Membrane probing structure with laterally scrubbing contacts

• US 7,893,704 B2
• Filed: 03/20/2009
• Issued: 02/22/2011
• Est. Priority Date: 08/08/1996
• Status: Expired due to Fees

• Current Assignee: Cascade Microtech Incorporated (FormFactor Incorporated)
• Original Assignee: Cascade Microtech Incorporated (FormFactor Incorporated)
• Inventors: Bayne, Mike, Gleason, K. Reed, Smith, Kenneth R.
• Primary Examiner(s): Nguyen; Vinh P
• Application Number:
  US12/383,209
• Publication Number:
  US 20090224783A1
• Time in Patent Office: 704 Days
• Field of Search: None
• US Class Current: 324/755.01
• CPC Class Codes: G01R 1/06711 Probe needles; Cantilever beams; "Bump" contacts; Replaceable probe pins
• CPC Class Codes: G01R 1/07342 the body of the probe being at an angle other than perpendicular to test object, e.g. probe card
• CPC Class Codes: G01R 1/0735 arranged on a flexible frame or film

Abstract

A membrane probing assembly includes a support element having an incompressible forward support tiltably coupled to a rearward base and a membrane assembly, formed of polyimide layers, with its central region interconnected to the support by an elastomeric layer. Flexible traces form data/signal lines to contacts on the central region. Each contact comprises a rigid beam and a bump located in off-centered location on the beam, which bump includes a contacting portion. After initial touchdown of these contacting portions, further over-travel of the pads causes each beam to independently tilt locally so that different portions of each beam move different distances relative to the support thus driving each contact into lateral scrubbing movement across the pad thereby clearing away oxide buildup. The elastomeric member backed by the incompressible support ensures sufficient scrub pressure and reliable tilt recovery of each contact without mechanical straining of the beam. In an alternative embodiment, the contacts comprise conductive beams each supported on a loose U-shaped flap formed in the membrane assembly where each flap and beam is tiltably supported in inclined position by an elastomeric hub interposed between the flap and support.

Claims

1. A structure suitable for use with a probe for probing an electrical device, said structure comprising:

(a) an elastic membrane; and

(b) a plurality of rigid contacts each supported by an elongate portion of a first surface of said elastic membrane and having a contacting portion located nearer a first end of said elongate portion than a second end of said elongate portion, displacement of said respective elongate portion relative to a second surface of said elastic membrane when said respective contacting portion is pressed into engagement with said electrical device causing said respective contact to tilt and said contacting portion to scrub laterally across said electrical device.

2. The structure of claim 1 wherein each of said contacting portions is spaced apart from an axis of moment of said respective contact.

3. The structure of claim 1 wherein said elastic membrane is in an overlying relationship to a support.

4. The structure of claim 3 wherein said support is made of incompressible material.

5. The structure of claim 3 wherein said support is rigid material.

6. The structure of claim 3 wherein said elastic membrane has a central region positioned in said overlying relationship to said support.

7. The structure of claim 3 wherein the distance of said lateral scrubbing movement of each contact after touchdown of each contacting portion is dependent for each contact on the distance traveled after touchdown in reducing the spacing between said support and said electrical device.

8. The structure of claim 1 wherein each of said contacts comprises a beam and said contacting portion.

9. The structure of claim 8 wherein said contacting portion is proximate an end of said beam.

10. The structure of claim 1 wherein each of said contacts is electrically connected to a corresponding flexible conductor.

11. The structure of claim 10 wherein each flexible conductor extends into a central region of said elastic membrane.

12. The structure of claim 1 further comprising a pressure control mechanism including a compressible member interposed between each contact and a support.

13. The structure of claim 12 further comprising a motion control mechanism locally operating in respect to each contact.

14. The structure of claim 13 further comprising a pressure control mechanism including a compressible member interposed between each contact and a support wherein said compressible member enables each beam to recover from said tiling motion in a manner avoiding mechanical straining of each contact.

15. The structure of claim 1 wherein each one of said contacts is tiltable independently of the other ones of said contacts.

16. The structure of claim 1 wherein said tilting motion is a result of parallel relative motion between a plane of said second surface of said elastic membrane and a plane of said electrical device.

17. The structure of claim 1 wherein said contacts are non-upright.

18. A structure suitable for use with a probe for probing an electrical device, said structure comprising a plurality of rigid contacts each of which defines a surface backed by a resilient pad and a contacting portion which is spaced apart from a midpoint of a length of said surface and spatially arranged for engagement with said electrical device, said contact pivoting about an axis of moment when said contacting portion is pressed into engagement with said electrical device and a restoring force is exerted on said surface by said resilient pad, said pivoting of said contact producing lateral movement of said contacting portion across said electrical device.

19. The structure of claim 18 wherein said contacts are asymmetrical.

20. The structure of claim 18 wherein said resilient pad comprises an elastic membrane in an overlying relationship to a support.

21. The structure of claim 20 wherein said support is made of incompressible material.

22. The structure of claim 20 wherein said support comprises a rigid material.

23. The structure of claim 20 wherein said elastic membrane has a central region positioned in said overlying relationship to said support.

24. The probe of claim 20 wherein the distance of said lateral scrubbing movement of each contact after touchdown of each contacting portion is dependent for each contact on the distance traveled after touchdown in reducing the spacing between said support and said electrical device.

25. The structure of claim 18 wherein said contact comprises said contacting portion and a beam including said surface.

26. The structure of claim 25 wherein said contacting portion is proximate an end of said beam.

27. The structure of claim 18 wherein each of said contacts is electrically connected to a corresponding flexible conductor.

28. The structure of claim 27 wherein each flexible conductor extends into a central region of an elastic membrane.

29. The structure of claim 18 further comprising a pressure control mechanism including a compressible member interposed between each contact and a support.

30. The structure of claim 29 further comprising a motion control mechanism locally operating in respect to each contact.

31. The structure of claim 30 further comprising a pressure control mechanism including a compressible member interposed between each contact and a support wherein said compressible member enables each contact to recover from said pivoting motion in a manner avoiding mechanical straining of each contact.

32. The structure of claim 18 wherein each one of said contacts is operable to pivot independently of the other ones of said contacts.

33. The structure of claim 18 wherein said pivoting motion is a result of parallel relative motion between a plane defining a support for said structure and a plane of said electrical device.

34. The structure of claim 18 wherein said contacts are non-upright.