Method and devices for localizing flat chips on a carrier plate

Details Method and devices for localizing flat chips on a carrier plate Method and devices for localizing flat chips on a carrier plate

1977-05-16

1979-05-08

Corbin, John K.

Optics: measuring and testing

By alignment in lateral direction

With light detector

250237G, G01B 1127, G02B 2738

Patent

active

041533674

ABSTRACT:
Small reference marks near two corners of a circuit chip in the form of optical gratings in which the grating lines of both reference marks are parallel are illuminated alternately by a laser beam which is projected in the location the reference marks would have if the chip is properly located. Detectors are arranged to pick up the first secondary maximum of each diffraction pattern when the chip is properly located on its carrier plate. Failure of the detectors to respond indicates a chip that must be removed. With a beam-splitting arrangement producing four closely bunched light spots, straddling each of the reference marks, and an appropriate number of detectors, directional error signals are obtainable by which mechanical correction movements can be controlled for automatic localization of the chip. The gratings may be produced at the same time as the integrated circuit as among the surface features of the chip or they may be impressed into the solder beads at the corners of the chip by which the chip is made fast to the carrier plate.

REFERENCES:
patent: 3269254 (1966-08-01), Cooper et al.
patent: 3544801 (1970-12-01), Dyck
patent: 3811779 (1974-05-01), Jacobs et al.
patent: 3861798 (1975-01-01), Kobayashi et al.
patent: 3891321 (1975-06-01), Hock
patent: 3996463 (1976-12-01), Jablonowski

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