Agilent 5DX Service Guide 7-5
5DX Series 3 Surface Map
Surface Map
The Surface Map process is accomplished by using a laser. Surface mapping is
performed to determine the Z-Axis positioning (or vertical reference) of each
board on a panel. This positional data defines the actual board surface in reference
to the Plane of Focus. The sampled Surface Map is then interpolated for all other
views used during the test process. Adjustments can be made for panel reference
point construction that exceed 1% by taking measurements on a grid of less than 1-
inch centers.
In this section...
This section describes the following topics:
n OFFSET (X&Y), 7-5
n Laser Adjustment, 7-5
OFFSET (X&Y)
The location of the Surface Map Laser is offset from the Field of View, to one side
of the Electron Beam. This physical offset is compensated for by locating a point
using the laminographic process, then finding the same location with the Surface
Map Laser by creating a scan of the identical fiducial or reference component
solder joint. The deltas between the intersection of the two images provide the X
and Y offset value. Both the X and Y Offset and the Surface Map identify identical
fiducials or reference component solder joints to perform respective alignment
tasks.
Laser Adjustment
Accurate positioning of the panel is critical for acquiring precise solder joint
characteristic measurements. When properly adjusted the XYZ Stage Assembly
should provide positioning repeatability and accuracy to a level of ±2.5 mils in the
X and Y directions and ±3 mils in the Z direction (within the central 60% of the
full 100 mils of travel). System accuracy can be adjusted to within ±3 mils of
repeatable motion (move and return) over a 25 mil span of panel movement in the
Z direction.
Laser Adjustment is accomplished by examining a tungsten target (a 2.5 cm square
of tungsten with a precision hole in the center), located on the stationary rail of the
XYZ Stage Assembly. This is known as the Self-test Coupon. The target is only a
few mils thick; therefore, when viewed by the Laminographic process, the target
will produce an extremely narrow field of focus. When the image of the tungsten
target is clearly focused and stable, the distance from the laser to the panel is
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