Metal fusion bonding – Process – Plural joints
Reexamination Certificate
1999-11-02
2001-07-17
Dunn, Tom (Department: 1725)
Metal fusion bonding
Process
Plural joints
C228S253000, C228S255000
Reexamination Certificate
active
06260754
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a cable feedthrough device, and more particularly to a substantially vacuum-tight device having stripline cables that pass through and are sealably connected to a metallic flange that can be subsequently mounted on a bulkhead or a vessel wall.
BACKGROUND OF THE INVENTION
In the liquid argon calorimetry system of the ATLAS experiment at the CERN Large Hadron Collider in Geneva, Switzerland, nearly a quarter million signal and calibration lines are required to pass through the walls of the ATLAS calorimeter cryostats. Signal feedthroughs for such applications can be constructed using individual pins sealed in glass or ceramic, but the conductor density required for the ATLAS calorimeter greatly exceeds the densities typically achieved using pin-based feedthrough technology. The two feedthrough planes, one extremely cold, the other relatively warm, would have to be very large to accommodate the required number of lines, resulting in a bulky device. The bulky design would complicate the assembly of the device and the installation of the requisite plumbing services in its vicinity. In addition, the large number of connectors required along the readout path would add to the construction expense and also result in degradation in signal quality.
An alternative to sealed pin technology for the fabrication of cable feedthrough devices entails the use of epoxy materials for the formation of vacuum-tight seals, as described in W. D. Wood and W. L. Wood, “Hermetic Sealing with Epoxy” in Mechanical Engineering, March 1990, Pave Technology Co. This technology, however, is suitable only for devices exposed to temperatures down to about −65° C.
Thus, there continues to be a need for a cable feedthrough device of compact design that is readily and inexpensively fabricated, and is also capable of maintaining vacuum-tightness even at very low temperatures. The device and process of the present invention meet this need.
SUMMARY OF THE INVENTION
In accordance with the present invention, a vacuum-tight cable feedthrough device comprises a metallic first flange that is penetrated by a slot. Passing through the slot is a flat stripline cable that comprises a plurality of conductive signal channels encompassed by a dielectric material on whose upper and lower surface is disposed a conductive material comprising a ground. Solder seals the stripline cable within the slot to provide a substantially vacuum-tight seal between the cable and the first flange.
In a preferred embodiment of the invention, the cable feedthrough device comprises a plurality, at least 16, of stripline cables. In a further preferred embodiment, the device includes a second flange and a bellows sealably connecting the first and second flanges, thereby providing a substantially vacuum-tight, flexible housing for the plurality of cables.
Further in accordance with the invention is a process for making a cable feedthrough device that, in a preferred embodiment, provides for applying a first solder by heating the first flange to a temperature about 20° to 50° C. below the first solder fusing temperature over about 25 minutes to 35 minutes, followed by heating the flange to about 20° to 50° C. above the first solder fusing temperature over about 2 minutes to 6 minutes, and then cooling the flange below the fusing temperature of the first solder.
The continuous cable feedthrough device of the present invention has several substantial advantages over the use of individually sealed pins: it provides desirable compactness; the uninterrupted passage of the cables results in a constant, controlled characteristic impedance along the entire signal path; the absence of pins and their mating connectors significantly lowers cost and simplifies installation; the continuous conductor through the soldered cable-flange interface provides improved electrical reliability.
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Bazizi Kamel Abdel
Haelen Thomas Eugene
Lobkowicz Frederick
Slattery Paul Francis
Dunn Tom
Johnson Jonathan
Nixon & Peabody LLP
University of Rochester
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