POGO probe card for low current measurements

• US 7,148,714 B2
• Filed: 02/07/2005
• Issued: 12/12/2006
• Est. Priority Date: 06/10/1997
• Status: Expired due to Fees

• Current Assignee: Cascade Microtech Incorporated (FormFactor Incorporated)
• Original Assignee: Cascade Microtech Incorporated (FormFactor Incorporated)
• Inventors: Cowan, Clarence E., Tervo, Paul A.
• Primary Examiner(s): Nguyen, Vinh P.
• Application Number:
  US11/053,119
• Publication Number:
  US 20050151557A1
• Time in Patent Office: 673 Days
• Field of Search: 324754-755, 324/761, 324/72.5, 324/158.1, 439/482, 439/824, 439 66- 72, 333246-248
• US Class Current: 324/756.03
• CPC Class Codes: G01R 1/067 Measuring probes
• CPC Class Codes: G01R 1/06711 Probe needles; Cantilever beams; "Bump" contacts; Replaceable probe pins
• CPC Class Codes: G01R 1/06733 Geometry aspects G01R1/06727 takes precedence
• CPC Class Codes: G01R 1/06772 High frequency probes
• 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

Abstract

A low-current pogo probe card for measuring currents down to the femtoamp region includes a laminate board having a layer of conductive traces interposed between two dielectric layers. A plurality of probing devices, such as ceramic blades, are edge-mounted about a central opening so that the probing needles or needles included therein terminate below the opening in a pattern suitable for probing a test subject workpiece. A plurality of pogo pin receiving pad sets, each including a guard pad, occupy the periphery of the board. Each guard pad is electrically connected to a trace from the layer of conductive traces. The pad sets may be connected to the probing devices by low noise cables or traces. Air trenches separate the pad sets for reducing cross talk and signal settling times.

Claims

1. A probe card comprising:

(a) a first conductive surface on said probe card;

(b) a second conductive surface on said probe card substantially surrounding said first conductive surface;

(c) a third conductive surface on said probe card;

(d) a fourth conductive surface on said probe card substantially surrounding said third conductive surface;

(e) said first, second, third, and fourth conductive surfaces are electrically insulated from one another;

(f) a first probing element supported by said probe card;

(g) a second probing element supported by said probe card;

(h) said first conductive surface electrically interconnected to said first probing element;

(i) said third conductive surface electrically interconnected to said second probing element;

(j) a first groove substantially surrounding said first conductive surface and not surrounding said third conductive surface;

(k) a second groove substantially surrounding said third conductive surface and not surrounding said first conductive surface.

2. The probe card of claim 1 wherein said first conductive surface receives a test signal and said second conductive surface receives a guard signal associated with said test signal.

3. The probe card of claim 1 wherein said first groove and said second groove include conductive material contained therein that is electrically interconnected with said second conductive surface and said fourth conductive surface, respectfully.