Owner's manual

7-14 Advanced Programming
7.4.6 Order of Pattern Placement and Timers
The order that the patterns are dispensed is an important part of optimizing the whole workpiece program.
For instance, in a U-shaped pattern, as shown in Figure 7-11, the first underfill line is dispensed at all
pattern locations on the workpiece. Then, the second underfill line is dispensed at all pattern locations.
Finally, the U-shaped seal pass is dispensed at all pattern locations. Timers are set for each of these steps
using the Reset Multipass Timer and Await Multipass Timer commands. This technique is demonstrated
in the exercises later in this section.
7.4.7 Chip Offset
Chip Offset is the distance between the edge of the part (usually a die) and the edge of the dispensing
needle and is primarily used for underfill applications. 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
7-12. A formula is used to calculate the Chip Offset:
Chip Offset = ½ d
n
+ 7 mil
where d
n
is the outer diameter of the needle
Reticles can also be used to provide the Chip Offset. Using reticles while programming can often be
easier and quicker to use than the Chip Offset formula. Refer to 4.4.7 Vision System Setup for instructions
on how to use reticles.
Item Description
1 Needle Tip
2 ½ Needle Diameter + 7 mils from Corner in X and Y-axes
3 Chip
4 Chip Offset Perimeter
Figure 7-12 Chip Offset
 NOTE Refer to Exercise 7-2 for step-by-step instructions on programming an underfill
workpiece using the features described in this section.
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