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I do not think that I will reveal a big secret, if I say that the quality of etching of printed circuit boards is also affected by several key factors. For the sample: if the etching process occurs in a solution of ferric chloride at room temperature, it lasts as a position from 40 minutes to 2.5 hours (depending on the saturation of the solution). If the solution is heated, then the etching process itself can be reduced by a factor of one and a half times. Of course, also the general, in perfection, the solution itself is forced to periodically mix, in this case the process takes place even faster. These factors directly affect the speed of etching. If you express about the quality of the motherboards, this applies in the first place to those radio amateurs who transfer the image to textolite using the "laser printer additionally iron" method. Despite the fact that the toner keeps on the foil hard enough, if the etching process is delayed by the time, the chlorine iron still caters to the toner. In this case, the tracks turn out to be "porous", which in turn degrades the quality of the board itself of the device as a whole.

Technically, the process of mixing the solution can be carried out in several ways (it all depends on the ingenuity of the " sharpness " of the hands), but the most optimal, in my opinion, is the "microbubble bath" method. It is in this way that factory rewards are manufactured. The essence of the method is quite simple, but very effective. On the day of a tank with a chlorous iron is located a plastic tube in which through equal intervals punched holes. At one end, the tube is muffled, and a compressed atmosphere is supplied from another. As a result, air bubbles rising from the bottom of the reservoir naturally mix the ferric chloride solution, thereby accelerating the etching process. It is not provided, of course, for the heating of the solution, but as if the etching process takes place quite hastily ( 5 to 10 minutes ), then this option does not in principle have any sense, the solution is simply preheated and is also poured into the reservoir already warm. So, on this entry can also be completed and proceed directly to the implementation of the conceived.

The tank . As a reservoir for this system, of course, it is possible to use any convenient capacity, I also had cuvettes for developing photographs. They look like this:

Printed circuit board etching tank

The tube . The tube can also be used any convenient, it seemed to me the most optimal to use the tube from a conventional medical dropper, you can buy it at a pharmacy for only 15 rubles . It is adhered to the usual glue "Moment crystal". The holes are made with a sewing needle, with a step of about 1 cm :

Tube for etching printed circuit boards

Naturally, on the one hand the tube is suppressed in advance, on the other hand the tip from the same dropper is fixed, for a more convenient connection to the spring of the atmosphere (about it a little later):

Tube for etching printed circuit boards

At this stage, it is still necessary to check the operation of the device itself, simply by pouring water into the container. The fact is that everything depends on the pressure of the compressor, the diameter of the hole also dances directly from it, so you may have to experiment:

Tube for etching printed circuit boards

Grid . Maybe someone will find this item superfluous. The fact is that the word in it will go about the grid stretched at an interval of about 1.5 centimeters from the bottom of the tank (the gap between the tube and the workpieces of the boards is still necessary). The grid does not need to be acted at all, in order to provide the necessary clearance it is possible to insert just 4-6 matches into the board holes (best in those that are designed to fix the board in the device) so that they form racks. You can create a grid, again, in several ways. My tool is as follows: from plastic about 1 mm thick, strips about 1.5 cm in width are cut out, also slightly less than each side of the tank. The result is two long two short strips:

Grid for etching printed circuit boards

On each strip, cuts are made for half the thickness of the plastic, in increments of one centimeter:

Then these strips are glued to each side of the used container:

And they are glued in such a way that the cuts are facing towards the wall of the tank, also through this cutting a thin line was passed:

Further from the line according to the following scheme, the net is drawn. First between the long opposite planks:

Then between short:

As a result, you should get a grid like the one stretched on a tennis racket:

Cover . Actually, this could be completed additionally, but when testing this unit with water, it turned out to be one not very pleasant feature. The fact is that the working unit sprinkles very small drops in different directions. Perhaps, for some it will not become a problem in any way, but personally I had a desire to make a cover. According to the dimensions of the cuvette, a blank was cut from the plastic, in which holes sufficient for ventilation were drilled, but insufficient for contamination of the surrounding space:

Cap. Etching of printed circuit boards

The cuts on the lid are made due to the fact that on one side a tube comes out, but on the other hand there is a drain (by the way, it is much more convenient to drain the solution with the lid closed, less likely to shed it). The lid is ready, it remains to make fasteners for it on the tank. It is not completely standard: it is attached to the cuvette clips, intended for fixing the coaxial cable:

Etching of printed circuit boards

There are only six of them ...

... two on each side as guides for the cover ...

... also two more like a stopper with a fully closed lid:

The way of life. Etching of printed circuit boards

Compressor . Now you can talk about the source of the air. The most common is a plastic bottle with a valve, into which air is pumped through the pump. A variation with the car camera is also possible. In my case, an ordinary microcompressor for the AEH-3 pool is used as a spring of the atmosphere, which has been slightly modified for more performance:

Compressor. Etching of printed circuit boards

Actually, the improvement was reduced to the most optimal arrangement of the magnet in the field of the coil (who at least once examined such devices, will understand what the speech is about). The route of such simple manipulations managed to increase the capacity of the compressor by about two times, which was quite enough.

That's the way, as a result of all the labors, an uncomplicated unit appeared ...

... which, nevertheless, increased the quality of the speed of the devices being manufactured several times.

PS Perhaps, someone in this system seems to be superfluous, because instead of a grid one can use matches, instead of a lid - a piece of plywood or an ancient magazine (only in no way by radio electronics, there is already an occupation of the principle), and instead of a compressor our own lungs Only all of the above amenities at work will not add exactly. However, this is just my purely personal view, but if all of the above is useful to someone, then I can confidently say that we have fulfilled the target we have put on for 100 years.

Sincerely, Electric Affairs Master
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