LUT technology: PCB manufacturing

What is LUT (laser-ironing technology)? This will tell our article.

Printed circuit boards

The design of electronic devices is closely related to the creation of printed circuit boards. If there is no desire to spend a lot of time on their manufacture, then the method described in the article is ideal for you. With the proper dexterity, it will fundamentally facilitate creativity. LUT technology can be divided into the following stages of PCB manufacturing:

1. Create a drawing.
2. We make a blank.
3. Transfer the drawing to it.
4. We poison the workpiece.
5. We clean it.
6. We make a drill.
7. Tinning board.

As you can see for yourself, in practice LUT technology at home can be implemented without significant problems and costs. Perhaps you don’t even have to get anything new, because everything you need for work can be easily found in the back room. LUT-technology for the manufacture of printed circuit boards is well suited in cases where there is a single production by a single electronics lover. Speaking about the merits, they primarily recall the cheapness, reliability and ease of work. Of course, these are not all the advantages, and neither of the above was more than enough for many home craftsmen to make their choice in favor of LUT technology.

Create a drawing

There is a wide selection of tools: from pencil to special programs. When creating a printed circuit board, you must try to achieve the following goals:

1. Minimize the number of jumpers.
2. Tracks relative to each other should be located strictly perpendicular and parallel.
3. Compact installation.

When creating drawings, consider the dimensions of the elements, the location of the findings of the parts and their sizes. It is also necessary to ensure that high-current conductors have wider paths. Creating a picture can be compared to playing a tetris game: you can mark up the elements as you like until you get the ideal that will help translate LUT technology into reality. An inkjet printer (or laser) will help you make it physical, touch it with your own hands.

Making a blank

So, we have a drawing, and we can talk about the size of the board. Now you need to cut out the picture, put it on the textolite and point it with a ruler. Isn't LUT technology so complicated yet? Foil, that’s what we need! Cut along the lines a blank of foil textolite. Smooth the edges around the perimeter with a file and clean the surface. To do this, you can use a fine sandpaper or wire grater (from those that clean dishes) along with a detergent.

Transferring a picture: general information

Let's say we printed the image on a laser printer. And now we need to transfer it to the blank from paper. Overlay what happened with the image on the foil. Iron evenly with an iron, but use only light effort. Peel paper, straighten and pickle. If you are printing a picture, it is advisable to set the minimum brightness to get a very dark image. It is also advisable to set the toner density to high in the advanced settings. This is necessary to avoid negative effects with gaps, which, alas, has LUT technology. The minimum size of the gaps is only welcome, it is desirable that they are not more than 0.2 millimeters.

Transfer drawing: paper

This is a subtle thing, therefore, it is necessary to approach its choice with responsibility. What samples are better perceived by LUT technology? The paper should be thick, you can take coated. Do not touch with fat fingers. It is not necessary to buy coated paper - you can take an advertising booklet. The main thing is that on one side it is white. Just in case, it is better to stock up with two copies of printed circuit boards. We cut and impose on the workpiece so that the pattern is on the side of the foil. We take an ordinary iron, we do not use steam. It is better to set the temperature to average. We hold part of the drawing so that it does not move off the workpiece. Start smoothly smoothing the image, but do not allow it to shift. Also, do not overdo it with force: if you press very hard, the toner will be smeared, and with it the tracks. This can also happen if the iron is too hot. If the edges of the workpiece were poorly processed, then you cannot smooth toner to it well. When everything is ready, the workpiece should cool. Then put it in a bowl of warm water. Add a tablespoon of acetic acid. The paper softens and begins to bubble. In about ten minutes, it will lag behind toner. Rinse the resulting image with plenty of water. At first, there may be individual defects, but when working with a second instance of experience should be enough to avoid them. In general, the LUT technology for the manufacture of printed circuit boards may seem quite complicated, but this is only at first. By the way, it was recommended to have two papers above in the article, and this is no accident. At the first call, many beginners make small mistakes that turn into smeared toner and other oversights. In order for the printed circuit board to turn out to be of higher quality, a recommendation was made to prepare a spare.

What if there is no laser printer?

You can use a permanent marker. Also for these purposes, nail polish applied with a thin brush is suitable. In general, you can act with at least one pencil and an eraser. It is used in these cases LUT technology using glue for the best result. When you wash off its remains with water, make sure that it is really gone. Also, when you drill holes, make sure that the conclusions in them will feel good.

We poison the workpiece

For this, ferric chloride is used. When buying a substance, make sure that it is in powder form. Such ferric chloride is most suitable for our purposes. Although the option of using a mixture of salt and copper sulphate is not excluded. But here it is necessary to observe certain proportions. So, for one liter of boiled water, you need to take two hundred grams of vitriol and add table salt until it stops dissolving. The resulting solution must be filtered. If it is heated to a temperature of 50 degrees Celsius, then it will take 15-20 minutes to bleed copper. But back to the ferric chloride. It is necessary to fill the pickling tank with water and add a teaspoon with a slide of ferric chloride. Be careful, because during the chemical reaction that occurs, heat will be generated strongly, and the resulting solution may even spatter a little. Mix everything well. Bring your finger to the solution and make sure it is not too hot. Then put the blank in it, preferably with the foil down - so that it lies on the surface. At first she will swim and grass. Over time, it will drown. Then we turn the printed circuit board with the foil up and put it in the solution. Periodically, the container with it must be shaken so that dissolved copper is washed off the surface. If bubbles appear, remove the circuit board, rinse it and continue etching. Depending on the temperature of the solution and its concentration, this process can take up to 1 hour.

Clean the toner blank

Now we face the problem of cleanliness. There are special solutions for this, but they do not find good reviews, and many people prefer the mechanical way to remove toner. To do this, it is recommended to use wire graters for washing dishes, which can provide a decent result.

Drill

It is worth noting that to a large extent this is a matter of purely individual preferences. But as recommendations, you can advise the use of DPR micromotors and replaceable collet chucks. The drill can be selected at 0.8 millimeters - in most cases this is more than enough.

Tinning

When you have drilled a printed circuit board, it is necessary to wash it with soap. Then sweep with a wire grater, rinse and dry again. Then it must be covered with a solution of rosin on alcohol. You can also cover the board with active solder grease on petroleum jelly. How wild it would not sound, but the thing is useful. Apply fat in a thin layer, rubbing it well on the surface. The solder should be placed so that the holes are not sealed. If this still happened, then we pick up a wooden toothpick, heat the “dirty” place and clean it.

PCB Guidelines

POS-61 can be recommended as solder. It is designed to work with circuits in cases where overheating is unacceptable. And if this happens, then the circuit board tracks may peel off. In the end, we can say that the considered technique looks complicated. But this is a deceptive proposition. Believe me, it will take you more time to create a good drawing than a printed circuit board. You can also give advice on the etching time: the fact is that if you leave the printed circuit board in the solution for several hours, then even the areas protected by the toner will not be saved. Therefore, it is highly advisable to adhere to the time limits indicated in the article.

Opportunities

It should be noted that LUT technology allows you to get a good result in terms of accuracy. So, some masters with her help learned to etch letters and numbers, the size of which is 0.3 millimeters! Amazing quality of work! Of course, to achieve it, you will need training and experience, however, as in any field of activity.

Conclusion

It should be noted that the LUT technology for manufacturing double-sided printed circuit boards does not differ much from the processes described in the article. Of course, you will have to complicate it a bit and spend more time - but the end result will be worth it. LUT technology allows you to quickly and efficiently create printed circuit boards for all kinds of circuits. If at first something does not work out, you should always remember that experience will allow us to figure it out. Therefore, you must consider your mistakes, learn from them and try again.