Termination feedthrough unit with ceramic insulator suitable for vacuum and corrosive applications
An electrical termination unit or feedthrough which may be used for routing electrical conductors through a chamber wall, or otherwise across a barrier between isolated atmospheric conditions. The electrical termination unit may have aluminum as the interface material to the chamber interface and may utilize a ceramic insulator. The electrical termination unit may have the aluminum used as the interface brazed directly to a ceramic surface of the insulator. The aluminum that forms the chamber interface may be formed within a hollow ceramic tube in the same process step that brazes the aluminum to the ceramic tube with a hermetic joint. Machining subsequent to the brazing of the aluminum to the ceramic insulator may allow for achievement of the final form desired. A method for manufacturing such an electrical termination unit.
1. A method for making an insulated electrical feedthrough or electrical termination unit, said method comprising the steps of:
putting aluminum into a hole in a ceramic piece, said ceramic piece having a first end and a second end, said hole providing an opening in said ceramic piece at the first end;
brazing the aluminum to create an aluminum rod within said ceramic piece joined with a hermetic joint between the aluminum and an inner surface of said hole in said ceramic piece;
removing a center of the aluminum rod to create an aluminum tube within said ceramic piece; and
removing a first portion of said ceramic piece at said first end of said ceramic piece to expose a portion of an outer surface of the aluminum tube, thereby resulting in the aluminum tube with a second portion of the aluminum tube hermetically joined along the outer surface of said aluminum tube to an interior of said hole within said ceramic piece within the center of an annular of said ceramic piece at the first end.
2. The method of claim 1 further comprising a step of brazing an end cap to the second end of said annular of said ceramic piece.
3. The method of claim 2 further comprising a step of affixing a conductor through said insulated electrical feedthrough.
4. The method of claim 1 wherein the step of brazing the aluminum comprises brazing the aluminum at a temperature of 770 degrees Celsius or greater.
5. The method of claim 4 wherein the step of brazing the aluminum comprises brazing at a pressure of 1×10E−4 Torr or lower.
6. The method of claim 5 wherein said aluminum comprises aluminum of greater than 98% aluminum by weight.
7. The method of claim 5 wherein said aluminum comprises aluminum of greater than 99% aluminum by weight.
8. The method of claim 4 wherein the step of brazing the aluminum comprises brazing at a pressure of 5×10E−5 Torr or lower.
9. The method of claim 4 wherein said aluminum comprises aluminum of greater than 98% aluminum by weight.
10. The method of claim 4 wherein said aluminum comprises aluminum of greater than 99% aluminum by weight.
11. The method of claim 1 wherein the step of brazing the aluminum comprises brazing the aluminum at a temperature of 800 degrees Celsius or greater.
12. The method of claim 1 wherein the step of brazing the aluminum comprises brazing the aluminum at a temperature in the range of 770 degrees Celsius to 1200 degrees Celsius.
13. The method of claim 12 wherein the step of brazing the aluminum comprises brazing at a pressure of 1×10E−4 Torr or lower.
14. The method of claim 12 wherein the step of brazing the aluminum comprises brazing at a pressure of 5×10E−5 Torr or lower.
15. The method of claim 1 wherein said aluminum comprises aluminum of greater than 98% aluminum by weight.
16. The method of claim 1 wherein said aluminum comprises aluminum of greater than 99% aluminum by weight.