Membrane probing system with local contact scrub

• US 7,109,731 B2
• Filed: 06/17/2005
• Issued: 09/19/2006
• 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: Gleason, K. Reed, Smith, Kenneth R., Bayne, Mike
• Primary Examiner(s): Nguyen, Vinh P.
• Application Number:
  US11/155,986
• Publication Number:
  US 20050231223A1
• Time in Patent Office: 459 Days
• Field of Search: 324/754, 324/755, 324/756, 324/758
• US Class Current: 324/754.13
• 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 probing assembly for probing an electrical device comprising:

(a) a forward support of incompressible material;

(b) a flexible membrane assembly having a central region positioned in overlying relationship to said forward support;

(c) a plurality of rigid contacts disposed on said central region each including a beam and a contacting portion, each contacting portion being arranged in suitable position for pressing engagement with a corresponding pad on said device, each beam being electrically connected to a corresponding flexible conductor that extends into said central region;

(d) a pressure control mechanism including an elastomeric member interposed between each contact and said support; and

(e) a motion control mechanism locally operating in respect to each contact to urge each beam, when the corresponding contacting portion is placed into pressing engagement with the respective pad, into tilting motion so that different portions of each beam move different distances relative to said forward support and so that each contact is driven in accordance with said tilting motion into lateral scrubbing movement across the corresponding pad, said elastomeric member being positioned so as to enable each beam to recover from said tilting motion in a manner avoiding mechanical straining of each beam.

2. The probing assembly of claim 1 wherein each one of said beams is tiltable independently of the other ones of said beams.

3. The probing assembly of claim 1 including a rearward base, said forward support being tiltably coupled to said rearward base so as to enable said forward support to automatically tilt relative to said rearward base toward a position parallel to said device in response to pressing engagement between respective ones of said contacting portions and corresponding ones of said pads.

4. The probing assembly of claim 1 wherein said contacting portion of each contact is included on a contact bump fixedly joined in off-centered location on the corresponding beam.

5. The probing assembly of claim 1 wherein said contacts are provided in pairs and the respective lateral scrubbing movements of said contacts in each pair are in opposite directions.

6. The probing assembly of claim 1 wherein the distance of said lateral scrubbing movement of each contact after touchdown of each contacting portion on the corresponding pad is uniformly dependent for each contact on the distance traveled after touchdown in reducing the spacing between said support and said corresponding pad.

7. The probing assembly of claim 1 wherein said elastomeric member is a unitary structure.

8. The probing assembly of claim 1 wherein said contacts are arranged by rows and columns.

9. The probing assembly of claim 1 wherein each beam is joined in overlapping relationship to the corresponding flexible conductor.

10. The probing assembly of claim 1 wherein said flexible membrane assembly is substantially continuous along said central region.

11. The probing assembly of claim 1 wherein each contact is supported by a continuous portion of said flexible membrane assembly.

12. A method for probing an electrical device comprising:

(a) providing a forward support of incompressible material;

(b) providing a flexible membrane assembled having a central region positioned in overlying relationship to said forward support;

(c) providing a plurality of rigid contacts disposed on said central region each including a beam and a contacting portion, each contacting portion being arranged in suitable position for pressing engagement with a corresponding pad on said device, each beam being electrically connected to a corresponding flexible conductor that extends into said central region;

(d) providing a pressure control mechanism including an elastomeric member interposed between each contact and said support; and

(e) urging each beam, when the corresponding contacting portion is placed into pressing engagement with the respective pad, into tilting motion so as to move different portions of each beam different distances relative to said support and so as to drive each contact in accordance with said tilting motion into lateral scrubbing movement across the corresponding pad, further including resiliently opposing said tilting motion by means of said elastomeric member so as to enable each contact to recover from said tilting motion in a manner avoiding mechanical straining of each beam.

13. The method of claim 12 including urging a shorter one of said contacts into tilting motion at a later time than an immediately neighboring larger one of said contacts.

14. The method of claim 12 including providing a rearward support tiltably coupled to said forward support and automatically tilting said forward support relative to said rearward support toward a position parallel to said device in response to pressing engagement between respective ones of said contacting portions and corresponding ones of said pads.

15. The method of claim 12 including providing contacts in pairs and driving said contacts in each pair so that the respective lateral scrubbing movements are in opposite directions.