User Manual

Beginning Programming 8-7
Pre-Move Delay Factor
Some fluids have a high viscosity which means that they do not dispense as quickly as lower
viscosity fluids. The Pre-Move Delay Factor increases the time that the dispensing head is
parked with the valve ON, prior to a programmed move. The delay at the beginning position
insures that a full line is dispensed. The units are seconds. Typically, 50 ms (0.050 sec) is
sufficient for most underfill fluids.
Down Speed
The Down Speed is how fast the dispensing head lowers to dispense. Low viscosity fluids
tend to drip and you may want to set this parameter higher. The units are inches/second.
Typically, 2 in/sec is sufficient.
Down Acceleration
This is the parameter that controls how fast the dispensing head accelerates to the Down
Speed. The units are inches/second
2
. Typically, 300 in/sec
2
is sufficient.
Dispense Gap
The Dispense Gap is the distance between the needle tip and the substrate during dispensing
operations. This distance is one of the more common adjustments made to optimize
dispensing programs. The units are in inches. Typically 15 - 20 mils (0.015 - 0.020 in) is
sufficient.
Speed
This refers to how fast the dispensing head moves during dispensing. This parameter is
actually not used for weight control lines, but basic lines where the speed of the dispensing
head affects the amount of fluid dispensed. The units are inches/second.
Shut-Off Distance
This parameter controls where dispensing is discontinued at the end of a move. Low
viscosity fluids require that you stop dispensing prior to the end of the move so that the fluid
does not exceed the pattern limits. The Shut-Off distance is the point where the valve stops
dispensing before the end of the move. The units are in inches. Typically, 30 mils (0.030 in)
is sufficient.
Suckback
At the end of dispensing a line or a dot, the valve is reversed for the Suckback period to
remove any material from the tip of the needle. The Suckback value should be set according
to fluid viscosity. Generally, 10 ms (0.010 seconds) is sufficient.
Dwell
This parameter is similar to the Pre-Move Delay Factor, except that it is used at the end of a
move. The Dwell is how long the dispensing head stays at the final position of a move
before retracting. This allows residual fluid to detach from the needle tip before the
dispensing head moves to the next location. The units are seconds. Typically, 0 - 20 ms
(0.020 sec) is sufficient.