Manufacturing & Prototyping

Plasma Treatments to Assist Fluid Manipulation in Microgravity

Altering the surface energy of container walls permits anchoring of fluids within the container. Lyndon B. Johnson Space Center, Houston, Texas A recent innovation has made manipulation of hazardous laboratory reagents in microgravity easier, thus enabling even more scientific research to be performed on the International Space Station (ISS). Prior to this innovation, moving fluids from container to container was performed only under conditions of redundant and physically separate layers of containment. This design paradigm restricts access to — and direct manipulation of — fluids in microgravity conditions.

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Stencil-less Jet Printing for PCB Assembly

Solder paste inkjet is an inline, solder-mask printing technology that enables 3D printing of different thicknesses of solder paste for prototype PCBs. Imagineering Inc., Elk Grove Village, Illinois For many years, stencil printing has been the standard method of depositing solder paste on surface mount assembly printed circuit boards (PCBs). It has provided a durable method of applying solder paste, but there were always difficulties that significantly slowed down a change from one product to another in the assembly operation, and added cost. A significant challenge in newer, smaller electronics assembly is the huge difference in size among components. Therefore, trying to apply the right amount of solder paste for each component with one stencil is difficult. The biggest problem is how to produce quick-turn prototypes without disrupting series production that is already running in the line. Product changeover requires time-consuming tweaks to the stencil printing process, while unnecessarily shutting down an expensive assembly line to change the product. The inability of the stencil’s technology to vary solder paste volume by part, on the run, remains the biggest impact on the soldering quality.

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In-Situ Mixing, Degassing, Decavitation, and Extrusion Modules for Fused Deposition Modeling 3D Printers

A resonant acoustics mixing mechanism equipped with high-vacuum pulling capacity will be employed. John H. Glenn Research Center, Cleveland, Ohio Additively manufactured 3D articles of certain high-temperature polymer composites such as ULTEM 1000 reinforced with chopped carbon fibers and printed by current state-of-the-art Fused Deposition Modeling (FDM) printers, suffer significantly with high porosity due to moisture-induced cavitation during the liquefying process under high printing temperatures because the pre-fabricated feedstock filaments contain excessive moisture trapped in polymer matrix or fiber interfaces that is extremely difficult to remove. During compounding (mixing of chopped fibers with resin) and the filament extrusion process, controlling moisture absorption is extremely difficult and very costly. Furthermore, compounding and filament fabrication are two separate processes normally performed at different plants, and thus add extra costs and technical challenge of keeping the material dry. In the case of the high-temperature polymer, it is even more difficult to control the residual moisture content and is more prone to blistering during FDM printing due to higher melting temperature.

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Stable, Flat Packaging Concepts for Large Detector Arrays

Applications include packing of back-illuminated and delta-doped arrays without damage to sensitive surfaces. NASA’s Jet Propulsion Laboratory, Pasadena, California A ceramic vacuum chuck is used to hold large detector arrays flat while being attached parallel to a rigid substrate. Once held in the vacuum chuck, the component is typically seized by epoxy against a rigid substrate. The problem that interferes with this operation happens when the epoxy spreads to places where it is not wanted, even into the gap between the component and its vacuum chuck, and over electrical contacts that are intended for wire bonding.

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Dual-Polarized W-Band Metal Patch Antenna Element for Phased Array Applications

Interlaced transmit/receive all-metal patch elements eliminate the need for discrete isolators and increase efficiency.W-band active phased array antennas have a very small inter-element pitch (≈2 mm). In this innovation, instead of trying to integrate isolators into the unit cell to separate transmit and receive signals, an interlaced triangular grid of metal patch elements has been developed. The isolation between transmit elements and receive elements has been demonstrated to be on the order of 25 dB or more, precluding the need for discrete isolator circuits. Using metal patch technology, the element and associated interconnect loss has been demonstrated to be 0.5 dB at 94 GHz, which represents an efficiency of 89%.

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High-Temperature Superconducting Bolometric Devices on Amorphous Silicon Nitride Membranes

Applications include defense-related infrared launch detection and night vision. NASA’s Jet Propulsion Laboratory, Pasadena, California There has been a great deal of interest in building bolometers from hightemperature superconductors due to their high transition temperatures and the associated ease of cooling. High-temperature superconducting (high Tc) bolometers are difficult to fabricate because the standard method of thermal isolation is not compatible with these materials. A method is described that allows a standard thermal isolation technique (using amorphous silicon nitride membranes) to be used with high-temperature superconductors.

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Uniformly Etched Lateral Gratings Applied to Pre-existing Ridge Waveguides

New technology is 100 times smaller and has fewer components with possibly the same performance. NASA’s Jet Propulsion Laboratory, Pasadena, California There is great difficulty in implementing lateral gratings in GaSb-based lasers. Commercially, single-frequency GaSb lasers have been fabricated using metal gratings deposited laterally to the ridge-waveguide (RWG) stripe. The disadvantage of this is that the laser performance is compromised by additional optical loss due to radiation absorption by the metal. Fabricating lasers in this way limits the potential for high-power performance. A better method is to etch gratings into the semiconductor, but generally, patterning these grating structures is difficult because of nonuniformity of the grating pattern and etching difficulty due to sub-micrometer dimensions.

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