Field-emission electron sources using carbon nanotubes (CNTs) are being targeted for low-power vacuum microelectronic applications for harsh-environment operation (high temperature, pressure, and corrosive atmosphere). While CNTs have demonstrated excellent properties in terms of low threshold field, low-power operation, and high-current densities, one of the problems that has persisted for vacuum electronic applications is the low yield of multi-electrode vacuum devices such as diodes, triodes, tetrodes, pentodes, etc.
A hybrid micro assembly process has been developed that allows mixing and matching of different types of electrode and dielectric layers assembled in a stack to create multi-electrode vacuum devices. The cathode, anode, extraction grid electrode, gate electrodes, and focusing electrodes all can be made from different materials micromachined to specific thickness. Following this, the electrodes are stacked. The electrode and dielectric layers are machined to contain alignment slots (similar to kinematic alignment structures) into which microspheres that function as precision spacers are placed. The stack is held in place using either vacuum-compatible epoxy or hard-mounted mechanical fixtures (such as assembly slots, alignment pin fasteners, etc.). This creates a hybrid vacuum device that is then placed inside standard vacuum packages, evacuated to high vacuums, and hermetically sealed.
The assembly process, when automated, is conducive for mass manufacturing of vacuum devices. The precision stages used in this development can be programmed to perform pick-and-place of different layers in an automated fashion, thus enhancing the speed of device fabrication. Hybrid assembly is modular by nature and allows selection of best-suited materials and dimensions for a given layer. This also allows for repairing the stacks with assembly or layer errors, and makes such a process easier. Most importantly, this assembly process helps to achieve a high degree of reproducibility among vacuum devices.
This work was done by Harish Manohara, Risaku Toda, Linda Y. Del Castillo, and Rakesh Murthy of Caltech for NASA’s Jet Propulsion Laboratory.
In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to:
Innovative Technology Assets Management
JPL
Mail Stop 321-123
4800 Oak Grove Drive
Pasadena, CA 91109-8099
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Refer to NPO-48958.
This Brief includes a Technical Support Package (TSP).
Assembly and Packaging to Mass-Produce Carbon Nanotube Vacuum Microdevices and Circuits
(reference NPO-48958) is currently available for download from the TSP library.
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Overview
The document is a Technical Support Package from NASA's Jet Propulsion Laboratory (JPL) focused on the assembly and packaging of carbon nanotube (CNT) vacuum microdevices and circuits. It is part of NASA Tech Briefs and is designated as NPO-48958. The document outlines the advancements in hybrid micro-assembly techniques and vacuum packaging that are essential for mass-producing these innovative devices.
Carbon nanotubes are recognized for their exceptional electrical, thermal, and mechanical properties, making them ideal candidates for a variety of applications, particularly in the aerospace sector. The document emphasizes the potential of CNTs in creating vacuum microdevices, which can lead to significant improvements in performance and efficiency compared to traditional technologies.
Key components discussed include CNT triodes, which are crucial for the development of these microdevices. The document provides insights into the planned micro-assembly processes, including the use of specialized jigs for hybrid micro-assembly. These jigs facilitate the precise placement and integration of CNTs into the device architecture, ensuring optimal performance.
The document also includes various views and diagrams, such as top, front, side, and cross-sectional views, illustrating the design and assembly processes. It highlights the importance of epoxy dispensing in the assembly process, which is critical for securing the components in place and ensuring the integrity of the vacuum environment.
Additionally, the document acknowledges the collaborative efforts of researchers, including Harish Manohara, Rakesh Murthy, Risaku Toda, and Linda Del Castillo, and recognizes the government sponsorship that supports this research. It emphasizes the broader implications of these developments, suggesting that the technologies derived from this research could have significant commercial applications beyond aerospace.
For further inquiries or assistance, the document provides contact information for the Innovative Technology Assets Management at JPL, encouraging engagement with the ongoing research and technology transfer initiatives.
In summary, this Technical Support Package serves as a comprehensive resource on the methodologies for assembling and packaging carbon nanotube vacuum microdevices, showcasing the innovative approaches being developed at NASA JPL and their potential impact on future technologies.
