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I make my own PCBs and etch them in a homemade bubble tank.

The tank has failed after a couple of years largely due to the etchant slowly eating it's way through some of the materials (glues, pipes, tubes, sealants etc) that the tank was made out of.

There are a few youtube videos showing etching using rocking tanks to slosh the etchant around (as compared to stirring using bubbles) see this... rocker tank 1

Has anyone got any experience of both methods and might be able to suggest which is best?

A bit of background might help. I make (on average) one board every 2-3 weeks. I used to use professional tanks, but was fed up of having to mix up 5 litres of liquid every time. (which would eventually need professional disposal). I ended up designing my own vertical bubble tank that would etch a post-card sized board using 250ml of etchant. I found this to be the perfect solution (for me) I would only have to mix up enough etchant for what I wanted, it would last for the couple of boards I might make that day, and then I could dispose of it properly myself and mix up a fresh batch next time needed to make a board.

It did a great job of making boards, The only problem with my design was making a tank that could survive the etchant, although most of the materials would survive weeks or months of exposure, after a while something was always getting eaten through and failing.

So rather than making another bubble tank, I though maybe a rocker tank, one advantage (to my thinking) being that a simple take-away container would be about the size I needed, and wouldn't require attempting to join pieces of Plexiglas.

The bubble tank made good boards, is a rocker tank as good?

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  • \$\begingroup\$ Have you considered spray tanks? The enchant is recycled through a peristaltic pump and sprayed on the board. \$\endgroup\$ – Nikon Jun 19 at 14:10
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Have you considered the magnetic stirrers used in a chem lab - they would probably agitate the fluid sufficiently then all you need is some type of bars / support to keep the panel above the stirrer... And you can use a glass container with should have a longer life...

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  • \$\begingroup\$ I'm not sure that the magnetic stirrers would offer any advantage over a simple rocking mechanism \$\endgroup\$ – ConanTheGerbil Jul 10 '18 at 20:50
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    \$\begingroup\$ As in simple, fewer moving parts, various sizes already available, no joining plexiglass... anyway I don't say you MUST use it but offered it as a suggestion - your money, time and choice... \$\endgroup\$ – Solar Mike Jul 10 '18 at 20:53
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    \$\begingroup\$ The rocker design seems to simplicity itself - a bowl on a hinged plate with a servo. The question I'm really after is does anyone know if the rocking tank produces as good a PCB as a traditional bubble tank? \$\endgroup\$ – ConanTheGerbil Jul 10 '18 at 21:05
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    \$\begingroup\$ If one was so much better than the other then the worst one would go out of business? Or the cheapest one is the most popular?... \$\endgroup\$ – Solar Mike Jul 10 '18 at 21:25
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    \$\begingroup\$ "simplicity itself - a bowl on a hinged plate with a servo". Versus what, a bowl with a motor, 2 magnets and no hinged plate? It always amazes me how people asking questions while they have made up their minds already. @Hemel This is a great advice and a technology used exactly for the purpose of stirring dangerous substances without risk of spilling. I suggest you take it. \$\endgroup\$ – Maple Jul 10 '18 at 21:45
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Sturdy plastic tupperware that seals strong works fine in my experience. If im not mistaken the copper etch only will corrode through soft metals such as copper of course-I didn't notice if you specified but I assume you're using ferric sodium chloride? if yes than a plastic tub will work fine. as for the ventilation and agitation, i keep mine sealed until I'm ready to open and inspect the boards and if needed i just shake the container a little-once the etching process starts its all coming off regardless. I guess the agitation is a way to speed it up? I just try to be careful when shaking it because ive had the protection come off from too much agitation...but my method is super simple-oil based paint marker -once it dries on the copper its on there good. and it is bullet proof to the etchant...hope that helped somewhat

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