diagnosing toner transfer problems

I don't think you got it clean enough. I usualy use some #0000 steel wool to polish. Also handle the cleaned board by it's edges, oils from your finger prints can contaminate the board. I think you need to iron for a longer time also, I seem to remember about 3-4 minutes.

Well, looks to me you pressed too hard. Use a light hand and longer heating time. gently smooth the paper over the board after it is very hot. All you want to due is make sure it is tacked down to the pcb, and not smashed onto it. Remember, it's not the pressure that attaches the toner - its the heat. Get some Emory cloth or wet/dry sanding paper as fine as you can get it. Then clean it with soap n water and dry with an old undershirt, not paper. Maybe even use a hair blow dryer on it. Any contaminant on the copper will make your traces not stick. JTT

[snip]

It looks like there has been a lot of pressure in small areas, which has made the toner spread out. Try to avoid any temptation to use the tip or an edge of the iron to get more pressure - you just end up spreading the toner around. I've found more time and heat are much more effective than more pressure.

Try ironing for longer, with modest pressure using only the flat of the iron. 5 minutes or more is not unusual for me.

Tim

There are 3 major factors that you have to get right for it work.

1- Cleanliness 2- Correct temperature 3 - correct and even pressure

Here's how I do the cleaning.. I do a light sanding if it's badly oxidized then follow that up with a good scrubbing using an SOS pad. The steel type with the soap in it. It comes out nice and shiny. Try not to touch the copper at this point to keep oil from your fingers from contaminating it. Next rinse it really well in very hot water to remove all the soap residue and finally wipe it with alcohol.

The correct temperature depends entirely on the toner. Not all toners are created equal. The toner is basically powdered plastic with some other junk mixed in and has to be heated to just the right temperature. For my printer

350deg is just right. If the temperature is too low if won't get soft enough to transfer. If it's too hot it will it be too liquid and tend to run together. Unfortunately temperature can only be determined by trial and error. It's also important to get an even temperature across the entire surface of the board. Large boards (bigger than the footprint of the iron) are harder to heat evenly. Warped boards also present a problem here. Depending on how the board was cut to size. There could be a slight ridge around the edges which will prevent the iron from contacting the copper towards the edges. I cut the boards a little large and trim down to size after etching. I use a radial arm saw with an 80 tooth carbide tipped blade and cut with the copper side up. IMPORTANT: wear a breathing mask! You don't want to be breathing fiberglass dust.

It is important to exert a firm and even pressure on the iron in order to assure even heating and to force the toner into all the microscopic crevasses in the board. This is probably the least critical factor, but still important.

Sorry, but your board looks like you had problems with all three factors. Probably not clean enough and uneven heating mostly. I was making lots of boards for awhile and solved the temperature and pressure problems by buying a T-Shirt heat press that has adjustable temperature and pressure. It works great, but was kinda pricey.

If you have problems with pitting in solid copper areas you might try burnishing the board after you remove the paper. You can do that by placing a clean sheet of paper over the board and reheating it with the iron. There is also some stuff called GreenTRF (Digi-Key P/N 182-1021-ND) that will seal the toner on the board and prevent pitting and etching under the edges. You would just use it instead of the paper in the burnishing step.

Mike

"The scientist is possessed by the sense of universal causation...His religious feeling takes the form of rapturous amazement at the harmony of natural law, which reveals the intelligence of such superiority that, compared with it, systematic thinking and acting of human beings is an utterly insignificant reflection." Albert Einstein (theoretical physicist)

Folks have already mentioned dwell time (don't get in a hurry) and pressure (use caution). Here's an old thread with some more ideas:

*-etchant-off-*-*+consistent+acetone+steel-wool-is-not-recommended+teaspoon+greenie.meanie+spoon+microscopic-roughness-*-improves-adhesion+pink.haze+oxidation

Your adhesion generally looks pretty good to me. Non-adherent areas are ones you didn't iron. Smearing--your greatest problem--comes from excessive massaging with the iron, though it might also result from movement of the paper.

My technique is to bring the board to temperature with the iron, then rub the iron on the board to effect the transfer. I also have a 2nd chance: as I soak the board, my paper comes off in layers. Leaving a thin layer of paper, I dry with the iron, which reveals non-adherent areas as raised white areas. After re-ironing, they're fine, and I proceed with soaking.

I manage 12/12/12 without difficulty, 8/8/8 with touch-ups.

HTH, James Arthur

You really have to clean the board. I mean some serious scrubbing in circular motion until its a dull shine.

I go at it with gloves on and soap and steel wool. then isoprophl alcohol and steel wool.

Then dry with paper towel. I use the blue PNP paper and I get 100% registration (15 mil traces and faily populated 8x8 sized boards)

I iron it with pressure until the paper sticks to the board. Then I iron as if I were irons cloths ... every 30 seconds Ill stop, examine the board and switch to a different side

Afterwards I let is sit on a wooden plank and place a heavy flat object (paper weight) on top of it for a few minutes

What others have said, and ... I don't iron it with it directly on a padded ironing board. I use a piece of plywood under the PC board - that helps to keep the pressure even across the surface.

Ed

I'd like to thank everyone who replied to my query. It took most of the day, but I managed to get a board that worked "well enough". This is after a half dozen failed attempts, two dozen science experiments to calibrate the iron, and two more attempts, the second of which was the first to actually work. Or at least, mostly work, but I got most of the boards on the panel (6 each of the important ones, three look usable) to come out "clean".

What was my problem? A combination of too much heat and inconsistent pressure. That's why I was having lifted toner *and* blurry toner in the same board. The solution? It seems to be a combination of these key points:

• Iron at maximum temperature.

• Pre-heat the board (I just sat the iron on it for 45 seconds)

• Medium pressure.

• Pass the iron from left to right, as if it were a laminator roller. I put a full sheet of paper over the stack, held one edge firmly, and moved the iron away from that edge to keep it from moving the toner paper. Two or three passes seems to be sufficient.

• *Immediately* move the board to water, so that the paper lets go of the toner before it expands due to the cold and rips the toner off.

I also baked the board after removing the paper, just to make sure the toner was stuck. I'm not sure there's any advantage in that. A few minutes at 350 seemed best, and again, right into the water to cool the toner before anything bad can happen to it.

Then, the usual 20 minute agitated FeCl bath. Also, goof-off removes the toner MUCH faster than acetone-based nail polish remover.

Final results:

low res:

(130k jpeg) high res: (1.2M jpeg)

A few lost traces here and there, but I only need one of each board for my immediate needs.

On the topmost six boards, I included some "test traces" to see how small traces worked. On the left of each board, from the top, they're: 7, 6, 5, 4, 10, and 8 mil lines with same-sized space (looks like 7 mil is my limit). The annuli on the right range from 12 mil down to 5.75 mil on a 13.5 mil drill. The smaller of the two ICs is a TVSOP-14, which is 0.2 mm (~8 mil) line/space. The smallest feature is the 01005 footprint, which is the 6 mil gap in the trace off pin 9 of that chip.

Thanks! DJ

Pulsar's transfer paper. The printed image is nice and crisp, and when you drop the board in water the paper just falls off after a minute or so when the last bit lets go. It's coated with a heat-proof yet quickly-water-soluble layer. When you take it out of the water, that side of the wet paper is very slippery.

I've never tried other papers, but I did use laser transparencies for my science experiments so I could examine the state of the toner before peeling it off to test adhesion. The toner didn't want to let go of that (duh).

What I did was print the board on regular paper, then cut out a piece of transfer paper just big enough for the board, taped it to the regular paper in the right spot (using Avery laser lables for tape), and printed again. My printer reprints within 0.1" or so (worst case), so I leave that much margin. I haven't missed yet.

The paper was trimmed to the same size as the pcb, maybe a tiny bit smaller, before ironing it. A thought: I might tape over the exposed borders next time I do this, so I don't waste time or etchant etching them.

what kind of paper did you use? i use magazine (glossy) paper or ink jet photo paper (glossy).. the ink jet paper washes away with water nicely.

--
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5

I ran across a website that recommends using a laminator, the kind that laminates protective plastic onto photographs.

The major drawback I see is that the board thickness is limited to .030 boards, but that's a minor consideration for most circuit designs.

The nice part is, this approach simplifies doing doublesided boards. The lineup of the paper has to be done carfully, but this system heats and presses both sides at the same time.

I checked at my local Staples store, and I find the same laminator on the shelf, Price about $60.00

Jim Pennell

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13:05 Pacific Time Zone
Sep 10 2006

International Time
20:05 UTC
10.09.2006

I got the idea from that.

Actually, I'm low on consumables anyway, so I ordered their starter kit (without goof-off) which gets me the laminator and the thinner boards. I'll use the remaining thick boards for boards with larger traces.

Bonus pic: the boards I made yesterday have a HAND SOLDERED 01005 capacitor on them now!

Now, if we just had an elegant solution for plated-through vias...