What type of paper to choose when printing loot. Paper for the manufacture of printed circuit boards using LUT technology or how to make a printed circuit board at home. Video of the use of Chinese thermal transfer paper

In mine, I mentioned the manufacture of printed circuit boards using special Chinese paper for LUT. I was bombarded with questions. And most recently, I recommended it to my friend, to whom it was difficult for me to explain exactly how to use such paper. So I decided to make a small video review on the use of Chinese paper.
I bought paper from Aliexpress. There is nothing complicated, try it! Now on Aliexpress you can choose the Russian language and prices in rubles - China is turning to face the Russian consumer. You can pay by bank card, Yandex.Money, WebMoney, QIWI, etc. Paper is sent by regular mail with tracking.

Order 10 A4 sheets. Free shipping.
Order a pack of thermal transfer paper, 50 A4 sheets. Free shipping.
Order a pack of thermal transfer paper, 100 A4 sheets. Free shipping.

Early for LUT, I tried different papers, most often I managed with improvised paper from glossy magazines. I rarely liked the result. There were difficulties with soaking, the toner did not always remain on the board. Caverns could form in the toner itself during etching due to air bubbles and other inconveniences. One way or another, the quality and repeatability did not suit me.

Miraculously came across a subject. All of these shortcomings are absent when using this wonderful piece of paper! I am happy as an elephant. The result is comparable in quality to a photo process, but without fussing with darkness, UV lamps, etc.

Printed track pattern

Finished result

Photo by Igor Kotov (datagor), added 11/17/2014

Video of the use of Chinese thermal transfer paper

Ironing

soaking

Links

There is such a method of manufacturing boards in which the tracks are printed using a laser printer on paper, and then the toner is transferred to the textolite foil with further etching in ferric chloride or something else. This method is called LUT: it is very cheap, does not require special skills, and at the same time, finished boards are of excellent quality. So, for high-quality transfer of printer toner from one surface to another, special high-temperature transfer paper is used.

In this study, I tried to find the real limits of the LUT, find out what are the minimum gaps and tracks and decide on the best paper for the process. The practical goal is to reach the cherished 0.1mm, which, as some say, can be done with a LUT.

Note: all photos are very high resolution from 300KB to 4MB in size so that all the details are visible. Therefore, I did not insert them into the text, but I give links to them.

General Process

I will not go into theory, but simply describe what and what I do in my home environment.

Sprint Layout program, I print on HP LaserJet 1200 (600dpi), foil textolite 1.5mm thick, one-sided, small iron, road, etching with ferric chloride, I wash the toner with solvent 646.

Before printing, I sand the board with 1000 sandpaper and wipe it with the 646th solvent.

Paper selection

Paper selection criteria:

• availability
• good toner coverage and adherence when printing
• good transfer of toner to the board from paper
• ease of removal from the board after transferring the toner
• coating (or mixing) the toner with a layer that closes the pores in it.

The last point requires clarification. The bottom line is that all LUT technology is based on laser printing, and any laser printing is based on toner, and any toner suitable for LUT suffers from one very unpleasant drawback: porosity. Because of this, strong underetching of the tracks occurs, even with a not very long etching time. And most importantly, large surfaces that are covered with toner are etched. They seem to be corroded from above, sometimes through and through. Photo paper in particular has a pseudo-photo layer that can mix with toner at high temperatures, coating it with an impenetrable plastic-like film that is resistant to etchants. However, in the experience of other amateurs, this layer often also lies tightly on the board and is difficult to tear off, or clogs into gaps, which makes it difficult or impossible to make small gaps. Abroad there is a commercial solution to this problem - GreenTRF folk. Who cares - read Google.

From the very beginning, I tried regular 80g/m2 office paper. It's complete nonsense. Doesn't dispense toner.

Then he did it on the pages of glossy magazines. It turns out not bad, but it takes a long time to soak, the transfer of toner to the board is not complete, the toner spreads strongly when heated with an iron.

HP Proprietary Matte Inkjet Photo Paper. The toner is poorly transferred to the board, no, the toner is not covered with anything on top, it remains porous.

HP Semi-Gloss Photo Paper. After 30 minutes of soaking, it is impossible to remove the paper from the board. All toner is covered with white plastic. It can only be removed with toner.

Thermal transfer paper for inkjet printers for transfer to clothing. I was afraid to shove it into the laser - it melts painfully easily. I wanted to melt the toner aors. Complete failure.

It would seem that everything was gone. There is no way out, try the same thing from other companies (still a cloud of money down the drain) or change hands.

But here is what Thomas Edison said:

"Too many people break down without even realizing how close they were to success at the moment they lost heart"

And he was very right!

After all this torment, I went to read about GreenTRF, about commercial systems for LUT, how they work, I tried to understand, and when I read about press "n" peel I read that the temperature there should not be very high (as for polyester). And I thought maybe I overheated.

I put the iron between dots 1 and 2 and used the same photo paper from HP Premium, which stuck tightly. Warmed up for 3 minutes, went to the bathroom, turned on the cold water and pulled the paper. She walked away with no resistance at all! On copper, 90 percent of the drawing remained! And very black. Almost no toner on paper!

After 3 trials, I found that it is optimal - one division above 2 points (on my ironing there are still a cloud of divisions between the points). In this case, the back of the paper is already starting to melt, so you need to enclose 1 sheet of plain paper. I tested on a small scarf, so I didn’t need to drive the iron back and forth, but I pressed normally and sometimes with little pressure passed along the contour. Warm up: 3.5-4 minutes.

After that, I immediately take a piece of paper, go to the bathroom, put it under cold water and after 3 seconds I remove the paper with one movement. Here's what happens:
/elektro/tt/IMG_3517.jpg

Where there was toner, the paper becomes bluish, and the toner on the board feels like plastic, shiny and glossy. However, there is no photo layer anywhere in the cracks! There is nothing to scratch! The paper, by the way, is very interesting, when it gets wet from the gloss side, it becomes covered with some kind of slippery gruel, like real photographic paper. As you can see, the toner went perfectly! The beauty!

My LaserJet 1200 swallows both a full sheet of 10x15 and a half sheet of 10x7.

Method of measurement

The method is simple: we take a camera, a ruler and an object, put the ruler on top of or next to the object and take a close-up macro shot. We count the number of pixels in 1 mm on the ruler, count the number of pixels on the object, divide the latter by the first and get the size of the object in pixels.

For those. who doubts this measurement technology, I conducted an accuracy test. I have a chip from TI psp54310pwp in a very small package. According to the datasheet, his leg is 0.19 mm thick, and the distance between the middle of the legs is 0.65 mm. In my way, after photographing the chip, the values ​​\u200b\u200bof 0.20 and 0.62, respectively, were obtained. So I don't think it's a question of accuracy.
/elektro/tt/4/IMG_3532.jpg

Track and Gap Thickness Testing

After that, I made a bath with ferric chloride more abruptly. Got it all out in 15 minutes. Here is the result:
/elektro/tt/IMG_3518.jpg

Looks great. All tracks came out completely (even 0.05mm), the gap 0.1 did not come out at all (but no one hoped), but 0.2 is quite intact.

I test all the tracks with a multimeter - all are intact. I'm testing gaps. Oops, 0.2mm conducts! Here you can see the place where there is a bridge:
/elektro/tt/IMG_3521.jpg
(circled in red)

One movement of the needle in this place and the problem is fixed.

But the question is, what are the real dimensions?

As before, we apply a ruler and take a macro photo:
/elektro/tt/IMG_3521.jpg

And we get: by 1 mm: 30 pixels

Tracks:

• 0.05mm 5px 0.17mm
• 0.10mm 7px 0.23mm
• 0.15mm 9px 0.30mm
• 0.20mm 10px 0.33mm

Sadly. And the paper is super, and the hands are not hooks, sort of. But less than 0.17 does not work! I did the maximum filling with toner when printing (this is when the printer is told that it is printing on a transparent film), maybe if it is not so bold, then the toner will not spread so much when melted with an iron.

gaps

• 0.2mm 6px 0.2mm
• 0.3mm 9px 0.3mm
• 0.4mm 13px 0.43mm

The gaps, for some reason, came out perfect!

In general, it turns out very nicely, but the tracks, alas, are not the right size.

Speaking of a laser printer as such. Here is my max gives 600dpi. Those. 236 lines per 1 cm. 24 lines per 0.1mm. It seems to me that at such sizes the errors are already prohibitive for this printer. Especially with a reloaded cartridge and a stale drum and no one knows what kind of toner.

Who even knows how much the toner "floats" when printing? Let's do a simple experiment. We print the same layout in normal mode on paper and see how thick they are on paper before transferring.

We carry out 4 experiments, the scale is a caliper (to be more precise):

• bold printing on photo paper
• plain print on photo paper
• normal printing on A4 plain paper (after running through the printer several times)
• control measurement of the board just made.

We measure only track 0.1. The method is the same as described below (1mm in pixels is determined in each frame separately)

1. bold printing on photo paper
   /elektro/tt/3/IMG_3524.jpg
   per 1 mm - 34 p.
   track 0.1 - 6p. - 0.17 mm
2. plain print on photo paper
   /elektro/tt/3/IMG_3525.jpg
   per 1 mm - 35 p.
   track 0.1 - 5p. - 0.15 mm
3. plain printing on A4 plain paper
   /elektro/tt/3/IMG_3526.jpg
   per 1 mm - 35 p.
   track 0.1 - 5p. - 0.15 mm
4. control measurement of a newly made board
   /elektro/tt/3/IMG_3527.jpg
   per 1 mm - 35 p.
   track 0.1 - 7p. - 0.2 mm

In this light, I have a question: what kind of 0.1mm tracks can we talk about if the print itself is ALREADY thicker, and there will still be a melt during transfer? It is foolish to hope that they will be trimmed to the desired width, since then the gaps will be trimmed and there will be problems.

Could there be a problem with the printer? Maybe 600dpi is not enough? In the office, a test pattern was printed on a printer with 1200 dpi (HP LJ 3055) on plain paper (80g/m2) and on the same HP Premium Photo Paper, and the dimensions of the pattern were measured at home.

The measurement was made only on track 0.1 (just taken as a reference, so as not to suffer too much).

Photo paper: 0.125 mm
Plain paper: 0.11mm

Not bad, yes. Not like at home at 600dpi. However, there is clearly a different toner, it does not sit very well on photographic paper. Lots of hairiness. Tracks 0.05 are visually printed with gaps on photo paper, but the measurement showed that there is a size of 0.09mm.

We transfer to copper.

So, the size on the copper track is 0.1mm - 0.17mm

I poisoned it in a cool solution, everything came down in 10 minutes.
/elektro/tt/4/IMG_3538.jpg
(there are undergrasses, with home at 600dpi there is no such thing, in some places the toner tears just, strangely)

The resulting track size is 0.1mm - one is 0.18mm the second is 0.20 (for some reason they came out different).

The size of the track is 0.05mm - 0.15mm, but it is terribly uneven, one track is torn in the middle.

The electrical test did not pass one track 0.05mm (well, which is actually 0.15) and the gap 0.2 closed too. After passing through the gap with a paper knife, everything went away.

Conclusion: 1200 dpi does not help, and the toner is less suitable there.

So, a new test pattern:
/elektro/tt/4/IMG_3534.jpg

There are places where the toner simply did not take on the paper, until I understand exactly why this sometimes happens, but it depends on how to turn on the water from the tap and when to pull the paper, it is better to let the water directly into the knock between the board and the paper.

It added seats for SMD.

One has a contact width according to the scheme of 0.44 mm, a gap of 0.17 mm.
Second: the width of the contact according to the scheme is 0.63mm, the gap is 0.62mm.
/elektro/tt/4/IMG_3544.jpg
At the top right there is still a place for an SMD capacitor of size 0402 (the frame is a silk screen type.

I take the mentioned HP photo paper, my printer with 600dpi. I'm typing.

Dimensions on paper:

• 0.63 mm - 0.63 mm
• 0.44 mm - 0.43 mm
• 0.1mm - 0.14 (already floated)

The resulting dimensions on the boards after etching:

• 0.63 mm - 0.65 mm
• 0.44 mm - 0.43 mm
• 0.1 mm - 0.22 mm
• 0.05 mm - 0.18 mm

And don't ask me why 0.43 didn't float. Maybe it's some kind of special size that the printer can print correctly and some kind of force keeps the toner together when melted.

It's nice that the paths are even, without gnawing.

The electrical test showed that all the tracks are intact, and there is a short circuit in the 0.2 gap. One connection in one place. Removed with a knife - no problem.

Of the 4 cases, in 100% in a gap of 0.2 it closes and in 100% it is treated with one pass of a knife or needle. It's probably best to do it then etch.

Checking the places for SMD showed that there are no short circuits at all. Since the size of the site is observed, then the gaps are observed. Those. there are gaps of about 0.17mm without short circuits. And don't ask why - I don't know!

conclusions

1. HP Premium Photo Paper (Q199HF) rocks the black!
2. If the laminator translates the toner, then you need a laminator MANDATORY with temperature control!
3. You have to eat fast! The more you weed, the more weed.
4. The temperature on the iron must be selected individually for the iron, toner, paper, and, possibly, the board (for this paper, you need to find the minimum at which all the toner passes after 4-5 minutes of warming up).
5. The limit of technology with a 600dpi printer and Chinese toner in a reloaded cartridge is 0.18mm
6. To get a track of 0.18-0.20, you need to draw 0.05-0.1 in the diagram! It is very important!

I think that the topic with 0.1mm tracks can be closed. There are no such tracks on LUT and cannot be! But what is there is quite enough to make TQPF144 for AVR32 without any special problems, you can even say that there are no problems at all (platform 0.25, gap 0.25 and everything is ok, there is a step of 0.5mm).

If someone thinks that he really made a track with 0.1mm LUT - I'm waiting for a macro photo with an attached ruler, let's laugh together.

Some far-reaching conclusions

Glossy photo paper is more absorbent than transparencies. The photomethod uses a transparent film over the resist. On this film, the thickness cannot be less than on glossy photo paper, i.e. we are talking about a minimum of 0.15mm. Further, during illumination, shading or highlighting of the tracks can occur, due to which they can be thicker or thinner, and significantly in relation to 0.15mm (i.e., for example, walk from 0.1 mm to 0.2 mm). In addition, the experiment with track 0.09 showed that it is easily etched and even gnawed in places by the etching compound. This is all theory, since I have never used the photo method, but it seems to me that there is a limit of about 0.15mm. If someone thinks that they have done less - a macro photo with a ruler in the studio.

ATTENTION! ATTENTION! ATTENTION! ATTENTION!

Later it turned out that the indicated HP Premium paper is absolutely not suitable for making boards larger than 3 by 5 cm, since shreds of toner break out when the paper is removed. Read the next section for information on the correct paper. The second part .

ATTENTION! ATTENTION! ATTENTION! ATTENTION!

Quite a few years ago, I first learned about the production of boards using the Laser Iron Technology. For me, it was like reinventing the wheel.
Read the continuation of the story under the cut.

Prior to this, the boards were painted with varnish using a drawing pen. To print circuit boards using LUT technology, I even bought a laser printer (12 years ago it was very expensive). In the process of working, I tried a bunch of different types of paper. Yes, and more than one square meter of boards made using this technology was made, on the third I stopped counting. At the moment I have settled on paper from the magazine "Popular Mechanics", before that I used paper from the magazine "Kitchens and Bathrooms", but it disappeared from sale.
But more recently, while reading reviews on Muska, I accidentally saw paper for printing circuit boards in one of the reviews, got on Ali and immediately ordered 10 pieces of test sheets for myself, deciding that if I liked it, I would order 50, since the price difference is between 10 and 50 only about two times.
By the way, be careful, I posted a link to the lot, but now there is a lot of 50 pieces for 10-something bucks at this place, while the name of the link remains the same, 10 sheets.

I recently received my order. What I was most afraid of happened, the paper came wrinkled.
As everyone understands, it is dangerous to put crumpled paper into the printer, the repair cost can be more than the cost of the paper itself. I opened a dispute for a 50% refund, because after trimming I can use about that much.

The paper was simply in a large envelope, without a bag or file, and a piece of some kind of cardboard was inserted, and this piece of cardboard was smaller than the paper. Actually, the main damage was in places where the cardboard was missing.

In the photo, the magazine that I used before and the paper I received, chose the leaf more carefully.

In order for the printer not to chew on my new leaf, I had to cut off a part, on the other hand I didn’t cut it off, since it’s not critical there, the main thing in that area is simply not to print anything.

Well, since such paper is a very specific product, there is simply no way without testing here.

In general, everyone who is interested, welcome under the spoiler.

PCB how it's done.

First, I trace the printed circuit board, I use the Sprint Layout 6 program, before that I used version 3 for a very long time, and I still can’t get used to the differences in control.

When making a board, I always leave a protective zone 5 mm wide around the perimeter, so the workpiece is taken 10 mm more in length and width than the required board, it’s so convenient for me.

The workpiece is cleaned with fine sandpaper, it is not the mirror surface that is important, but rather a lot of micro-scratches, then the toner holds better.

We print our future board on paper (I usually print 2 pieces at once, just in case), on the smooth side, by the way, the whole process was done in one take, i.e. I did not correct or alter anything specifically for the review, this was the meaning of the test.
Do not forget that you need to print in a mirror image with respect to the required printed circuit board pattern.

Then I put the blank on a specially trained book :), or rather, this is not a book, but an annual binder of Radio magazines, in cardboard cover. I do this so that the workpiece does not slip during the process, and does not spoil what is under it from heating.

After that, I lay the printout with a drawing to the copper, then I cover it with a sheet of ordinary printer paper on top, so it slips less at the initial stage, the most difficult moment is to prevent the sheet with the print from slipping to the side, I first put the iron with a wide part on the book and paper, and then smoothly I drop it on the workpiece.

Then, with smooth movements, with a little pressure, we iron our future board, I make several passes from different sides of the board so that the edges are ironed better, you can’t press hard, otherwise the toner may float, if you don’t press at all, then most likely the toner will not stick to the workpiece. I stare at this blank for about a minute.
By the way, I use Static Control toner, in my opinion this is the best toner for LUT ...

The gluing process is completed, the paper stuck evenly and beautifully.

Now we throw our board into a bowl of water for 5-10 minutes, you can leave the water on, this will help the paper become softer faster.

After 5-10 minutes, under a slight pressure of water (preferably at room temperature), we roll up the paper with a finger, the tracks should remain in place, you don’t need to do this too carefully, because if the toner is erased with a finger, then such a board must be redone, normally glued toner is not erased with a finger , only scratches.

The photo shows the result of transferring the drawing to fiberglass. The toner is black, before when I used magazine paper, the toner had a grayish tint, as there were particles of paper left on it. Everything is beautiful here, the holes are clean, there are no sticks between the tracks.
I specifically selected a printed circuit board for the test with both large filled polygons and small tracks.

Before etching, I make such a “table”, at the corners of the board, in places free from the drawing, I drill 4 holes into which I insert matches (or toothpicks), while the board is placed with the drawing down.

Boards are usually etched with a solution of ferric chloride in water.
(III)
After immersing the board in the solution, it must be lifted almost immediately and air bubbles removed, otherwise there will be unetched places.

After some time (depending on the solution), the board is etched.

I wash off the toner that has already worked out its function with acetone (well, or any suitable solvent).

Well, here I will show what print quality I ended up with.
The place for the processor is closer to the center of the board, the width of the pads is 0.45mm, the width of the tracks is 0.45-0.5mm It can be seen that even the shape of the pad is perfectly preserved.

And this is a path along the edge of the board, there are two such places. Usually I correct such places with a permanent waterproof marker, I didn’t do this on purpose for the test.

After washing off the toner, I drill the necessary holes, then I clean the board with sandpaper zero.

After all these operations, I just cut off the excess, if this is done before stripping, then you can damage the tracks closest to the edge of the board with sandpaper. I pass the edges of the board with a little needle file to remove the sharp remnants of fiberglass after the scissors.

Now I cover the board with flux (I use alcohol F3), and tin the tracks.
I know some people don't, but I prefer tinned track boards. In general, a matter of taste, well, copper does not oxidize, and microcracks are filled with solder.

The last step is to wash off the remaining flux with acetone.

Everything, the board is ready.

Yes, I know about the photo method, I know about applying a mask and silkscreen, etc. etc.
These are all good and very useful things, but I think that for most applications, the option I described is enough. It is very quick and easy to make a board this way, and you need to have a minimum of chemicals and tools.
The board I made may be featured in one of my future reviews, some readers will probably even know what kind of device it will be.

Basically my resume.
Pros.
I liked it, I think I will order 50 or 100 sheets.
The toner sticks well to the base.

Minuses.
The seller packaged very poorly, for which he was a big minus.
The price, especially the price when buying a lot of 10 leaves, but it’s quite enough for a test, although looking for magazines, and then leaves in magazines without pictures (it’s better to use pages either white or with text only for printing) is already pretty fed up.

In general, experts, do not judge strictly, I tried to describe as best I could, I will be very happy with advice and additions, and I hope that my review helped someone.
And yes, I know that BiK is cheaper :)))