE). The projected patterns produced by the manufactured DOEs were found to agree with the simulated patterns except for the case where the DOE feature size was too small for the available process technology to handle. A post-processing software solution was developed to extract information from the pictures, called Laser Camera Measurement (LCM). The software returns the x, y and z coordinate of each laser spot in a picture and provides the ability to measure a live video stream from the camera. The accuracy of the measurement is dependent of the distance to the object. Some of the patterns showed very promising results, giving a 3-D resolution of ~0.6 cm, in each dot, at a distance of 1 m from the camera. Lengths can be resolved up til 3 m distance from the submarine.

  • 2.
    Bruhn, F. C.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    Pauly, Kristian
    Kaznov, Viktor
    Extremely Low Mass Spherical Rovers for Extreme Environments and Planetary Exploration with MEMS2005In: Proc. of Int. Symp. on Artificial Intelligence, Robotics and Automation in SpaceArticle in journal (Refereed)
  • 3.
    Bruhn, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    Miniaturized Multifunctional System Architecture for Satellites and Robotics2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis describes and evaluates the design of nanospacecraft based on advanced multifunctional microsystems building blocks. These systems bring substantial improvements of the performance of nanosatellites and enable new space exploration, e.g. interplanetary science missions using minute space probes. Microsystems, or microelectromechanical systems, allows for extreme miniaturization using heritage from IC industry. Reducing mass and volume of spacecraft gives large savings in terms of launch costs.

    Definition and categorization of system and module level features in multifunctional microsystems are used to derive a spacecraft optimization algorithm which is compatible with commonly used concurrent engineering methods.

    The miniaturization of modules enables modular spacecraft architectures comprising powerful multifunctional microsystems, which are applicable to satellites between 10 and 1000’s of kg.

    This kind of complete spacecraft architecture has been developed for the NanoSpace-1 technology demonstrator satellite. The spacecraft bus uses multifunctional design to enable distributed intelligence and autonomy, graceful degradation, functional surfaces, and distributed power systems. The increase in performance of the new spacecraft architecture as compared with conventional nanosatellites is orders of magnitudes in terms of power storage, scientific payload mass ratio, pointing stabilization, and long time space operation.

    This high-performance system-of-microsystems architecture has been successfully employed on two space robotic concepts: a miniaturized submersible vehicle for Jupiter’s Moon Europa and a miniaturized spherical robot. The submersible is enabled by miniaturization of electronics into 3-dimensional, vertically integrated multi-chip-modules together with new interconnection methods. These technologies enabled the submersible vehicle tube-shaped design within 20 cm length and 5 cm diameter. The spherical rover was developed for long range and networked science investigations of interplanetary bodies. The rover weighs 3.5 kg and is shown to endure direct reentry on Mars, which increases the ratio between the landed mobile payload mass and the initial mass in Mars orbit by a factor of 18.

    List of papers
    1. Nanospace-1: The Impacts of the First Swedish Nanosatellite on Spacecraft Architecture and Design
    Open this publication in new window or tab >>Nanospace-1: The Impacts of the First Swedish Nanosatellite on Spacecraft Architecture and Design
    2003 In: Acta Astronautica, Vol. 53, p. 633-643Article in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-93730 (URN)
    Available from: 2005-11-03 Created: 2005-11-03Bibliographically approved
    2. Nanospace-1: Spacecraft Design using Advanced Modular Architecture (AMA)
    Open this publication in new window or tab >>Nanospace-1: Spacecraft Design using Advanced Modular Architecture (AMA)
    In: AIAA Journal of Spacecraft and RocketsArticle in journal (Refereed) Submitted
    Identifiers
    urn:nbn:se:uu:diva-93731 (URN)
    Available from: 2005-11-03 Created: 2005-11-03Bibliographically approved
    3. Spacecraft Design Optimization - A multifunctional Microsystem Module Implementation Method
    Open this publication in new window or tab >>Spacecraft Design Optimization - A multifunctional Microsystem Module Implementation Method
    Article in journal (Refereed) Submitted
    Identifiers
    urn:nbn:se:uu:diva-93732 (URN)
    Available from: 2005-11-03 Created: 2005-11-03Bibliographically approved
    4. Distributed Communication Architecture in Spacecraft System-of-Microsystems - A preliminary Analysis
    Open this publication in new window or tab >>Distributed Communication Architecture in Spacecraft System-of-Microsystems - A preliminary Analysis
    Show others...
    Article in journal (Refereed) Submitted
    Identifiers
    urn:nbn:se:uu:diva-93733 (URN)
    Available from: 2005-11-03 Created: 2005-11-03Bibliographically approved
    5. MEMS Enablement and Analysis of the Miniature Autonomous Submersible Explorer
    Open this publication in new window or tab >>MEMS Enablement and Analysis of the Miniature Autonomous Submersible Explorer
    Show others...
    2005 In: IEEE Journal of Oceanic Engineering, Vol. 30, no 1, p. 165-178Article in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-93734 (URN)
    Available from: 2005-11-03 Created: 2005-11-03Bibliographically approved
    6. A Preliminary Design for a Spherical Inflatable Microrover for Planetary Exploration
    Open this publication in new window or tab >>A Preliminary Design for a Spherical Inflatable Microrover for Planetary Exploration
    Show others...
    2008 (English)In: Acta Astronautica, ISSN 0094-5765, E-ISSN 1879-2030, Vol. 63, no 5-6, p. 618-631Article in journal (Refereed) Published
    Abstract [en]

    The Spherical Mobile Investigator for Planetary Surface (SMIPS) concept aims at making use of the latest developments within extreme miniaturization of space systems. The introduction of Microelectromechanical Systems (MEMSs) and higher level Multifunctional Microsystems (MMSs) design solutions gives the robot high performance per weight unit. The untraditional spherical shape makes it easily maneuverable and thus provides a platform for scientific investigations of interplanetary bodies. Preliminary investigations of the SMIPS concept show several advantages over conventional robots and rovers in maneuverability, coverage, size, and mass. A locomotion proof-of-concept has been Studied together with a new distributed on-board data system configuration. This paper discusses theoretical robot analysis, an overall concept, possible science, enabling technologies, and how to perform scientific investigations. A preliminary design of an inflatable multifunctional shell is proposed.

    National Category
    Aerospace Engineering
    Identifiers
    urn:nbn:se:uu:diva-93967 (URN)10.1016/j.actaastro.2008.01.044 (DOI)000258632900009 ()
    Available from: 2006-01-19 Created: 2006-01-19 Last updated: 2017-12-14Bibliographically approved
    7. Extremely Low Mass Spherical Rovers for Extreme Environments and Planetary Exploration with MEMS
    Open this publication in new window or tab >>Extremely Low Mass Spherical Rovers for Extreme Environments and Planetary Exploration with MEMS
    2005 In: Proc. of Int. Symp. on Artificial Intelligence, Robotics and Automation in SpaceArticle in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-93736 (URN)
    Available from: 2005-11-03 Created: 2005-11-03Bibliographically approved
  • 4.
    Bruhn, Fredrik C.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    Carsey, Frank D.
    Köhler, Johan
    Mowlem, Matt
    German, Chris
    Stenmark, Lars
    Behar, Alberto E.
    MEMS Enablement and Analysis of the Miniature Autonomous Submersible Explorer2005In: IEEE Journal of Oceanic Engineering, Vol. 30, no 1, p. 165-178Article in journal (Refereed)
  • 5.
    Bruhn, Fredrik C.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    Jansson, Sven-Erik
    Nilsson-Zandkarimi, Peter
    Köhler, Johan
    Redell, Ola
    Distributed Communication Architecture in Spacecraft System-of-Microsystems - A preliminary AnalysisArticle in journal (Refereed)
  • 6.
    Bruhn, Fredrik C.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    Köhler, Johan
    Stenmark, Lars
    Thornell, Greger
    Spacecraft Design Optimization - A multifunctional Microsystem Module Implementation MethodArticle in journal (Refereed)
  • 7.
    Bruhn, Fredrik C.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    Rathsman, Peter
    Stenmark, Lars
    Nanospace-1: Spacecraft Design using Advanced Modular Architecture (AMA)In: AIAA Journal of Spacecraft and RocketsArticle in journal (Refereed)
  • 8.
    Bruhn, Fredrik
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    Köhler, Johan
    Stenmark, Lars
    Nanospace-1: The Impacts of the First Swedish Nanosatellite on Spacecraft Architecture and Design2003In: Acta Astronautica, Vol. 53, p. 633-643Article in journal (Refereed)
  • 9.
    Köhler, Johan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    Bringing Silicon Microsystems to Space: Manufacture, Performance, and Reliability2001Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The incorporation of extremely compact multifunctional microsystems is a highly profitable long-term approach in spacecraft design. These systems bring substantial launch-cost reductions, and enable exciting space exploration and science missions.

    Silicon microsystems technology is an adequate choice for the multifunctional microsystem development. However, the development of basic microsystems technology cannot be financed within application-specific space missions. Rather, the microsystems technology should be matured through fundamental research.

    Silicon microsystems technology was used to develop a cold gas microthruster system suitable for minute movements of spacecraft (low Δv). In a hybrid integration, the system unit contains three silicon microsystem parts with four individual thrusters in total, together with external control electronics. The total mass is 0.35 kg.

    Further integration will result in a mass of 0.08 kg. Complete system integration means that all package and interconnection levels are integrated into the silicon microsystem units. Several vital issues must be addressed, e.g. the reliable bonding of silicon wafers, the microfabrication process compatibility, and the manufacture process sequence. A graphical tool is introduced for process sequence evaluation.

    Wafer bonding is used as fabrication process, assembly tool, and packaging technique. The quality and reliability of the bonded interfaces must be assessed in order to secure the operation of the microsystems in space. Therefore, statistical methods for burst test evaluation have been developed.

    Weibull fracture probability functions have been derived in order to interpret the bond quality. In addition, rank-sum tests on spot series and analysis of variance are performed for bond quality diagnostics. The dependence on annealing temperature and surface-activation are presented, together with diagnosed degradation of insufficiently annealed bonds due to different spaceflight environments (thermal cycling, vibration, γ-irradiation).

  • 10.
    Lekholm, Ville
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    Schlieren imaging of microrocket jets2009Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this report, microrockets from the company NanoSpace were studied using schlieren imaging techniques. The rocket chips are manufactured using MEMS technology, which requires compromises regarding the shape of the nozzle. The rocket chips are 22x22x0.85 mm, manufactured from laminated silicon. The nozzles are approximately 20 µm wide at the throat, and 350 µm wide at the exit. A semi in-line schlieren apparatus was designed, set up, and aligned. A small vacuum chamber was constructed, and a series of tests was conducted in order to qualitatively evaluate the consequences of these compromises, and other performance issues. It was found that the existing 1 kW quartz-tungsten-halogen lamp was sufficient as a light source, standard photographic equipment served well as an imaging device, and a 400 mm, f/7.9 achromatic doublet as schlieren lens, resolved enough detail in the exhaust gas to perform the studies. At maximum magnification, the viewing area was 7 by 4.5 mm, captured at 14 Mpixel, or about 1.5 µm/pixel. Several different rocket chips were studied, with helium, nitrogen and xenon as propellant gases. Feed pressure ranged from 0.5 bar to 3.5 bar, and the rockets were studied at atmospheric pressure and in vacuum, and with and without heaters activated. Through these studies, verification and visualization of the basic functionality of the rockets were possible. At atmospheric pressure, slipping of the exhaust was observed, due to the severe overexpansion of the nozzle. In vacuum, the nozzle was underexpanded, and the flow was seen to be supersonic. There was a measurable change in the exhaust with the heaters activated. It was also shown that the method can be used to detect leaks, which makes it a valuable aid in quality control of the components.

  • 11.
    Nguyen, Hugo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    Bejhed, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Materials Science. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    Williams, Kirk
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Materials Science. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    Jonsson, Kerstin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Materials Science. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    Kratz, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Materials Science. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    Eriksson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Materials Science. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    Köhler, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Materials Science. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    Lang, Martin
    Stenmark, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Materials Science. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    Micropropulsion systems research and manufacture in Sweden2003In: Proceedings of the 4th Round Table on Micro/Nano Technology for Space, ESTEC, Noordwijk, The Netherlands, ESTEC/ESA , 2003, p. 476-485Conference paper (Refereed)
    Abstract [en]

    Micropropulsion for spacecraft is an enabling technology for many future missions, and may increase the performance and drastically reduce the mass required for advanced propulsion systems. The Swedish activities in micropropulsion at The Angstrom Space Technology Centre (ASTC) are outlined. The research targets two major issues: the development of system parts, and the research into integration techniques and strategies. This paper collects a multitude of devices relevant to the micropropulsion system design, together with representative functional demonstrations.

    The items are mainly intended for chemical micropropulsion systems or fuel-feed systems for electric propulsion. In particular, gas handling devices, sensors, and actuators are presented. These include silicon nozzles, thin film heaters, suspended microcoil heaters, proportional piezoelectric valves, proportional and isolation valves using phase-change material, thermal throttle flow-regulators, high-pressure regulators, 3D-particle filters, and sensors for strain, pressure, flow, and thrust. Moreover, integration techniques and interface structures are presented, for example low-temperature plasma-assisted silicon wafer bonding, multiwafer bonding, thin film soldering, hermetic electric through-wafer via connections, and multiconnector through-wafer vias.

    Emphasis is on how these items are designed to allow for system integration in a multiwafer silicon stack, comprising a complete micropropulsion system. In this manner, all items form a parts collection available to the system design. This strategy is exemplified by three micropropulsion systems researched at the ASTC.

    First, the cold/hot gas micropropulsion system is suitable for small spacecraft or when the demands on stability and pointing precision are extreme. The system performance depends strongly on the use of gas flow control. The complete gas handling system of four independent thrusters is integrated in the assembly of four structured silicon wafers. Each independent thruster contains a proportional valve, sensors for pressure, temperature, and thrust feedback, a converging-diverging micronozzle, and a suspended microcoil heater. The mass of the system is below 60 g. In total, this will provide the spacecraft with a safe, clean, low-powered, redundant, and flexible system for three-axis stabilization and attitude control.

    Second, a Xenon feed system for ion propulsion is heavily miniaturized using microsystems technology. Basically, a micromachined high-pressure regulator receives the gas from the storage, and the flow is further modulated by a thermally controlled flow restrictor. The flow restrictor microsystem comprises narrow ducts, thin film heaters, suspended parts for heat management, and flow sensors. Hereby, the amount of xenon required by the electric propulsion systems can be promptly delivered. The complete system mass is estimated to 150g.

    Third, within the EU IST program, the ASTC participates in the development of a micro-pyrotechnic actuator system (Micropyros), suitable for short-duration space propulsion. The Micropyros integrate a full matrix of minute solid combustion rocket engines into panels situated on the spacecraft hull. The thrusters can be individually ignited, and each deliver thrust in the millinewton range. The ASTC focuses on the integration of the propulsion part by low-temperature bonding, and the characterization of the complete system.

  • 12.
    Nguyen, Hugo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    Köhler, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    Stenmark, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    The merits of cold gas micropropulsion in state-of-the-art space missions2002Conference paper (Refereed)
    Abstract [en]

    Cold gas micropropulsion is a sound choice for space missions that require extreme stabilisation, pointing precision or contamination-free operation. The use of forces in the micronewton range for spacecraft operations has been identified as a mission-critical item in several demanding space systems currently under development.

    Cold gas micropropulsion systems share merits with traditional cold gas systems in being simple in design, clean, safe, and robust. They do not generate net charge to the spacecraft, and typically operate on low-power. The minute size is suitable not only for inclusion on high-performance nanosatellites but also for high-demanding future space missions of larger sizes.

    By using differently sized nozzles in parallel systems the dynamic range of a cold gas micropropulsion system can be quite wide (e.g. 0 – 10 mN), while the smallest nozzle pair can deliver thrust of zero to 0.5 or 1 mN using continuously proportional gas flow control systems.

    The leakage is turned into an advantage enabling the system for continuous drag compensation. In this manner, the propellant mass efficiency can be many times as higher than that in a conventional cold gas propulsion system using ON-OFF-control.

    The analysis in this work shows that cold gas micropropulsion has emerged as a high-performance propulsion principle for future state-of-the-art space missions. These systems enable spacecraft with extreme demands on stability, cleanliness and precision, without compromising the performance or scientific return of the mission.

  • 13.
    Nguyen, Hugo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Materials Science.
    Thorslund, Robert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Materials Science.
    Thornell, Greger
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Materials Science.
    Köhler, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Materials Science.
    Stenmark, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Materials Science.
    Structural Integrity of Flat Silicon Panels for Nanosatellites: Modeling and Testing2006In: Journal of Spacecraft and Rockets, ISSN 0022-4650, E-ISSN 1533-6794, Vol. 43, no 6, p. 1319-1327Article in journal (Refereed)
    Abstract [en]

    To utilize the high mass fraction of silicon material in a nanosatellite based on micro-electro-mechanical systems, part of the structural function has been assigned to the flat silicon stacks embracing these systems. Three modules for destructive testing in bending, warping and shearing cases were built with 68x68x1 mm silicon stacks bonded in aluminium frames by in-situ casting of silicone rubber. The rubber served as the deformation zone between the stiff and brittle silicon stacks and their weaker and ductile aluminium frames. A special test module of the same size was built with strain gauges of Nichrome (thin film deposited directly on the surface of the silicon stack). Elastic deformation tests on this as well as simulations using finite element analysis were performed for bending, warping and shearing loads of up to 80, 40 and 99 N, respectively. The test module was disassembled after the test series and examined. The actual thickness of the rubber was measured and entered into the model for simulation. The correlation between simulations and experimental measurements was good with deviation of about 30%. The results show that the rubber works well as a mechanical interface. Its thickness influences the stress in the silicon stack significantly. The silicon stack stiffens the module by a factor of 46 and lowers the stress in its frame 24 times in shearing mode, which is the most relevant loading case for the satellite framework. Thus, the concept of using flat silicon panels as structural elements is fully feasible.

  • 14.
    Seppänen, Henri
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Kurppa, Risto
    University of Helsinki.
    Meriläinen, Antti
    University of Helsinki.
    Hæggström, Edward
    University of Helsinki.
    Real time contact resistance measurement to determine when microwelds start to form during ultrasonic wire bonding2013In: Microelectronic Engineering, ISSN 0167-9317, E-ISSN 1873-5568, Vol. 104, p. 114-119Article in journal (Refereed)
    Abstract [en]

    We prove that we can, using contact resistance as a tool, determine the instant when the bonding process starts, i.e. microwelds start to form during ultrasonic bonding. This knowledge permits us to reduce the uncertainty in the estimated bonded area by 5–18%. We proved our claim by combining a real-time contact resistance measurement, aborted ultrasound bonding, and classical SEM analysis of the bonded surfaces. We measured and analyzed, using a 4-wire Kelvin cross setup, the contact resistance of 25 μm by diameter AlSi(1%) wires bonded to a gold pad. The microweld area of 69 bonds was determined. We focused on inferring exactly when do the microwelds start to form. Post hoc analysis showed a linear correlation between the total microweld area and the time elapsed since the initial contact resistance drop. This work may help minimizing the sonication impact which may allow working with thin bond wires and fragile substrates.

  • 15.
    Seppänen, Henri
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ångström Space Technology Centre, ÅSTC.
    Rauhala, Timo
    Kiprich, Sergiy
    Ukkonen, Jukka
    Simonsson, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Kurppa, Risto
    Janhunen, Pekka
    Hæggström, Edward
    One kilometer (1 km) electric solar wind sail tether produced automatically2013In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 84, no 9, article id 095102Article in journal (Refereed)
    Abstract [en]

    We produced a 1 km continuous piece of multifilament electric solar wind sail tether of μm-diameter aluminum wires using a custom made automatic tether factory. The tether comprising 90 704 bonds between 25 and 50 μm diameter wires is reeled onto a metal reel. The total mass of 1 km tether is 10 g. We reached a production rate of 70 m/24 h and a quality level of 1‰ loose bonds and 2‰ rebonded ones. We thus demonstrated that production of long electric solar wind sail tethers is possible and practical.

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