PCB toner transfer issue

[mike_mike]

Hello, I have a problem regarding the toner transfer method. I tried the heat transfer using the clothes iron (set on maximum temp) and using the heatless method (with acetone and alcohol). I tried using 2 different laser printers (HP and Samsung), and I set the maximum toner output. I used special paper and some paper found into magazines.
In both cases I have the following issue: the toner does not stick on the surface of the laminate in some places (you can see marked with red color in the image. The pcb in the photo is made by heatless method).
What should I do in order to stick all the toner on the surface on the laminate ?

[ledtester]

For small imperfections like these you could just touch up the board with some nail polish. Some people recommend a Sharpie. More ideas:

https://www.electro-tech-online.com/threads/best-brand-of-permanent-marker-for-toner-transfer-touchup.36302/

[janoc]

Toner not sticking usually means the board has not been pre-heated enough or hasn't been cleaned/scrubbed/degreased properly.

Also, don't use clothes iron but get a cheap laminator and pass the board through multiple times. It is very difficult to achieve an even pressure across the board with the iron, typically the edges will not transfer, as in your case.

The small imperfections in the middle - that is normal, it happens sometimes. You correct that with a sharpie or a drop of paint.

[Doctorandus_P]

If you're willing to invest a bit of money, you can get an XY plotter with an UV laser and use that to selectively light the PCB.

There are a few youtube vids for this method. I think Morco Reps made one of them.

[Refrigerator]

Looks like the problem is your ironing.
Also if you want another way to try then get inkjet photopaper and print on the glossy side with your laser printer.
The paper will peel off with no water or soaking and will leave clean traces underneath.
To prep the board use sandpaper, 600 grit works fine.
Scuffing pads don't get a good enough surface.

[mike_mike]

I think that the problem is the ironing. I measured the temperature of the iron, with an IR thermometer, and it was about 150-160 C. This is when the temp of the iron is set to maximum.
I ironed the laminate a few more minutes than before, and now it looks like attached. In total about 5-6 minutes of ironing.
Also, should be a good ideea to use a plane piece of 10mm thick metal as a underneath "table" when ironing ?

[rfdes]

I've seen the following technique used to help eliminate the uneven pressure using an iron.  Using a baking 'Rolling Pin' under the board is touted as an excellent method for eliminating this problem.  I've never used this method as I have a laminator but you might want to give it a try.
Here is a link to the method:
https://pcbfx.com/main_site/pages/tech_support/tips_n_tricks/rolling_pin.html


Good luck and keep plugging.
Jim

[janoc]

If you're willing to invest a bit of money, you can get an XY plotter with an UV laser and use that to selectively light the PCB.

There are a few youtube vids for this method. I think Morco Reps made one of them.

Uh jeeze no. That someone does this on Youtube doesn't mean that this is a viable or practical method.

That takes ages, UV laser isn't exactly cheap or healthy and dialing this in (the power, focus, etc.) is a nightmare. Not to mention that the copperclads are never 100% flat, so the focus (and thus trace width) will change significantly as the laser goes over the board. There are solutions for it (e.g. using the focusing system from a Bluray burner) but that is far from trivial to make work, especially when you have constant vibration from the plotter.

If you want to use photolithography, just print on transparencies and use UV LEDs or UV lamp. Way faster and easier. Heck, if you still insist on a plotter (which is really a poor way of making boards because it is so slow!) you can even stick a sharpie in it and draw the traces directly. The result would be likely comparable to a poorly calibrated laser and much cheaper.

[janoc]

I think that the problem is the ironing. I measured the temperature of the iron, with an IR thermometer, and it was about 150-160 C. This is when the temp of the iron is set to maximum.
I ironed the laminate a few more minutes than before, and now it looks like attached. In total about 5-6 minutes of ironing.
Also, should be a good ideea to use a plane piece of 10mm thick metal as a underneath "table" when ironing ?

Go to the nearest store and buy a cheap laminator for 20 bucks. It will save you all this and do a better job.

Also, should be a good ideea to use a plane piece of 10mm thick metal as a underneath "table" when ironing ?

No, unless you heat it. You want your copperclad to be hot, otherwise the toner won't stick to it. Putting it on a metal piece that will wick the heat away (= heatsink) is not a good plan. There is no need for this, just do it on a flat table. Or buy that laminator.

[tooki]

Ditch the clothes iron for a proper laminator, and get something finer to scrub the board with. That looks rather coarse to me.

[KL27x]

What should I do in order to stick all the toner on the surface on the laminate ?

Might wanna try the pre-etch. It's one of those "myths" from 30-40 years ago. It's been bunked by 100's people since then as total nonsense. But it works for me.
 
Wet scrub the board with stainless steel wool and a drop of dishsoap, then rinse. Dip the board in your etchant, and let it drip dry for 10 seconds. Then dunk it in tapwater to rinse it. Dry it with a heat gun. Then try transferring.

The major downside of this method is that Sharpie won't adhere and bond to this oxidized surface.  So if you still have errors that need to be fixed, you have to scrape away to clean copper to get Sharpie to hold. My boards don't have errors. And they're too fine to be fixed with sharpie, even if there were. It also takes a bit higher temps to get the transfer to take. Never tried the solvent transfer.

The major upside, aside from not experiencing missing chunks of transfer, is that you don't get any fattening of the traces or distortion. Some printers lay on enough toner that this is an issue, if you don't do a pre etch.

It seems to depend on your exact printer and maybe other factors. But I love to mention this, since it's been "debunked"  and no one mentions it anymore.

I've been doing toner transfer boards for 12 years. Since I perfected this method about 8-9 years ago, including using Pulsar paper, I have made probably close to 100 boards between 8/8 and 10/10 and never had to redo a single one.

[wilfred]

If you look at a datasheet for toner such as this toner for my Brother laser printer ( http://sds.brother.co.jp/sdsapp/content/PT462-06-AU_20200403-English.pdf ) you see it has a melting point of 110 degrees Celsius. Your iron should be more than sufficient to melt toner onto a copper board. The issue is time and even pressure. The copper if at room temp will suck a fair bit of heat from the iron. So I suggest before buying a laminator is to press on with the iron. (Yeah, deliberate pun. I'm ashamed)

Pre-heat the PCB to where it is uncomfortably warm to handle, but not scorching hot. This will reduce the ironing time because the iron will cool down less early on. I've tried using a toaster but just resting the iron on it will suffice. Keep the iron moving because they aren't designed with even temp across the baseplate. I rotate the iron because I feel it maintains even pressure effectively. With a pre-heated board it only needs a couple minutes, you only have to melt the toner.

As for flattening the PCB I use a cork saucepan coaster. They have just a little give in them to work quite nicely.You don't need to press hard just light pressure is sufficient.

I also give the blank copper a good scrub beforehand with an abrasive kitchen cleaner. In Australia I use Jif, but I've also used Ajax powder.

The key is consistent methods and once you establish a working technique stick to it. I think this is easier to do with an iron than a laminator. Although I haven't tried a laminator. I'm sticking with what works for me and that, contrary to many internet "opinions", is also a Brother laser printer. One thing I never liked about the laminator was because the board is thicker than the plastic pouch/paper sandwich the pressure seems likely to be higher near the edges as the rollers are forced further apart than they're designed to be as the PCB is squeezed through. Some people report good results so I'm just saying that's another reason I stick with the iron.

[Wimberleytech]

What should I do in order to stick all the toner on the surface on the laminate ?

Might wanna try the pre-etch. It's one of those "myths" from 30-40 years ago. It's been bunked by 100's people since then as total nonsense. But it works for me.
 

I have never tried this, but it sounds like a good idea to me.
As others have said with my own comments...
1) Use a laminator (that is what I do)
2) Clean the board
3) Use copper fill so that etch rate is more constant throughout (Hey, eve IC dudes take this into account)
4) Don't expect perfection...just goodenough!

<edit>
More thoughts.
I also use that transfer film (the stuff artists use) and, with my laminator, I transfer that stuff directly to the pcb.  It sticks to the toner and fills in the pinholes that were left in the toner.
When doing the first toner transfer, I rinse the board with the toner paper on it and let it get soft.  Then I gently peel it off while running water on it.

If you don't want to mess with the transfer film, you can fill the pinholes by putting your board in an acetone vapor for about a minute or two.  It has been a long time since I used this technique.

I use ScotchBrite pads to clean my boards.

I don't do many boards myself.  Generally if I just need a one-off for a project or testing an idea.

[cdev]

I iron on a pristine piece of flat wood as my ironing board. Also before I attempt the toner transfer I vigorously scour the copper on the pcb with a scouring pad, like the kind you use for washing dishes. Much more than you have there but also not very deeply. I find finer scratches work best. I do this long enough so the copper is completely covered with fine scratches. Then I use very cheap glossy paper, I find the cheapest colored printed junk mail  that's still printed heavily (colored newspaper ads work well too) he cheapest paper works well for toner transfer. Plus its free. And then when I am removing the paper after its been ironed (it should stick and be difficult to remove, because the toner goes into the scratches) I'm very gentle.

Practice makes perfect. Your first attempt looks fine. You can get away with much thinner traces. As mentioned, you can fill in any gaps with a  sharpie.

[CatalinaWOW]

Many suggestions here make it easier and more consistent, but are not necessary.  If you want those go to a commercial house.  Several are cheap, fast and reliable and give you hole drilling, plated through holes and solder mask in the bargain.

But many like to make their own.  Me too sometimes.  I find that the two keys are surfaces cleanliness and enough heat everywhere.  For the latter I just hold the iron in place longer than often recommended while moving it around.  Holding it long gets the same results as preheat.  You need to be sure nothing moves.  I usually tape the board to a surface and tape the transfer to the same surface.  Be sure to let things cool before removing the transfer paper.