[HN Gopher] Agitating homemade PCBs with ease
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       Agitating homemade PCBs with ease
        
       Author : PaulHoule
       Score  : 28 points
       Date   : 2024-09-23 22:15 UTC (4 days ago)
        
 (HTM) web link (blog.arduino.cc)
 (TXT) w3m dump (blog.arduino.cc)
        
       | MegaDeKay wrote:
       | Or just scrub the board with a bit of ferric chloride and a
       | sponge. I've also seen a modified version of this method that
       | might be better for larger boards that puts the board and the
       | sponge in a ziploc bag with some etchant poured in. Use two
       | sponges for a double sided board.
       | 
       | https://hackaday.com/2009/07/13/etch-pcbs-with-ferric-chlori...
        
         | squarefoot wrote:
         | > Or just scrub the board with a bit of ferric chloride and a
         | sponge.
         | 
         | If you use ink pen and transfer pads like I did decades ago,
         | the sponge would almost certainly wipe the pads off. The best
         | way that I'm aware of to ensure the copper is being
         | consistently covered by the solution is to use an air pump to
         | produce bubbles under it. Those used in aquariums are quite
         | cheap and durable.
        
         | wrs wrote:
         | Yes! The sponge technique takes a little practice to get
         | consistent results, but it works well (at least for small
         | boards), and lets you use microscopic amounts of etchant, which
         | is good for cleanup. I find it's especially good when trying to
         | do relatively small traces, because you get such fine control
         | over the process. (I have to say though, nowadays I'd usually
         | rather wait six days for JLCPCB to do it for me.)
        
       | StayTrue wrote:
       | I don't think this is the best way to clean PCBs but it would
       | make a great machine for marinating food, moving the marinade
       | around continuously for max/even absorption.
        
         | _Microft wrote:
         | This is not a cleaning process (in the sense of "removing
         | dirt"). One way to create PCBs is to use a board with a copper
         | surface, put a protective mask on the locations that should
         | have traces or pads and then etch away copper from everwhere
         | (else). In the end, only copper under the protective mask will
         | remain. Etching is faster when the solution is moved around
         | during the process. This machine does exactly that.
        
         | MegaDeKay wrote:
         | It would make a poor machine for marinating food. Most of the
         | foods you'd marinate should be refrigerated during the process.
         | A much better way to marinate is throw everything into a ziploc
         | with as much air removed as you can to maximize contact. Flop
         | it around every now and then if you like.
        
       | Workaccount2 wrote:
       | I have made a number of PCB's at home. By far the best etchant is
       | warm hydrochloric acid (30%) and peroxide (3%). In a 1:2 mixture
       | (HCL:Peroxide). Will etch a board in about 3 minutes. But be sure
       | to do it outside.
        
       | buildsjets wrote:
       | Am I the only one who finds it immensely sad that they are using
       | a microcontroller, code, and a servomotor to replicate the motion
       | of one of the simplest and most basic of machines to construct, a
       | crank and kingpin?
       | 
       | This is a project for Lego, not Arduino.
        
         | dmb2 wrote:
         | No, I came to the comments after having this exact reaction.
        
         | topspin wrote:
         | My design would have a pivoting arm holding the PCB in the
         | fluid and bump or rotate the arm with a cam. Why put the big
         | container full of caustic liquid in motion when you can just
         | move the PCB?
         | 
         | I've been nerd sniped thinking about this. Latest thinking:
         | simple sliding bar clamp to hold two edges of the PCB. The PCB
         | hangs down into the solvent tank. The bar on the clamp drops
         | into vees at both ends. One end of the bar is bumped with a
         | motorized cam, the other has a spring. The clamp+PCB oscillates
         | back and forth and the arms agitate the fluid. When the cycle
         | is complete you just lift the clamp+PCB out of the tank. The
         | tank doesn't move. Tank shape can be optimized to minimize
         | working fluid and agitation.
        
         | pstrateman wrote:
         | The YouTube video acknowledges the over engineering in the
         | title.
        
       | dvh wrote:
       | Piece of string and this bash script:                  while
       | true; do           eject           eject -t        done
        
       | amelius wrote:
       | I don't understand. Ordering PCBs online is nowadays almost as
       | fast as ordering the components. Why would you want to make them
       | yourself?
        
         | bobmcnamara wrote:
         | There are reasons.
         | 
         | Mine: phased Vivaldi antenna arrays. Iteration is painful if
         | you have shipping in your run debug loop.
        
           | amelius wrote:
           | Ok, but that usecase is very exceptional.
        
         | daghamm wrote:
         | EUR40 to receive it in 3 days or EUR0 to have it in 3 hours.
        
         | brotchie wrote:
         | My thoughts exactly. It's fun as a hobby I guess, but sitting
         | down and soldering a non-trivial board sounds like a PITA vs
         | paying $50 for a respin of 5x boards with full pick-and-place
         | assembly, delivered in <5 days.
        
         | avaldez_ wrote:
         | >Why would you want to make them yourself?
         | 
         | Welp, not everyone lives in the US or Europe. Living in South
         | America my only options are either spend ~$100 for a two weeks
         | _fast delivery_ or have it for free ~2 months later. Not many
         | options for the hobbist maker over here. There are local
         | services but they are more expensive (and slower if that's even
         | possible) or just middleman for PCBWay or JLCPCB.
        
           | amelius wrote:
           | But how long does it take for your components to be
           | delivered?
        
       | Animats wrote:
       | The usual way to agitate PCB etching today is to put an aquarium
       | bubbler at the bottom of the tank.[1] Cheap, compact, simple, and
       | you need less etching solution.
       | 
       | [1] https://www.circuitspecialists.com/et20
        
       | daghamm wrote:
       | I built a similar device some years ago only to realise that all
       | my servomotors where cheap knockoffs that broke after 5 minutes
       | l.
       | 
       | Has anyone managed to get those $2 servos on Ali to work
       | reliably?
        
       | ein0p wrote:
       | Just buy them in China. Super cheap even in small quantity and
       | very high quality. Shipping isn't too bad either. Beats the heck
       | out of figuring out how to dispose of ferric chloride. They'll
       | even populate the boards for you for a reasonable fee if your
       | design uses SMD parts
        
         | pavl wrote:
         | Can you recommend a Website/service?
        
           | ein0p wrote:
           | I've been using https://jlcpcb.com/ and have nothing but good
           | things to say about the results. Caveat: my latest order was
           | well over a year ago.
           | 
           | BTW if someone knows of any domestic US alternatives, please
           | list them. I'd be more than happy to pay 2x the price for
           | faster turnaround, but certainly not 10x the price.
        
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