Microfabrication of Tunnels

a tunnel and microfabrication technology, applied in the field of hollow bore formation, can solve the problems of slipping off center, limited accuracy of drilled depth, and inability to reliably and precisely form very small holes of arbitrary shape for long lengths

Inactive Publication Date: 2018-02-01
THE UNITED STATES OF AMERICA AS REPRESENTED BY THE SECRETARY OF THE NAVY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This approach enables the reliable and precise formation of small, high-aspect-ratio hollow bores with arbitrary shapes and lengths, overcoming the limitations of traditional methods by using a single photolithographic process, enhancing efficiency and reducing stress and accuracy issues.

Problems solved by technology

However, these methods are all limited in their ability to reliably and precisely form very small holes of arbitrary shape for long lengths.
In the (a) drilling round holes methods, drilling a beam tunnel typically limits the cross sectional shape to round, and has a limited depth that the bore can be drilled to accurately.
Furthermore, during drilling, there is a tendency to walk off-center, and the method relies on extremely fragile micro-drill bits.
In brazing, stresses due to cyclical heating typically tend to separate the two halves where they were joined, which can reduce reliability.
The (d) laser ablation method is typically limited in the depth of the cut.
In the (f) casting method, molten metal around a mold requires the forms to be subjected to high temperatures, which can introduce issues of thermal expansion, can complicate the removal of the molds, and typically has a tendency to leave gaps and voids in the casting.
In the case of some pure metals such as copper, cast melting tends to form large crystal grains, which are typically unable to fill the smallest features properly.
Finally, (g) conventional multi-layer LIGA techniques require a minimum of three layers, each requiring a separate exposure step, electroforming step and polishing step, and these techniques are only capable of square or rectangular beam tunnel shapes or approximations to true cylinders.

Method used

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  • Microfabrication of Tunnels
  • Microfabrication of Tunnels
  • Microfabrication of Tunnels

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Embodiment Construction

[0016]Referring now to the drawings, in which like numerals represent like elements, aspects of the exemplary embodiments will be described in connection with the drawing set.

[0017]In general, this invention is a method to form arbitrarily shaped cross sections of a hollow bore, or beam tunnel, of arbitrary length by means of forms, such as fibers or sheets, stretched over the surface that are substantially transparent to ultraviolet light such that a 3-D mold structure is formed by intersection of these forms with structures formed out of photoresist during an exposure to the ultraviolet light using photolithographic techniques.

[0018]FIG. 1 is a top and side view of the methodology of the invention in accordance with an exemplary embodiment of the invention. Specifically, FIG. 1 represents individual steps, illustrated as panels, which will be discussed below. One of ordinary skill in the art will understand that some minor steps, such as cleaning steps, polishing steps, and / or bak...

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Abstract

A system and method to form beam tunnels in interaction circuits. Forms, such as fibers or sheets can be located and secured above a substrate at a desired size and desired shape to form the final shape of the beam tunnels. Fiber holders can be utilized to position the forms above the substrate. A photoresist can then be applied over the substrate embedding the forms. A single exposure LIGA process can be performed on the photoresist, including the steps of ultraviolet photolithography, molding, and electroforming. After the process, the forms can be removed to leave the beam tunnels in the interaction circuits.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a divisional application of U.S. patent application Ser. No. 13 / 420,696, filed on Mar. 15, 2012 and which will issue as U.S. Pat. No. 9,777,384 on Oct. 3, 2017, which claims the benefit of U.S. Provisional Patent Application No. 61 / 471,828, filed on Apr. 5, 2011, both of which are incorporated by reference herein in their entireties.FIELD OF THE INVENTION[0002]The invention relates to forming hollow bores. More specifically, the invention relates to a method for forming any number of very small, precise high-aspect-ratio hollow bores, or “beam tunnels,” of arbitrary cross sectional shape and arbitrarily long length in metals for the purpose of transporting electron beams.BACKGROUND[0003]Vacuum electron devices that generate electromagnetic power in the gigahertz (GHz=109 Hz) to terahertz (THz=1012 Hz) frequency range often rely on very small metal structures, known as “interaction circuits,” that support electromagneti...

Claims

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Application Information

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Patent Type & AuthorityApplications(United States)
IPC IPC(8): C25D1/00G03F7/00C25D1/02
CPCG03F7/00C25D1/02C25D1/003
InventorJOYE, COLIN D.
OwnerTHE UNITED STATES OF AMERICA AS REPRESENTED BY THE SECRETARY OF THE NAVY