Instruction Manual

9-2 Advanced Programming
Skip and Prompt can be used for production runs. Occasionally chips are placed skewed on a workpiece
or a defect interferes with a fiducial. In this case, if
Skip is chosen, the program will automatically skip
the fiducial or part it is searching for and continue with the next step in the program. If
Prompt is
selected, the Operator is asked to either re-teach the unfound location, or skip it and continue the run.
Skip Mark Options
When you create a pattern in FmNT, there is an option called Skip Marks that can be activated and used
for the new pattern. Skip marks are specialized fiducials that can greatly increase throughput in
applications that require the same pattern to be placed in multiple locations on one board. For example, if
Workpiece has the same L-fill pattern dispensed at multiple locations, and there is a possibility that some
of those locations may need to be skipped, both Workpiece and L-fill can have skip marks to indicate
status. When the program executes, the Workpiece skip mark can be used to indicate if the entire board is
good or not. Depending on how the skip mark is used, if the Workpiece skip mark is not found, the L-fill
skip marks will be checked, and any L-fill pattern whose skip mark could not be found will be skipped.
Weight Control on Multiple Passes
Weight control lines are usually used for all lines in multiple pass programs. Different line styles are
sometimes defined for each line of the program. For instance, the first L-shaped line in an L-shaped
pattern usually is defined with a higher weight than the second L-shaped “seal pass”. This assumes that
the fluid will flow underneath the die to the opposite corner.
Chip Offset
Chip Offset is the distance between the edge of the part (usually a die) and the edge of the dispensing
needle. It is defined to ensure that the needle does not chip the die edge during dispensing. The Chip
Offset is used in the X-axis and the Y-axis as shown in Figure 9-1. A formula is used to calculate the
Chip Offset:
½d
n
+ 7 mil = Chip Offset
where d
n
is the outer diameter of the needle.
Reticles can also be used to perform the same function as Chip Offset. Using reticles while programming
can often be easier and quicker to use than the Chip Offset formula. Refer to “Vision System Setup” in
the Setup and Configuration section of this manual for instructions on how to use reticles.