Methods for fabricating an apparatus having a hermetic seal
Apparatus and Methods for fabricating apparatus having a hermetic seal to seal a portion of an apparatus, for example and without limitation, a portion having a MEMS sensor. One such method uses crimping devices to compress a seal in a cavity formed in a housing that includes a MEMS sensor attached to a stress isolator. Under such compression, the seal deforms to hermetically seal surfaces around the inside, outside and bottom of the stress isolator.
1. A method of sealing a sensor to a housing comprising:
providing a housing with a top and a bottom and a hole that passes through the housing from the top to the bottom wherein the housing further comprises a first cavity with a first inner wall, a first outer wall and a first cavity bottom and wherein the housing further comprises a second cavity with a second inner wall, a second outer wall and a second cavity bottom and both the first cavity and the second cavity extend down into the housing from the top and surround the hole wherein the first outer wall of the first cavity is the second inner wall of the second cavity;
providing a seal with a toroidal shape with an open seal top;
pressing the seal inside the first cavity such that a seal bottom is pressed against the first cavity bottom;
providing an isolation member coupled to the sensor;
placing the isolation member down into the first cavity such that the isolation member extends down into the open top of the seal;
placing a collar down into the second cavity; and
pressing the collar down such that the collar deforms the second inner wall of the second cavity and seals the housing to the isolation member.
2. The method of claim 1 , wherein the seal is pressed down with approximately 0.5 tons per square inch.
3. The method of claim 1 , wherein the collar is pressed down with approximately 2 tons per square inch.
4. The method of claim 1 , wherein the seal is sized to fit snugly within the first cavity.
5. The method of claim 1 , wherein the housing is cylinder shaped.
6. The method of claim 1 , wherein the seal is made from copper.
7. The method of claim 1 , wherein the seal is a copper alloy.
8. The method of claim 1 , wherein the sensor is a MEMS sensor.
9. The method of claim 1 , wherein the collar is made from steel.
10. The method of claim 1 , further comprising deforming the seal such that the seal seals the isolation member to the housing.
11. The method of claim 1 , wherein the housing is comprised from one or more of stainless steel, brass and aluminum.
12. The method of claim 1 , wherein the collar has a first hole that passes through the collar, wherein the first hole is coaxial with the hole in the housing, the first cavity and the second cavity.
13. The method of claim 1 , wherein the sensor is a pressure sensor.