Thompson Vertimag vertical-drive pumps banish unwanted bubbles

The design features of Finish Thompson Vertimag vertical magnetic drive pumps, available in the UK through Michael Smith Engineers, have helped eliminate quality control problems which can occur in the manufacture of printed circuit boards.

These problems are caused by the presence of microbubbles within plating solutions, following their transfer via traditional vertical pumps, during the PCB manufacturing process.

Traditional vertical pumps incorporate a shaft, typically motor supported, which is directly connected to an impeller in a cantilever configuration.

The shaft and impeller are housed within a vertical tubular column containing weep holes which allow pumped fluid to weep out of the wall. This prevents fluid from ascending into the motor internals – a potential cause of pump failure.

These holes are, however, a design flaw in standard vertical pumps, as they allow air to enter the pump column and seep into the plating solution.

As this air passes into the high-velocity fluid flow, it is broken into thousands of tiny microbubbles. These bubbles remain suspended in the pumped solution, plaguing the user with quality problems.

In the past, when circuits were wider, these microbubbles were not a problem. However, in today’s PCB technology, the microbubbles can be larger than the actual circuit width. Should a microbubble occur in the place where a circuit is meant to be, a gap will be created, breaking the current flow in the printed circuit and resulting in a rejected circuit board.

The magnetic-drive design of the Vertimag pump has provided a solution. The design incorporates an airtight, sealed column, eliminating the holes where air was introduced.

Not only does the design eliminate microbubbles, but the airtight column also helps reduce environmental emissions and prolongs the life of the motor.

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