An index table comprising a base, a main plate mounted on the base, a drive wheel mounted for rotation on one side of the main plate about a first axis transverse to the main plate, a work plate on the other side of the main plate rotatably mounted about a second transverse axis spaced from the first transverse axis, and a segment wheel mounted on the one side of said main plate and fixed with relation to the work plate. Circumferentially spaced segment drivers are mounted on the drive wheel and are adapted to engage circumferentially spaced slots on the segment wheel to intermittently drive the segment wheel and in turn the work plate. A yoke plate is mounted on the one side of the main plate for movement radially with respect to the drive wheel and the segment wheel. As the drive wheel rotates, each segment driver engages the yoke plate and moves the yoke plate relative to the segment wheel. As the yoke plate is moved radially outwardly and inwardly, it swings arms pivoted to the main plate, moving pins on the arms into and out of engagement with the sides of a pair of adjacent spaced slots on the segment wheel to unlock and lock the work plate in position. Movement of the yoke plate also functions to operate oil pistons that supply lubrication to the index table.

An index table utilizing eccentric pins for the accurate alignment thereof, and a method of alignment using a laser tarnsmitter/receiver and optical prism.

The arrangement of test points on an integrated circuit (IC) undergoing testing in a probe station often requires rotation of the IC or the probes when performing a series of tests. A chuck with indexed rotation promotes rapid rotation of the device under test to a new test position and increases the productivity of the probe station. The device under test is mounted on a device mounting member that is affixed to a shaft rotationally mounted in a base. A resilient seal supports the device mounting member and forms a sealed chamber over a substantial part of the area of the device mounting member. Applying vacuum or pressure to the sealed chamber urges the device mounting member and base toward contact. The support provided by the resilient seal over substantial portion of device mounting member's diameter promotes stability and consistent planarity of the device mounting member without regard to the orientation of the shaft to device mounting member.

The arrangement of test points on an integrated circuit (IC) undergoing testing in a probe station often requires rotation of the IC or the probes when performing a series of tests. A chuck with indexed rotation promotes rapid rotation of the device under test to a new test position and increases the productivity of the probe station. The device under test is mounted on a device mounting member that is affixed to a shaft rotationally mounted in a base. A resilient seal supports the device mounting member and forms a sealed chamber over a substantial part of the area of the device mounting member. Applying vacuum or pressure to the sealed chamber urges the device mounting member and base toward contact. The support provided by the resilient seal over substantial portion of device mounting member's diameter promotes stability and consistent planarity of the device mounting member without regard to the orientation of the shaft to device mounting member.

A rotary chuck with indexed rotation promotes rapid rotation of a device under test and increases the productivity of a probe station on which the device is being tested. A device mounting member of a rotatable chuck is supported for rotation on a first surface of a base until a vacuum is applied drawing the device mounting member into contact with a second surface of the base and constraining the device mounting member against rotation.