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Browse Prior Art Database

Illumination Method for Chip Inspection

IP.com Disclosure Number: IPCOM000100621D
Original Publication Date: 1990-May-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Saitoh, F: AUTHOR

Abstract

An illumination method is described which can brighten only solder balls on a semiconductor chip. It reduces light reflection from circuit lines on the chip and provides a contrasty solder ball image.

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This is the abbreviated version, containing approximately 100% of the total text.

Illumination Method for Chip Inspection

       An illumination method is described which can brighten
only solder balls on a semiconductor chip.  It reduces light
reflection from circuit lines on the chip and provides a contrasty
solder ball image.

      In automatic chip mounting, image processing is usually used to
detect solder balls on the chip.  However, conventional illumination
methods are not sufficient to separate solder balls from circuit
lines, resulting in a noisy, low contrast image.  The present method
can solve such a problem.

      As shown in the figures, the present method uses a circular
frame 1 including four slots 2 which are provided on the inner
surface of the frame 1 and displaced 90 degrees from each other.
Optical fibers connected to a light source (not shown) extend within
the frame 1 to emit a light from each of the slots 2.  A chip
3 whose solder balls are to be detected is placed horizontally inside
the frame 1 and oriented such that the chip 3 is illuminated by the
slot lights from the directions of the diagonals of the chip 3. Since
circuit lines usually run over the chip horizontally and vertically,
this arrangement for illumination reduces light reflection from the
circuit lines and minimizes noise caused by the circuit lines.
Light-emitting diodes may be provided at the slots in place of the
optical fibers.