Manual

10 Operation

Theory of Operation

A typical cross-section of the internal workings of the DispenseJet is shown in Figure 4-1. During a

dispensing cycle, a solenoid-driven air pressure valve compresses a spring. The compressed spring retracts

a needle plunger and the fluid chamber space vacated by the needle plunger is filled with fluid. When air

exhausts from the solenoid valve, the spring expands and the needle plunger returns to its seat with an

impact force that ejects the fluid through the dispensing nozzle onto the substrate and then immediately

blocks the fluid from flowing through the nozzle. If desired, the dispensed fluid can be assisted by a short

burst of air from a co-axial air solenoid to assure consistent spreading of the fluid by disturbing the fluid

surface tension.

Fluid to be dispensed by the DispenseJet is contained in a syringe or an external reservoir and is fed to the

DispenseJet fluid chamber at 7 to 69 kPa (1 to 10 psi). To stabilize viscosity and improve flow characteristics

of the fluid, the fluid is fed through a heater that typically warms the fluid from the ambient room temperature

to an ideal and controlled temperature of 40

C (104

F).

In the jetting process, the DispenseJet moves in an X-Y plane to dispense a variety of pre-programmed

patterns in a confluence to create a uniform film of flux. (There is no movement required in the Z-axis during

or between the dispense cycles). The fluid, which was dispensed on the substrate, forms a dot or a line

depending on application.

The micro-adjustment controls the needle travel distance. When turned clockwise, it decreases the piston

travel and fluid flow, and when turned counterclockwise it increases the piston travel and fluid flow.

Item Description Item Description

1 Micro-adjustment 4 Needle

2 Spring 5 Heater

3 Air Piston 6 Nozzle

Figure 4-1 Typical Jet DispenseJet Internal Workings