Isolation technique for pressure sensing structure

• US 6,938,490 B2
• Filed: 02/20/2003
• Issued: 09/06/2005
• Est. Priority Date: 01/19/2000
• Status: Expired due to Term

• Current Assignee: Measurement Specialties, Inc. (France) (TE Connectivity Limited)
• Original Assignee: Measurement Specialties, Inc. (France) (TE Connectivity Limited)
• Inventors: Lopopolo, Gerald, Wagner, David E., Hoffman, James H.
• Primary Examiner(s): Lefkowitz, Edward
• Assistant Examiner(s): ALLEN, ANDRE J
• Application Number:
  US10/371,509
• Publication Number:
  US 20030150275A1
• Time in Patent Office: 929 Days
• Field of Search: 737/18, 737/24, 737/25, 737/26, 737/27, 737/19, 737/20, 737/21
• US Class Current: 73/708
• CPC Class Codes: G01L 19/0069 from the sensor to its support
• CPC Class Codes: G01L 19/0645 using isolation membranes, specially adapted for protection
• CPC Class Codes: G01L 19/146 using flexible element between the transducer and the support
• CPC Class Codes: G01L 19/147 Details about the mounting of the sensor to support or covering means
• CPC Class Codes: G01L 9/0042 Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms details about the integration or bonding of piezoresistor in or on the diaphragm G01L9/0052 and G01L9/0057 respectively
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• 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 2924/15151 the die mounting substrate comprising an aperture, e.g. for underfilling, outgassing, window type wire connections

Abstract

An electronic pressure-sensing device is isolated from corrosive, conductive gasses and fluids by a corrosion resistant metal diaphragm welded to a pressure port. The pressure-sensing device is attached to a support structure with a hole that provides a path from the diaphragm area to the pressure-sensing device. A fill fluid is sealed behind the diaphragm and fills the hole through the support structure to the electronic pressure-sensing device. In this design, any hostile chemical applied is completely isolated from the electronic sensor and associated adhesive seals by the metal diaphragm.

Claims

1. A pressure sensor comprising:

a plate having a hole therein;

a pressure sensing die mounted to said plate, said pressure sensing die comprising a diaphragm in fluid communication with said hole, said diaphragm comprising a pressure sensitive electrical element formed in or on said diaphragm;

a cap glass-flit bonded to said pressure sensing die such that a cavity is formed between said cap and said diaphragm, wherein said pressure sensitive elecirical element provides an indication of the difference between the pressure on each side of the diaphragm.

2. Sensor of claim 1 wherein said cavity contains a vacuum.

3. Sensor of claim 1 wherein said cap and die are made from the same material.

4. Sensor of claim 1 wherein said cap and die comprise silicon.

5. Sensor of claim 1 wherein said element comprises a capacitor.

6. Sensor of claim 1 wherein said element comprises a resistor.

7. Sensor of claim 1 wherein glass fit serves as an adhesive bond for bonding said cap to said pressure sensing die.

8. Sensor of claim 7 wherein said cap is bonded directly to said pressure sensing die with said glass frit.

9. Sensor of claim 1 wherein said cap comprises a top and side walls extending from said top toward said die, the bottom of said side walls being glass-fit bonded to said die.

10. Sensor of claim 1 further comprising a support structure provided between said die and said plate, said support structure having a hole therein in fluid communication with the hole in said plate.

15. Method of claim 1 further comprising providing a support structure between said die and said plate, said support structure having a hole therein in fluid communication with the hole in said plate.

11. A method for making a pressure sensor comprising:

providing a pressure sensing die comprising a diaphragm, said diaphragm comprising a pressure sensitive electrical element formed therein;

glass-fit bonding a cap to said pressure sensing die such that a cavity is formed between said cap and said diaphragm;

mounting said pressure sensing die on a plate having a hole therein such that said diaphragm is in fluid communication with said hole, wherein said pressure sensitive electrical element provides an indication of the difference between the pressure on each side of the diaphragm.

12. Method of claim 11 wherein glass frit serves as an adhesive bond for bonding said cap to said pressure sensing die.

13. Method of claim 11 wherein said cap is bonded directly to said pressure sensing die with said glass frit.

14. Method of claim 11 wherein said cap comprises a top and side walls extending from said top toward said die, the boffom of said aide walls being glass-frit bonded to said die.