Methods for batch fabrication of cold cathode vacuum switch tubes

DWPI Title: Batch fabricating cold cathode vacuum switch tubes used in e.g. air-bag triggering involves stacking assembly of layers having tube sub-assemblies, aligned through common layer/heating in vacuum oven to allow joining into cohesive structure
Abstract: Methods are disclosed for batch fabrication of vacuum switch tubes that reduce manufacturing costs and improve tube to tube uniformity. The disclosed methods comprise creating a stacked assembly of layers containing a plurality of adjacently spaced switch tube sub-assemblies aligned and registered through common layers. The layers include trigger electrode layer, cathode layer including a metallic support/contact with graphite cathode inserts, trigger probe sub-assembly layer, ceramic (e.g. tube body) insulator layer, and metallic anode sub-assembly layer. Braze alloy layers are incorporated into the stacked assembly of layers, and can include active metal braze alloys or direct braze alloys, to eliminate costs associated with traditional metallization of the ceramic insulator layers. The entire stacked assembly is then heated to braze/join/bond the stack-up into a cohesive body, after which individual switch tubes are singulated by methods such as sawing. The inventive methods provide for simultaneously fabricating a plurality of devices as opposed to traditional methods that rely on skilled craftsman to essentially hand build individual devices.
Use: As method for batch fabrication of cold cathode vacuum switch tubes (claimed) used in applications requiring stand-off of high voltages and fast switching of large currents. Such applications include triggering of air-bags, the initiation of explosives, control of high energy physics equipment, power supplies and capacitive discharge units (CDUs).
Advantage: The method allows batch fabrication of vacuum switch tubes that reduce manufacturing costs and improve tube to tube uniformity. The method provides for simultaneously fabricating several devices as opposed to traditional methods that rely on skilled craftsman to essentially hand build individual devices. The method provides cold cathode vacuum switch tubes that by action of a trigger signal are capable of rapidly and repeatedly, switching large currents at high voltages, in extreme environments of shock, radiation and temperature. The method provides batch fabrication (e.g. several fabricated simultaneously) of vacuum switch tubes providing lower cost and enhanced product uniformity over methods based on hand assembly of individual piece parts (e.g. individuals fabricated serially). The methods by employing a stacked assembly of layers, provides for fabricating several switch tubes simultaneously in a batch fabrication approach, greatly eliminating hand assembly and piece part counts, thereby reducing the cost of producing a vacuum switch tube. The methods additionally reduce the spread in operational characteristics on a part to part basis, compared to methods based on traditional hand assembly of individual units. The methods can further reduce the cost of switch tubes by employing joining (e.g. brazing) processes that do not require the metallization of ceramic components.
Novelty: Batch fabricating cold cathode vacuum switch tubes involves heating stacked assembly (200) of layers having spacedly adjacent vacuum switch tube (100) sub-assemblies arranged in common layer, where assembly has trigger electrode layer (206), cathode layer having graphite cathodes (204); first electrically insulating layer, spacedly adjacent trigger probes having ceramic insulator with carbon coating, where probe has conductor, second insulating layer (210), anodes (202) extending through clearance (240) through second layer, braze alloy layer (224a) and unit for aligning common layer.
Filed: 7/7/2008
Application Number: US2008168625A
Tech ID: SD 10375.0
This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention.
Data from Derwent World Patents Index, provided by Clarivate
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