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Results for “Direct Write Deposition”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Process Recipes for Additively Printed Copper Ink Flexible Circuits using Direct Write Methods

In this paper, the process-recipes and process-performance relationships for additive-printing of copper circuits using direct-write methods have been studied. The process has been implemented on the direct write platform. Interest in the use of additive printing methods for the manufacture of micro-circuits has grown immensely in recent times. Direct write methods have been shown to have the ability to create circuits in a limited manner. However, the process recipes and the effect of process parameters on the manufactured properties are not well understood. Copper ink is a good and cost-effective alternative to silver ink but its use has lagged owing to an increased propensity for oxidation. In this paper, photonic curing has been used to sinter copper ink to make the traces conductive. The method flashes high energy light that sinter metal particles instantaneously and the temperature of the substrate remains low. The effect of the different photonic sintering profiles on the mechanical and electrical properties of the printed traces has been studied in this paper.The print process parameters also play an important role in the line width and height that has been studied to print with the desired line profile for the end application. An LC filter circuit is been printed with SMD components been attached using an electrically conductive adhesive (ECA). The manufactured flexible LC filter is been tested for its frequency sweep to compare with the commercially available LC filer with the help of the Bode plot.

Process control↗
NASA NTRSDate not supplied

On-Demand Manufacturing of Electronics

The On-Demand Manufacturing of Electronics (ODME) project develops materials, processes, and device designs to enable electronics, sensors, and semiconductors to be produced in microgravity environments. The demonstration of these technologies provides a pathway for space-based manufacturing of circuits, wearables, energy storage devices, and other electronics. This has facilitated the terrestrial production of devices including a wide range of sensors, printed batteries, and circuits that are additively manufactured using techniques available on the Advanced Toolplate System (ATS). Recent parabolic flight campaigns conducted with the ATS suggest that direct ink write (DIW) technology is suitable for depositing functional material inks in reduced gravity environments. The development of the Advanced Toolplate system also includes several other new tools, including miniaturized versions of the direct write head, fused filament fabrication head, micro-mill, component pick & place head, and two newly developed deposition technologies, the Electrohydrodynamic (EHD) inkjet head (for semiconductors), and the Electrodeposition head (for high performance circuits). These experiments are designed to compare processing and material behavior in zero gravity versus ground-based data for validation of microgravity advantages and de-risking of future orbital demonstrations of these technologies. The ability to conduct experiments in microgravity is a pivotal step in enabling electronic manufacturing technology in space for both terrestrial and deep space applications.

Cadre Francis↗
NASA NTRS2017

Predictive Modeling of Fast-Curing Thermosets in Nozzle-Based Extrusion

This work presents an approach to modeling the dynamic spreading and curing behavior of thermosets in nozzle-based extrusions. Thermosets cover a wide range of materials, some of which permit low-temperature processing with subsequent high-temperature and high-strength working properties. Extruding thermosets may overcome the limited working temperatures and strengths of conventional thermoplastic materials used in additive manufacturing. This project aims to produce technology for the fabrication of thermoset-based structures leveraging advances made in nozzle-based extrusion, such as fused deposition modeling (FDM), material jetting, and direct writing. Understanding the synergistic interactions between spreading and fast curing of extruded thermosetting materials will provide essential insights for applications that require accurate dimensional controls, such as additive manufacturing [1], [2] and centrifugal coating/forming [3]. Two types of thermally curing thermosets -- one being a soft silicone (Ecoflex 0050) and the other being a toughened epoxy (G/Flex) -- served as the test materials in this work to obtain models for cure kinetics and viscosity. The developed models align with extensive measurements made with differential scanning calorimetry (DSC) and rheology. DSC monitors the change in the heat of reaction, which reflects the rate and degree of cure at different crosslinking stages. Rheology measures the change in complex viscosity, shear moduli, yield stress, and other properties dictated by chemical composition. By combining DSC and rheological measurements, it is possible to establish a set of models profiling the cure kinetics and chemorheology without prior knowledge of chemical composition, which is usually necessary for sophisticated mechanistic modeling. In this work, we conducted both isothermal and dynamic measurements with both DSC and rheology. With the developed models, numerical simulations yielded predictions of diameter and height of droplets, along with width and height of extruded lines cured at varied temperatures. Experimental results carried out on a goniometric platform and a nozzle-based 3D printer showed agreement with the numerical simulations. Finally, this presentation will show how the models are adaptable to the planning of tool paths and designs in additive manufacturing.

Xie, Jingjin↗
NASA NTRS1985

Mod silver metallization: Screen printing and ink-jet printing

Basic material efforts have proven to be very successful. Adherent and conductive films were achieved. A silver neodecanoate/bismuth 2-ethylhexanoate mixture has given the best results in both single and double layer applications. Another effort is continuing to examine the feasibility of applying metallo-organic deposition films by use of an ink jet printer. Direct line writing would result in a saving of process time and materials. So far, some well defined lines have been printed.

Vest, R. W.↗
NASA NTRS1991

In-situ integrated processing and characterization of thin films of high temperature superconductors, dielectrics and semiconductors by MOCVD

In this strategy of depositing the basic building blocks of superconductors, semiconductors, and dielectrics having common elements, researchers deposited superconducting films of Y-Ba-Cu-O, semiconductor films of Cu2O, and dielectric films of BaF2 and Y2O3 by metal oxide chemical vapor deposition (MOCVD). By switching source materials entering the chamber, and by using direct writing capability, complex device structures like three terminal hybrid semiconductor/superconductor transistors can be fabricated. The Y-Ba-Cu-O superconducting thin films on BaF2/YSZ substrates show a T(sub c) of 80 K and are textured with most of the grains having their c-axis or a-axis perpendicular to the substrate. Electrical characteristics as well as structural characteristics of superconductors and related materials obtained by x-ray deffraction, electron microscopy, and energy dispersive x-ray analysis are discussed.

Singh, R.↗
NASA NTRS1983

Laser assisted deposition

Applications of laser-based processing techniques to solar cell metallization are discussed. Laser-assisted thermal or photolytic maskless deposition from organometallic vapors or solutions may provide a viable alternative to photovoltaic metallization systems currently in use. High power, defocused excimer lasers may be used in conjunction with masks as an alternative to direct laser writing to provide higher throughput. Repeated pulsing with excimer lasers may eliminate the need for secondary plating techniques for metal film buildup. A comparison between the thermal and photochemical deposition processes is made.

Dutta, S.↗
NASA NTRS1995

Diamond thin film temperature and heat-flux sensors

Diamond film temperature and heat-flux sensors are developed using a technology compatible with silicon integrated circuit processing. The technology involves diamond nucleation, patterning, doping, and metallization. Multi-sensor test chips were designed and fabricated to study the thermistor behavior. The minimum feature size (device width) for 1st and 2nd generation chips are 160 and 5 micron, respectively. The p-type diamond thermistors on the 1st generation test chip show temperature and response time ranges of 80-1270 K and 0.29-25 microseconds, respectively. An array of diamond thermistors, acting as heat flux sensors, was successfully fabricated on an oxidized Si rod with a diameter of 1 cm. Some problems were encountered in the patterning of the Pt/Ti ohmic contacts on the rod, due mainly to the surface roughness of the diamond film. The use of thermistors with a minimum width of 5 micron (to improve the spatial resolution of measurement) resulted in lithographic problems related to surface roughness of diamond films. We improved the mean surface roughness from 124 nm to 30 nm by using an ultra high nucleation density of 10(exp 11)/sq cm. To deposit thermistors with such small dimensions on a curved surface, a new 3-D diamond patterning technique is currently under development. This involves writing a diamond seed pattern directly on the curved surface by a computer-controlled nozzle.

Aslam, M.↗
NASA NTRS2018

Nanoscale Fabrication of Microwave Detectors from Commercially-Available CVD-Grown Monolayer Graphene

Using commercially-available monolayer graphene, synthesized by means of chemical vapor deposition, microwave power sensing elements have been nanofabricated and integrated with microwave-grade test structures suitable for on-wafer probing. The graphene, situated on a thermal oxide, was first cleaned of stray contaminants in a forming gas environment briefly held at 250 degrees Celsius using a rapid thermal annealer. Immediately following this step, the graphene was passivated with a protective aluminum oxide layer (approximately S nm in thickness). Micrometer-scale Corbino disc test structures were then fabricated in direct contact with the graphene using a self-aligned process, which relies on the fact that tetramethylammonium hydroxide develops the photoresist while removing the aluminum oxide. Graphene nanoribbons (with widths as small 400 nm) were then fabricated across the Corbino disc gaps using electron-beam writing in conjunction with a negative tone resist. The same developer exposed the majority of the graphene while defining nanometer-scale lines of photoresist stacked upon aluminum oxide. These stacks served as etch-stops while the unprotected graphene was ion-milled in an oxygen plasma. Finally, the photoresist was removed leaving behind passivated graphene nanoribbons. Damage caused by the fabrication was evaluated by comparing the Raman spectra of the grapheme before and after processing.

detectors↗
NASA NTRS2012

Dirtier Air from a Weaker Monsoon

The level of air pollution in China has much increased in the past decades, causing serious health problems. Among the main pollutants are aerosols, also known as particulate matter: tiny, invisible particles that are suspended in the air. These particles contribute substantially to premature mortality associated with cardiopulmonary diseases and lung cancer1. The increase of the aerosol level in China has been commonly attributed to the fast rise in pollutant emissions from the rapid economic development in the region. However, writing in Geophysical Research Letters, Jianlei Zhu and colleagues2 tell a different side of the story: using a chemical transport model and observation data, they show that the decadal scale weakening of the East Asian summer monsoon has also contributed to the increase of aerosol concentrations in China. The life cycle of atmospheric aerosols starts with its emission or formation in the atmosphere. Some aerosol components such as dust, soot and sea salt are emitted directly as particles to the atmosphere, but others are formed there by way of photochemical reactions. For example, sulphate and nitrate aerosols are produced from their respective precursor gases, sulphur dioxide and nitrogen oxides. Aerosol particles can be transported away from their source locations by winds or vertical motion of the air. Eventually, they are removed from the atmosphere by means of dry deposition and wet scavenging by precipitation. Measurements generally show that aerosol concentrations over Asia are lowest during the summer monsoon season3, because intense rainfall efficiently removes them from the air. The East Asian summer monsoon extends over subtropics and mid-latitudes. Its rainfall tends to concentrate in rain belts that stretch out for many thousands of kilometres and affect China, Korea, Japan and the surrounding area. Observations suggest that the East Asian summer monsoon circulation and precipitation have been in decline since the 1970s4. In particular, a weaker East Asian summer monsoon is characterized by weaker southerly or southwesterly winds, a deficit in rainfall over northern China and larger rainfalls in southern China. By contrast, when the East Asian summer monsoon is strong, the southerly winds and strong rainfalls extend to northern China. The decadal scale decline in the strength of the East Asian summer monsoon since the 1970s would imply an increase in aerosol concentrations in northern China, north of 28deg N, and a decrease in southern China if emissions were kept the same. One obvious reason for this direction of aerosol change is that the reduction of monsoon rainfall in northern China would cause less wet scavenging of aerosols by precipitation. Zhu et al.2 investigated this relationship between aerosol concentrations and the strength of the East Asian summer monsoon and showed that the two parameters have strong negative correlations: the summer aerosol concentrations near the surface over eastern China.

Chin, Mian↗
NASA NTRS2004

MARIE Dose and Flux Measurements in Mars Orbit

We present results from the Martian Radiation Environment Experiment (MARIE), aboard the 2001 Mars Odyssey spacecraft in orbit around Mars. MARIE operated successfully from March 2002 through October 2003. At the time of this writing, the instrument is off due to a loss of communications during an extremely intense Solar Particle Event. Efforts to revive MARIE are planned for Spring 2004, when Odyssey's role as a communications relay for the MER rovers is completed. During the period of successful operation, MARIE returned the first detailed energetic charged particle data from Mars. Due to limitations of the instrument, normalizing MARIE data to flux or dose is not straightforward - several large corrections are needed. Thus normalized results (like dose or flux) have large uncertainties and/or significant model-dependence. The problems in normalization are mainly due to inefficiency in detecting high-energy protons (signal-to-noise problems force the trigger threshold to be higher than optimal), to the excessively high gains employed in the signal processing electronics (many ions deposit energy sufficient to saturate the electronics, and dE/dx information is lost), and to artifacts associated with the two trigger detectors (incomplete registration of dE/dx). Despite these problems, MARIE is efficient for detecting helium ions with kinetic energies above about 30 MeV/nucleon, and for detecting high-energy ions (energies above about 400 MeV/nucleon) with charges from 5 to 10. Fluxes of these heavier ions can be compared to fluxes obtained from the ACE/CRIS instrument, providing at least one area of direct comparison between data obtained at Earth and at Mars; this analysis will be presented as a work in progress. We will also present dose-rate data, with a detailed explanation of the many sources of uncertainty in normalization. The results for both flux and dose will be compared to predictions of the HZETRN model of the GCR.

Zeitlin, C.↗