Santa Barbara Research Center

Raytheon Company

Timothy S Romano

Karl H Neumann

Gary B Hughes

Tom K Evans

Leonard E Peck

Adam M Kennedy

Nevil Q Maassen

Robert E Zahuta

Kenneth L Gustafson

Larry E Cobb

Arthur A Eneim

Donald E Salzer

Steven M McCabe

An electrical feedthrough (34) is prepared by furnishing an aluminum oxide feedthrough plate (70) and at least one feedthrough pin (80) having a length greater than the thickness of the feedthrough plate (70). A pin bore (78) is formed through the feedthrough plate (70) for each feedthrough pin (80). Each pin bore (78) has a pin bore (78) size greater than the feedthrough pin (80) size, preferably by an amount no greater than that required to permit the penetration of a brazing metal (88) between the pin bore (78) and the feedthrough pin (80). Each feedthrough pin (80) is inserted into its respective pin bore (78) and brazed into place utilizing a metallic active braze alloy (88) and no glassy seal. The feedthrough plate (70) may be simultaneously brazed to a package structure (22) using active or nonactive brazing.

Electrical feedthrough and its preparation

A structure (20) is formed of a first article (22) such as a cold finger (82), a second article (24) such as an electronic component (78) to be affixed to and cooled by the cold finger (82), and a bonding element (26) disposed between and bonding together the first article (22) and the second article (24). The bonding element (26) includes a porous metallic body (28), such as a screen, a mesh, a felt, or a foam, and a mass of resin adhesive (36) impregnated into the metallic body (28). The mass of adhesive (36) contacts and bonds to the first article (22) and to the second article (24), and the porous metallic body (28) forms a substantially continuous, high-conductivity path between the first article (22) and the second article (24).

Bonded structure with high-conductivity bonding element

A getter assembly (38) includes a porous getter element (40) having an outer periphery (44), and a porous, thermally conductive, annular getter support (42) overlying the getter element (40) and contacting the outer surface (44) of the getter element (40). The getter assembly (38) further includes a wall (24) sized so that the annular getter support (42) is received within the wall (24) with a friction fit between an outer periphery (50) of the annular getter support (42) and an inner periphery of the wall (24). The getter support (42) supports the getter element (40) from the wall (24) and provides a thermally conductive pathway from the wall (24) to the getter element (40). The annular getter support (42) is typically a screen, a mesh, a felt, or a foam, which is deformable to conform to the inner wall (24) and to slide into the wall (24) with a friction fit that ensures good thermal contact.

Getter assembly having porous metallic support and its use in a vacuum

A gold-coated molybdenum article (30) is made by furnishing a substrate (32) made of pure molybdenum or an alloy of molybdenum, and preparing a slurry of gold powder, acrylic binder, and acetone liquid carrier. The slurry is applied to a portion of a surface of the substrate. The substrate with applied slurry is heated in vacuum or inert atmosphere to an elevated temperature, preferably about 2040.degree. F., and thereafter cooled to ambient temperature. The result is an article (30) having at least a portion of the substrate (32) covered with an adherent gold coating (34).

Preparation of gold-coated molybdenum articles and articles prepared

A vacuum system (20) includes an enclosure (22) having a vacuum-tight wall (26) and an internally threaded aperture (66) through the wall (26). A tip-off fitting (24) has a base (50) with a bore (52) therethrough, a hollow tube (62) fixed to the base (50) with a vacuum-tight seal, such that an interior (64) of the tube (62) is in communication with the bore (52) in the base (50), and an external thread (58) on the exterior of the base (50). The external thread (58) on the exterior of the base (50) is dimensioned to threadably engage the internal thread (68) on the aperture (66). There is a disengageable vacuum sealant (70) such as a layer of indium metal between the external thread (58) of the base (50) and the internal thread (68) of the aperture (66). The vacuum system (20) is evacuated through the tip-off fitting (24) and sealed by closing off the hollow tube (62). At a later time, the vacuum system can be brought to atmospheric pressure and then reseated by replacing the tip-off fitting with another tip-off fitting and repeating the evacuation and sealing.

Semi-permanent vacuum closure with multiple retubulation capability

A lower vacuum housing (34) of a sensor dewar (26) is fabricated in a single brazing operation from ceramic and metallic components. The components are assembled with ceramic-to-metal interfaces and metal-to-metal interfaces. Brazing is accomplished by active brazing of the ceramic-to-metal interfaces and non-active brazing of the metal-to-metal interfaces. Specific combinations of active braze alloys and non-active braze alloys are provided for various combinations of dewar materials.

Brazed lower vacuum housing for a dewar

A feedthrough (34) is formed of a feedthrough plate (44) having at least one bore (46) therethrough and a feedthrough pin (48) hermetically sealed into the bore (46). The feedthrough pin (48) includes an elongated pin (50) having an axis of elongation (52), a recess (54) in at least one end of the pin (50), the recess (54) extending parallel to the axis of elongation (52), and a gold coating (56) within the recess (54). There are preferably a plurality of bores (46) in the feedthrough plate (48) and a corresponding plurality of the feedthrough pins (48). The gold coatings (56) at the ends of the feedthrough pins (48) are desirably lapped to ensure coplanarity and a smooth surface finish especially suited for wire bonding or tab bonding.

Feedthrough pin and process for its preparation, and electrical

A vacuum package assembly (20) is prepared by self-welding the flanges (32 and 43) of two housings (28 and 36) together under an applied pressure, while the housings (28 and 36) and any enclosed structure or device are contained within an evacuated enclosure. The flanges (32 and 43) are preferably made of copper, with their respective self-welding members (34 and 46) specially prepared to enhance self-welding performance. The preferred treatment for the self-welding members (34 and 46) is to deposit a thin layer of nickel onto the self-welding members (34 and 46 ), deposit a thin layer of gold over the nickel, and heat the bonding member to elevated temperature to interdiffuse the gold into the self-welding member (34 and 46 ).

Vacuum package tubeless enclosure with self-welded flanges

A radiation detector assembly (20) includes a radiation detector (2), a silicon readout device (3) coupled to the radiation detector, and a platform 13 for supporting from a first major surface (13a) the readout device and the radiation detector. A second major surface (13b) includes a boss (14) for coupling, via an active brazing operation, to a cryogenic cooler. The platform is monolithic structure comprised of aluminum nitride (AlN) and eliminates at least one adhesive joint found in the prior art. AlN is selected because of its inherent material properties including a higher thermal diffusivity, relative to typical ceramic materials, for providing a reduced cooldown time of the detector to cryogenic temperatures. AlN also has a 300K- 77K thermal contraction characteristic that closely matches that of the silicon readout device and a high modulus of elasticity, thereby reducing distortion of the readout device thus minimizing stresses on indium bump interconnects. AlN also has dielectric characteristics that permit thin film metalization of the surface (13a) for providing electrical signal distribution.

Quick cooldown/low distortion hybrid focal plane array platform for use

An infrared detector assembly (10) of the type used in munition and night vision systems having an RF activated getter (50). Such detector assemblies (10) include a tubular coldfinger (22) surrounded by a vacuum and which supports infrared detector array (26) and related components. In accordance with this invention, RF getter (50) is located remote from detector array (26) and engages an inner wall surface (56) of a metallic dewar housing (14). The RF getter (50) is activated via RF inductive heating directly through the metal dewar housing (14) such that sensitive IR detector components and hermetic braze joints are kept below their critical temperature. As a result, the present invention provides longer vacuum life and greater operational reliability of infrared detector assembly (10).

Remote fired RF getter for use in metal infrared detector dewar

An infrared detector assembly (10) of the type used in munitions and night vision systems having an improved coldfinger assembly (42). Such detector assemblies (10) include a tubular coldfinger (22) which is surrounded by a vacuum and an end-cap (28) mounted to the coldfinger tube (22) to define a cold end (24) which supports the infrared detector array (30) and related components. In accordance with this invention, the coldfinger tube (22) is a thin-walled titanium cylinder and the end-cap (28) is made of tungsten. The components are metallurgically bonded at the cold end (24) by an active brazing alloy deposited during vacuum furnace brazing. The titanium coldfinger (22) provides the necessary bending stiffness to support cold end components. The tungsten end-cap (28) provides a low distortion, thermally stable focal-plane. The metallurgical bond (46) provides for a hermetic seal which inhibits structural distortion during brazing, and during cyclical cooling of the detector assembly (10).

Distortion free dewar/coldfinger assembly

A hollow, elongated tip-off tube 12 is comprised of a copper substrate having a layer of gold plating diffused into the surface thereof. The gold is applied over a nickel strike and the tube is heated within a vacuum furnace to diffuse the gold into the copper surface. The gold diffused inner surface of the tube is found to have superior self-welding characteristics and increased strength and durability. The nobility of the inner surface resists the formation of an oxide coating thereon which eliminates the need to clean the inner surface of the tube before pinch-off. Thus, the entrapment of residual cleaning chemicals within the pinch-off area is avoided.

Growing community of inventors

Goleta, CA, United States of America

Timothy S Romano