PCB Etching Tank

The PCB Etchant tank system can be utilised with any sort of etch resist, this station by default documents toner transfer methods.

Author

Maintainer

Unclaimed

  • PCB Board
  • Matte Photo Paper (Hopefully supplied)
  • Wet and Dry Sandpaper or Kerosene to remove toner.
  1. Apply etch resist via toner transfer!
    1. Go to the etching station and turn on the laminator to preheat that sucka. The switch is on the station, not on the laminator. The red light indicates its on.
    2. Grab your design, print it out on normal paper and check your component sizes on it. Do it. Seriously. Your settings for the laser printer should be putting it out at 1:1, but sometimes its off and you need to make it 1:1.01 or so.
    3. Go to the printer, tap the touchscreen to wake it up. Below the touchscreen is a small 2 line screen with arrow keys and 5 buttons. Press Mode, right, down x 8, right to get to Tray selection. Ensure the tray being used is Tray 1. Press Mode repeatedly to exit the menu system.
    4. Clean your goddamn hands, and only touch the edges of the paper. Oils will make your life suck here. Put a sheet of the photo paper into the left side of Tray 1. If you’re using the matte paper that's part of the station, any side is fine. Print your MIRRORED design on it. Add some text on there to confirm its mirrored. Check it like six times or you’ll be doing weird soldering hacks and end up with a pile of mess like whats on the space RepRap. Just terrible, don’t let it happen to you. Printing multiple copies to a single sheet will also help when you stuff up your first 3 attempts, you terrible excuse for a functioning adult.
    5. Swear profusely as the printer jams repeatedly. If it didn’t, you are blessed by some higher power. Skip to A.7.
    6. Put a fresh piece of paper into Tray 2, go through those settings in step 1.2. again and select Tray 2.
    7. Cross fingers and try again. If its still jamming, go back to Tray 1. Eventually one or the other will work. This is the most difficult part, if that's any consolation to the printer hell you now endure.
    8. Now you have your design, don’t freaking touch it, Oil and Cheeto dust on your fingers will nix a good transfer. Put it somewhere safe.
    9. Cut your board to size, make it a little bigger than you actually need.
    10. Get your wet-and-dry sandpaper and wet it, then go to town on that bad boy till it’s nice and shiny. Dry it off and DON’T TOUCH IT.
    11. Cut out whichever print is best. You want the paper and board about the same size so the laminator behaves properly. Apply the printed design face down to the board. Tape it with blue painters tape on one edge. Masking tape is also fine but not as good. The important bit is the type of adhesive they use and how it reacts to heat.
  2. Start your etching engines!
    1. Go to the etching station!
    2. Open the window and hang the extraction fan out there.
    3. Is there etchant in the tank? Is it super blue, or below the minimum line? If there's nothing in there, follow the instructions on the ammonium persulphate container. If its below the minimum, top it up with some water, maybe add a few more spoonfuls of etchant to refresh it. If its bluer than a Dr Manhattan’s penis, probably time to tip it out and start fresh. If you’re going to open a new container of the etchant, start a new tank anyway.
    4. Turn on the Agitator, Heater and Extractor.
  3. Toner transfer: you’re not done yet!!
    1. So the Laminator should be good and hot now. I’ve personally found that heat is more effective than repeat passes, so the hotter it is the better.
    2. Feed your PCB through the laminator with the taped edge first.
    3. The paper should be stuck nicely to your PCB now. If it hasn’t, try again. If its not sticking, it’s all gone terribly wrong. Repent, go to 1.3. Don’t touch anything this time, may $deity have mercy on your soul.
    4. Repeatedly feed your PCB through the laminator at every possible angle until the mind numbing tedium destroys your innate self preservation instinct. Then keep going. This means about 10 times at a minimum, if you cheap out and only do it like 3 times you’ll get patchy transfer at best.
      1. If you’re doing very tiny things, its better to wait for the laminator to get really, really hot rather than do repeated passes. More passes can smudge out the toner. Not noticeable on bigger stuff, very noticeable on 0.5 pitch connectors and the like.
    5. By now you’ve either given up or you’ve noticed that the etchant is above 60oc now. That’s cool, grab your PCB and chuck it in some water to soak.
    6. Take a break, have a Kit-Kat, drink something, deplore the condition of your fellow man via the intertubes, whatever.
    7. Once the paper is soaked through you can remove it. remove as much as you can with your fingers without using nails you barbarian.
    8. Grab the toothbrush and go to town. This removes hard to reach plaq.. i mean paper and goop that you cant see or feel, but will block etchant.
    9. Inspect the transfer. Touch up any broken traces with a sharpie or toner resist pen. If you use the toner resist pen, make sure you let the thing dry properly. Be aware that the toner resist pen is much weaker than the toner, and will wear off in the tank. check for joins that shouldn’t be there, use a sharp knife to scrape away toner. Or start over because it’s bad and you should feel bad.
  4. Holy Hanna Barbera, actually etching!!
    1. Like most things, all the work is in the prep. Etching is no different. Now you have a board with some kind of resist on it, clip it with one or more of the clips.
    2. Check that the etchant is above 60oc. There should be a thermometer in the tank. If there isn’t, check the yellow rod on the backplane. If its not in there either, start yelling at people.
    3. Hang your board in the solution, make sure to replace the extraction hood or you’ll start to feel rather ill rather quickly. (seriously, it feels like you have the flu approaching)!
    4. Wait for a while. Depending on the size of your board and how strong the etchant is, it should only take 3-10min. If you have fine traces, keep a very close eye.
    5. Check the board regularly after 5min. Keep in mind its fairly hard to over etch through the toner if the transfer is good, but you can wear off the resist pen stuff.
    6. Its done! Wash it off in your water.
    7. Remove the toner. Use sandpaper on fiberglass boards, and use kerosene on kapton tape (pyralux). If you use kerosene on fiberglass, it’s porous and will make your board look dirty. If you use sandpaper on kapton it will damage the finish and look awful.
    8. Run a multimeter across everything to check you haven’t bridged or broken anything.
    9. If you’re happy with the board, grab the tinning powder out of the purple container. put a small pile on the board, and use a credit card to cut it into lines for snort…. I mean, er, get a damp paper towel, and rub the powder into the board. The copper tracks will change to a silver colour when this is done correctly with enough powder. Wash off the board again with water, and towel dry.
    10. Success! The board is done. Use a hacksaw or bandsaw or the score and bend method to cut your board to its final size. If you’re doing through hole, rejoice at the drilling that awaits you.

Station Proposal (Tier 1)

Abstract

This proposal will produce a station that will allow simple PCB manufacture.

Prior Requirements

  • Chemicals handling procedure

Materials

  • Existing
    • Laser Printer
    • Laminator
  • Upfront
    • Etchant Kit: ~$100
    • Water Container: Negligable
  • Ongoing
    • Paper Towels: Negligable
    • Photo paper for transfer: ~$10, Officeworks. Ausinc Photo Paper
    • Tinning Powder: ~$4ea, Vials from Ultrakeet.
    • Ammonium Persulphate: ~$12, Jaycar

Build

Etchant tank on plywood base with hard mounted kit accessories, ie pump etc. Spaces for work and consumables etc. Roughly 80cm of desk space. Packable away if dry.

Documentation

  • Step by step instructions on laminated cards. Mirrored on any online resources, ie wiki etc.
  • Consumables list with product links.
  • Upfront cost materials with product links.

Maintenance

  • Routinely maintain quality of etchant
  • Replace supplies when low

Station Proposal (Tier 2)

Materials