Claims
- 1. An integrated shield and coil assembly for an electromagnetic acoustic transducer (EMAT), comprising:
- a substrate, having first and second surfaces on which electrical circuits can be etched;
- a coil pattern, having conductors etched onto the first surface of the substrate; and
- a shield pattern, having a configuration corresponding to and aligned with the coil pattern, to substantially shield the coil pattern from electrostatic noise present on the workpiece and to prevent eddy current generation in the shield caused by the coil pattern, etched onto the second surface of the substrate.
- 2. The integrated shield and coil assembly according to claim 1, wherein the substrate comprises a polyimide material.
- 3. The integrated shield and coil assembly according to claim 1, wherein the substrate comprises a polyimide material on which the coil pattern has been etched as a flexible copper coil.
- 4. The integrated shield and coil assembly according to claim 1, wherein the shield pattern comprises a fine grating copper shield.
- 5. The integrated shield and coil assembly according to claim 1, wherein the shield pattern comprises a copper strip shield.
- 6. The integrated shield and coil assembly according to claim 1, wherein the coil pattern and the shield pattern each comprise one or more conductors.
- 7. The integrated shield and coil assembly according to claim 1, wherein the shield pattern on the second surface is coextensive with and aligned with the coil pattern on the first surface to eliminate capacitively coupled noise.
- 8. The integrated shield and coil assembly according to claim 1, further comprising a layer of electrically insulating material lying directly on the coil pattern and substrate and attached thereto by a suitable layer of non-electrically conductive adhesive.
- 9. The integrated shield and coil assembly according to claim 8, wherein the layer of electrically insulating material lying directly on the coil pattern and substrate and attached thereto by a suitable layer of non-electrically conductive adhesive comprises a polyimide material.
- 10. The integrated shield and coil assembly according to claim 8, wherein the layer of electrically insulating material lying directly on the coil pattern and substrate and attached thereto by a suitable layer of non-electrically conductive adhesive comprises a ceramic material.
- 11. The integrated shield and coil assembly according to claim 8, wherein the layer of electrically insulating material lying directly on the coil pattern and substrate and attached thereto by a suitable layer of non-electrically conductive adhesive comprises an insulator with good high temperature properties.
- 12. The integrated shield and coil assembly according to claim 1, further comprising a layer of thin, durable, electrically insulating material lying directly on the shield pattern and substrate and attached thereto by adhesive means.
- 13. The integrated shield and coil assembly according to claim 12, wherein the layer of thin, durable, electrically insulating material lying directly on the shield pattern and substrate and attached thereto by adhesive means comprises two separate layers, one being a layer of poorly conducting metal located proximate a workpiece during an inspection to provide a rugged wear surface in hostile environments and the other being attached to the shield pattern and substrate by the adhesive means to insulate the shield pattern from the layer of poorly conducting metal.
- 14. A shielded electromagnetic acoustic transducer (EMAT) sensor unit for inspecting a workpiece and having a magnet, and an integrated coil and shield assembly, the assembly comprising:
- a substrate, having first and second surfaces on which electrical circuits can be etched;
- a coil pattern, etched onto the first surface of the substrate; and
- a shield pattern, having a configuration corresponding to and aligned with the coil pattern, to substantially shield the coil pattern from electrostatic noise present on the workpiece and to prevent eddy current generation in the shield caused by the coil pattern, etched onto the second surface of the substrate; and
- means for securing the substrate to the magnet so that the second surface of the substrate is located proximate the workpiece during an inspection.
- 15. The EMAT sensor unit according to claim 14, wherein the substrate comprises a polyimide material.
- 16. The EMAT sensor unit according to claim 14, wherein the substrate comprises a polyimide material on which the coil pattern has been etched as a flexible copper coil.
- 17. The EMAT sensor unit according to claim 14, wherein the shield pattern comprises a fine grating copper shield.
- 18. The EMAT sensor unit according to claim 14, wherein the shield pattern comprises a copper strip shield.
- 19. The EMAT sensor unit according to claim 14, wherein the coil pattern and the shield pattern each comprise one or more conductors.
- 20. The EMAT sensor unit according to claim 14, wherein the shield pattern on the first surface is coextensive with and aligned with the coil pattern on the second surface to eliminate capacitively coupled noise.
- 21. The EMAT sensor unit according to claim 14, further comprising a layer of electrically insulating material lying directly on the coil pattern and substrate and attached thereto by a suitable layer of non-electrically conductive adhesive.
- 22. The EMAT sensor unit according to claim 21, wherein the layer of electrically insulating material lying directly on the coil pattern and substrate and attached thereto by a suitable layer of non-electrically conductive adhesive comprises a polyimide material.
- 23. The EMAT sensor unit according to claim 21, wherein the layer of electrically insulating material lying directly on the coil pattern and substrate and attached thereto by a suitable layer of non-electrically conductive adhesive comprises a ceramic material.
- 24. The EMAT sensor unit according to claim 21, wherein the layer of electrically insulating material lying directly on the coil pattern and substrate and attached thereto by a suitable layer of non-electrically conductive adhesive comprises an insulator with good high temperature properties.
- 25. The EMAT sensor unit according to claim 14, further comprising a layer of thin, durable, electrically insulating material lying directly on the shield pattern and substrate and attached thereto by adhesive means.
- 26. The EMAT sensor unit according to claim 25, wherein the layer of thin, durable, electrically insulating material lying directly on the shield pattern and substrate and attached thereto by adhesive means comprises two separate layers, one being a layer of poorly conducting metal located proximate a workpiece during an inspection to provide a rugged wear surface in hostile environments and the other being attached to the shield pattern and substrate by the adhesive means to insulate the shield pattern from the layer of poorly conducting metal.
CROSS REFERENCE TO RELATED APPLICATION
The present application is a continuation-in-part application of Ser. No. 08/251,542, filed May 31, 1994 and to issue on Jul. 25, 1995 as U.S. Pat. No. 5,436,873.
US Referenced Citations (6)
Number |
Name |
Date |
Kind |
4149421 |
B ottcher et al. |
Apr 1979 |
|
4296486 |
Vasile |
Oct 1981 |
|
4777824 |
Alers et al. |
Oct 1988 |
|
5140860 |
H usherelrath et al. |
Aug 1992 |
|
5164921 |
Graff et al. |
Nov 1992 |
|
5436873 |
MacLauchlan et al. |
Jul 1995 |
|
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
251542 |
May 1994 |
|