Browse Prior Art Database

Electro Optical Alignment of Substrates

IP.com Disclosure Number: IPCOM000073913D
Original Publication Date: 1971-Feb-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Bojman, W: AUTHOR

Abstract

When testing a complex module substrate or when chip positioning necessary to determine the exact location of the chip pads on the substrates so as to be able to automatically position the ships or test probes correctly without human intervention. This electrical-optical system precisely identifies the location of a mark deposited on the surface of a substrate on the screen of a television camera, such that the location of the center mark will inherently describe the location of each chip pad in a specified cluster.

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Electro Optical Alignment of Substrates

When testing a complex module substrate or when chip positioning necessary to determine the exact location of the chip pads on the substrates so as to be able to automatically position the ships or test probes correctly without human intervention. This electrical-optical system precisely identifies the location of a mark deposited on the surface of a substrate on the screen of a television camera, such that the location of the center mark will inherently describe the location of each chip pad in a specified cluster.

The locating mark is a patch, rectangular or square, of sufficient dimensions and is located in the center or in the proximity to a pad cluster. Any other geometrical shape may be employed as long as an orthogonal symmetry is preserved. Preferably, the locating mark is opposed on the substrate with respect to the pad formation. A sensor such as a standard closed-circuit television camera is equipped with optics to magnify the locating mark to a size in the order of one-tenth of the area of the vidicon screen. Electronically, the area viewed by the TV camera is divided into quadrants. The video signal is amplified and shaped sufficiently to recognize the signal levels corresponding to the substrate as opposed to the signal levels corresponding to the locating mark.

As illustrated at A, the areas corresponding to the locating mark are integrated quadrant by quadrant and electronically a numerical comparison of the...