This Automatic Agitator Speeds Up DIY PCB Fabrication
Chris Borge’s DIY automatic agitator expedites the PCB etching process.
As makers, we should all thank our lucky stars that it is now easy and affordable to get professional PCBs in just a couple of weeks. But sometimes even that short amount of time is too much of a wait when you want to quickly test a new design. Sometimes, you want a functioning PCB the same day and that is why you may turn to the old DIY PCB fabrication techniques that were popular among the makers of yore. If you take the chemical route, then you can speed up the process by building this automatic agitator designed by Chris Borge.
Unlike PCB milling, which simply cuts away the copper cladding of a blank circuit board, chemical etching dissolves the copper. Before starting etching, you must first apply a mask to protect the portions of the copper (traces and pads) that you want to keep. There are different masking methods, but they all leave the rest of the copper exposed. The circuit board blank then goes into a bath of chemical etchant that eats way all of the unmasked copper.
It can take a while (often hours) to dissolve the copper, but agitation will speed up the process. It’s like churning clothes in soapy water, rather than letting them soak. Because manual agitation is boring and tiring, Borge designed this basic machine to do the work automatically.
This machine is about as simple as they come. It has a platform for the PCB to rest on, within a bag full of the chemical etchant. That platform than tilts back and forth in an endless cycle, sloshing the liquid around. And that’s it — agitation achieved!
Aside from bearings and fasteners, almost all of the mechanical parts for this project are 3D-printable. Borge hasn’t done so yet, but he usually uploads his designs. When/if he does, anyone can build their own agitator.
Because the motion is so simple, it would have been possible to connect a DC motor directly to power and let that drive a reciprocating mechanism. But instead, Borge used an Arduino to control a servo motor that does the same thing. Maybe that is a frivolous use of a microcontroller, but it certainly simplifies the mechanical design. Either way, it seems to work great and now Borge can have PCBs ready to test in no time.