Cleaning PCB's before P'n"P thread

[nightingale]

just curious,
i start by steel-wooling the copper, then i usually use this stuff called "ZUD". i think it is a borax trype cleaner, and then i use rubbing alcohol to go over the copper before i iron on my press and peel. i have had good luck with smaller/medium boards, but i am trying to make a board for the analog delay form ggg: http://www.generalguitargadgets.com/diagrams/ad3208_lo.gif

i am having trouble getting the p'n'p to completely "take" on this giant board. it seems like the PCB is not clean enough in spots. i have scrubbed this thing until my hands hurt.
i just thought i would run it by you guys and see what everyone else used. the best cleaner that i can think of that leaves behind no "build-up" is rubbing alcohol. i found some older threads in the archive, but i know there are alot of new cleaning products on the market.

i am considering giving "oxy clean" a shot. it's a new "wonder cleaner" very popular now in the states.

[nightingale]

bumping,
just wanted to see what you guys clean your pcb's with.

[Nasse]

I been thinkin the subject after some longish discussion months ago. Somebody (Mark Hammer and others?) mentioned how quickly the cleaned copper could oxidise or perhaps form some kind of invisible but nasty layer with minerals in water, depending how "hard" or "soft" local water is.

I have not tried but thought I should try just etch after cleaning with steel wool and not use tap water at all, or use distilled water.

My wife was at some art course and they etched copper with ferric chloride (got some nice small pieces of copper plate). She told me they used acetic acid C2H4O2 for cleaning the copper before etching.

[Gringo]

I use paint thinner after steel wooling, before ironing the transfer.

Make sure you apply enough (and even) heat to every spot in the board, too.

[stm]

I never use steel wool.  I've heard from several experienced people that the residues of steel over copper preclude good soldering afterwards.  

I've always used a piece of cotton with toothpaste with excellent results.  After a while the copper surfaces becomes neat and shiny, without the scratched texture that the steel wool produces.  Then I just rinse with tap water, clear with a piece of paper towel, and the apply tonertransfer immediately.

[D Wagner]

If the board looks dirty, I use a brillo pad (with the pink soap).  Then, I use 400 grit wet/dry paper under running water.  I wet sand the board in both directions until it is completely shiny.  I then dry it with highly absorbant paper towels and give it a light rubbing with alcohol (90%) just before PnP application.

Not to be overlooked: I also sand the cut edges of the board at an angle, with 220 grit paper to remove any lip that might keep the iron from making good contact.

[David]

just curious,
i start by steel-wooling the copper, then i usually use this stuff called "ZUD". i think it is a borax trype cleaner, and then i use rubbing alcohol to go over the copper before i iron on my press and peel. i have had good luck with smaller/medium boards, but i am trying to make a board for the analog delay form ggg: http://www.generalguitargadgets.com/diagrams/ad3208_lo.gif

i am having trouble getting the p'n'p to completely "take" on this giant board. it seems like the PCB is not clean enough in spots. i have scrubbed this thing until my hands hurt.
i just thought i would run it by you guys and see what everyone else used. the best cleaner that i can think of that leaves behind no "build-up" is rubbing alcohol. i found some older threads in the archive, but i know there are alot of new cleaning products on the market.

i am considering giving "oxy clean" a shot. it's a new "wonder cleaner" very popular now in the states.

NG-

Is your steel wool clean?  I've used the real fine stuff for furniture refinishing and had good results with it.  You have to toss it when it gets grungy, though.

Does your PCB sit right on the ironing board when you're ironing the PNP?
Have you tried resting the PCB on a thin piece of plywood or Masonite?  Something hard, flat and level that doesn't mind heat?  I've had good results with this.  Keeps the board level as you iron and it seems to concentrate the iron's heat on the PCB.  Of course, I have to come clean and mention that I've used laser transparencies, not PNP.

Is your iron hot enough?

You might need to do your transferring on a section of the board at a time.

[nightingale]

thanks,
i have alot of new ideas to try now.. the toothpaste one sounds interesting, also i've never tried paint thinner.

Is your steel wool clean?

i ususally grab a new peice of stele wool for each board.

Does your PCB sit right on the ironing board when you're ironing the PNP?Have you tried resting the PCB on a thin piece of plywood or Masonite?

i iron my PCB at my bench, which is 1/2inch ply.

You might need to do your transferring on a section of the board at a time.

those were my thoughts when i was doing it. my iron barely covers the whole board.

i am about to print another layout onto another peice of press'n'peel.
i will let you guys know how it goes.
thanks for the new ideas.

i havn't had any problems with press'n'peel for a long time, i just can't get it right on this large board.

[MartyB]

Set your copier to darker.  The more powdered plastic toner you can transfer the better the traces - as long as there's not alot of artefact or trace merging.  Also the better quality copperclad will be very flat and smooth.  I have a large pile of CC at home that's alittle trickier to use because there's 'show through' of the glass fibers on the copper side (i.e. texture).  That kind leads more to inadequate transfer using the pnp method.

HTH
Martyb

[nightingale]

man,
i just tried it again using the paint thinner idea. it seemed to really clean the board but i got the same reesult. what a rough couple of days for my sheets of p'n'p.

it must be a heat issue.

since the board is much larger, the copper must be taking alot more heat than i estimated.

Set your copier to darker.

i have it set to 600 dpi. i guess i will try again tonight with more heat. i need to take a break today, because it is not feeling much like a fun hobby right now... lol!

thanks!

[Paul Perry (Frostwave)]

It might be the physical size of the larger board that is the problem. Because, you have succeeded before!
These prior successes  make me think it is not a cleaning problem.
Some people preheat the board with a heat gun.

[MartyB]

Are you using a laser or inkjet printer?  This only works with toner transfer copiers.

[MR COFFEE]

I have not had a charmed relationship with PnP and getting it to stick to copper laminate and make flawless PCBs. After much trial and error, what I have finally hit on that works for me on boards as large as 6" x 9" is as follows:

1)Turn on the Iron and let it get up to temperature. I have never had a problem because of too high a temperature, but I have heard others say they have.

2)Use a file or sandpaper to smooth off any burring along the edges of the board. The copper surface must be smooth, and cutting the laminate to size often raises burrs along the cut edges. Make sure the edges of the copper laminate do not have ANY burring that might interfere with the iron being able to make perfectly flat contact from iron to the PnP to the board beneath.  

3) Next, I use a copper-pot-cleaning scrubbing powder ("Bar Keeper's Friend" or similar) to get the board thoroughly clean and shiny using a ScotchGuard pad or Brillo pad(steel wool pad with soap in it).

4) Rinse the board for a minute or so under clean tap water.

5) Repeat above again if it doesn't look PERFECT, just like a copper mirror.

4) Dry with plain white paper towel with NO Daisys or whatever printed on it (the kind they recommend for cooking on in a microwave oven). The idea here is NO CONTAMINATION on the copper.

5) Then take a BRAND NEW, dry, ScotchBrite pad (if someone outside the States knows the generic name for these, please chime in) and scrub the board, first from one diagonal corner to the other and then continue scrubbing with strokes parallel to that diagonal all the way to each of the other corners, so there is a uniform pattern of mild scratching (like a very fine, "brushed metal" type of finish) diagonally all across the PCB. Apparently, even though it appears perfectly clean after the copper cleaner, it still leaves a slight residue that interferes with adhesion.
IMPORTANT: Steel wool doesn't seem to do the same thing that the ScothBrite pad does. It just doesn't seem to leave as clean a surface. I suspect that very fine sandpaper would work OK too, but I haven't tried that. Steel wool seems to leave a residue of some kind.

6) Now, do the same thing again using the ScothBrite pad, only this time in the cross direction (other corner to it's diagonal corner).

7) Now, put a Kleenex (thanks for this tip goes to RG) over the board and put the iron on it and "preheat" the board for about 30 seconds - NO longer.

IMPORTANT: Don't use the kind that are advertised to be kinder to your poor, tender nose - they have lotion in them. Again, the idea is NO CONTAMINATION.

IMPORTANT: Don't try to iron the PnP transfers on a padded ironing board. I use a flat ceramic cook top, but a piece of glass would probably do if you have the other kind of stove. The surface you place the board on  needs to be hard and stable so you can apply lots of pressure to the iron when it's on the PnP.

Next, I carefully place the Pnp on the board and smooth it out with my CLEAN fingers, starting from one end of the layout and moving slowly toward the other. Because the board is preheated, the toner pattern on the PnP starts to stick in place fairly quickly. Avoid wrinkles and uneven application (humps or "bubbles").

9) Now, Place the iron on top of the PnP, and press down firmly, but be VERY careful to NOT move the iron. I have read people say they had problems from "too much pressure". I haven't, and I think the problems they had had more to do with pressing down hard and MOVING the iron, smearing the image. The toner just isn't that thick for it mush out and give a less sharp image from pressure. Just don't SLIDE it while you are pressing down.

IMPORTANT: DON'T USE THE IRON LIKE YOU WERE TRYING TO IRON A SHIRT. It WILL smear the image.

10) On a large circuit board, CONTINUE PRESSING DOWN on the iron without moving it on the first area for about 30-60 seconds, then release the downward pressure and move the iron to an overlapping area, and reapply downward pressure. Repeat until you have covered the entire board area with the hot part of the clothes iron, and then go over the whole board again. On small boards, you may not need to move the iron and you can just hold it in one place covering the entire board.

11) Put the board in a zip-lock plastic bag, squeeze out the air, zip it shut, and put it in the Freezer for 10-15 minutes until it is really cold.

12) Take the board out of the bag, place it on a table, and, VERY carefully lift up one edge of the PnP film with a fingernail. Peel off the film SLOWLY, keeping the film at about a 90 degree angle to the board, with, of course, a small fillet (curved part of the film) where it is coming off the surface of the board, leaving your toner image in place. The fillet sould be about the diameter of a pencil.

IMPORTANT: If a small area doesn't seem to be sticking (usually out near the edge of your board, you can try ironing it again ONCE in hopes of getting it to stick. If it doesn't stick the second time, it wasn't that you didn't heat it enough: it's board contamination keeping it from sticking. All you can do then is draw on it with a "Sharpie" pen, or clean the image off with Acetone or Lacquer thinner and start ALL OVER from the Cleaning powder stage (uggh!). Sometimes it take a few tries to get the hang of it. It took me less than 10 tries, but not a lot less than 10 attempts, to figure out what I was doing wrong and (FINALLY) get a perfect, photo quality transfer.

[R.G.]

Really clean copper has a salmon pink color, and water wets it perfectly.

For really dirty copper, get the road tar, motor oil, chewing gum, and tree resin off with nasty solvents. Naptha (lighter fluid) is nice and less flammable than some others. Acetone is super, but flammable. Outdoors only, no smoking, and no flame sources near you.

Once you're down to the brown oxide, a mild abrasive works. I used Bon Ami, works great. Wet the copper, sprinkle it on, and have a go with your bare fingers. Get the entire surface evenly polished. By the way, this is a great way to check for those nasty edge burrs, as you'll cut your fingers if you haven't sanded or filed the edges nicely.

When you're done with the Bon Ami (or your favorite treatment) rinse the &*()^ out of the copper.

==> Truly clean copper is salmon pink and clings to a sheet of water<==

Water does not bead up and flow off in rivulets.