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NASA NTRS1994

Spacecraft Data Simulator for the test of level zero processing systems

The Microelectronic Systems Branch (MSB) at Goddard Space Flight Center (GSFC) has developed a Spacecraft Data Simulator (SDS) to support the development, test, and verification of prototype and production Level Zero Processing (LZP) systems. Based on a disk array system, the SDS is capable of generating large test data sets up to 5 Gigabytes and outputting serial test data at rates up to 80 Mbps. The SDS supports data formats including NASA Communication (Nascom) blocks, Consultative Committee for Space Data System (CCSDS) Version 1 & 2 frames and packets, and all the Advanced Orbiting Systems (AOS) services. The capability to simulate both sequential and non-sequential time-ordered downlink data streams with errors and gaps is crucial to test LZP systems. This paper describes the system architecture, hardware and software designs, and test data designs. Examples of test data designs are included to illustrate the application of the SDS.

Shi, Jeff↗

NASA NTRS1995

Development of microchannel plate x-ray optics

The goal of this research program was to develop a novel technique for focusing x-rays based on the optical system of a lobster's eye. A lobster eye employs many closely packed reflecting surfaces arranged within a spherical or cylindrical shell. These optics have two unique properties: they have unlimited fields of view and can be manufactured via replication of identical structures. Because the angular resolution is given by the ratio of the size of the individual optical elements to the focal length, optical elements with size on the order of one hundred microns are required to achieve good angular resolution with a compact telescope. We employed anisotropic etching of single crystal silicon wafers for the fabrication of micron-scale optical elements. This technique, commonly referred to as silicon micromachining, is based on silicon fabrication techniques developed by the microelectronics industry. We have succeeded in producing silicon lenses with a geometry suitable for a 1-d focusing x-ray optics. These lenses have an aspect ratio (40:1) suitable for x-ray reflection and have very good optical surface alignment. We have developed a number of process refinements which improved the quality of the lens geometry and the repeatability of the etch process. In addition to the silicon fabrication, an x-ray beam line was constructed at Columbia for testing the optics. Most recently, we have done several experiments to find the fundamental limits that the anisotropic etch process placed on the etched surface roughness.

Kaaret, Philip↗

NASA NTRS1995

Japan's technology and manufacturing infrastructure

The JTEC panel found that, after four decades of development in electronics and manufacturing technologies, Japanese electronics companies are leaders in the development, support, and management of complex, low-cost packaging and assembly technologies used in the production of a broad range of consumer electronics products. The electronics industry's suppliers provide basic materials and equipment required for electronic packaging applications. Panelists concluded that some Japanese firms could be leading U.S. competitors by as much as a decade in these areas. Japan's technology and manufacturing infrastructure is an integral part of its microelectronics industry's success.

Boulton, William R.↗

NASA NTRS1994

A decade of neural networks: Practical applications and prospects

On May 11-13, 1994, JPL's Center for Space Microelectronics Technology (CSMT) hosted a neural network workshop entitled, 'A Decade of Neural Networks: Practical Applications and Prospects,' sponsored by DOD and NASA. The past ten years of renewed activity in neural network research has brought the technology to a crossroads regarding the overall scope of its future practical applicability. The purpose of the workshop was to bring together the sponsoring agencies, active researchers, and the user community to formulate a vision for the next decade of neural network research and development prospects, with emphasis on practical applications. Of the 93 participants, roughly 15% were from government agencies, 30% were from industry, 20% were from universities, and 35% were from Federally Funded Research and Development Centers (FFRDC's).

Kemeny, Sabrina↗

NASA NTRS1991

Metallurgical coatings and thin films; Proceedings of the International Conference, 18th, San Diego, CA, Apr. 22-26, 1991. Vols. 1 & 2

A conference on metallurgical coatings and thin films produced papers in the areas of coatings for use at high temperatures; hard coatings and deposition technologies; diamonds and related materials; tribological coatings/surface modifications; thin films for microelectronics and high temperature superconductors; optical coatings, film characterization, magneto-optics, and guided waves; and methods for characterizing films and modified surfaces.

Mcguire, Gary E.↗

NASA NTRS1993

Heavy-ion fragmentation studies in thick water absorbers

Proposed long-term space missions could expose crewmembers to significant fluxes of galactic cosmic radiation (GCR) particles and secondary particles created from nuclear collisions. An assessment of radiobiological risks is dependent upon an accurate description of the charged-particle radiation field inside the human body. As shield thickness increases and the incident ions are slowed, the production of secondary particles contributes an increasingly significant fraction of the total dose until eventually secondary particles become more important than the primary particles. The nuclear mean free path of the GCR ions (which usually have nuclear charge between 1 (protons) and 26 (iron), both inclusive) are comparable with thicknesses typical of spacecraft structures and the human body. Collisions in these media will create projectile and target fragments with charge less than that of the primary particle, and each interaction event can have a multiplicity of more than one emerging interaction product. Projectile fragments usually continue on with very nearly the velocity of the primary ion (the so-called straightahead approximation). Having sufficient energy, the fragments may collide with atomic nuclei in thick shields and create a second generation of fragments, and so on. Target fragments are emitted from a struck nucleus, usually with much lower energy than projectile fragments and nearly isotropically in the rest frame of the absorbing medium. The resulting spectrum of particles and their energy loss rates will be very different from that in the unshielded environment, will determine the radiobiological impact on exposed living tissues -- whether in space or in ground-based radiobiology experiments -- and will play an important role in radiation effects on microelectronics.

Shavers, M. R.↗

NASA NTRS1995

Decision process for effective system reuse

The speed of growth in high technology differs for software, hardware and firmware. Hardware innovations come in leaps, as opposed to the gradual improvements in software and firmware technologies. This inhibits the full utilization of the hardware advances and reduces the cost benefit ratio of high technology ventures. The Microelectronics Systems Branch has committed its resources to use the look ahead technique whereby the technology is researched in its use, current development track and its future capabilities. This knowledge is used to meet the requirements of the space program not only in the nineties but also through 2005. This paper illustrates Analytical Hierarchy Process techniques used effectively and very successfully to support projects reusing systems with predicted enhancements.

Mirchandani, Chandru↗

NASA NTRS1995

Determination Of LETs Of SRAMs By Use Of A Laser

Report describes experimental study of use of microelectronic advanced laser scanner (MEALS) to cause single-event upsets (SEUs) in integrated logic circuits. Basic concepts of SEU testing by use of MEALS described in "Laser Scanner Tests for Single-Event Upsets" (NPO-18216), "Single-Event-Upset Laser Scanner With Optical Bias" (NPO-18217), and "More About Laser Scanner Tests for Single-Event Upsets" (NPO-18494). Study part of continuing effort to study SEU effects of ionizing radiation on such circuits and to use MEALS as relatively inexpensive SEU-prescreening laboratory apparatus serving as alternative to heavy-ion acclerator.

Kim, Quiesup↗

NASA NTRS1995

Architecture Of A Sciencecraft To Fly Past Pluto

Two reports discuss architecture of proposed small sciencecraft carrying scientific instruments on trajectory passing near Pluto and continuing into interstellar space. Emphasizes those aspects of design pertaining to compactness, efficiency, and small mass (dry mass less than 100 kg). System block diagram of sciencecraft divided into blocks for sensors, integrated microelectronics, and motive effectors.

Price, Humphrey W.↗

NASA NTRS1995

Liquid metal micro heat pipes for space radiator applications

Micromachining is a chemical means of etching three-dimensional structures, typically in single-crystalline silicon. These techniques are leading toward what is coming to be referred to as MEMS (micro electro mechanical systems), where in addition to the ordinary two dimensional (planar) microelectronics, it is possible to build three-dimensional micromotors, electrically-actuated microvalves, hydraulic systems, and much more on the same microchip. These techniques become possible because of differential etching rates of various crystallographic planes and materials used for semiconductor microfabrication. The University of Cincinnati group in collaboration with NASA Lewis formed micro heat pipes in silicon by the above techniques. Work is ongoing at a modest level, but several essential bonding and packaging techniques have been recently developed. Currently, we have constructed and filled water/silicon micro heat pipes. Preliminary thermal tests of arrays of 125 micro heat pipes etched in a 1 inch x 1 inch x 250 micron silicon wafer have been completed. These pipes are instrumented with extremely small P-N junctions to measure their effective conductivity and their maximum operating power. A relatively simple one-dimensional model has been developed in order to predict micro heat pipes' operating characteristics. This information can be used to optimize micro heat pipe design with respect to length, hydraulic diameter, and number of pipes. Work is progressing on the fabrication of liquid-metal micro heat pipes. In order to be compatible with liquid metal (sodium or potassium), the inside of the micro heat pipes will be coated with a refractory metal (such as tungsten, molybdenum, or titanium).

Gerner, F. M.↗

NASA NTRS1996

An introduction to NASA's advanced computing program: Integrated computing systems in advanced multichip modules

Recent changes within NASA's space exploration program favor the design, implementation, and operation of low cost, lightweight, small and micro spacecraft with multiple launches per year. In order to meet the future needs of these missions with regard to the use of spacecraft microelectronics, NASA's advanced flight computing (AFC) program is currently considering industrial cooperation and advanced packaging architectures. In relation to this, the AFC program is reviewed, considering the design and implementation of NASA's AFC multichip module.

Fang, Wai-Chi↗

NASA NTRS1995

Proceedings of the International Conference on Integrated Micro/Nanotechnology for Space Applications

The recent evolution of microelectronic technologies coupled with the growth of micro-electro-mechanical systems (MEMS) has had significant impact in the commercial sector. The focus of this conference was to anticipate and extend the incorporation of nano-electronics and MEMS into application specific integrated microinstruments (ASIM's) in space systems. Presentations ranged from mission application of nano-satellites to silicon micromachining for photonic applications.

Source record↗

NASA NTRS1995

Silicon Micromachined Sensor for Broadband Vibration Analysis

The development of a family of silicon based integrated vibration sensors capable of sensing mechanical resonances over a broad range of frequencies with minimal signal processing requirements is presented. Two basic general embodiments of the concept were designed and fabricated. The first design was structured around an array of cantilever beams and fabricated using the ARPA sponsored multi-user MEMS processing system (MUMPS) process at the Microelectronics Center of North Carolina (MCNC). As part of the design process for this first sensor, a comprehensive finite elements analysis of the resonant modes and stress distribution was performed using PATRAN. The dependence of strain distribution and resonant frequency response as a function of Young's modulus in the Poly-Si structural material was studied. Analytical models were also studied. In-house experimental characterization using optical interferometry techniques were performed under controlled low pressure conditions. A second design, intended to operate in a non-resonant mode and capable of broadband frequency response, was proposed and developed around the concept of a cantilever beam integrated with a feedback control loop to produce a null mode vibration sensor. A proprietary process was used to integrat a metal-oxide semiconductor (MOS) sensing device, with actuators and a cantilever beam, as part of a compatible process. Both devices, once incorporated as part of multifunction data acquisition and telemetry systems will constitute a useful system for NASA launch vibration monitoring operations. Satellite and other space structures can benefit from the sensor for mechanical condition monitoring functions.

Gutierrez, Adolfo↗

NASA NTRS1995

Advancing MEMS Technology Usage through the MUMPS (Multi-User MEMS Processes) Program

In order to help provide access to advanced micro-electro-mechanical systems (MEMS) technologies and lower the barriers for both industry and academia, the Microelectronic Center of North Carolina (MCNC) and ARPA have developed a program which provides users with access to both MEMS processes and advanced electronic integration techniques. The four distinct aspects of this program, the multi-user MEMS processes (MUMP's), the consolidated micro-mechanical element library, smart MEMS, and the MEMS technology network are described in this paper. MUMP's is an ARPA-supported program created to provide inexpensive access to MEMS technology in a multi-user environment. It is both a proof-of-concept and educational tool that aids in the development of MEMS in the domestic community. MUMP's technologies currently include a 3-layer poly-silicon surface micromachining process and LIGA (lithography, electroforming, and injection molding) processes that provide reasonable design flexibility within set guidelines. The consolidated micromechanical element library (CaMEL) is a library of active and passive MEMS structures that can be downloaded by the MEMS community via the internet. Smart MEMS is the development of advanced electronics integration techniques for MEMS through the application of flip chip technology. The MEMS technology network (TechNet) is a menu of standard substrates and MEMS fabrication processes that can be purchased and combined to create unique process flows. TechNet provides the MEMS community greater flexibility and enhanced technology accessibility.

Koester, D. A.↗

NASA NTRS1995

Advanced packaging for Integrated Micro-Instruments

The relationship between packaging, microelectronics, and micro-electrical-mechanical systems (MEMS) is an important one, particularly when the edges of performance boundaries are pressed, as in the case of miniaturized systems. Packaging is a sort of physical backbone that enables the maximum performance of these systems to be realized, and the penalties imposed by conventional packing approaches is particularly limiting for MEMS devices. As such, advanced packaging approaches, such as multi-chip modules (MCM's) have been touted as a true means of electronic 'enablement' for a variety of application domains. Realizing an optimum system of packaging, however, in not as simple as replacing a set of single chip packages with a substrate of interconnections. Research at Phillips Laboratory has turned up a number of integrating options in the two- and three-dimensional rending of miniature systems with physical interconnection structures with intrinsically high performance. Not only do these structures motivate the redesign of integrated circuits (IC's) for lower power, but they possess interesting features that provide a framework for the direct integration of MEMS devices. Cost remains a barrier to the application of MEMS devices, even in space systems. Several innovations are suggested that will result in lower cost and more rapid cycle time. First, the novelty of a 'constant floor plan' MCM which encapsulates a variety of commonly used components into a stockable, easily customized assembly is discussed. Next, the use of low-cost substrates is examined. The anticipated advent of ultra-high density interconnect (UHDI) is suggested as the limit argument of advanced packaging. Finally, the concept of a heterogeneous 3-D MCM system is outlined that allows for the combination of different compatible packaging approaches into a uniformly dense structure that could also include MEMS-based sensors.

Lyke, James L.↗

NASA NTRS1995

The Impact on Space Radiation Requirements and Effects on ASIMS

The evolution of highly miniaturized electronic and mechanical systems will be accompanied by new problems and issues regarding the radiation response of these systems in the space environment. In this paper we discuss some of the more prominent radiation problems brought about by miniaturization. For example, autonomous micro-spacecraft will require large amounts of high density memory, most likely in the form of stacked, multichip modules of DRAM's, that must tolerate the radiation environment. However, advanced DRAM's (16 to 256 Mbit) are quite susceptible to radiation, particularly single event effects, and even exhibit new radiation phenomena that were not a problem for older, less dense memory chips. Another important trend in micro-spacecraft electronics is toward the use of low-voltage microelectronic systems that consume less power. However, the reduction in operating voltage also caries with it an increased susceptibility to radiation. In the case of application specific integrated microcircuits (ASIM's), advanced devices of this type, such as high density field programmable gate arrays (FPGA's) exhibit new single event effects (SEE), such as single particle reprogramming of anti-fuse links. New advanced bipolar circuits have been shown recently to degrade more rapidly in the low dose rate space environment than in the typical laboratory total dose radiation test used to qualify such devices. Thus total dose testing of these parts is no longer an appropriately conservative measure to be used for hardness assurance. We also note that the functionality of micromechanical Si-based devices may be altered due to the radiation-induced deposition of charge in the oxide passivation layers.

Barnes, C.↗

NASA NTRS1996

Fluid Dynamics and Solidification of Molten Solder Droplets Impacting on a Substrate in Microgravity

This program investigates the fluid dynamics and simultaneous solidification of molten solder droplets impacting on a flat substrate. The problem of interest is directly relevant to the printing of microscopic solder droplets in surface mounting of microelectronic devices. The study consists of a theoretical and an experimental component. The theoretical work uses axisymmetric Navier-Stokes models based on finite element techniques. The experimental work is performed in microgravity to allow for the use of larger solder droplets that make feasible the performance of accurate measurements while maintaining similitude of the relevant fluid dynamics groups (Re, We) and keeping the effect of gravity negligible.

Poulikakos, Dimos↗

NASA NTRS1995

Marketing NASA Langley Polymeric Materials

A marketing tool was created to expand the knowledge of LaRC developed polymeric materials, in order to facilitate the technology transfer process and increase technology commercialization awareness among a non-technical audience. The created brochure features four materials, LaRC-CP, LaRC-RP46, LaRC-SI, and LaRC-IA, and highlights their competitive strengths in potential commercial applications. Excellent opportunities exist in the $40 million per year microelectronics market and the $6 billion adhesives market. It is hoped that the created brochure will generate inquiries regarding the use of the above materials in markets such as these.

Flynn, Diane M.↗