Manual

9-2 Advanced Programming
Re-using Fiducials and Height Sense Information
If your workpiece contains many parts, and the pattern to be dispensed is a two or three part
pattern such as the L-shaped and U-shaped patterns, checking fiducials and the substrate
height during every pass can be time consuming. In many cases, it is unnecessary since the
likelihood that the parts could move before the timers expire is very low. Rather than finding
fiducials and doing a Height Sense check during every pass, fiducials and Height Sense
checks are performed once for each part and the information is stored and reused during the
second pass. This is called “Re-using Fiducials” and is enabled by selecting “Pass Block”
from the Pattern button on the Program Commands toolbar. This feature is a significant time-
saving option.
Fiducial Options
In Setup Vision on the Configuration menu, there is a Vision Parameter called “Fiducial
Options” with the choices “Pause after search,” “Skip” and “Prompt”. Activating “Pause
after search” means that FMW will pause after every fiducial search and display a message
box indicating the status of the fiducial. This can be helpful during programming sessions, but
is not recommended for production runs since it requires an operator response in order to
continue. When developing a dispensing program, pausing after a fiducial search to verify that
the correct fiducial was found is a good way to determine the best fiducial to use for an
application.
“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 FMW, 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.