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TECHNOLOGY OF MANUFACTURE OF PRINTED BOARDS
In the absence of ferric chloride, it can be successfuly replaced by a solution of copper sulfate, also sodium chloride. In 500 ml of hot (about 80 ° C) water, dissolve four tablespoons of table salt and two spoons of copper sulphate, powdered into powder. The solution acquires a dark green color. It is ready for use at once after preparation. The resulting number of solution is sufficient to remove about 200 cm 2 of foil. If the conductor pattern on the reward is made with a heat-resistant paint (for example, nitro-enamel), the temperature of the solution can be brought up to 50 ° C, while the etching intensity increases. When applying the picture with "Kalmaar" ink, the solution must be cooled down to room temperature; it's time to pickle - at about 8 pm You can etch compensations also in an aqueous solution of common salt, but because of the long process time, the edges of the conductors on the reward are often uneven. The addition of copper sulfate accelerates the process in 1 ... 4 times.
Numbering of the conductors of the board
Radio amateurs installing their systems on printed circuit boards may benefit from the advice below. Each conductor in the diagram is assigned a serial number, and it is placed next to all the conclusions of the details attached to this conductor. On the printed rewards, it seems that these numbers are put on the appropriate conductors; It is best to etch numbers with conductors. This marking reduces the number of different inscriptions on the board, facilitates installation, setting up additional search for feasible malfunctions. The marking is especially convenient when the printed conductors are made in the form of foil islands. If the pay guides are also narrow, long ones, then it is necessary to provide in the convenient places platforms for placing numbers.
About drawing the picture on the board
When carrying out drawing of conductors with paint on foil reward, round platforms, centered on the holes for the pins, are usually applied by the drawing board, fixed in the drawing compass or "ballerinka". It is also much easier to carry out this operation either with an awl or with a thick needle. After drilling holes, the surface of the foil must be degreased. Then, the blade of the awl is dipped into the paint, it is inserted into the hole of the board and is scrolled once or twice in it. The density of the paint should be such that a drop of it, draining from the blade, spreads on the board in the form of a circle of the required diameter. In order for the mugs to be the same, dip the awl in the same depth, preferably up to the stop in the bottom of the vessel with the paint. After the paint has dried, reward images are drawn with images of conductors. An essential advantage of the described method of drawing a drawing of contact pads is the lack of podtravlivaniya foil directly around the hole, as the paint, pouring into it, protects the foil during etching.
Layout also marking the PCB
The layout is simplified if a layer of plasticine 0.5 ... 1 mm thick, preferably of light tone, is applied to the reward surface in the proposed installation area of the element. The layer must also be smooth, too. Then the part is prepared for marking. To do this, all its conclusions should be shortened to the same length (10 ... 15 mm) also bend so that they are perpendicular to the base of the part, otherwise inaccuracies may occur when marking holes. Then the part is lowered downwards with the conclusions to the intended location of its installation and is also slightly pressed into the clay, until the pins touch the surface of the board in any way. If the part is carefully removed now, the holes will be clearly visible. Light hammer blows on the sharpened punch mark the centers of future holes in the board. After the marking, the layer of plasticine is removed with any flat object and holes are drilled. This method is also convenient to use when assembling parts on the board. With a certain skill, it significantly reduces the time spent on this job.
Available means of manufacturing precision printed circuit boards
Foil aluminum household (thin).
Self-adhesive labels for printing on them with a laser printer
Rubber sheet. As much as possible smooth, it is better soft with a thickness of 5 mm, with a smooth (not porous) top layer.
Take a sheet of plain paper on which your printer prints. Put on it a slightly smaller piece of foil, matte side up, also gently, but evenly glue it on one short side of stripes, cut off from self-adhesive labels. Scotch tape can not be glued, because the printer has a stove on which the scotch will additionally remain. The adhesive surface should not, of course, protrude beyond the edge of the paper. Now we fill this system in the printer, so that the glued edge of the foil goes main, also we force the printer to drag this sheet (print a text file from one space . glued the foil should be firmly, smoothly, so as not to form the folds. breaks along the edges should not be. The sheet of foil that emerges from the printer owns clear bands from the wheels with which the printer pulls the paper. Data strips are located, these rooms will be non-working, they can not make a true image.
The reward should be surrounded by a 2 mm wide track that turns out badly, but it protects the rest of the board. But on this way it is convenient then to cut compensation. Perhaps the easiest way would be to cover the award on an impressive sheet of paper on a scale also scanned. We put a sheet of paper in the printer and draw a picture. Look, that it was on the right scale also on the right sheet space. Now we make another design from a sheet of paper, a foil and a sticky strip, with the difference that now we know where the picture will become, and a small piece of foil is needed. If there are extra fields of foil, then the likelihood is that you will paint it on the cracks, and on it there are folds that cover the whole thing. Under the foil there must be a clean paper, otherwise the foil of the reverse side will stick to the paper. We print the picture of the remuneration in addition, we carefully consider it. Navernjaka in what place something happened because of the unpaired foil, the hitting sticks, etc., in this case it is better to print still on the new piece of foil. If the whole picture went away also stuck, you probably did not print it on the matte, but on the smooth side of the foil. another time, for some reason, large surfaces of toner in the middle are lagging behind the foil with small bubbles, but this in no way affects the quality. Well, at what time everything will turn out correctly, also qualitatively, we carefully cut the foil from the paper. Now put on a heat-resistant surface of the sheet rubber, on it - foil pencil kverphu, additionally cover with a piece of oldly peeled foamed fiberglass, foil down. We place a hot iron, and we also attach it to something heavy. Another subtlety. The foil adores to curl, to corrode, etc., and at what time it is covered with fiberglass, it turns out to be slightly longer than necessary, additionally it gathers into small folds, taking away all the occupation. If you make the foil a little longer than the preform of the fiberglass, the foil can be slightly stretched by turning the non-working fields onto the non-flected side of the fiberglass. After 5 minutes carefully remove the iron, but on its premise we put something cold also heavy, but with a smooth lower surface. Minutes later 10 the construction will finally cool down, while the fiberglass with the foil attached to it is damaged. Thin aluminum foil sticks in the chlorine gland very quickly, leaving, right, some rags, which interfere with the normal copper tear. Therefore, the reward should be washed with water, at the same time you can look at the quality of the resulting picture, also if necessary, podpetushirovat. If the trucks are lubricated - you inadvertently removed the iron or put a cool grusz. If there is no way out somewhere - the iron is extremely cold, or a little while before the heating. If the ways became wide or even merged - the iron was extremely hot, or the board was too long. After some treading, it will be possible to do without pressing the iron with the hand. Properly similar to the temperature, you can simply press the iron for about 30 seconds, then apply a cold bladder. The foil, it seems, differs considerably from the heat, as well as on the trimmed "bootheart" it is noticeable, as if it is stretched. If you do not act in a wide way along the edges of the board, then the cooling compressible foil will make a picture on the edges.
For the manufacture of impressive printed circuit boards, you can proceed on the other: we lay the glass-cloth on the table with foil, then press the aluminum foil down onto it. We superimpose a pair of three sheets of paper carefully. In this case, the iron must move smoothly. You have to look, so that the foil does not slip on the fiberglass, you also have to start to grill it, too, from one side, so that the foil that is expanding from the heat can calmly do so, too, and do not go into folds. When only the foil was rubbed, you washed the board, also made sure that everything is normal, it is convenient to protect all sorts of fields and fields with the same nakleechkami. They pazmokayut, but not in the distance at all, and also their glutinous layer does not dissolve the general. Well, later on, you will have a one-off fee.