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Precision Mechanism for Use in a System Requiring Precise Alignment

IP.com Disclosure Number: IPCOM000081874D
Original Publication Date: 1974-Aug-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 3 page(s) / 100K

Publishing Venue

IBM

Related People

Hogan, RE: AUTHOR [+3]

Abstract

Referring to the drawing, the theta mechanism of the precision mechanism provides automatic rotational adjustment of the device under test (wafer) with respect to the contactor, or probe structure (not shown) under control of a closed servo loop (not shown). The servo loop signals are provided by an electrooptical correlating system (not shown) of 30 arc seconds sensitivity. The theta mechanism includes the following components: D. C. torque motor A, harmonic drive reducer B, theta bearings C and bearing housing D. The D. C. torque motor has "infinite" resolution. Its orienting capability is further increased by harmonic drive reduction (180:1). Its function is as follows: The wave generator B2 is fastened to shaft E which is located in housing F with bearings G. On the other end of shaft E is located the rotor A1 of the D.

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Precision Mechanism for Use in a System Requiring Precise Alignment

Referring to the drawing, the theta mechanism of the precision mechanism provides automatic rotational adjustment of the device under test (wafer) with respect to the contactor, or probe structure (not shown) under control of a closed servo loop (not shown). The servo loop signals are provided by an electrooptical correlating system (not shown) of 30 arc seconds sensitivity. The theta mechanism includes the following components: D. C. torque motor A, harmonic drive reducer B, theta bearings C and bearing housing D. The D. C. torque motor has "infinite" resolution. Its orienting capability is further increased by harmonic drive reduction (180:1).

Its function is as follows: The wave generator B2 is fastened to shaft E which is located in housing F with bearings G. On the other end of shaft E is located the rotor A1 of the D. C. torque motor.

The stator A2 of the torque motor is located concentric to the rotor via housing F and hearings G. Air gap H must be maintained. Stationary gear B1 is fastened to housing D. The flex spline B3 is fastened to Z-motor housing J which in turn is located via bearings C in base housing D. The wafer chuck K is mounted on triangular shaft L of the Z-slide mechanism which is located in Z-slide housing M. Z-slide housing M is fastened to Z-motor housing J via screws N.

By applying a current to the armature of motor A, the rotor A1 turns C.W. or C.C.W. The armature A1 together with the permanent magnetic field of stator A2 act together and convert electrical current directly into torque. With this torque applied, the wave generator B2 rotates and flexes the flex spline B3. The flex spline advances one tooth per revolution on the stationary gear B1. There are n- 1 teeth on the flex spline in relation to the stationary gear B1. Since the Z-motor housing J and Z-slide housing M are fastened...