Apparatus for near surface nondestructive eddy current scanning of a conductive part using a multi-layer eddy current probe array

• US 5,262,722 A
• Filed: 04/03/1992
• Issued: 11/16/1993
• Est. Priority Date: 04/03/1992
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Kornrumpf, William P., Charles, Richard J., Hedengren, Kristina H. V.
• Primary Examiner(s): Strecker, Gerard R.
• Assistant Examiner(s): EDMONDS, WARREN
• Application Number:
  US07/862,699
• Time in Patent Office: 592 Days
• Field of Search: 324/234, 324/236, 324/237-243, 324/260-262, 336/20, 336/200, 336/206
• US Class Current: 324/242
• CPC Class Codes: G01N 27/902 by moving the sensors
• CPC Class Codes: G01N 27/904 with two or more sensors

Abstract

An apparatus for near surface, nondestructive eddy current scanning of a conductive part using a multi-layer eddy current probe array. Such structures of this type, generally, employ an ultra-thin, flexible, film-like, multi-layer eddy current probe array which is adapted to provide routine inspection of conductive parts while also providing improved signal integrity, signal transmission and isolation.

Claims

1. Apparatus for near surface inspection scanning of an electrically conductive part comprising:

an eddy current probe array having a plurality of probe elements further comprising substantially identical eddy current sense elements and at least one drive element operatively connected to said sense elements such that said sense elements and said drive elements are disposed within a flexible, multi-layer, dielectric structure wherein said at least one drive element is electrically interconnected to at least one external alternating current source, said plurality of sense elements are mutually coupled to said at least one drive element through an inspection surface during scanning of said part, and said a plurality of sense elements are electrically interconnected to a select plurality of output channels in order to operatively collect scan responsive signals therefrom;

a plurality of conductive pathways substantially located within said sense elements such that said pathways provide individual electrical interconnection to said probe elements and cooperate as transmission lines; and

a substantially lossless, structurally supporting connector means operatively connected to said sense elements which cooperate to electrically interconnect said conductive pathways to external electronic devices.

2. Apparatus in accordance with claim 1 wherein said flexible structure is fabricated using a photo-lithographic process to alternately dispose patterns onto at least one layer of a dielectric material.

3. Apparatus in accordance with claim 1 further including means for aligning and registering said flexible structure including a slideably mounted mechanical scanning apparatus.

4. Apparatus in accordance with claim 2 wherein fabrication is accomplished by High Density Interconnect processing to accommodate computerized control of said patterns.

5. Apparatus in accordance with claim 2 wherein said at least one drive element is disposed onto at lest one layer.

6. Apparatus in accordance with claim 5 wherein each of said sense elements is comprised of at least one coil winding deposited onto said at least one layer.

7. Apparatus in accordance with claim 6 wherein said sense elements are selectively comprised of a plurality of electrically interconnected coil windings.

8. Apparatus in accordance with claim 7 wherein at lest one of said sense elements is comprised of at lest two coil windings electrically interconnected in a differential mode.

9. Apparatus in accordance with claim 7 wherein at least one of said sense elements is comprised of at least two coil windings electrically interconnected in an absolute mode.

10. Apparatus in accordance with claim 3 wherein said scanning apparatus slideably scans said inspection surface in a predetermined direction such that said sense elements are organized into a plurality of parallel rows disposed substantially normal to said predetermined scanning direction with at least one row of said parallel rows staggered with respect to at least one other row.

11. Apparatus in accordance with claim 7 wherein select conductive pathways electrically interconnecting select individual drive elements cooperate as transmission lines.

12. Apparatus in accordance with claim 11 wherein select conductive pathways electrically interconnecting select individual sense elements cooperate as transmission lines.

13. Apparatus in accordance with claim 12 wherein conductive shielding strips are selectively disposed between select said conductive pathways.

14. Apparatus in accordance with claim 1 wherein said conductive pathways terminate on either surface of said dielectric structure and are organized into respective terminal leads.

15. Apparatus in accordance with claim 14 wherein said connector means further comprises a substantially rigid, nonconductive connector module integral with said dielectrical structure and including conductive finger-like strips disposed thereon such that said strip electrically interconnect with said terminal leads.

16. Apparatus in accordance with claim 15 wherein said connector module is operatively inserted into an edge connector having a plurality of miniature contact strips for making respective electrical interconnection with said finger-like strips such that said edge connector provides electrical interconnection to said external electronic device.

17. Apparatus in accordance with claim 15 wherein an elastomeric connector having a plurality of conductive matrix elements disposed throughout an insulating, surface pressure deformable substrate and extending substantially therethrough, is disposed between said finger-like strips of said connector module and corresponding electrical conduct surfaces of said external electronic device to make electrical interconnection therebetween.

18. Apparatus in accordance with claim 17 wherein said connector means further includes mechanical coupling means integral to said connector module to operatively couple with corresponding mechanical coupling means integral to said external electronic device.

19. Apparatus in accordance with claim 18 wherein said mechanical coupling means includes at least one insertion opening and at least one correspondingly disposed insertion pin.

20. Apparatus in accordance with claim 14 wherein said connector means comprises said flexible eddy current probe array structure having said terminal leads organized as exposed surface contact leads, said structure being laminated onto a substantially rigid, nonconductive substrate in order to form an insertion edge having said surface contact leads exposed for insertion into an edge connector, said edge connector having a plurality of corresponding electrical contact surfaces in order to make electrical interconnection therewith.

21. Apparatus in accordance with claim 20 wherein said array structure is laminated onto a surface of said substrate in order to accommodate single-sided electrical interconnection.

22. Apparatus in accordance with claim 20 wherein said array structure is laminated onto both surfaces of said substrate in order to accommodate double-sided electrical interconnection.

23. Apparatus in accordance with claim 14 wherein said terminal leads are organized as a plurality of contact pads disposed on an exposed surface of said probe array structure after lamination onto a substantially rigid, nonconductive substrate wherein selectively aligned contact pads are brought into electrical interconnection with respective contact surfaces of said external electronic device by electrically coupling through an elastomeric connector disposed therebetween, said connector provides a plurality of conductive matrix elements disposed throughout an insulating, surface pressure deformable substrate, wherein said matrix elements provide direct, electrical interconnection therebetween.

24. Apparatus in accordance with claim 23 wherein means for selective alignment includes at least one structurally integral registration and coupling means aligned with respect to said contact pads in order to correspondingly couple with at least one similarly disposed coupling means on said external electronic device.

25. Apparatus according to claim 3 wherein said array is outwardly affixed onto a substantially rigid, nonconductive supporting surface such that said supporting surface is the mated complement of said inspection surface.

26. Apparatus according to claim 3 wherein clamping means are an integral part of said eddy current probe array structure.

27. Apparatus according to claim 26 wherein said clamping means includes at lest one structurally integral coupling means designed to couple with a mounting apparatus such that said mounting apparatus includes at least one corresponding coupling means for clamping thereto, said mounting apparatus operating to actuate said supporting surface for scanning of said inspection surface.

28. Apparatus according to claim 26 wherein said clamping means includes at least one coupling means aligned to couple with said rigid supporting surface such that said supporting surface includes at least one corresponding coupling means for precisely positioning said probe array structure with respect to said inspection surface.