Self-leveling membrane probe

• US 4,906,920 A
• Filed: 10/11/1988
• Issued: 03/06/1990
• Est. Priority Date: 10/11/1988
• Status: Expired due to Term

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Matta, Farid, Huff, Richard E.
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): Nguyen, Vinh P.
• Application Number:
  US07/256,029
• Time in Patent Office: 511 Days
• Field of Search: 324/158 F, 324/158 P, 324/73 PC, 324/73 AT, 439/482, 439/842
• US Class Current: 324/750.22
• CPC Class Codes: G01R 1/0735 arranged on a flexible frame or film

Abstract

A self-leveling membrane probe [10] is disclosed. A carrier [12] supports a translation stage [18] through radial flexure pivots [14]. A flexible membrane [22] having a first and second side is stretched over the translation stage [28] and held in high tension across its central portion compared to the tension maintained in its outer portion. The membrane'"'"'s [22] center of the first side faces a device under test (DUT) (not shown) and carries contact bumps [34] that relay electric signals in and out of the DUT. The second side opposite the contact bumps [34] is occupied by a receptacle [32] including a rotation plate [30] and a conical well [32b] designed to receive a pivot pin [26] enbedded in a reference plate [24] suspended from above by the translation stage [18]. The pin [26] and well [32b] function together as a bearing and provide an automatic compensating rotation in response to an alignment mismatch between the probe [10] and a device under test. When the contact bumps [34] encounter uneven test pads, one end of the rotation plate [30] is pushed upwards away from the test wafer. Since the pivot pin [26] is held in a constant vertical position by the fixed reference plate [24], the rotation plate [30] reacts to the imbalanced force applied from below by rotating about the pointed end [26a] of the pivot pin [26] which is seated at the bottom of the conical well [32b]. The resulting angular deflection of the rotation plate [30] aligns the contact bumps [34] on the membrane [22] to the inclined plane of the input-output pads.

Claims

1. An apparatus for providing an automatic compensating action which causes a substantially coplanar alignment between a substantially flat membrane probe and a substantially flat device under test (DUT), the apparatus comprising:

(a) a carrier means;

(b) a translation means,

(i) separated into at least an upper plate and a lower plate;

(ii) the upper plate being rigidly joined to a lower surface portion of the translation means;

(iii) the upper plate being formed to include a pivot means, extending away from the upper plate and toward the lower plate; and

(iv) the lower plate defining within itself a socket sized and oriented to receive the pivot means;

said carrier means being effective for supporting said translation means;

(c) a spring means, formed for coupling together the support means and the translation means; and

(d) a flexible substantially planar surface;

(i) formed to be coupled to both the support means and to the translation means; and

(ii) formed to have on an exterior surface a plurality of electrical contacts positioned for establishing at least one electric connection to a device under test;

whereby the pivot means, when carried by the socket, wobbles to thereby allow the two plates to float with respect to each other, thereby allowing the membrane to float while in contact with a device under test to cause the membrane to wobble across the DUT to make electrical contact with each portion of the DUT.

2. A self-leveling membrane probe apparatus for correcting an alignment mismatch between a plurality of contact bumps and a plurality of corresponding input-output pads on a device under test, the apparatus comprising:

(a) an upper carrier;

(b) a translation stage defining within itself a lower central aperture;

said upper carrier being effective for supporting said translation stage;

(c) a plurality of flexure pivots attached to the upper carrier and to the translation stage;

(d) a lower carrier;

(e) a flexible membrane;

(i) affixed to the lower carrier toward the periphery of the membrane;

(ii) stretched across the lower central aperture of the translation stage from the lower carrier;

(iii) the membrane being provided with a plurality of contact bumps for engaging a device under test;

(f) a pivot pin embedded in the translation stage; and

(g) a pivot pin receptacle positioned on a central surface of the membrane for holding the pivot pin and for allowing the receptacle and the central surface of the membrane to move freely about a vertical axis of the pivot pin.

3. A self-leveling membrane probe defined in claim 2, wherein the pivot pin receptacle includes:

(a) a rotation plate that is pushed against the membrane on a side opposite from the contact bumps by the pivot pin; and

(b) the pivot pin being held in a conical well carried within the rotation plate.