Apparatus and method for measuring the gripping strength of a vacuum wand
US5783754A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 28, 1996 |
| Grant date | Jul 21, 1998 |
| Priority date | — |
| Expiry date | Feb 28, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01L5/0033
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus for measuring the gripping strength of a wafer holder, such as a vacuum wand or an automated robotic arm, is used to periodically test wafer holders during manufacture of wafers, and thereby eliminate the damage caused to wafers by worn wafer holders. The apparatus includes a hold tester to be held by the wafer holder and a gauge coupled to the hold tester that indicates the force applied by the wafer holder to the hold tester. The wafer holder is coupled to a predetermined region on the hold tester, and the wafer holder gauge is pulled away from the hold tester until the wafer holder becomes separated from the hold tester. The maximum force applied by the wafer holder on the hold tester is measured by the gauge and the above described process is repeated to obtain a second measurement of the force. If the difference in the two force measurements is less than a predetermined deviation, and if one of the two measured forces is below a predetermined gripping strength, the wafer holder is considered defective and a correction process is used to find and fix correctable defects. In the correction process, the defects can be corrected, for example, by replacing the wafer ho…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.