Agilent 5DX Service Guide 7-3
5DX Series 3 XYZ Panel Orientation (Loaded)
Panel Alignment
Panel alignment is derived by taking three reference measurements from various
locations on each loaded panel. The CAD translation program determines three
locations on each panel to be used for triangulating the panel’s X and Y
orientation. The most accurate method of determining accurate panel alignment is
by applying registration artwork on the printed circuit board. This registration
artwork is called a “fiducial.” These markings are created in the same process as
the printed circuit board conductive land or trace patterns. Fiducials provide a
common measurable point for component mounting and surface mapping
applications.
The XYZ Stage Assembly moves the board into each of the three selected views
and performs X-ray Laminography to identify actual locations of each reference
point. The Laminographic images containing this data are stored in the image
buffer.
A software location algorithm determines the location of these points within the
image by converting pixels to mils to evaluate distance measurements from the
digital image information. CAD information is used to identify the characteristics
of each reference point within the image. Once all three reference points are found
in the images the X-Y reference values are compared with the X-Y encoder values
and the offset magnitude is determined.
Alignment Accuracy
The System Controller pre-loads the XYZ move coordinates, to each of the Motion
Controllers. Once a requested motion has been performed, the resulting new
position is checked against the requested move location to determine if the move
has been satisfactorily accomplished. The processor converts the error (or offset
amount) from nanometers (CAD Locations) to pixels (Image elements) and
applies the corrective values to each solder joint location analyzed in the image.
• Satisfactory Move — A satisfactory move is a move in which the requested
move location and the actual settled position are the same or within acceptable
tolerances.
• Movement Error — Failure to achieve the requested move location when
compared with the actual settled position of the panel (exceeding acceptable
tolerances). In this instance the normal flow of the 5DX System is suspended
and an exception is generated. The system will then issue a “retry” for two
attempts before generating an error report and stopping further testing.
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