-There is a thin stainless sheet with the characteristic of a flexible spring, having positioning holes provided by etching. (Figures1, 2).

-The etching process allows formation of precise reference holes for positioning on the hoop-shaped materials having a certain length for application of semiconductor processing.

-The reference positioning holes help ensure that the accuracy of pitch is consistently maintained at a high level. However, the shape of the reference positioning holes will inevitably suffer slight variations in the inside diameter and changes in the state of cross section of the inside diameter edge, which are caused by variations in the etching process (deterioration of etching solution, temperature, and other factors) (Figure 3).

-To avoid the effects of variations in the hole diameter, non-contact position alignment based on the image processing is most preferable, but this has a disadvantage of requiring high investment in equipment.

-Secure positioning based on the reference positioning holes may be attained using a proper fixture through selection of appropriate tip geometry of dowel pins and a design allowing the dowel pins to slide up and down (Figures4,5).

Precautions

-When dowel pins are used, the fixture reference plane and the bottom face of the etched sheet must be placed horizontally without any gap between them before positioning to other component parts.