Amplified pressure transducer

• US 5,257,547 A
• Filed: 11/26/1991
• Issued: 11/02/1993
• Est. Priority Date: 11/26/1991
• Status: Expired due to Fees

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Boyer, Gregory S.
• Primary Examiner(s): WOODIEL, DONALD
• Application Number:
  US07/798,476
• Time in Patent Office: 707 Days
• Field of Search: 73/706, 73/720, 73/721, 73/726, 73/727, 73/717, 73/718, 73/719, 73/722, 73/723, 73/724, 73/725, 73/728, 73/756, 73/431, 338/4, 361/283
• US Class Current: 73/756
• CPC Class Codes: G01L 19/0038 being part of the housing other details about the housing G01L19/14
• CPC Class Codes: G01L 19/14 Housings G01L19/0007, G01L19/0084, G01L19/0092, G01L19/04, G01L19/06 take precedence
• CPC Class Codes: G01L 19/142 Multiple part housings
• CPC Class Codes: G01L 19/148 Details about the circuit board integration, e.g. integrated with the diaphragm surface or encapsulation
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/10253 Silicon [Si]
• CPC Class Codes: H01L 2924/19107 off-chip wires

Abstract

A pressure transducer is provided which incorporates numerous stress reducing characteristics. A pressure sensor is mounted to a ceramic plate with a buffer plate there between to isolate the pressure sensor from stresses that could be transmitted through the ceramic plate. The ceramic plate is necessary for the purpose of supporting a plurality of electronic components which comprise an amplification and compensation circuit. The ceramic plate is separated from all parts of its housing except a minimal central surface on a support boss which provides the support for the pressure sensitive device. Electrical communication between conductive paths on the ceramic plate and terminals extending through the housing is provided by flexible electrical conductors. A cover is attached to the housing with snap acting contact which further isolate the housing from the cap. The housing and cap are constructed to support the housing in a noncontact association with an external device when feet on the cap are attached directly to the external device. This offset positioning of the housing with respect to the external component further isolates the housing from sources of external stress. The combined stress isolated techniques used in the present invention permit a pressure sensor to measure very low pressures with a high degree of sensitivity without introducing measurement problems that would otherwise be incumbent in this type of transducer because of externally caused stresses transmitted from external forces and originating in the transducer because of thermal stress.

Claims

1. A pressure transducer, comprising:

a housing having a base surface and a plurality of walls attached to said base surface;

a support boss attached to said base surface;

a pressure sensitive device attached to said support boss with said support boss being disposed in contact with a central portion of a first surface of said pressure sensitive device, said pressure sensitive device being supported by said support boss in noncontact association with said plurality of walls;

first means for connecting said pressure sensitive device in fluid communication with a first region external to said housing;

a plurality of electrically conductive terminals rigidly attached to said housing and extending from a first position proximate said pressures sensitive device to a second position external to said housing; and

a cover attached to said housing to enclose said pressure sensitive device between said housing and said cover, said pressure sensitive device comprising a ceramic member and a pressure sensor disposed on said ceramic member, a first surface of said ceramic member being said first surface of said pressure sensitive device, said pressure sensitive device further comprising a cap disposed on a second surface of said ceramic member, said pressure sensor being disposed between said cap and said second surface.

2. The transducer of claim 1, wherein:

said pressure sensitive device further comprises a buffer plate disposed between said second surface and said pressure sensor.

3. The transducer of claim 2, wherein:

said buffer plate is attached to ceramic member with flexible adhesive, said pressure sensor is attached to said buffer plate with flexible adhesive and said ceramic member is attached to said support boss with flexible adhesive.

4. The transducer of claim 2, wherein:

said pressure sensor comprises a diaphragm disposed in fluid communication with said connecting means.

5. The transducer of claim 4, further comprising:

flexible electrical conductors connected in electrical communication between said terminals and said ceramic member.

6. The transducer of claim 5, wherein:

said first connecting means is connected in fluid communication with a first side of said diaphragm of said pressure sensor.

7. The transducer of claim 6, further comprising:

a second means for connecting a second side of said diaphragm of said pressure sensor in fluid communication with a second region outside said housing.

8. The transducer of claim 7, wherein:

said first connecting means comprises a first opening extending through said ceramic member in fluid communication with a cavity of said buffer plate and said first side of said diaphragm of said pressure sensor and said second connecting means comprises a second opening extending though said ceramic member in fluid communication with said second side of said diaphragm of said pressure sensor.

9. The transducer of claim 7, wherein:

said flexible electrical conductors are made of gold.

10. The transducer of claim 1, wherein:

said cover comprises a first means for attaching said transducer to an object, said first attaching means being shaped to support said housing in noncontact association with said object.

11. The transducer of claim 10, wherein:

said cover further comprises a second means for attaching said transducer to said object, said second attaching means being shaped to support said housing in noncontact association with said object.

12. The transducer of claim 1, wherein:

said cover and said housing are removably attached together with a plurality of snap acting connectors.

13. A pressure transducer, comprising:

a housing;

a boss extending from said housing;

a pressure sensitive device attached for support to said boss;

a first conduit connecting said pressure sensitive device in fluid communication with a first region external to said housing;

an electrically conductive terminal attached for support to said housing and extending through said housing from a first position proximate said pressure sensitive device to a second position external to said housing;

a cover attached to said housing, said pressure sensitive device being disposed between said housing and said cover, said pressure sensitive device being supported by said boss in noncontact association with said housing and said cover; and

first means for attaching said transducer to an object, said first attaching means being configured to support said housing in noncontact relation with said object.

14. The transducer of claim 13, further comprising:

said means for attaching said transducer to said object, said second attaching means being configured to support said housing in noncontact relation with said object.

15. The pressure transducer of claim 13, wherein:

said pressure sensitive device comprises a ceramic plate having a first side attached to said boss and a second side having a pressure sensor disposed thereon, said conduit being connected in fluid communication with said pressure sensor.

16. The transducer of claim 15, wherein:

a buffer plate is disposed between said pressure sensor and said second side of said ceramic plate, said buffer plate having a cavity, said conduit being connected in fluid communication with said cavity.

17. The transducer of claim 16, wherein:

said pressure sensor comprises a diaphragm which is pressure responsive, said diaphragm having a first side and a second side.

18. The transducer of claim 16, further comprising:

a flexible electrical conductor connected in electrical communication between said terminal and said ceramic plate.

19. The transducer of claim 18, wherein:

said conduit extends through said boss in fluid communication with said first side of said diaphragm.

20. The transducer of claim 19, further comprising:

a cap disposed on said second side of said ceramic plate, said pressure sensor being disposed between said cap and said second side of said ceramic plate.

21. The transducer of claim 20, further comprising:

a second conduit connected in fluid communication with a second side of said diaphragm, said second conduit extending through said boss.

22. The transducer of claim 21, wherein:

said first conduit extends through a first opening in said ceramic plate and said second conduit extends through a second opening in said ceramic plate.

23. The transducer of claim 16, wherein:

said buffer plate is attached to said ceramic plate with a flexible adhesive, said pressure sensor is attached to said buffer plate with flexible adhesive and said ceramic plate is attached to said boss with flexible adhesive.

24. A pressure transducer, comprising:

a housing;

a boss attached to said housing;

a pressure sensitive device attached to said boss;

a first conduit extending through a portion of said housing and through a portion of said boss, said conduit being connected in fluid communication with said pressure sensitive device and with a first region external to said pressure transducer;

an electrically conductive terminal attached to said housing and extending through a portion of said housing, one end of said terminal being proximate and said pressure sensitive device;

a cover attached to said housing, said pressure sensitive device being disposed between said housing and said cover, said pressure sensitive device being supported by said boss in noncontact relation with said housing and said cover; and

first means attached to said cover for supporting said housing in noncontact relation with an object.

25. The transducer of claim 24, wherein:

said first supporting means comprises a first plurality of feet extending from said cover.

26. The transducer of claim 25, further comprising:

second means attached to said cover for supporting said housing in noncontact relation with said object.

27. The transducer of claim 26, wherein:

said second supporting means comprises a second plurality of feet extending from said cover.

28. The transducer of claim 24, further comprising:

a flexible electrical conductor connected in electrical communication with said terminal and said pressure sensitive device.

29. The transducer of claim 24, wherein:

said pressure sensitive device comprises a ceramic plate with a first side and a second side, said first side being attached to said boss, said pressure sensitive device further comprising a pressure sensor disposed on said ceramic plate, said pressure sensor being disposed in fluid communication with said first conduit.

30. The transducer of claim 29, wherein:

said pressure sensitive device further comprises a buffer plate, said buffer plate having an opening extending therethrough, said opening being in fluid communication with said conduit and said pressure sensor.

31. The transducer of claim 29, wherein:

said pressure sensor comprising a diaphragm having a first side and a second side, said first side being disposed in fluid communication with said first conduit.

32. The transducer of claim 31, further comprising:

a second conduit extending through said housing and said boss, said second conduit being in fluid communication with said second side of said diaphragm and a second region external to said pressure transducer, said second conduit comprising an opening through said ceramic plate.

33. The transducer of claim 29, further comprising:

a cap disposed on said second side of said ceramic plate, said cap comprising a portion of said second conduit.

34. The transducer of claim 24, wherein:

said cover and said housing are separably attached together.

35. The transducer of claim 34, wherein:

said cover and said housing are attached together with pressure activated clips.

36. The transducer of claim 24, further comprising:

means for attaching said pressure transducer to a circuit board.