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At least 163 records · Page 9

Wraparound-contact solar cells

Positive and negative electrical contacts are on back surface of wraparound-contact solar cell. With both terminals on nonilluminated side, cells can be connected back-to-back, and interconnection of many cells can be automated by using printed-circuit techniques. Cells are made by screen-printing layer of dielectric around edge of cell and extending top contact over dielectric to back surface. Wraparound also facilitates application of transparent covers and encapsulants. Efficiencies of cells are in excess of seventeen percent.

Baraona, C. R.↗

Printed Electronic Devices in Human Spaceflight

The space environment requires robust sensing, control, and automation, whether in support of human spaceflight or of robotic exploration. Spaceflight embodies the known extremes of temperature, radiation, shock, vibration, and static loads, and demands high reliability at the lowest possible mass. Because printed electronic circuits fulfill all these requirements, printed circuit technology and the exploration of space have been closely coupled throughout their short histories. In this presentation, we will explore the space (and space launch) environments as drivers of printed circuit design, a brief history of NASA's use of printed electronic circuits, and we will examine future requirements for such circuits in our continued exploration of space.

Bacon, John B.↗

Integrated circuit flat-pack lead bender

Tool bends leads quickly and accurately for mounting on printed circuit boards. It has grooves and bend-angles aligned for particular circuit board applications.

Koster, C. H.↗

MOSFET Switching Circuit Protects Shape Memory Alloy Actuators

A small-footprint, full surface-mount-component printed circuit board employs MOSFET (metal-oxide-semiconductor field-effect transistor) power switches to switch high currents from any input power supply from 3 to 30 V. High-force shape memory alloy (SMA) actuators generally require high current (up to 9 A at 28 V) to actuate. SMA wires (the driving element of the actuators) can be quickly overheated if power is not removed at the end of stroke, which can damage the wires. The new analog driver prevents overheating of the SMA wires in an actuator by momentarily removing power when the end limit switch is closed, thereby allowing complex control schemes to be adopted without concern for overheating. Either an integral pushbutton or microprocessor-controlled gate or control line inputs switch current to the actuator until the end switch line goes from logic high to logic low state. Power is then momentarily removed (switched off by the MOSFET). The analog driver is suited to use with nearly any SMA actuator.

Gummin, Mark A.↗

All 2D Material Printed Diodes and Circuits on Paper for Sustainable Electronics

Sustainable electronics aim to reduce environmental impact by using ecofriendly materials, energy-efficient manufacturing, and recyclable components. However, existing approaches rely on complex, resource-intensive methods, rare metals, or nanomaterials with limited stability as well as plastic substrates, raising sustainability issues. Solution-processed two-dimensional (2D) materials offer a promising alternative: water-based and biocompatible conductive, semiconductive, and insulating 2D material inks can be produced with scalable techniques and are suitable for the fabrication of fully printed devices on low-cost and biodegradable paper substrates. However, 2D material only and fully printed diodes on paper have not yet been reported. Here, we demonstrate fully inkjet-printed 2D material-based diodes on paper using metal-insulator-semiconductor and metal-insulator-metal-semiconductor architectures. Water-based graphene and MoS2 inks, prepared by liquid-phase exfoliation, are used for the metallic and insulating films, while electrochemical exfoliation is used to produce the semiconducting MoS2 ink. The highest forward-to-reverse current ratio obtained is 330 (at ±2 V), while the forward current density is 1 mA/cm2 (at 1 V), making the diode performance comparable to the best solution-processed diodes reported so far. However, in contrast to previous works, fabrication occurs entirely at room temperature and ambient pressure, without using high-pressure sputtering, thermal evaporation, and any precious metal ink. The devices maintain stable performance under bending up to strain of 4% over 10,000 cycles. Finally, the diodes are successfully integrated with other 2D-material based electrical components to realize fully printed RC circuits, differentiators, integrators, and AC-to-DC converters onto paper, hence demonstrating the suitability of our approach for sustainable and disposable integrated circuits.

2D materials↗

Cooling/grounding mount for hybrid circuits

Extremely short input and output connections, adequate grounding, and efficient heat removal for hybrid integrated circuits are possible with mounting. Rectangular clamp holds hybrid on printed-circuit board, in contact with heat-conductive ground plate. Clamp is attached to ground plane by bolts.

Bagstad, B.↗

A 96% Alumina based Packaging System for 500°C Test of SiC Integrated Circuits

With the development of silicon carbide (SiC) sensors and electronic devices for operation at 500°C, compatible packaging technologies are needed for long term high temperature test and deployment of these sensors and electronic devices. 96% Al2O3ceramic is an excellent electrically insulating material with acceptable dielectric constant and low dielectric loss over wide temperature and frequency ranges. This paper presents a packaging system for low power integrated circuits including a prototype 8-I/O chip-level package and printed circuit board (PCB) based on 96% Al2O3ceramic substrates and Au thick-film metallization for 500°C applications. The details related to designs of packages and PCBs, packaging materials, and specific packaging step recipes including wire -bonding and die-attach, are presented. Some test results of this prototype packaging approach applied to SiC integrated circuits at 500°C are reviewed.

High Temperature, Packaging, Alumina, Thick Film↗

A 96% Alumina based Packaging System for 500°C Test of SiC Integrated Circuits

With the development of silicon carbide (SiC) sensors and electronic devices for operation at 500°C, compatible packaging technologies are needed for long term high temperature test and deployment of these sensors and electronic devices. 96% Al2O3 ceramic is an excellent electrically insulating material with acceptable dielectric constant and low dielectric loss over wide temperature and frequency ranges. This paper presents a packaging system for low power integrated circuits including a prototype 8-I/O chip-level package and printed circuit board (PCB) based on 96% Al2O3 ceramic substrates and Au thick-film metallization for 500°C applications. The details related to designs of packages and PCBs, packaging materials, and specific packaging step recipes including wire - bonding and die-attach, are presented. Some test results of this prototype packaging approach applied to SiC integrated circuits at 500oC are reviewed.

high temperature↗

Advanced On-Board Processor (AOP)

Advanced On-board Processor the (AOP) uses large scale integration throughout and is the most advanced space qualified computer of its class in existence today. It was designed to satisfy most spacecraft requirements which are anticipated over the next several years. The AOP design utilizes custom metallized multigate arrays (CMMA) which have been designed specifically for this computer. This approach provides the most efficient use of circuits, reduces volume, weight, assembly costs and provides for a significant increase in reliability by the significant reduction in conventional circuit interconnections. The required 69 CMMA packages are assembled on a single multilayer printed circuit board which together with associated connectors constitutes the complete AOP. This approach also reduces conventional interconnections thus further reducing weight, volume and assembly costs.

Source record↗

Design guidelines for advanced LSI microcircuit packaging using thick film multilayer technology

Ceramic multilayer circuitry results from the sequential build-up of two or more layers of pre-determined conductive interconnections separated by dielectric layers and fired at an elevated temperature to form a solidly fused structure. The resultant ceramic interconnect matrix is used as a base to mount active and passive devices and provide the necessary electrical interconnection to accomplish the desired electrical circuit. Many methods are known for developing multilevel conductor mechanisms such as multilayer printed circuits, welded wire matrices, flexible copper tape conductors, and thin and thick-film ceramic multilayers. Each method can be considered as a specialized field with each possessing its own particular set of benefits and problems. This design guide restricts itself to the art of design, fabrication and assembly of ceramic multilayer circuitry and the reliability of the end product.

Peckinpaugh, C. J.↗

Cavity-backed, micro-strip dipole antenna array

A flush-mounted antenna assembly includes a generally rectangular, conductive, box structure open along one face to form a cavity. Within the cavity a pair of mutually orthogonal dielectric plane surfaces in an "egg crate" arrangement are mounted normal to the plane of the open face, each diagonally within the cavity. Each dielectric plane supports a pair of printed circuit dipoles typically each fed from the opposite side of the dielectric plane by a printed "cone-shaped" feed line trace which also serve as an impedance matching device and functions as a balun connected from an unbalanced strip line external feed. The open face of the conductive cavity can be flush mounted with a randome thereover, the assembly thereby being flush with the skin of a aircraft or space vehicle.

Ellis, H., Jr.↗

Printed wiring board system programmer's manual

The printed wiring board system provides automated techniques for the design of printed circuit boards and hybrid circuit boards. The system consists of four programs: (1) the preprocessor program combines user supplied data and pre-defined library data to produce the detailed circuit description data; (2) the placement program assigns circuit components to specific areas of the board in a manner that optimizes the total interconnection length of the circuit; (3) the organizer program assigns pin interconnections to specific board levels and determines the optimal order in which the router program should attempt to layout the paths connecting the pins; and (4) the router program determines the wire paths which are to be used to connect each input pin pair on the circuit board. This document is intended to serve as a programmer's reference manual for the printed wiring board system. A detailed description of the internal logic and flow of the printed wiring board programs is included.

Brinkerhoff, C. D.↗

Coating Circuit Boards With Silicone

Techniques appropriate to boards containing CMOS circuits detailed. Document presents procedure for applying thin conformal coating to such electronic assemblies as printed-circuit boards and wire-wrapped boards. Coating is from 1 to 7 mils (25 to 178 micrometers) thick and composed of room-temperature-vulcanizing (RTV) silicone. Specifies materials, equipment, spraying method, and quality requirements. Takes into account special needs of circuits made with complementary metal-oxide/semiconductor (CMOS) devices on circuit boards. Special attention given to preventing damage by electrostatic discharge, to which CMOS circuits especially sensitive.

Gaudiano, S.↗

RF Device for Acquiring Images of the Human Body

A safe, non-invasive method for forming images through clothing of large groups of people, in order to search for concealed weapons either made of metal or not, has been developed. A millimeter wavelength scanner designed in a unique, ring-shaped configuration can obtain a full 360 image of the body with a resolution of less than a millimeter in only a few seconds. Millimeter waves readily penetrate normal clothing, but are highly reflected by the human body and concealed objects. Millimeter wave signals are nonionizing and are harmless to human tissues when used at low power levels. The imager (see figure) consists of a thin base that supports a small-diameter vertical post about 7 ft (=2.13 m) tall. Attached to the post is a square-shaped ring 2 in. (=5 cm) wide and 3 ft (=91 cm) on a side. The ring is oriented horizontally, and is supported halfway along one side by a connection to a linear bearing on the vertical post. A planar RF circuit board is mounted to the inside of each side of the ring. Each circuit board contains an array of 30 receivers, one transmitter, and digitization electronics. Each array element has a printed-circuit patch antenna coupled to a pair of mixers by a 90 coupler. The mixers receive a reference local oscillator signal to a subharmonic of the transmitter frequency. A single local oscillator line feeds all 30 receivers on the board. The resulting MHz IF signals are amplified and carried to the edge of the board where they are demodulated and digitized. The transmitted signal is derived from the local oscillator at a frequency offset determined by a crystal oscillator. One antenna centrally located on each side of the square ring provides the source illumination power. The total transmitted power is less than 100 mW, resulting in an exposure level that is completely safe to humans. The output signals from all four circuit boards are fed via serial connection to a data processing computer. The computer processes the approximately 1-MB data set into a three-dimensional image in a matter of seconds. The innovation is to configure the receiver array in a ring topology surrounding the scanned object. The ring is then scanned vertically to cover the necessary two-dimensional surface. This fabrication of the ring is made possible by using planar antenna and circuit technology. A planar circuit board serves as a medium for both antennas and signal processing components. Using this technique, parts counts are kept low, and the cost per element is a small fraction of a waveguide-based system.

Gaier, Todd C.↗

Tuning the Selectivity of Carboxylic Acid–Based Eutectic Solvents for the Dissolution and Electrochemical Separation of Metal Oxides

Extracting metals from natural resources and recovering from waste materials with less-hazardous solvents is essential for sustainable technological advancements. The commonly employed method utilizes harsh chemicals for metal dissolution and the ensuing separation. Here, in this study, we examined the potential of eutectic solvents (types III and IV) as alternative media for the selective dissolution of metals and metal oxides and their subsequent electrochemical separation. Notably, type III eutectics composed of betaine:acetic acid and triazole:lactic acid exhibited excellent solubility for cobalt oxide (24.1 g·L –1 ) and copper oxide (30.5 g·L –1 ), respectively. In comparison, the type IV eutectic mixture of Ca(NO 3 ) 2 ·4H 2 O:acetic acid demonstrated the highest conductivity and lowest viscosity with solubility for both copper oxide (6.1 g·L –1 ) and metallic copper (5.4 g·L –1 from a used electronic circuit). Using a Ca(NO 3 ) 2 ·4H 2 O:acetic acid mixture, copper was selectively dissolved from a waste printed circuit board and subsequently electrodeposited onto a nickel electrode. These findings highlight the tunability of DESs for the selective recovery of metals from electronic waste, offering a promising approach for sustainable metal recycling and resource recovery.

electrodeposition↗

Input gate circuit converted for use as linear amplifier

Commercially available integrated circuit that is marketed as a digital computer input gate circuit was converted to a linear amplifier in a microphone circuit that has high input impedance, low output impedance, low cost, and is small enough to fit on a standard printed circuit card.

Harper, T. P.↗

Battery peak charge voltage monitor for dual air density satellite

A battery peak charge voltage monitor was developed for use on the dual air density satellite (DADS). This device retains a reading of the maximum voltage reached by the spacecraft battery during periods of charging, and makes it available during periods of data transmission. The monitor is connected across the battery and operates solely from the battery; it is powered continuously with quiescent input current of only 3 milliamperes. Standard integrated circuits and a thin-film resistor network are utilized. The monitor occupies approximately 40 square centimeters of a printed-circuit board within a larger electronic package.

Shull, T. A.↗