Method and apparatus for measuring gripping strength of a vacuum wand

Abstract

A method and apparatus for measuring the vacuum gripping strength of a vacuum wand or robotic arm provides a pressure gauge and a conduit extending from the pressure gauge and terminating at an opening formed in a receiving surface. A vacuum wand head is positioned on the receiving surface such that the gripping surface of the vacuum wand forms a conterminous boundary with the receiving surface and the vacuum port of the vacuum wand is aligned over the opening formed in the receiving surface. The receiving surface replicates a wafer surface so that the same vacuum gripping strength as would be delivered to a wafer being gripped by the vacuum wand, is thereby sensed by the pressure gauge. Spring loaded positioning members act in conjunction with a clamp member and a mechanical stop position the vacuum wand head in the receiving area and over the opening and also to assure that the gripping surface of the vacuum wand head is flush against the surface of the receiving area. Diminution of vacuum gripping strength caused by scratches or other defects of the gripping surface that cause vacuum leaks between gripping surface and the wafer surface, are similarly reproduced and sensed by the pressure gauge.