Printed circuit board– this is a dielectric base, on the surface and in the volume of which conductive paths are applied in accordance with electrical diagram. The printed circuit board is designed for mechanical fastening and electrical connection between each other by soldering the leads of electronic and electrical products installed on it.
Operations for cutting out a workpiece from fiberglass, drilling holes and etching a printed circuit board to obtain current-carrying paths, regardless of the method of applying the pattern to printed circuit board are performed using the same technology.
Manual application technology
PCB tracks
Preparing the template
The paper on which the PCB layout is drawn is usually thin and for more precision drilling holes, especially when using manual homemade drill so that the drill does not lead to the side, it is necessary to make it more dense. To do this, you need to glue the printed circuit board design onto thicker paper or thin thick cardboard using any glue, such as PVA or Moment.
Cutting the workpiece
A blank of foil fiberglass laminate of a suitable size is selected, the printed circuit board template is applied to the blank and outlined around the perimeter with a marker, a soft pencil or marking with a sharp object.
Next, the fiberglass laminate is cut along the marked lines using metal scissors or sawed out with a hacksaw. Scissors cut faster and there is no dust. But we must take into account that when cutting with scissors, fiberglass is strongly bent, which somewhat worsens the adhesion strength of copper foil and if the elements need to be re-soldered, the tracks may peel off. Therefore, if the board is large and has very thin traces, then it is better to cut it using a hacksaw.
The template of the printed circuit board pattern is glued to the cut-out workpiece using Moment glue, four drops of which are applied to the corners of the workpiece.
Since the glue sets in just a few minutes, you can immediately begin drilling holes for radio components.
Drilling holes
It is best to drill holes using a special mini drilling machine with a carbide drill with a diameter of 0.7-0.8 mm. If a mini drilling machine is not available, you can drill holes with a low-power drill with a simple drill. But when working universal hand drill The number of broken drills will depend on the hardness of your hand. You definitely won’t be able to get by with just one drill.
If you cannot clamp the drill, you can wrap its shank with several layers of paper or one layer of sandpaper. You can wrap a thin metal wire tightly around the shank, turn to turn.
After finishing drilling, check whether all holes are drilled. This can be clearly seen if you look at the printed circuit board up to the light. As you can see, there are no missing holes.
Applying a topographic drawing
In order to protect the places of foil on fiberglass laminate that will be conductive paths from destruction during etching, they must be covered with a mask that is resistant to dissolution in an aqueous solution. For the convenience of drawing paths, it is better to pre-mark them using a soft pencil or marker.
Before applying the markings, it is necessary to remove traces of the glue that was used to glue the printed circuit board template. Since the glue has not hardened much, it can be easily removed by rolling it with your finger. The surface of the foil must also be degreased using a rag using any means, such as acetone or white alcohol (the so-called purified gasoline), or any dishwashing detergent, for example Ferry.
After marking the tracks of the printed circuit board, you can begin to apply their design. Any waterproof enamel is well suited for drawing paths, for example alkyd enamel PF series, diluted to a suitable consistency with white alcohol solvent. You can draw paths different instruments– a glass or metal drawing pen, a medical needle and even a toothpick. In this article I will tell you how to draw circuit board traces using a drawing pen and ballerina, which are designed for drawing on paper with ink.
Previously, there were no computers and all drawings were drawn with simple pencils on whatman paper and then transferred in ink to tracing paper, from which copies were made using photocopiers.
Drawing begins with contact pads, which are drawn with a ballerina. To do this, you need to adjust the gap of the sliding jaws of the ballerina drawing board to the required line width and to set the diameter of the circle, perform the adjustment with the second screw, moving the drawing blade away from the axis of rotation.
Next, the ballerina's drawing board is filled with paint to a length of 5-10 mm using a brush. For applying a protective layer to a printed circuit board, PF or GF paint is best suited, since it dries slowly and allows you to work quietly. NTs brand paint can also be used, but it is difficult to work with because it dries quickly. The paint should adhere well and not spread. Before painting, the paint must be diluted to a liquid consistency, adding a suitable solvent to it little by little with vigorous stirring and trying to paint on scraps of fiberglass. To work with paint, it is most convenient to pour it into a bottle of manicure varnish, in the twist of which there is a solvent-resistant brush installed.
After adjusting the ballerina's drawing board and obtaining the required line parameters, you can begin to apply the contact pads. To do this, the sharp part of the axis is inserted into the hole and the base of the ballerina is rotated in a circle.
At correct setting using a drawing board and the desired consistency of paint around the holes on the printed circuit board, the circles are perfect round shape. When a ballerina begins to paint poorly, the remaining dried paint is removed from the gap of the drawing board with a cloth and the drawing board is filled with fresh paint. To draw all the holes on this printed circuit board with circles it took only two refills of the drawing pen and no more than two minutes of time.
Once the round pads on the board are drawn, you can start drawing the conductive paths using a hand drawing pen. Preparing and adjusting a manual drawing board is no different from preparing a ballerina.
The only thing additionally needed is a flat ruler, with pieces of rubber 2.5-3 mm thick glued to one of its sides along the edges, so that the ruler does not slip during operation and the fiberglass, without touching the ruler, can freely pass under it. A wooden triangle is best suited as a ruler; it is stable and at the same time can serve as a hand support when drawing a printed circuit board.
To prevent the printed circuit board from slipping when drawing tracks, it is advisable to place it on a sheet of sandpaper, which consists of two sandpaper sheets sealed together with the paper sides.
If they come into contact when drawing paths and circles, then you should not take any measures. You need to let the paint on the printed circuit board dry until it does not stain when touched, and use the tip of a knife to remove the excess part of the design. In order for the paint to dry faster, the board should be placed in a warm place, for example in winter time to the heating battery. IN summer time years - under the rays of the sun.
When the design on the printed circuit board is completely applied and all defects are corrected, you can proceed to etching it.
Printed circuit board design technology
using a laser printer
When printing on a laser printer, the image formed by the toner is transferred, due to electrostatics, from the photo drum on which the laser beam drew the image, onto paper. The toner is held onto the paper, preserving the image, only due to electrostatics. To fix the toner, the paper is rolled between rollers, one of which is a thermal oven heated to a temperature of 180-220°C. The toner melts and penetrates the paper texture. Once cooled, the toner hardens and adheres firmly to the paper. If the paper is heated again to 180-220°C, the toner will again become liquid. This property of toner is used to transfer images of current-carrying tracks onto a printed circuit board at home.
After the file with the printed circuit board design is ready, you need to print it using a laser printer onto paper. Please note that the image of the printed circuit board drawing for this technology must be viewed from the side where the parts are installed! An inkjet printer is not suitable for these purposes, as it works on a different principle.
Preparing a paper template for transferring the design to the printed circuit board
If you print a printed circuit board design on ordinary paper for office equipment, then due to its porous structure, the toner will penetrate deeply into the body of the paper and when the toner is transferred to the printed circuit board, most of it will remain in the paper. In addition, there will be difficulties in removing paper from the printed circuit board. You will have to soak it in water for a long time. Therefore, to prepare a photomask, you need paper that does not have a porous structure, for example, photo paper, backing from self-adhesive films and labels, tracing paper, pages from glossy magazines.
I use old stock tracing paper as the paper for printing the PCB design. Tracing paper is very thin and it is impossible to print a template directly on it; it gets wrinkled in the printer. To solve this problem, before printing, you need to apply a drop of any glue to a piece of tracing paper of the required size in the corners and glue it to a sheet of A4 office paper.
This technique allows you to print a printed circuit board design even on the thinnest paper or film. In order for the toner thickness of the drawing to be maximum, before printing, you need to configure the “Printer Properties” by turning off the economical printing mode, and if this function is not available, then select the coarsest type of paper, for example cardboard or something similar. It’s entirely possible that you won’t get a good print the first time, and you’ll have to experiment a little to find the best print mode for your laser printer. In the resulting print of the design, the tracks and contact pads of the printed circuit board must be dense without gaps or smudging, since retouching at this technological stage is useless.
All that remains is to cut the tracing paper along the contour and the template for making the printed circuit board will be ready and you can proceed to the next step, transferring the image onto fiberglass laminate.
Transferring a design from paper to fiberglass
Transferring the printed circuit board design is the most critical step. The essence of the technology is simple: paper, with the side of the printed pattern of the tracks of the printed circuit board, is applied to the copper foil of fiberglass and pressed with great force. Next, this sandwich is heated to a temperature of 180-220°C and then cooled to room temperature. The paper is torn off, and the design remains on the printed circuit board.
Some craftsmen suggest transferring a design from paper to a printed circuit board using an electric iron. I tried this method, but the result was unstable. It is difficult to simultaneously heat the toner to desired temperature and uniform pressing of the paper to the entire surface of the printed circuit board when the toner hardens. As a result, the pattern is not completely transferred and gaps remain in the pattern of the printed circuit board tracks. Perhaps the iron was not heating up enough, although the regulator was set to maximum iron heating. I didn’t want to open the iron and reconfigure the thermostat. Therefore, I used another technology, less labor-intensive and providing one hundred percent results.
On a piece of foil fiberglass laminate cut to the size of the printed circuit board and degreased with acetone, I glued tracing paper with a pattern printed on it in the corners. On top of the tracing paper I placed, for more even pressure, heels of sheets of office paper. The resulting package was placed on a sheet of plywood and covered on top with a sheet of the same size. This entire sandwich was clamped with maximum force in clamps.
All that remains is to heat the prepared sandwich to a temperature of 200°C and cool. An electric oven with a temperature controller is ideal for heating. It is enough to place the created structure in a cabinet, wait for the set temperature to reach, and after half an hour remove the board to cool.
If you don’t have an electric oven at your disposal, you can also use gas oven, adjusting the temperature using the gas supply knob using the built-in thermometer. If there is no thermometer or it is faulty, then women can help; the position of the control knob at which pies are baked is suitable.
Since the ends of the plywood were warped, I clamped them with additional clamps just in case. To avoid this phenomenon, it is better to clamp the printed circuit board between metal sheets 5-6 mm thick. You can drill holes in their corners and clamp printed circuit boards, tighten the plates using screws and nuts. M10 will be enough.
After half an hour, the structure has cooled enough for the toner to harden, and the board can be removed. At the first glance at the removed printed circuit board, it becomes clear that the toner transferred from tracing paper to the board perfectly. The tracing paper fit tightly and evenly along the lines of the printed tracks, rings of contact pads and marking letters.
The tracing paper easily came off from almost all the traces of the printed circuit board; the remaining tracing paper was removed with a damp cloth. But still, there were gaps in several places on the printed tracks. This can happen as a result of uneven printing from the printer or remaining dirt or corrosion on the fiberglass foil. Any spaces can be filled in waterproof paint, manicure polish or touch up with a marker.
To check the suitability of a marker for retouching a printed circuit board, you need to draw lines on paper with it and moisten the paper with water. If the lines do not blur, then the retouching marker is suitable.
It is best to etch a printed circuit board at home in a solution of ferric chloride or hydrogen peroxide with citric acid. After etching, toner can be easily removed from the printed tracks with a swab soaked in acetone.
Then holes are drilled, conductive paths and contact pads are tinned, and radioelements are sealed.
This is the appearance of the printed circuit board with radio components installed on it. The result is a power supply and switching unit for the electronic system, which complements an ordinary toilet with a bidet function.
PCB etching
To remove copper foil from unprotected areas of foiled fiberglass laminate when making printed circuit boards at home, radio amateurs usually use chemical method. The printed circuit board is placed in an etching solution and, due to a chemical reaction, the copper unprotected by the mask dissolves.
Recipes for pickling solutions
Depending on the availability of components, radio amateurs use one of the solutions given in the table below. Etching solutions are arranged in order of popularity of their use by radio amateurs at home.
| Name of solution | Compound | Quantity | Cooking technology | Advantages | Flaws |
|---|---|---|---|---|---|
| Hydrogen peroxide plus citric acid | Hydrogen peroxide (H 2 O 2) | 100 ml | Dissolve citric acid and table salt in a 3% solution of hydrogen peroxide. | Availability of components, high etching speed, safety | Not stored |
| Citric acid (C 6 H 8 O 7) | 30 g | ||||
| Salt(NaCl) | 5 g | ||||
| Aqueous solution of ferric chloride | Water (H2O) | 300 ml | IN warm water dissolve ferric chloride | Sufficient etching speed, reusable | Low availability of ferric chloride |
| Ferric chloride (FeCl 3) | 100 g | Hydrogen peroxide plus hydrochloric acid | Hydrogen peroxide (H 2 O 2) | 200 ml | Pour 10% hydrochloric acid into a 3% hydrogen peroxide solution. | High etching rate, reusable | Great care required |
| Hydrochloric acid (HCl) | 200 ml | ||||
| Aqueous solution of copper sulfate | Water (H2O) | 500 ml | Dissolve table salt in hot water (50-80°C), and then copper sulfate | Component Availability | The toxicity of copper sulfate and slow etching, up to 4 hours |
| Copper sulfate(CuSO4) | 50 g | ||||
| Table salt (NaCl) | 100 g | ||||
Etch printed circuit boards in metal utensils not allowed. To do this, you need to use a container made of glass, ceramic or plastic. The used etching solution may be disposed of in the sewer system.
Etching solution of hydrogen peroxide and citric acid
A solution based on hydrogen peroxide with citric acid dissolved in it is the safest, most affordable and fastest working. Of all the solutions listed, this is the best by all criteria.
Hydrogen peroxide can be purchased at any pharmacy. Sold in the form of a liquid 3% solution or tablets called hydroperite. To obtain a liquid 3% solution of hydrogen peroxide from hydroperite, you need to dissolve 6 tablets weighing 1.5 grams in 100 ml of water.
Citric acid in crystal form is sold in any grocery store, packaged in bags weighing 30 or 50 grams. Table salt can be found in any home. 100 ml of etching solution is enough to remove 35 micron thick copper foil from a printed circuit board with an area of 100 cm 2. The used solution is not stored and cannot be reused. By the way, citric acid can be replaced with acetic acid, but because of its pungent odor, you will have to etch the printed circuit board outdoors.
Ferric chloride pickling solution
The second most popular etching solution is water solution ferric chloride. Previously, it was the most popular, since on any industrial enterprise ferric chloride was easy to obtain.
The etching solution is not demanding on temperature; it etches quickly enough, but the etching rate decreases as the ferric chloride in the solution is consumed.
Ferric chloride is very hygroscopic and therefore quickly absorbs water from the air. As a result, a yellow liquid appears at the bottom of the jar. This does not affect the quality of the component and such ferric chloride is suitable for preparing an etching solution.
If the used ferric chloride solution is stored in an airtight container, it can be reused many times. Subject to regeneration, just pour iron nails into the solution (they will immediately be covered with a loose layer of copper). If it gets on any surface, it leaves a difficult-to-remove yellow spots. Currently, ferric chloride solution is used less frequently for the manufacture of printed circuit boards due to its high cost.
Etching solution based on hydrogen peroxide and hydrochloric acid
Excellent etching solution, provides high etching speed. Hydrochloric acid, with vigorous stirring, is poured into a 3% aqueous solution of hydrogen peroxide in a thin stream. It is unacceptable to pour hydrogen peroxide into acid! But due to the presence of hydrochloric acid in the etching solution, great care must be taken when etching the board, since the solution corrodes the skin of the hands and spoils everything it comes into contact with. For this reason, the etching solution with hydrochloric acid It is not recommended to use it at home.
Etching solution based on copper sulfate
The method of manufacturing printed circuit boards using copper sulfate is usually used if it is impossible to produce an etching solution based on other components due to their inaccessibility. Copper sulfate is a pesticide and is widely used for pest control in agriculture. In addition, the etching time of the printed circuit board is up to 4 hours, while it is necessary to maintain the solution temperature at 50-80°C and ensure a constant change of the solution at the surface being etched.
PCB etching technology
For etching a board in any of the above etching solutions, glass, ceramic or plastic dishes, for example from dairy products. If you don’t have a suitable size container at hand, you can take any box of thick paper or cardboard of a suitable size and line its inside plastic film. An etching solution is poured into the container and a printed circuit board is carefully placed on its surface, pattern down. Due to the forces of surface tension of the liquid and its light weight, the board will float.
For convenience, a plug can be glued to the center of the board using instant glue. plastic bottle. The cork will simultaneously serve as a handle and a float. But there is a danger that air bubbles will form on the board and the copper will not be etched in these places.
To ensure uniform etching of copper, you can place the printed circuit board on the bottom of the container with the pattern facing up and periodically shake the tray with your hand. After some time, depending on the etching solution, areas without copper will begin to appear, and then the copper will completely dissolve on the entire surface of the printed circuit board.
After the copper is completely dissolved in the etching solution, the printed circuit board is removed from the bath and thoroughly washed under running water. Toner is removed from the tracks with a rag soaked in acetone, and paint is easily removed with a rag soaked in a solvent that was added to the paint to obtain the desired consistency.
Preparing the printed circuit board for installation of radio components
The next step is to prepare the printed circuit board for the installation of radio elements. After removing the paint from the board, the tracks need to be processed in a circular motion with fine sandpaper. There is no need to get carried away, because the copper tracks are thin and can be easily ground off. Just a few passes with abrasive with light pressure are enough.
Next, the current-carrying paths and contact pads of the printed circuit board are coated with alcohol-rosin flux and tinned soft solder electric soldering iron. To prevent the holes on the printed circuit board from being covered with solder, you need to take a little bit of it onto the soldering iron tip.
After completing the manufacture of the printed circuit board, all that remains is to insert the radio components into the designated positions and solder their leads to the pads. Before soldering, the legs of the parts must be moistened with alcohol-rosin flux. If the legs of the radio components are long, then before soldering they need to be cut with side cutters to a protrusion length above the surface of the printed circuit board of 1-1.5 mm. After completing the installation of parts, you need to remove any remaining rosin using any solvent - alcohol, white alcohol or acetone. They all successfully dissolve rosin.
It took no more than five hours to implement this simple capacitive relay circuit from laying out the tracks for manufacturing a printed circuit board to creating a working sample, much less than it took to type up this page.
PCB is a sheet insulating material, usually fiberglass, on one or two sides of which there are conductive, usually copper, tracks. The parts are inserted into holes in the board and soldered to these tracks. The conductive tracks are located in such a way that if they are correctly inserted into the required holes and soldered well, then these tracks will connect the parts together in such a way that a kind of electronic device is obtained.
There is also surface mounting, when the parts are located on the same side as the printed tracks and are soldered to them without pushing the leads into the holes. This method is most often used in very compact devices, when installing miniature parts. At home, so to speak, in the kitchen, it’s easier to do the first option. This is what we will talk about here.
There are many ways and methods for manufacturing printed circuit boards in “kitchen” conditions, described in various amateur radio literature. Here, without claiming originality, we consider one of them, suitable for the manufacture of printed circuit boards for simple electronic devices. As an example, we will make a board for the sound signaling device described in this magazine in the article “Electronic bell for a bicycle.” In order not to flip through the magazine again, the timer circuit, as well as the printed circuit board drawing and wiring diagram, are repeated here in figures 1, 2 and 3, respectively.
Preparing the drawing
But, before making a printed circuit board, you need to find out at what scale its drawing is given. In radio magazines, the drawing is almost always given on a scale of 1:1. But it is different in different publications.
If the board drawing is given in a different scale, it needs to be re-shot or redrawn on a scale grid, so that the image is on a scale of 1: 1. Here the image is immediately on a 1:1 scale, and nothing needs to be reduced or enlarged.
PCB material
The main material for printed circuit boards is foil-coated fiberglass. This is an insulating sheet on which copper foil is glued on one or both sides. From this sheet you need to cut a blank - a piece slightly larger in size than the printed circuit board. It is usually recommended to use a metal file, but if you have sufficient physical strength, this can be done with metal scissors - it will be faster and with less sweat.
Then, the foil must be carefully sanded with fine sandpaper, but not to the point of holes, but so as to remove only the layer of oxides. No need to strive mirror shine, it’s better to have a lot of small scratches. The essence of further actions is to protect the desired areas of the foil from the etching solution.
Transferring a drawing
Now you need to transfer Figure 2 to this foil. The easiest way to do this is with an awl, a light hammer, carbon paper (“carbon paper”, which is placed between sheets of paper to write on several sheets at once), and ballpoint pen.
Rice. 1. Scheme of a simple electronic device.
Rice. 2. Printed circuit board for an electronic device.
Rice. 3. Layout of components on the printed circuit board.
You need to place the blank under the sheet with the image of the tracks (Fig. 2). However, you can make a photocopy first so as not to spoil the magazine. Then, between the sheet with the image of the tracks and the workpiece, lay a carbon copy with the ink side facing the workpiece. Using paper clips or another method, secure this “sandwich”.
Next, using an awl and a light hammer, you need to slightly, just a little bit, mark the points where the holes should be. Then, using a ballpoint pen, draw the tracks so that their contours are transferred through the carbon paper to the workpiece. Now let’s disassemble the “sandwich”.
Drilling holes
We take a micro-drill (an electric screwdriver or a small screwdriver will work as a micro-drill), and use a metal drill with a diameter of 1-1.2 mm to drill holes in the punched areas. It is better to blow off the sawdust rather than brush it away with your hand, otherwise you can erase the carbon copy design. Do not paw the surface of the board on the foil side, because your fingers leave “sweat-grease” marks, which can interfere with etching in the future.
Drawing tracks
The next stage is drawing the tracks themselves. There are many ways to do this. You can use nail polish (with an appropriate brush), tsapon-varnish, nitro paint, bitumen varnish. In this case, the writing instrument is a nail polish brush, a drawing pen, a pen for drawing, a sharpened match.
But all this became a thing of the past, after felt-tip pens (markers) for writing on CDs and DVDs appeared in office supply stores.
This can be said to have "revolutionized the kitchen industry" of printed circuit boards. We take a “For CD” or “For DVD” marker, thick black, fresh, smelling “tasty” of either alcohol or acetate, and meticulously draw with it the mounting pads and printed tracks, painting their surface tightly, in several layers.
At the same time, the rest of the surface must be left unpainted (and unpatched). The mark from the For CD or For DVD marker dries instantly, so the workpiece is ready for etching immediately after the drawing process is completed.
Etching tracks
The most suitable reagent for etching is a ferric chloride solution. Now ferric chloride in powder form is sold almost everywhere in the same place where radio components are sold. You need to dilute 50-60 grams per glass of warm water.
Stir with a non-metallic object (an ordinary metal teaspoon is convenient, of course, but it will ruin everything and spoil itself). Then, having made a small hole in a corner of the board unoccupied by paths, you can hang this board on a nylon line and lower it into this very glass (the glass must be non-metallic).
So that the board is somewhere in the middle of the glass, completely covered with a solution of ferric chloride. After all the unpainted foil has dissolved, remove the workpiece and rinse with water. Wash off the marker paint with any alcohol-containing liquid, for example... cheap cologne.
Rinse again with water, dry with a hairdryer and you can arrange the parts according to Figure 3 and solder.
lupo, well, then continue in the same way, especially since the board is custom-made, and, obviously, time is limited, and you will spend quite a lot of time on mastering LUT. My “secrets” from the days when I painted with paint:A) use of an insulin syringe with a removable thin (pink) needle ground down (not bitten off!) to 4-5 mm.
b) using not nitro paints, but PF enamels diluted with appropriate solvents (in no case with acetone or acetone-containing solvents! - contrary to apparent logic, PF diluted with acetone will dry for a week).
c) sufficiently liquid dilution of the enamel and adjustment of the “feed” by inserting a wire into the needle - the diameter is selected experimentally - to prevent spontaneous leakage of the “ink”. For the same purpose, it is not advisable to fill the syringe more than 2-3 mm above the needle level. In this case, the paint is “sucked out” from the needle due to the capillary effect only when drawing. You need to have a piece of cardboard on hand - even with a short break, you will have to “paint” the needle by inflating the syringe, and at the same time a drop will crawl out, which, if you try to “paint” the syringe directly on the board, will lead to a blot.
d) first, ALL the nickels of the contact pads are outlined, then the board is given time to dry to the point of “non-sticking” to the nickels of the ruler - at least 3 hours)
e) drawing lines is carried out under a ruler with the lower edge beveled inward - to prevent paint from leaking. In this case, according to the project, first they draw horizontal lines(with a margin on both sides - PF, unlike nitrate, is good because it is easier to carefully clean it before it is completely dry (even under a ruler, which is very convenient when cleaning the “grids” formed with this technology, for example, on the turns of multi-bit buses), then the board is given time to dry, and then vertical lines are drawn. At this moment, as a rule, “forgotten” horizontal lines are discovered - then vertical lines are also drawn with a reserve, and in place of the missing horizontal lines, marks are made with a BALL PEN - for subsequent completion .
f) after the verticals have dried, the diagonals are drawn if necessary, and you can immediately clean up smudges, “tails” of the horizontals, etc. The advantage of PF is that it retains its plasticity for quite a long time and does not chip when stripped, unlike nitrate. Thanks to this, once you have mastered the skill, you can CALMLY “draw” two tracks between the legs of the microcircuit with a pitch of 2.5 mm. 0.5 mm track if these recommendations are followed - standard width paths, with VERY great care, careful selection of paint thickness and the diameter of the insert wire - 0.3 mm can be pulled out. Will they merge with the heels of their legs? And X with them - after drying, the insulating gaps are calmly and without tension “finished” with a scraper. There is no need to try to eliminate streaks IMMEDIATELY - this will only lead to dirt on the board! Let them dry (I usually marked the resulting “strips” that required further attention in the design drawing with a highlighter marker, and eliminated them after COMPLETE drawing of the board tracks).
g) let the board dry for at least 4 hours, at least until the feeling of your finger “sticking” to the last drawn tracks disappears.
h) Well, that's it... Next - ferric chloride, final inspection and, if necessary, cleaning. The strength of the paint makes it possible, in case of high unevenness of the distribution (a very dense pattern with thin tracks in some places, and large etched areas in others), in order to avoid etching of already etched tracks, stop the general mixing of the solution and apply manual forced (with a foam swab) on large etched surfaces.
i) I wash off the paint from the etched board not with a solvent, but under a tap - using a piece of burlap and Pemoxol (or any other abrasive detergent) - this allows you to immediately tin the board with a soldering iron after washing off the paint and blotting up drops from the board, dousing it with alcohol-rosin flux (preferably activated LTI-120)
j) Enjoy!
Nostalgia... I haven’t used this method for years... And if you have time and laser printer- ask in the Search on forums or in Google a request LUT(Laser Ironing Technology), and there will be happiness. With practiced skills (not a single recommendation is a dogma, much depends on the printer, media, paper and personal preferences), this technology allows you to produce boards with a quality even higher than industrial silk-screen printing, with a very stable result. I’ll add a secret from myself, which for some reason was missed in the “educational education” on LUT - with this technology, wide (power) paths and large painted areas are printed rather poorly - very ugly pinpoint etch marks occur. In this case, I usually draw all the tracks in a project wider than 1 mm and draw the “islands” of the foil only with a contour (a 0.5 mm line), after printing the design on the board, painting the inter-circuit space in the classic way - with a syringe with paint.
We all love to assemble circuits, but not everyone wants and knows how to lay out printed circuit boards. Most often we look for a ready-made signet on the Internet and in most cases we find it. It would seem, go ahead, poison and solder! But not everything is so rosy, because often these found signets look like this:
Not a single signed item. A complete rebus, a riddle! And, it seems, turn on the “mosch” and fill in the elements, because the diagram is at hand. But the program was created to make our lives easier, and not vice versa.
Therefore, I will briefly, from the beginning, tell you how to approach the layout of the board in Sprint-Layout, so that you don’t have to guess later what kind of detail I put in here. Let's do the right thing right away!
You can’t cover everything in one short article; I’ll go over some of the main points. So let's create new project, set the name of the board and the expected size (it can be easily adjusted later).
Be sure to select a suitable working mesh.
For small projects with large elements, a 1.27 mm mesh is suitable, for more advanced and dense elements 0.635 mm, and so on. Elements and tracks will be placed with reference to the nodes of this grid. You can make a mesh for Soviet parts: 2.5 mm or 1 mm.
Be sure to understand the layer system in the program, understand how everything works, and use the photo view.
Make inscriptions on layers for inscriptions, and make paths and polygons on layers for copper, etc.
The archive contains a help program in Russian.
Let's start adding details to the board. At this stage, you should not confuse the values of “Type” and “Denomination”; later I will tell you why.
Enter the values, adjust the font size to taste, and click OK.
We see an element with markings. Now we can distribute and “compact” our markings.
Select the denomination and drag it with the mouse to Right place. Before this, you need to reduce the grid size to an acceptable level.
Now, that's better.
Now we move the element symbol closer. If necessary, you can rotate it by selecting it first.
Next, so as not to suffer so much with each element, we simply copy it and change the data in the element’s properties.
Our board is already quite ready for manufacturing, but why do we need to overload the solution with excess copper?
No need! We will minimize the area of copper being etched. To do this, select all the elements on the board and click the “Metalization” button at the bottom of the program window and change the value to an acceptable one, for example 0.5 mm.
Everything is fine, but some legs can and sometimes even need to be placed on a metallized area. There's nothing complicated.
Select the required legs and change the metallization offset value to 0. That's it, now the leg is on the earth bus.
What if you need a thermal barrier to facilitate soldering on large sites? Select drawing paths and draw a thermal barrier.
This is the simplest and most obvious way. But you can also take advantage of the program’s built-in capabilities for creating thermal barriers. Select the desired pad and explore the menu on the right.
Check the "Thermal barrier" checkbox and configure the direction and width of the barrier's "bridges". It is very convenient because you can configure many sites at once. The thermal barrier function only works when the automatic ground test is turned on. Not supported by all versions of Sprint-Layout. Use fresh.
Everything is drawn, we can admire the result by clicking the “photo view” button.
A nuance - you can edit the size of the element labels individually; to do this, select the “victim” and click the properties button on the right. The settings are quite extensive. However, it is better to install all the inscriptions in the same style.
The turn of “cosmetics” has come. So that all the drawings of elements on the board have a uniform appearance and line thickness, do the following:
1. select the layer with element labeling;
2. turn off the tracks layer;
3. select all (ctrl+A);
4. adjust the thickness of the lines of all elements at the same time;
5. Activate the tracks layer again.
Beauty! By the way, don’t forget to adjust the colors of the layers in the program to suit everyone’s taste, for those who found my palette a bit gloomy.
Now let’s remember the beginning of the article and find out why you shouldn’t enter the value of an element in the field for its type. It’s simple, it turns out that when we added elements, we already generated a list of elements!
Of course, a more correct practice is the primacy of the diagram in the project, then creating a list of elements is the job of the program for drawing diagrams. In the ABACOM software package it is sPLAN.
Editor's note
All that remains is to purchase according to the list and end up with a beautiful payment self-made. And people are not ashamed to show such a drawing on the forum, and there will be no unnecessary questions about the board.
Files
And here is a Russian help on Sprint-Layout and an excellent free book by our comrade Mikhail Tsarev (Tsoy73):▼ 🕗 12/27/16 ⚖️ 2.14 Mb ⇣ 170
When a laser printer is available, radio amateurs use a printed circuit board manufacturing technology called LUT. However, such a device is not available in every home, since even in our time it is quite expensive. There is also a manufacturing technology using photoresist film. However, to work with it you also need a printer, but an inkjet one. It’s already simpler, but the film itself is quite expensive, and at first it’s better for a novice radio amateur to spend the available funds on a good soldering station and other accessories.
Is it possible to make a printed circuit board of acceptable quality at home without a printer? Yes. Can. Moreover, if everything is done as described in the material, you will need very little money and time, and the quality will be very good. high level. Anyway electricity“will run” along such paths with great pleasure.
List of necessary tools and consumables
You should start by preparing the tools, devices and consumables that you simply cannot do without. To realize the most budget method To make printed circuit boards at home, you will need the following:- Software for drawing design.
- Transparent polyethylene film.
- Narrow tape.
- Marker.
- Foil fiberglass.
- Sandpaper.
- Alcohol.
- Unnecessary toothbrush.
- Tool for drilling holes with a diameter of 0.7 to 1.2 mm.
- Ferric chloride.
- Plastic container for etching.
- Brush for painting with paints.
- Soldering iron.
- Solder.
- Liquid flux.
Today there are a huge number of programs for developing printed circuit boards, but for a novice radio amateur the most simple option will be Sprint Layout. The interface is easy to master, it is free to use, and there is a huge library of common radio components.
Polyethylene is needed to transfer the pattern from the monitor. It is better to take a stiffer film, for example, from old covers for school books. Any tape will be suitable for attaching it to the monitor. It’s better to take a narrow one - it will be easier to peel off (this procedure does not harm the monitor).
It’s worth looking at markers in more detail, as this is a sore subject. In principle, any option is suitable for transferring a design onto polyethylene. But to draw on foil fiberglass, you need a special marker. But there is a little trick to save money and not buy quite expensive “special” markers for drawing printed circuit boards. The fact is that these products are absolutely no different in their properties from ordinary permanent markers, which are sold 5-6 times cheaper in any office supply store. But the marker must have the inscription “Permanent”. Otherwise nothing will work.
You can take any foiled fiberglass laminate. It's better if it's thicker. For beginners, working with such material is much easier. To clean it, you will need sandpaper with a grit size of about 1000 units, as well as alcohol (available at any pharmacy). The last consumable can be replaced with nail polish mixing liquid, which is available in any house where a woman lives. However, this product smells quite nasty and takes a long time to dissipate.
To drill the board, it is better to have a special mini-drill or engraver. However, you can go a cheaper route. It is enough to buy a collet or jaw chuck for small drills and adapt it to a regular household drill.
Ferric chloride can be replaced with others chemicals, including those that you probably already have in your home. For example, a solution is suitable citric acid in hydrogen peroxide. Information on how alternative compositions to ferric chloride are prepared for etching boards can be easily found on the Internet. The only thing worth paying attention to is the container for such chemicals - it should be plastic, acrylic, glass, but not metal.
There is no need to talk in more detail about the soldering iron, solder and liquid flux. If a radio amateur has come to the question of making a printed circuit board, then he is probably already familiar with these things.
Development and transfer of a board design to a template
When all of the above tools, devices and Consumables prepared, you can start developing the board. If the device being manufactured is not unique, then it will be much easier to download its design from the Internet. Even a regular drawing in JPEG format will do.
If you want to go a more complicated route, draw the board yourself. This option is often unavoidable, for example, in situations where you do not have exactly the same radio components that are needed to assemble the original board. Accordingly, when replacing components with analogues, you have to allocate space for them on fiberglass, adjust holes and tracks. If the project is unique, then the board will have to be developed from scratch. This is what the above-mentioned software is needed for.
When the board layout is ready, all that remains is to transfer it to a transparent template. The polyethylene is fixed directly to the monitor using tape. Next, we simply translate the existing pattern - tracks, contact patches, and so on. For these purposes, it is best to use the same permanent marker. It does not wear off, does not smudge, and is clearly visible.
Preparation of foil fiberglass laminate
The next step preparations are underway fiberglass. First you need to cut it to the size of the future board. It is better to do this with a small margin. To cut foil fiberglass laminate, you can use one of several methods.Firstly, the material can be cut perfectly using a hacksaw. Secondly, if you have an engraver with cutting wheels, it will be convenient to use it. Thirdly, fiberglass can be cut to size stationery knife. The principle of cutting is the same as when working with a glass cutter - a cutting line is applied in several passes, then the material is simply broken off.
Now you definitely need to clean the copper layer of fiberglass from protective coating and oxide. The best way There is no better way to solve this problem than using sandpaper. The grain size is taken from 1000 to 1500 units. The goal is to obtain a clean, shiny surface. It is not worth stripping the copper layer to a mirror shine, since small scratches from sandpaper increases surface adhesion, which will be needed further.
Finally, all that remains is to clean the foil from dust and fingerprints. To do this, use alcohol or acetone (nail polish remover). After processing, we do not touch the copper surface with our hands. For subsequent manipulations, we grab the fiberglass by the edges.
Combination of template and fiberglass
Now our task is to combine the pattern obtained on polyethylene with the prepared fiberglass laminate. To do this, the film is applied to the desired location and positioned. Leftovers are wrapped on reverse side and are attached using the same tape.
Drilling holes
Before drilling, it is recommended to secure the fiberglass laminate with the template to the surface in some way. This will allow for greater accuracy and will also prevent sudden rotation of the material as the drill passes through. if you have drilling machine for such work, the described problem will not arise at all.
You can drill holes in fiberglass at any speed. Some work at low speeds, others at high speeds. Experience shows that the drills themselves last much longer if operated at low speeds. This makes them more difficult to break, bend and damage the sharpening.
The holes are drilled directly through the polyethylene. Future contact patches drawn on the template will serve as reference points. If the project requires it, we promptly change drills to the required diameter.
Drawing tracks
Next, the template is removed, but not thrown away. We still try not to touch the copper coating with our hands. To draw paths we use a marker, always permanent. It is clearly visible from the trail it leaves. It is better to draw in one pass, since after the varnish, which is included in the permanent marker, has hardened, it will be very difficult to make edits.
We use the same polyethylene template as a guide. You can also draw in front of the computer, checking the original layout, where there are markings and other notes. If possible, it is better to use several markers with tips different thicknesses. This will allow you to draw both thin paths and extensive polygons more efficiently.
After applying the drawing, be sure to wait some time necessary for the final hardening of the varnish. You can even dry it with a hairdryer. The quality of future tracks will depend on this.
Etching and cleaning marker tracks
Now comes the fun part - etching the board. There are several nuances here that few people mention, but they significantly affect the quality of the result. First of all, prepare the ferric chloride solution according to the recommendations on the package. Usually the powder is diluted with water in a ratio of 1:3. And here's the first piece of advice. Make the solution more saturated. This will help speed up the process, and the drawn paths will not fall off before everything necessary is etched out.
Immediately the second tip. It is recommended to immerse the bath with the solution in hot water. You can heat it in a metal bowl. An increase in temperature, as is known since school curriculum, significantly speeds up chemical reaction, which is what etching our board is. Reducing the procedure time is to our advantage. The tracks made with a marker are quite unstable, and the less they sour in the liquid, the better. If at room temperature fee in ferric chloride is etched for about an hour, then in warm water this process is reduced to 10 minutes.
In conclusion, one more piece of advice. During the etching process, although it is already accelerated due to heating, it is recommended to constantly move the board, as well as clean off the reaction products with a drawing brush. By combining all the manipulations described above, it is quite possible to etch out excess copper in just 5-7 minutes, which is easy excellent result for this technology.
At the end of the procedure, the board must be thoroughly rinsed under running water. Then we dry it. All that remains is to wash away the traces of the marker that are still covering our paths and patches. This is done with the same alcohol or acetone.
Tinning of printed circuit boards
Before tinning, be sure to go over the copper layer again with sandpaper. But now we do it extremely carefully so as not to damage the tracks. The simplest and affordable way tinning - traditional, using a soldering iron, flux and solder. Rose or Wood alloys can also be used. There is also so-called liquid tin on the market, which can greatly simplify the task.But all these new technologies require additional costs and some experience, so for the first time it will be suitable classic method tinning. Liquid flux is applied to the cleaned tracks. Next, solder is collected onto the soldering iron tip and distributed over the copper remaining after etching. It is important to warm up the traces here, otherwise the solder may not “stick”.
If you still have Rose or Wood alloys, then they can be used outside the technology. They melt just fine with a soldering iron, are easily distributed along the tracks, and do not bunch up into lumps, which will only be a plus for a beginning radio amateur.
Conclusion
As can be seen from the above, budget technology making printed circuit boards at home is really affordable and inexpensive. You don't need a printer, an iron, or expensive photoresist film. Using all the tips described above, you can easily make simple electronic ones without investing in it big money, which is very important in the first stages of amateur radio training.