Pressure sensor having a laminated substrate

• US 5,285,690 A
• Filed: 01/24/1992
• Issued: 02/15/1994
• Est. Priority Date: 01/24/1992
• Status: Expired due to Term

• Current Assignee: Invensys Systems Incorporated (Invensys PLC)
• Original Assignee: The Foxboro Company (Schneider Electric SE)
• Inventors: Vernon, Robert D., Koen, Edward F.
• Primary Examiner(s): WOODIEL, DONALD
• Application Number:
  US07/825,620
• Time in Patent Office: 753 Days
• Field of Search: 73/720, 73/721, 73/726, 73/727, 73/756, 73/718, 73/724, 73/708, 73/706, 29/621.1, 29/25.41, 29/25.42, 361/283, 338/4, 338/42
• US Class Current: 73/727
• CPC Class Codes: G01L 19/0084 to the outside of the housing other details about the housing see G01L19/14
• CPC Class Codes: G01L 19/147 Details about the mounting of the sensor to support or covering means
• CPC Class Codes: G01L 27/007 Malfunction diagnosis, i.e. diagnosing a sensor defect
• 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 2224/73265 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: Y10T 29/49103 Strain gauge making

Abstract

A pressure sensor sub-assembly (18) has a solid-state sensing element (22) mounted on a laminated ceramic substrate (20) and has the electrical signal contacts (22a) on the sensing element electrically connected to connector pins (24) on the substrate. A manufacturing process can fabricate a batch of sub-assemblies on a substrate structure that is sub-divided to form the separate sub-assemblies. The sensor sub-assemblies can be tested, and graded, before or after the sub-division step, and then each mounted in a housing.

Claims

1. In pressure sensor apparatus, the combination comprising

A. a substrate having first and second opposed sides, said substrate being laminated of at least first and second layers and having electrical conductors extending between said opposed sides in apertures through said substrate, and wherein said apertures are sealed pressure-wise,

B. a bonding layer on said first side of said substrate,

C. electrical connector elements connected with said electrical conductors and mounted on said substrate to extend from said second side of said substrate, said connector elements being disposed for removable and replaceable connection with mating connector elements, and

D. a pressure sensing element having a sensor diaphragm and electrical contacts and developing at said electrical contacts an electrical signal responsive to diaphragm deflection, said sensing element being bonded by said bonding layer to said first side of said substrate and said contacts being connected electrically to said conductors, said sensing element defining a chamber between one side of said sensor diaphragm and said substrate and wherein said sensor diaphragm deflects in response to the pressure difference and between said chamber and the pressure on the other side of said sensing element.

2. In pressure sensor apparatus according to claim 1, the further combination of

A. housing means enclosing the assembly of said substrate and said sensing element, said housing means having an interior surface and having first passages through which said connector elements are accessible externally of said housing means, and

B. means mounting and pressure sealing said substrate to said interior surface of said housing means, said pressure sealing means sealing said first passages closed.

3. In pressure sensor apparatus according to claim 1, wherein said laminated layers define a planar surface on which said bonding layer secures said sensing element.

4. In pressure sensor apparatus according to claim 1, wherein said bonding layer is any one of a compliant adhesive, an epoxy, and a solder, and secures said sensing element to said substrate.

5. In pressure sensor apparatus according to claim 1, wherein said bonding layer is a compliant adhesive stenciled onto said first side of said substrate.

6. In pressure sensor apparatus according to claim 1, the further combination in which said substrate has at least a third layer disposed on said first and second layers and defining a peripheral wall that encloses a recess in which said bonding layer and said sensing element are disposed.

7. In pressure sensor apparatus according to claim 6, wherein said bonding layer is a compliant adhesive deposited within said recess.

8. In pressure sensor apparatus according to claim 1, the further combination of means forming a pressure passage through said substrate and communicating with said chamber.

9. In pressure sensor apparatus according to claim 8,

A. the further combination of housing means mounting said substrate with said connector elements accessible for electrical connection externally of said housing means, and

B. wherein said housing means has a base element having an aperture therethrough in fluid communication with said pressure passage.

10. In pressure sensor apparatus according to claim 1, the further combination wherein said substrate has a pressure passage extending from said first side and said sensing element is in pressure communication with said pressure passage for diaphragm deflection in response to pressure applied at said first side of said substrate relative to the pressure in said passage.

11. In pressure sensor apparatus according to claim 1, the further combination wherein said substrate is a laminate of plural ceramic layers and said sensor element is of silicon.

12. Pressure sensor apparatus having a minimum testable format and for post-testing assembly in a housing, said pressure sensor apparatus comprising

A. a ceramic substrate having first and second opposed sides, said substrate being laminated of at least first and second layers apertured with a through pressure passage, said substrate further having electrical conductors extending between said opposed sides, said substrate being pressure-tight between said opposed sides except at said pressure passage,

B. a bonding layer on said first side of said substrate,

C. electrical connector elements mounted on said substrate and connected with said electrical conductors, said connector elements extending from said substrate and being disposed for removable and replaceable connection with mating connector elements,

D. a solid-state pressure sensing element having a sensor diaphragm and electrical contacts and developing at said electrical contacts and electrical signal responsive to diaphragm deflection, said sensing element being bonded to said first side of said substrate by said bonding layer and said contacts being connected electrically to said conductors,

E. whereby the electrical response of said sensing element to pressure differentials between said first side and said pressure passage can be tested at said connector elements before the post-testing assembly.

13. In pressure sensor apparatus, the combination comprising

A. a substrate having a first side, said substrate being laminated of at least first and second layers and having electrical conductors extending from said first side in apertures through said substrate, and wherein said apertures are closed pressure-wise,

B. a bonding layer on said first side of said substrate,

C. electrical connector elements connected with said electrical conductors and mounted on said substrate to extend therefrom for removable and replaceable connection with mating connector elements, and

D. a pressure sensing element having a sensor diaphragm and electrical contacts, and developing at said electrical contacts an electrical signal responsive to diaphragm defection, said sensing element being bonded by said bonding layer to said first side of said substrate and said contacts being connected electrically to said conductors, said sensing element defining a chamber between one side of said sensor diaphragm and said substrate and wherein said sensor diaphragm deflects in response to the pressure difference and between said chamber and the pressure on the other side of said sensing element.

14. In pressure sensor apparatus according to claim 13, the further combination of

A. housing means mounting said substrate with said sensing element thereon, said housing means having an interior surface and having first passages through which said connector elements are accessible externally of said housing means, and

B. means mounting and pressure sealing said substrate to said interior surface of said housing means, said pressure sealing means sealing said first passages closed.

15. Pressure sensor apparatus having a minimum testable format and for post-testing assembly in a housing, said pressure sensor apparatus comprising

A. a dielectric substrate having a first side and being laminated of at least first and second layers apertured with a through pressure passage, said substrate having electrical conductors exposed on said first side,

B. a bonding layer on said first side of said substrate,

C. electrical connector elements mounted on said substrate and connected with said electrical conductors, said connector elements extending from said substrate for removable and replaceable connection with mating connector elements,

D. a solid-state pressure sensing element having a sensor diaphragm and electrical contacts and developing at said electrical contacts an electrical signal responsive to diaphragm deflection, said sensing element being bonded to said first side of said substrate by said bonding layer and said contacts being connected electrically to said conductors,

E. whereby the electrical response of said sensing element to pressure differentials between said first side and said pressure passage can be tested at said connector elements before the post-testing assembly.