Browse Prior Art Database

Real Time, On Line Develop Etch Strip Process Control Tool Using Machine Vision

IP.com Disclosure Number: IPCOM000108025D
Original Publication Date: 1992-Jan-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 3 page(s) / 111K

Publishing Venue

IBM

Related People

Diez, ES: AUTHOR [+3]

Abstract

Disclosed is a tool which will accept unpopulated, large, panel printed circuit boards coming off the develop etch strip (DES) line and inspect them at various locations on the panel to determine the amount of under- or over-etching occurring on the DES line. Specifically, the tool features a vision system which "snaps" pictures "on the fly" at prede termined locations on the panel, where vision targets have been printed. These patterns are made up of copper circuitry and are analyzed by the vision system to determine the amount of etching present at that location. The tool is controlled by a PS/2* mod-70, and analyzes one target per passing panel in less than two seconds. The results are displayed, archived, and fed back via RS-232 to a DES controller, thus closing the loop on the real-time DES process control.

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Real Time, On Line Develop Etch Strip Process Control Tool Using Machine Vision

       Disclosed is a tool which will accept unpopulated, large,
panel printed circuit boards coming off the develop etch strip (DES)
line and inspect them at various locations on the panel to determine
the amount of under- or over-etching occurring on the DES line.
Specifically, the tool features a vision system which "snaps"
pictures "on the fly" at prede termined locations on the panel, where
vision targets have been printed.  These patterns are made up of
copper circuitry and are analyzed by the vision system to determine
the amount of etching present at that location.  The tool is
controlled by a PS/2* mod-70, and analyzes one target per passing
panel in less than two seconds.  The results are displayed, archived,
and fed back via RS-232 to a DES controller, thus closing the loop on
the real-time DES process control.

      The tool is comprised of a heavy-duty steel tube frame which
supports a motorized conveyor system, cameras, light guides, and a
pinched roller arrangement (Figure 1).  These components are used to
register, flatten, and transport a panel under a series of cameras
which "snap" pictures of specific predetermined locations along the
X-Y area of the panel.  The bottom rollers of the pinched roller
arrangement are spring-loaded to allow for different panel thickness.
Three camera/ light systems are supported immediately above the
pinched roller arrangement at different points along a steel cross
member (X direction).  Three proximity sensors are located under the
conveyor along the frame (Y direction) that sense the trailing edge
of the panel as it moves down the conveyor.  In general, there can be
any number of camera/light systems and proximity sensors.
Fiber-optic light guides are fed to the cameras to provide intense
lighting of each field of view (approximately .25 inch x .25 inch in
this implementation).  By selecting any of the cameras and waiting
for the panel trailing edge to trigger any of the sensors, the vision
system can be set up to "snap" and store a picture of any of the
target locations on the panel.

      The tool is controlled by an IBM 7561 PS/2 Mod-70 equipped with
a DI/DO card and a 640x48...