How do I etch PC boards?

[Lemosteam]

@peteski, I can't recall- how do you remove the paint?

[ednadolski]

A quick and easy method for small projects can be found on Youtube at :

/>
A black felt tip marker pen is used to trace or hand draw the schematic on a board cut to size, left to dry, then etched using ferric chloride solution which you should be able to buy from any electronics store or photographic chemical supplier.  You do not need a special etch resist pen, any marker with a pigmented ink will do.

The steps are :
- Design and trace the NEGATIVE copy of the circuit on the copper clad side of a piece of PCB board cut to size, and drill holes for the electronic components to be fitted.
- Properly clean the board.  I use a detergent wash followed by denatured alcohol to remove traces of grease.
- After cleaning, only handle the board with cotton gloves.
- I use a felt tip marker with a 1 mm tip to draw the diagram on the copper clad side, and draw two lines (to 2mm wide), which I then mark over with a second tracing when dry.  Make sure the deposited trace has a reasonably thick layer to prevent undercutting when etching.  Let it dry completely before etching. 
- When working with ferric chloride, wear safety goggles and rubber gloves, it is highly corrosive.
- Pour a little ferric chloride in a flat bottomed plastic tub (do NOT use a metal container), to just cover the board with the copper clad side up.
- Hot water can be used to speed up the process.  Place the etching container in a larger container and fill the larger container with water.
- Gently agitate continuously until the copper has been completely etched away, leaving the marked tracing on the board.  Again, only use plastic tools to agitate/lift the board from the solution.
- When done, remove the board from the solution and dip/wash in clean water to stop the etching.  Complete etching could take anywhere from 10 to 20 minutes.  I lift the board from the solution using plastic tongs, and gently blow the solution off the surface to see how it is progressing.
- Dry the board with paper towels, and clean off the tracing with denatured alcohol.
- Ferric chloride can be reused a few times, but will require longer etching time each time it is reused.  Keep used solution in a separate container and mark how many times it has been used.
- Disposal of ferric chloride may be regulated in the US, please check local regulations.   I dilute with copious quantities of water and pour down an outside drain.
- Clean all containers and tools used for making/handling the board under an outside tap; do NOT clean inside.  Ferric chloride etches copper alloy metals, so pipes and fittings could suffer damage.

Hope this helps.
Steve

Interesting process, thanks for posting.   But for a genuine one-off/prototype project, I'm not sure that I see the benefits over say simply hand-wiring a circuit on a pre-drilled perf board.  And this has the downside of handling & disposing of caustic chemicals.   What have I overlooked?

Are there any online layout programs or etch houses that can produce a board layout from a schematic?

Thanks,
Ed

[woodone]

Years ago I built the CT-16 command set up that Model Railroader ran a series on. I tried the photo process and failed time after time.
I never could get a good board using this process.
I needed to make 4 complete CT-16 systems so making more that one board I needed to be able to make more than just one at a time.
I finally used a silk screen to place resist ink on the boards. This worked very well for me. With the Silk Screen print you could see right away if you had a good print- if you did not- I simpley wiped it off and printed another on the same board until I had a real good image.
After etching I used lacquer thinner to remove the resist paint. 

[Mark W]

There are hundreds of iron-transfer etching videos on Youtube, but I found most of them too vague, or too deathly slow. 
This two part video are the ones I found most helpful, still quite slow and a little potato quality, but covers all the important steps clearly.

/>

/>

Here's some of my own results. 

Toner transfered to brass. I went in and filled big gaps with a sharpie.  I later found that misting the brass with 91% prior to laying the transfer (wet transfer) somehow helped more toner to actually transfer. 

https://i.imgur.com/e66EJoz.jpg

Right after the etching bath.

https://i.imgur.com/UFpbTCm.jpg

Cleaned with Acetone and ready for paint

https://i.imgur.com/PaBkJH4.jpg

Painted:

https://i.imgur.com/f8zeTWo.jpg

And installed:

https://i.imgur.com/gI4KhHh.jpg

[peteski]

John,  the paint I use (Testors) is removed with lacquer thinner (but Testors thinner or mineral spirit would work too - just a bit less aggressively).

Mark, the PulsarProFx PC board making method works like the process you described, but it is much more predictable and repeatable. They also use laser printer to print the photomask, but they use a "special" dextrose-coated paper (to me that sounds like uncoated decal paper).  After the toner is transfered to the copper clad board by running it through a laminator (which just used for transfering the toner onto the copper), then run it through the laminator again, but this time using one of their color transfer sheets. The ink layer from that sheet then melts into the toner creating a solid etchant-resistant pattern on the copper. That way there is no futzing with markers to fill in the less dense toner areas to make them solid.

[mmagliaro]

Interesting process, thanks for posting.   But for a genuine one-off/prototype project, I'm not sure that I see the benefits over say simply hand-wiring a circuit on a pre-drilled perf board.  And this has the downside of handling & disposing of caustic chemicals.   What have I overlooked?

Are there any online layout programs or etch houses that can produce a board layout from a schematic?

Thanks,
Ed

Circuits made on a PC board are generally  more durable than ones made with point-to-point wiring on a pre-drilled perf board.  I have used those perf boards myself.  Don't get me wrong.  They are darn handy.  But PC boards make for a really neat, strong arrangement of the parts.

Drawing out the pattern on a copper board with a Sharpie and then rocking it in a tray of ferric chloride for 20 minutes or so is pretty easy to do.  I made a lot of boards that way "in the old days" (the 1980s).  It works fine as long as you don't try to make the traces too thin.  I don't think I'd try it for anything with chips on it.   For that, I used the iron-on "PnP Blue" sheets.    But for discrete component boards, a Sharpie worked for me.

As far as the toxic chemicals, well yeah, there is that.  I don't know of any good way to get rid of that stuff.  I used to just seal it up in a plastic bottle with a screw cap and put it in the trash, which ain't great because that just goes to a land fill.  MG Chemicals website says you can neutralize the acid with washing soda and then pour off all the liquid down the drain (AFTER IT IS NEUTRALIZED).  But the copper sludge that remains still has to be put in the trash.