Inspired by a project published in the magazine ELEKTOR about converting one of those little membrane air pumps used on fishtanks and stuff into a vacuum pump, I went and opened up the pump that came with my pcb etching machine. Exciting!
For this one there isn’t even any modification necessary as the inlet is connected to the regulator by a hose which can be easily redirected. True, it might need another hole in the case to poke the hose through, but if that is all there’s to it…will try tonight!
That hose is acutally a bypass outlet. If the valve is open, pressure goes out of the tube instead of the port on the side of the pump. The REAL inlet is just below the black nozzle, it’s a small hole in the orange pump casing. Look at picture below!
The resulting vacuum can then be used to evacuate the air out of a clear plastic foil sandwich containing the pcbs with attached layouts, effectively removing all air bubbles and pressing the layouts against the photo resist – like it is done when curing epoxide resins. I am pretty curious if this will solve the problems I’ve been having with blurred pcb traces.
Read more about the idea and its use over at the original authors (french) website. Just look for “Pompe A Vide” after the redirect.