Printed-circuit boards automated dispensing

This chapter introduces the reader to the automated dispensing equipment commonly used in electronics packaging, printed circuit board assembly, and other electronics manufacturing. Automated dispensers excel in the areas of manufacturing that can be most helpful in the construction of fuel stacks. 

Jet-dispensing equipment uses a closed-loop, positive shut-off piston to dispense the adhesive. The adhesive is pressurized at the syringe to assure constant flow. Using a spring-driven ball and seat mechanism, the adhesive fills the void left when the ball retracts from the seat. When the ball returns, the force due to acceleration breaks the stream of adhesive, which is then jetted through the nozzle in precisely controlled amounts onto the printed-circuit board (Figure 4.14). Unlike contact automated... 

Automated production requires a workpiece carrier that can be used all the way along the production line. Consequently, the design is such that the carrier can be conveyed by the printed-circuit board conveyor to all the machines in the process chain. The appropriate number of workpiece carriers is required if production is to be continuous. An interface for energy supply and communication between the automatic machines and the workpiece carrier is necessary, particularly for the dispensing unit and the automatic placement machines. The electronics built into the workpiece carrier render it unsuitable for reflow soldering, so a handling step has to be included so that the MID can be lifted on to a separate, passive workpiece carrier for this process. This transfer can be manual or by means of an industrial robot such as the Scara robot. 

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