Back when I was making PCBs I used to immerse in water until the paper very soft and easy to tear, so as I remove it part of the paper remains on top of the transferred toner. Have you ever tried that?

Yes. I tried using catalog paper, which seemed to be a favorite, soaked and soaked, rubbed and rubbed, scrubbed with toothbrush; only to discover that I had incomplete toner transfer.

 

I used the toner transfer method. Photo method requires too many chemicals...

Oh I misunderstood. So much the better I prefer the transfer method anyway, because of exactly that reason.

 

Oh I misunderstood. So much the better I prefer the transfer method anyway, because of exactly that reason.

It only requires one more chemical, bringing the total to 2.

 

Oh I misunderstood. So much the better I prefer the transfer method anyway, because of exactly that reason.

As you've read from the posts, not everyone has had the same experience. My experience with paper was poor, but some have gotten good (or at least acceptable) results. With the inkjet transparencies, I've had very good results. All of the text on that board, except for my initials, is 8 mil width with 8 mil space.

The key is to find a good transfer medium and a compatible laser printer. I've done transfer with good results without the printer set to it's densest toner setting.

 

Hi Ivan,

This is the largest board I've done (~6" on the long side). It was before I had perfected my technique and I had problems with outermost traces. The board was too large for my etching pan and having to remove so much copper undercut and even opened some traces. This wasn't my design. On my designs, I use copper fill to minimize the amount of copper that needs to be removed.

 

Yes. I tried using catalog paper, which seemed to be a favorite, soaked and soaked, rubbed and rubbed, scrubbed with toothbrush; only to discover that I had incomplete toner transfer.

I see, glossy (photo) papers can be very different. Actually a friend of mine was using the transfer method very successfully until they changed the brand of photo paper at the store he was buying it from. The later had really thick glossy layer that was impossible to remove without damaging the transferred toner. So I do consider your suggestion of using transparency paper. Also I'll see if I can find the printer you suggested. It's probably out of production at this point but anyway.

 

[snip] I'll see if I can find the printer you suggested. It's probably out of production at this point but anyway.

If you can get a print sample from any printer you're considering to try before you buy, that'd be your best option.

And not all transparencies will work. I tried regular transparencies and got reasonable transfer, but they didn't want to release the toner. The inkjet transparencies have some sort of coating and (some) will release all of the toner if you let the cool a bit after ironing. If you can't find a transparency that works, I can send you a sample of what I use.

 

It only requires one more chemical, bringing the total to 2.

I see, I don't rule out methods at this point, I had experience with the transfer method so I'm probably biased... but the photo method becomes a must when the tracks get thinner than 0.1mm does it not?

 

If you can get a print sample from any printer you're considering to try before you buy, that'd be your best option.

Thanks.
So it should be transparency doesn't absorb toner at all so as I peel it out the whole thing remains on the board.
If I can find such a transparency than it would work even if the printer doesn't have thick print. Maybe it's more about the paper than the printer?!

 

If I can find such a transparency than it would work even if the printer doesn't have thick print. Maybe it's more about the paper than the printer?!

You still want to get good toner coverage on the transparency. If you look at the ground plane in the top left corner of the small board, you'll see a spot where copper started etching. I could have touched up with a Sharpie marker, but didn't bother.

Your technique will have a big impact on your results. I went through a lot of trial and error to arrive at what works best for me.

 

True. I have laser transfer paper but have never been able to use it successfully.

Well, @MrChips... it seems that the time for me to contribute something of real value to this forum has finally arrived... What I am to give away has cost me years of research and practice and endless headaches... But I've been helped so much by the members of this forum that I'd be nothing short of an egotistical fool if I were to keep this to myself only.

For a long time I tried to develop a quick and reliable way of producing PCBs in my own workshop with mixed results. I tried toner transfer, photo-etching, screen printing, direct printing, etc... and I failed miserably on some of them, and had mixed results with others... UNTIL...

I discovered the holy grail of toner transfer using a paper especially designed for ceramic and metallic surfaces.... I'm not exaggerating.

The paper is called M3 [M-Cubed] Transfer Paper, and it's sold by QLT. They are the only suppliers that sell this miracle paper.
It is not cheap, it costs $60.00 dlls for a pack of 100 A-size (8.5" x 11") sheets, but the price is not off the roof either, especially when you consider its capabilities.
Its performance is, at least for me, nothing short of miraculous. The paper peels off with the greatest ease, does not leave residue on the surface, and does not need to be submerged in a water tray for it to be removed.... Just print, press and peel.... and you're ready for etching.

But you need to know how to use it... and it helps tremendously to have your own heat press, instead of trying to use an ordinary iron. Trust me, the investment is very much worth the results.

So without much further ado, here's the process in full detail.

1. After designing your circuit, print it using a laser printer (not inkjet, nor laserjet, nor any other type of printer that does not use toner) that does not heat the paper when it prints it. Most old laser printers have a built-in hollow roller tube that has a heating element inside whose purpose is to heat the sheet as it passes through, so as to fuse the toner to the sheet.... You cannot use this kind of printer for this application or the paper will fuse to the roller and make a mess inside your printer. What you need to get is a printer that uses laser-diode technology that will only heat the spot on the paper where the toner is, and not the entire sheet. I own an Okidata C3400n Color LED Printer that does the job nicely. Unfortunately this specific printer has been discontinued, but there are many newer printers out there that will work just fine for this... just make sure that your printer uses laser LED technology.
2. Set the printer for maximum resolution and heavy paper, And use the color red for printing all of your circuit's traces. This color of toner is the one that I've found to be the most etch resistant. You may try using other colors (including black) at your own risk.
3. Preheat the heat press to 350°F
4. Clean the FR4 using a degreasing solution, and dry thoroughly. I like to use Windex for that.
5. Make sure that the FR4 is completely clean and that it doesn't have any fibers or dust particles, or tiny pieces of paper towel, if that is what you used to clean it with. If there are fibers or dust on the FR4, then try blowing them off, but do not touch it with your fingers, if you can avoid it.
6. In the heat press, place a 1/8" thick sheet of silicon red rubber on top of the FR4 copper clad laminate (I've found that a size of 6" x 4" 2mm thick works best) and preheat the FR4 by pressing it for 75 seconds.
7. After the FR4 has been preheated, lift the silicon rubber and allow it to cool for a couple of minutes. You don't have to remove either the rubber nor the FR4 from the press for this. Just roll the rubber sheet back to expose the FR4 and allow it to cool a little bit, but no longer than two minutes.
8. Cut the 4 x 6" circuit out from the sheet that you just printed. I recommend leaving an extra 1" flap of paper in the final cutout, this will leave you with a rectangle measuring 4" x 7" that contains the circuit. This makes it a lot easier to peel the paper off later on.
9. Place the printed sheet on top of the FR4, and then place the silicon rubber back on top of that.
10. Press for another 75 seconds.
11. Remove the rubber sheet from the press
12. Using something other than your hands (I use a cooking spatula), remove the PCB from the press.
13. Allow the PCB to cool to room temperature. This takes a little over 5 minutes. You can blow some air on it with a ventilator to cool it faster, if you want.
14. Peel the paper off the PCB, and make sure that all traces are perfect and that none of the ink has remained on the paper. If some little bits of ink remained on the paper (which shouldn't have happened, if you followed my instructions carefully) then retouch the traces at the PCB using one of those stinky permanent ink markers.
15. Voila! You're done! You're ready to etch your PCB!
16. After etching, do not try to remove the toner from the PCB using a solvent or anything else. Just let the toner be. Do all the drilling that is necessary and solder all the components on the board, without doing a thing about the toner. The toner will melt away when you apply the solder and all of your components (including SMT caps and resistors) will be soldered with ease. The only exception to this might be SMT chips. For this case I recommend scratching the toner off the PCB at the place where the chip will be installed, and tin those traces with a little solder so you can later solder the chip by gently pressing each pin to its corresponding trace with the soldering tip. This takes some practice to master, but I've done it with chips that have a pin spacing of only 0.025".
17. Also, leaving the toner on the PCB will better protect the traces from corrosion due to moisture.

• One last thing. The transfer paper has a shelf life of about two years. After this time, it becomes harder and harder to peel off, and it might even begin to jam in the printer, which is a real nuisance since you have to open the thing and carefully remove and clean the mess that has stuck inside.

In a later post I plan to show how I built my etching tank, especially designed to process the PCBs quickly, and using the least possible amount of Ferric Chloride (Iron [III] Chloride, FeCl3).

 

Well, @MrChips... it seems that the time for me to contribute something of real value to this forum has finally arrived...

Boy, and that's just my first day at this forum, you guys rock!

 

Boy, and that's just my first day at this forum, you guys rock!

Glad to be of service...

 

_cmartinez,

Nice description and good detail. Sounds like it might be worth a try. Do you have a picture of a PCB with copper pours made with that method?

John

 

_cmartinez,

Nice description and good detail. Sounds like it might be worth a try. Do you have a picture of a PCB with copper pours made with that method?

John

Stupid me, it's been years since I've taken pictures of my PCBs undersides before I added the components.

Here's a pic of one before assembly that wasn't done quite right. For one thing, I did it in a hurry, and for another, I had not yet perfected my etching tank (I'll post later the details of my tank, for those who might be interested). You can see here and there a few dots of leftover copper that were not attacked by the FeCl3. But the circuit worked alright, with no bridging between traces or anything. You can also see two or three drilling mistakes that I made... again, this happened for doing things in a rush.
Anyway, the traces are 0.013" wide. And the PCB measures about 4-1/4" x 2-1/4".

The other two pics belong to much larger boards that I made for a corrugated plastic tube production line monitoring system. The many small PCBs connected through ribbon cables to the main board are J-type thermocouple ADC devices. I've also included a close up pic of that assembly, which includes SMT chips, among other things.

 

Those look darn nice.

John

 

I'll post later the details of my tank, for those who might be interested.

Yes I'm interested.

 

Here's a much better PCB that I made when I had perfected my transfer and etching technique. I've included the pic in its full resolution to more clearly show the details.

 

Those boards are beautiful. I did a quick search for a printer that MIGHT replace your Okidata. Apparently Brother uses the laser led rather than a heated drum. The HL3140CW is about $210, offers 600X2400 dpi and 19 ppm (http://www.staples.com/Brother-HL-3...&kpid=154691&gclid=CJvqpob4ssUCFYURHwodY34A8Q ). I have the 2270DW (black only) and it has been a wonder desktop printer.

Getting that special paper in small amounts may be the real problem.

John

 

Those boards are beautiful. I did a quick search for a printer that MIGHT replace your Okidata. Apparently Brother uses the laser led rather than a heated drum. The HL3140CW is about $210, offers 600X2400 dpi and 19 ppm (http://www.staples.com/Brother-HL-3...&kpid=154691&gclid=CJvqpob4ssUCFYURHwodY34A8Q ). I have the 2270DW (black only) and it has been a wonder desktop printer.

Getting that special paper in small amounts may be the real problem.

John

Yes... the printer you're suggesting will most probably work.