Missing die detection

Details Missing die detection Missing die detection

2006-05-16

2006-05-16

Allen, Stephone B. (Department: 2878)

Radiant energy

Photocells; circuits and apparatus

With circuit for evaluating a web, strand, strip, or sheet

C250S215000, C356S614000

Reexamination Certificate

active

07045803

ABSTRACT:
An indication of whether or not a target object is present at a site of a collet assembly is derived by monitoring light reflected from the site. The use of reflected light enables the presence of objects to be detected, especially transparent objects. In a preferred arrangement for determining if a sapphire die is present in a die-handling collet assembly, light from a source is collimated or focused into a narrow beam and directed through a beam splitter at the target site of the collet assembly. Light reflected from the surface of the die is further reflected by the beam splitter toward a photo-sensor. The reflected light is measured when the collet passes over a dark background while on the way to deliver a die at a bonding position and again while returning after attempting to place the die at the bonding position. A determination of a die present in the former and absent in the latter is indicative of a well-placed die at the bonding position.

REFERENCES:
patent: 3814931 (1974-06-01), Kuroda et al.
patent: 6153887 (2000-11-01), Furuta
patent: 03208348 (1991-09-01), None

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