Substrate tester having shorting pad actuator method and apparatus

• US 5,917,329 A
• Filed: 04/17/1997
• Issued: 06/29/1999
• Est. Priority Date: 04/17/1997
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Morrison, Thomas, Wojszynski, Brian J., Cadwallader, Robert H., Yager, William A., Probst, Klaus
• Primary Examiner(s): Abrams, Neil
• Application Number:
  US08/840,836
• Time in Patent Office: 803 Days
• Field of Search: 324/754, 324/757, 324/758, 324/761, 439/482
• US Class Current: 324/750.25
• CPC Class Codes: G01R 31/2886 Features relating to contacting the IC under test, e.g. probe heads; chucks G01R31/2865 takes precedence, test connections, e.g. test sockets, or probes per se, G01R1/04 or G01R1/06

Abstract

An electrical contacting apparatus for testing a substrate (54) and having a principal axis includes an electrical contact pad, a guide plate (106), a supporting bridge (132), and a mechanism for providing a contact actuation force. The guide plate includes side edges with guide pins (108) extending radially outward from a center of each side edge. The electrical contact pad (114) is mounted and centered upon a top surface of the guide plate (106). The support bridge supports the guide plate to enable a pivotal movement of the guide plate about a point on the principal axis. Lastly, the contact actuation force mechanism provides a contact actuation force to a center of the bottom surface of the guide plate to maintain an equal force across the electrical contact pad in a direction of the principal axis, whereby the electrical contact pad provides a desired contacting force equally balanced across an entire contact area defined by an area of contact between the electrical contact pad and a substrate being contacted. The substrate (54) is to be clamped between test probes (52) and the contact pad (114).

Claims

1. An electrical contacting apparatus having a principal axis, said apparatus comprising:

an electrical contact pad;

a guide plate having side edges with guide pins extending radially outward from a center of each side edge, wherein said electrical contact pad is mounted and centered upon a top surface of said guide plate;

means for supporting said guide plate to enable a pivotal movement of said guide plate about a point on the principal axis; and

means for providing a contact actuation force to a center of the bottom surface of said guide plate to maintain an equal force across said electrical contact pad in a direction of the principal axis, whereby said electrical contact pad provides a desired contacting force equally balanced across an entire contact area defined by an area of contact between said electrical contact pad and a substrate being contacted.

2. The electrical contacting apparatus of claim 1, wherein

said electrical contact pad includes a shorting pad, the shorting pad having a gold foil wrapped around a generally square block of flexible material and bonded to a magnetic base plate, and

said guide plate includes a generally square shape, wherein the shorting pad is mounted upon said guide plate such that the corners of the shorting pad are offset from the corners of the guide plate by an amount on the order of forty-five degrees, further wherein the guide pins include X-Y guide pins for preventing a rotation of guide plate about the principal axis.

3. The electrical contacting apparatus of claim 1, wherein

said support means includes a support bridge having a cavity extending therein from a bottom surface thereof and further having an aperture disposed in a top surface thereof connected with the cavity, wherein the cavity is larger than the aperture and angularly offset with respect to one another about the principal axis by a prescribed amount, said guide plate further being supported within the cavity with said electrical contact pad positioned within the aperture.

4. The electrical contacting apparatus of claim 3, further wherein

the cavity in said support means includes a generally square cavity of a dimension slightly larger than the size of the guide plate, the aperture having a size dimension larger than said electrical contact pad, the cavity and aperture being angularly offset from each other about the principal axis by an amount on the order of 45 degrees, the cavity further having slots therein for receiving the guide pins of said guide plate, the guide pins preventing said guide plate from rotating about the principal axis, and said support means further including four compression springs disposed between said guide plate and an underside of the top surface of said support bridge within the cavity.

5. The electrical contacting apparatus of claim 1, wherein

said contact actuation force means includes a diaphram actuated piston, the piston having a raised balancing center point thereon for engaging the center of the bottom surface of said guide plate.

6. The electrical contacting apparatus of claim 5, further wherein

said contact actuation force means further includes a piston support bridge for supporting and guiding the diaphram actuated piston therein, further wherein the diaphram actuated piston includes an elongated oblong piston, and four compression springs disposed between the diaphram actuated piston and an underside of the top surface of the piston support bridge, wherein the raised balancing center point of the piston includes a raised bullet portion having a rounded contacting end which extends through an aperture in the top surface of the piston support bridge upon an actuation of the diaphram actuated piston.

7. The electrical contacting apparatus of claim 1, wherein

said electrical contact pad includes a shorting pad, the shorting pad having a gold foil wrapped around a generally square block of flexible material and bonded to a magnetic base plate,

said guide plate includes a generally square shape, wherein the shorting pad is mounted upon said guide plate such that the corners of the shorting pad are offset from the corners of the guide plate by an amount on the order of forty-five degrees, further wherein the guide pins include X-Y guide pins for preventing a rotation of guide plate about the principal axis,

said support means includes a support bridge having a cavity extending therein from a bottom surface thereof and further having an aperture disposed in a top surface thereof connected with the cavity, wherein the cavity is larger than the aperture and angularly offset with respect to one another about the principal axis by a prescribed amount, said guide plate further being supported within the cavity with said electrical contact pad positioned within the aperture, and

said contact actuation force means includes a diaphram actuated piston, the piston having a raised balancing center point thereon for engaging the center of the bottom surface of said guide plate.

8. A substrate processing apparatus having an electrical contactor characterized by a principal axis, said apparatus comprising:

an electrical contact pad;

a guide plate having side edges with guide pins extending radially outward from a center of each side edge, wherein said electrical contact pad is mounted and centered upon a top surface of said guide plate;

means for supporting said guide plate to enable a pivotal movement of said guide plate about a point on the principal axis; and

means for providing a contact actuation force to a center of the bottom surface of said guide plate to maintain an equal force across said electrical contact pad in a direction of the principal axis, whereby said electrical contact pad provides a desired contacting force equally balanced across an entire contact area defined by an area of contact between said electrical contact pad and a substrate being contacted.

9. An method of electrically contacting a substrate with a contactor having a principal axis, said method comprising the steps of:

providing an electrical contact pad;

providing a guide plate having side edges with guide pins extending radially outward from a center of each side edge, wherein the electrical contact pad is mounted and centered upon a top surface of the guide plate;

providing means for supporting the guide plate to enable a pivotal movement of the guide plate about a point on the principal axis; and

providing a contact actuation force to a center of the bottom surface of the guide plate to maintain an equal force across the electrical contact pad in a direction of the principal axis, whereby the electrical contact pad provides a desired contacting force equally balanced across an entire contact area defined by an area of contact between the electrical contact pad and the substrate being contacted.

10. The electrical contacting method of claim 9, wherein

the electrical contact pad includes a shorting pad, the shorting pad having a gold foil wrapped around a generally square block of flexible material and bonded to a magnetic base plate, and

the guide plate includes a generally square shape, wherein the shorting pad is mounted upon the guide plate such that the corners of the shorting pad are offset from the corners of the guide plate by an amount on the order of forty-five degrees, further wherein the guide pins include X-Y guide pins for preventing a rotation of guide plate about the principal axis.

11. The electrical contacting method of claim 9, wherein

the support means includes a support bridge having a cavity extending therein from a bottom surface thereof and further having an aperture disposed in a top surface thereof connected with the cavity, wherein the cavity is larger than the aperture and angularly offset with respect to one another about the principal axis by a prescribed amount, the guide plate further being supported within the cavity with the electrical contact pad positioned within the aperture.

12. The electrical contacting method of claim 11, further wherein

the cavity in the support means includes a generally square cavity of a dimension slightly larger than the size of the guide plate, the aperture having a size dimension larger than the electrical contact pad, the cavity and aperture being angularly offset from each other about the principal axis by an amount on the order of 45 degrees, the cavity further having slots therein for receiving the guide pins of the guide plate, the guide pins preventing the guide plate from rotating about the principal axis, and the support means further including four compression springs disposed between the guide plate and an underside of the top surface of the support bridge within the cavity.

13. The electrical contacting method of claim 9, wherein

providing the contact actuation force includes providing a diaphram actuated piston, the piston having a raised balancing center point thereon for engaging the center of the bottom surface of the guide plate.

14. The electrical contacting method of claim 13, further wherein

providing the contact actuation force further includes providing a piston support bridge for supporting and guiding the diaphram actuated piston therein, further wherein the diaphram actuated piston includes an elongated oblong piston, and four compression springs disposed between the diaphram actuated piston and an underside of the top surface of the piston support bridge, wherein the raised balancing center point of the piston includes a raised bullet portion having a rounded contacting end which extends through an aperture in the top surface of the piston support bridge upon an actuation of the diaphram actuated piston.

15. The electrical contacting method of claim 9, wherein

the electrical contact pad includes a shorting pad, the shorting pad having a gold foil wrapped around a generally square block of flexible material and bonded to a magnetic base plate,

the guide plate includes a generally square shape, wherein the shorting pad is mounted upon the guide plate such that the corners of the shorting pad are offset from the corners of the guide plate by an amount on the order of forty-five degrees, further wherein the guide pins include X-Y guide pins for preventing a rotation of guide plate about the principal axis,

the support means includes a support bridge having a cavity extending therein from a bottom surface thereof and further having an aperture disposed in a top surface thereof connected with the cavity, wherein the cavity is larger than the aperture and angularly offset with respect to one another about the principal axis by a prescribed amount, the guide plate further being supported within the cavity with the electrical contact pad positioned within the aperture, and

providing the contact actuation force includes providing a diaphram actuated piston, the piston having a raised balancing center point thereon for engaging the center of the bottom surface of the guide plate.

16. A method of electrically contacting a substrate during a substrate processing operation with a contactor having a principal axis, said method comprising the steps of:

providing an electrical contact pad;

providing a guide plate having side edges with guide pins extending radially outward from a center of each side edge, wherein the electrical contact pad is mounted and centered upon a top surface of the guide plate;

providing means for supporting the guide plate to enable a pivotal movement of the guide plate about a point on the principal axis; and

providing a contact actuation force to a center of the bottom surface of the guide plate to maintain an equal force across the electrical contact pad in a direction of the principal axis, whereby the electrical contact pad provides a desired contacting force equally balanced across an entire contact area defined by an area of contact between said electrical contact pad and a substrate being contacted.