SEMICONDUCTOR STRAIN TRANSDUCERS

• US 3,662,312 A
• Filed: 03/24/1969
• Issued: 05/09/1972
• Est. Priority Date: 03/23/1968
• Status: Expired due to Term

• Current Assignee: Zetex Plc (Diodes Incorporated)
• Original Assignee: Charles Trevor Jones, William Thorp
• Inventors: Thorp, William, Jones, Charles Trevor
• Primary Examiner(s): Tubbesing, T. H.
• Assistant Examiner(s): Kinberg, R.
• Application Number:
  US04/809,848
• Time in Patent Office: 1,142 Days
• Field of Search: 338/2,3,5,6,9,4 73/88.5SD,398AR
• US Class Current: 338/4
• 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 19/148 Details about the circuit board integration, e.g. integrated with the diaphragm surface or encapsulation
• CPC Class Codes: G01L 9/0054 integral with a semiconducting diaphragm

Abstract

A strain transducer having a plurality of piezo-resistive sensing elements formed adjacent to one major face of a semiconductor wafer is wholly assembled by employing techniques compatible with the structure of the semiconductor wafer, these techniques including bonding the wafer to a rigid metal supporting ring which in turn is bonded to an annular insulating member secured to the transducer housing.

Claims

1. A strain transducer including a semiconductor wafer having a plurality of piezo-resistive strain sensing elements formed adjacent to one major wafer face and defined by P-N junctions, a metal ring alloyed to circumferential parts of the semiconductor wafer, an annular member of insulating material having a plane surface at least partially metallized and cooperating with the metal ring to which it is bonded, a housing for the wafer secured to the insulating annular member and enclosing the major wafer face adjacent to the sensing elements with the opposite major wafer face arranged to be exposed to the medium the pressure of which is required to be measured, leads extending externally of the housing, wires extending between contacts to the sensing elements and said leads extending externally of the housing and intermediate means supported by said annular member within said housing for electrically connecting each wire to an associated lead through the intermediate means.

2. A transducer as claimed in claim 1 in which the wires extending from the contacts of the sensing elements are bonded to electrically discrete metallized pads provided on the insulating annular member, and the intermediate means are arranged to contact the metallized pads.

3. A transducer as claimed in claim 1 in which the intermediate means are resiliently deformable and each is mounted in compression between the insulating annular member and a lead extending externally of the housing.

4. A transducer as claimed in claim 3 in which the intermediate means are leaf springs.

5. A transducer as claimed in claim 1 in which the intermediate means are masses of deformable conductive material bonded between the insulating annular member and the leads extending externally of the housing.

6. A transducer as claimed in claim 1 in which a thin-film trimming resistor is provided on a surface of the insulating annular member within the housing.

7. A transducer as claimed in claim 1 in which the leads extending externally of the housing comprise the conductivE parts of a connection member incorporated in the housing.

8. A transducer as set forth in claim 1 further including an electrically insulating layer on said opposite major face for electrically isolating the sensing elements in the wafer from the medium.

9. A transducer as set forth in claim 8 further including a metallic coating on the insulating layer.

10. A transducer as set forth in claim 8 wherein said housing is metallic, and further including a metallic coating on said insulating layer, said coating being in electrical contact with said housing, and a connection member capping said housing at one end, said connection member including said leads which extend externally of the housing.

11. A strain transducer including a semiconductor wafer having a plurality of piezo-resistive strain sensing elements formed adjacent to one major wafer face and defined by P-N junctions, a metal ring alloyed to circumferential parts of the semiconductor wafer, an annular member of insulating material having a plane surface at least partially metallized and cooperating with the metal ring to which it is bonded, a housing for the wafer secured to the insulating annular member and enclosing the major wafer face adjacent to the sensing elements with the opposite major wafer face arranged to be exposed to the medium the pressure of which is required to be measured leads extending through the housing, means for electrically connecting contacts to the sensing elements and said leads, said means including a resilient connection within the housing.

12. A transducer as claimed in claim 11 in which the electrical connecting means further includes wires extending from the contacts to the sensing elements to discrete metallized pads provided on the insulating annular member and resilient spring elements within the housing arranged to contact the metallized pads and the leads.

13. A transducer as claimed in claim 12 in which the spring elements are resiliently deformable and each is mounted in compression between the insulating annular member and a lead extending externally of the housing.

14. A transducer as claimed in claim 11 in which the resilient connection includes masses of deformable conductive material bonded between the insulating annular member and the leads extending externally of the housing, said insulating annular member being resilient in character.

15. A strain transducer as set forth in claim 11 wherein the outer periphery of said annular member is secured to the housing so as to support the metal ring and wafer such as to provide a space between the inner wall of the housing and the radial outer periphery of the metal ring and the wafer and insulative means within said space for electrically insulating said wafer from the housing.