Electronic boards to order. How to make a printed circuit board with your own hands: laser ironing technology (LUT) at home

Conditions on a specific example. For example, you need to make two boards. One is an adapter from one type of housing to another. The second is the replacement of a large microcircuit with a BGA package with two smaller ones, with TO-252 packages, with three resistors. Board sizes: 10x10 and 15x15 mm. There are 2 options for manufacturing printed circuit boards in: using a photoresist and using the "laser iron" method. Let's use the "laser iron" method.

PCB manufacturing process at home

1. We are preparing a PCB project. I use the DipTrace program: convenient, fast, high quality. Developed by our compatriots. Very convenient and pleasant user interface, in contrast to the generally recognized PCAD. There is a conversion to PCAD PCB format. Although many domestic firms have already begun to accept in the DipTrace format.

DipTrace has the ability to see your future creation in volume, which is very convenient and visual. This is what I should get (the boards are shown at different scales):

2. First, we mark the textolite, cut out the blank for printed circuit boards.

3. We output our project in a mirror image in the highest possible quality, without skimping on toner. Through long experiments, paper was chosen for this - thick matte photo paper for printers.

4. Do not forget to clean and degrease the board blank. If there is no degreaser, you can walk on copper fiberglass with an eraser. Next, using an ordinary iron, we “weld” the toner from the paper to the future printed circuit board. I hold for 3-4 minutes under slight pressure, until the paper turns slightly yellow. I set the heat to max. I put another sheet of paper on top for more even heating, otherwise the image may "float". An important point here is the uniformity of heating and pressure.

5. After that, after letting the board cool down a bit, put the blank with the paper stuck to it in water, preferably hot. Photo paper gets wet quickly, and after a minute or two, you can carefully remove the top layer.

In places where there is a large accumulation of our future conductive tracks, the paper sticks to the board especially strongly. We haven't touched it yet.

6. Let the board get wet for a couple more minutes. Carefully remove the rest of the paper with an eraser or rubbing with your finger.

7. We take out the workpiece. We dry. If somewhere the tracks turned out to be not very clear, you can make them brighter with a thin CD marker. Although it is better to ensure that all tracks come out equally clear and bright. It depends on 1) the uniformity and sufficiency of heating the workpiece with an iron, 2) accuracy when removing paper, 3) the quality of the textolite surface, and 4) successful selection of paper. With the last point, you can experiment to find the most suitable option.

8. We put the resulting blank with future conductor tracks printed on it in a solution of ferric chloride. We poison 1.5 or 2 hours. While we are waiting, we will cover our "bath" with a lid: the fumes are quite caustic and toxic.

9. We take out the finished boards from the solution, rinse, dry. Toner from a laser printer is wonderfully washed off the board with acetone. As you can see, even the thinnest conductors with a width of 0.2 mm came out quite well. There is very little left.

10. Ludim printed circuit boards made using the "laser iron" method. Wash off the remaining flux with gasoline or alcohol.

11. It remains only to cut out our boards and mount the radio elements!

conclusions

With some skill, the "laser iron" method is suitable for making simple printed circuit boards at home. Short conductors from 0.2 mm and wider are quite clearly obtained. Thicker conductors work just fine. The time for preparation, experiments with the selection of the type of paper and temperature of the iron, etching and tinning takes about 3-5 hours. But this is much faster than if you order boards from a company. Cash costs are also minimal. In general, for simple budget amateur radio projects, the method is recommended for use.

How to prepare a board made in Eagle for production

Preparation for production consists of 2 stages: technology restrictions check (DRC) and generation of files in Gerber format

DRC

Every PCB manufacturer has technology restrictions on minimum trace widths, trace spacing, hole diameters, and so on. If the board does not meet these restrictions, the manufacturer refuses to accept the board for production.

When creating a PCB file, the default technology limits are set from the default.dru file in the dru directory. As a rule, these limits do not correspond to the limits of real manufacturers, so they need to be changed. You can set the limits just before generating the Gerber files, but it's better to do it right after the board file is generated. To set restrictions, press the DRC button

gaps

Go to the Clearance tab, where the gaps between the conductors are set. We see 2 sections: different signals And Same signals. different signals- defines gaps between elements belonging to different signals. Same signals- defines gaps between elements belonging to the same signal. When moving between input fields, the picture changes, showing the meaning of the input value. Dimensions can be specified in millimeters (mm) or thousandths of an inch (mil, 0.0254 mm).

Distances

The Distance tab defines the minimum distances between the copper and the edge of the board ( Copper/Dimension) and between the edges of the holes ( Drill/Hole)

Minimum dimensions

On the Sizes tab for double-sided boards, 2 parameters make sense: Minimum Width- minimum conductor width and Minimum Drill is the minimum hole diameter.

Belts

The Restring tab defines the sizes of the bands around the vias and pads of the output components. The width of the girdle is set as a percentage of the hole diameter, while you can set a limit on the minimum and maximum width. For double-sided boards, the parameters make sense Pads/Top, pads/bottom(pads on the top and bottom layers) and Via/Outer(through holes).

masks

On the Masks tab, the gaps from the edge of the pad to the solder mask are set ( stop) and solder paste ( Cream). Clearances are specified as a percentage of the smaller pad size, and you can set a limit on the minimum and maximum clearance. If the board manufacturer does not specify special requirements, you can leave the default values ​​​​on this tab.

Parameter limit defines the minimum via diameter that will not be covered by the mask. For example, if you specify 0.6mm, then vias with a diameter of 0.6mm or less will be masked.

Running a check

After setting the restrictions, go to the tab file. You can save the settings to a file by clicking the button. Save as.... In the future, for other boards, you can quickly load the settings ( Load...).

Push button apply the set technology limits apply to the PCB file. It affects layers tStop, bStop, tCream, bCream. Also, vias and pads on output components will be resized to fit the constraints set on the tab. Restring.

Button press Check starts the constraint control process. If the board satisfies all restrictions, the program status line will display the message No errors. If the board does not pass control, a window appears DRC Errors

The window contains a list of DRC errors, indicating the error type and layer. By double-clicking on a line, the area of ​​the board with the error will be displayed in the center of the main window. Error types:

too little clearance

hole diameter too small

intersection of tracks with different signals

foil too close to board edge

After correcting the errors, you need to start the control again, and repeat this procedure until all errors are eliminated. The board is now ready to be output to Gerber files.

Gerber file generation

From the menu file choose CAM Processor. A window will appear CAM Processor.

The set of file generation parameters is called a task. The task consists of several sections. The section defines output parameters for a single file. Eagle comes with the gerb274x.cam task by default, but it has 2 drawbacks. Firstly, the lower layers are displayed in a mirror image, and secondly, the drill file is not displayed (one more task will have to be performed to generate the drill). Therefore, consider creating a task from scratch.

We need to create 7 files: board borders, copper top and bottom, silkscreen top, solder mask top and bottom, and drill.

Let's start with the borders of the board. In field Section enter the name of the section. Checking what's in the group style installed only pos. Coord, Optimize And Fill pads. From the list device choose GERBER_RS274X. In the input field file enter the name of the output file. It is convenient to place the files in a separate directory, so in this field we will enter %P/gerber/%N.Edge.grb . This means the directory where the board source file is located, the subdirectory gerber, the original board file name (without extension .brd) with added at the end .edge.grb. Note that subdirectories are not created automatically, so you will need to create a subdirectory before generating files gerber in the project directory. In the fields offset enter 0. In the list of layers, select only the layer Dimension. This completes the creation of the section.

To create a new section, press Add. A new tab appears in the window. Set the section parameters as described above, repeat the process for all sections. Of course, each section must have its own set of layers:

copper top - Top, Pads, Vias

copper bottom - Bottom, Pads, Vias

silkscreen on top - tPlace, tDocu, tNames

top mask - tStop

bottom mask - bStop

drilling - Drill, Holes

and the filename, for example:

top copper - %P/gerber/%N.TopCopper.grb

bottom copper - %P/gerber/%N.BottomCopper.grb

top silkscreen - %P/gerber/%N.TopSilk.grb

top mask - %P/gerber/%N.TopMask.grb

bottom mask - %P/gerber/%N.BottomMask.grb

drilling - %P/gerber/%N.Drill.xln

For a drill file, the output device ( device) should be EXCELLON, but not GERBER_RS274X

Keep in mind that some board manufacturers only accept files with names in the 8.3 format, that is, no more than 8 characters in the file name, no more than 3 characters in the extension. This should be taken into account when naming files.

We get the following:

Then open the board file ( File => Open => Board). Make sure the board file has been saved! Click Process Job- and we get a set of files that can be sent to the board manufacturer. Please note that in addition to the actual Gerber files, information files will also be generated (with extensions .gpi or .dri) - they do not need to be sent.

You can also display files only from individual sections by selecting the desired tab and pressing Process Section.

Before sending the files to the board manufacturer, it's a good idea to preview the output with a Gerber viewer. For example, ViewMate for Windows or for Linux. It can also be useful to save the board in PDF (in the board editor File->Print->PDF button) and upload this file to the manufacturer along with the gerberas. And then they are also people, this will help them not to make a mistake.

Technological operations that must be performed when working with photoresist SPF-VShch

1. Surface preparation.
a) cleaning with polished powder ("Marshalit"), size M-40, washing with water
b) decapitation with 10% sulfuric acid solution (10-20 sec), washing with water
c) drying at T=80-90 gr.C.
d) check - if within 30 seconds. a continuous film remains on the surface - the substrate is ready for use,
if not, repeat all over again.

2. Deposition of photoresist.
The photoresist is applied on a laminator with Tshafts = 80 gr.C. (See laminator operating instructions).
For this purpose, the hot substrate (after the drying oven) is simultaneously directed from the SPF roll into the gap between the rolls, with the polyethylene (matt) film directed towards the copper side of the surface. After pressing the film to the substrate, the movement of the rollers begins, while the polyethylene film is removed, and the photoresist layer is rolled onto the substrate. Mylar protective film remains on top. After that, the SPF film is cut on all sides to fit the substrate and kept at room temperature for 30 minutes. Exposure is allowed for 30 minutes to 2 days in the dark at room temperature.

3. Exposure.
Exposure through a photomask is carried out on SKCI or I-1 installations with UV lamps of the DRKT-3000 or LUF-30 type with a vacuum of 0.7-0.9 kg/cm2. The exposure time (to obtain a picture) is regulated by the installation itself and is selected experimentally. The template must be well pressed against the substrate! After exposure, the workpiece is aged for 30 minutes (up to 2 hours is allowed).

4. Manifestation.
After exposure, the process of developing the picture is carried out. For this purpose, the upper protective layer, the lavsan film, is removed from the surface of the substrate. After that, the workpiece is lowered into a solution of soda ash (2%) at T=35 gr.C. After 10 seconds, the process of removing the unexposed part of the photoresist using a foam swab begins. The time of manifestation is selected empirically.
Then the substrate is removed from the developer, washed with water, decapitated (10 sec.) with a 10% solution of H2SO4 (sulfuric acid), again with water and dried in an oven at T=60°C.
The resulting drawing should not flake off.

5. The resulting drawing.
The resulting pattern (photoresist layer) is resistant to etching in:
- ferric chloride
- hydrochloric acid
- copper sulphate
- aqua regia (after additional tanning)
and other solutions

6. Shelf life of photoresist SPF-VShch.
Shelf life of SPF-VShch is 12 months. Storage is carried out in a dark place at a temperature of 5 to 25 gr. C. in a vertical position, wrapped in black paper.

Direct interaction with a number of PCB manufacturers in China, enables us to produce printed circuit boards with the following characteristics:

• production of printed circuit boards from two-layer to multilayer (30 layers);
• various material (FR4, high temperature FR4, aluminum backed, ceramic backed, F4,BT,PPE,PPT,PTFE) thickness from 0.1mm to 6mm;
• with a minimum gap and thickness of conductors - 0.075 mm;
• with copper thickness from 6 to 140 microns;

• with a mask of black, blue, green, yellow, red, matte and temporary (peelable);
• Immersion tin/silver/gold, electroplated tin/gold and spot plating;
• contract manufacturing of printed circuit boards with a high level of quality and compliance with all necessary standards;
• production of printed circuit boards with delivery time - from two weeks!

The cost of ordering printed circuit boards

Manufacturing printed circuit boards

50% Discount
when ordering
Full construction

Taking into account the level of development of modern electronics, as well as its complex functionality, the desire of manufacturers to increase the level of reliability and extend the operational life of the equipment is growing. Accordingly, the requirements for printed circuit boards are significantly increased. And an increase in the degree of integration imposes more serious requirements on the technology of manufacturing boards. That is why we offer our customers the manufacture of products that fully meet all the established requirements of electronics and its development.

You can order a printed circuit board from M-Plata at one of the best prices on the market among competing offers. To do this, you can use both the online order service and send us the necessary information by mail: a completed order form and files in any CAD system.

Order urgent PCB manufacturing in Moscow

It is here that you can place an order for printed circuit boards, which will be ready in the shortest possible time. Note that the quality and reliability of electronics do not decrease due to the efficiency of manufacturing products. M-Plata closely cooperates with well-known and reliable Chinese manufacturers of printed circuit boards, as well as with manufacturing companies operating in our country. Thanks to this fruitful interaction, we can offer the following boards:

• Two-layer, multilayer (up to 32 layers).
• Boards made of aluminum, ceramics, as well as the usual FR-4 and high-temperature FR4.
• Used finish coating (including local) with immersion gold, tin, silver, as well as HASL.
• High-tech boards in class "5" with a minimum gap size and a small thickness of conductors

To produce a printed circuit board to order at M-Plata, you will need to enter the parameters of the printed circuit board directly on the website online and upload the project files in any CAD system. If the board will be in a multi-blank, then the gerbera files for the multi-blank are required. You can also place an order by sending us a letter with the necessary documentation. Properly designed board and technical accompanying documentation allows you to comply with all technological standards during production and, accordingly, ensure the high quality of manufactured electronics. We guarantee prompt response to each request received.

Andreev S.

At home, you can make printed circuit boards. in terms of quality almost in no way inferior to factory production. By following a certain procedure, you yourself can repeat this for your homemade products.

First you need to prepare a pattern of printed tracks. How to breed a printed circuit board will not be discussed here, suppose that the drawing is already there, taken from a magazine, the Internet, or drawn by you personally or using a special program. The preparation of the pattern depends on how the pattern of printed tracks is supposed to be applied to the workpiece. Three methods are now the most popular - manual drawing with an indelible marker, the "laser iron" method and photo exposure on photoresist.

First way

The first method is suitable for simple boards. Here, the end point of the preparation of the drawing should be the image on paper at a scale of 1: 1, viewed from the side of the tracks. It’s good if there is already a 1:1 paper image, for example, in the Radioconstructor magazine, basically all boards are 1:1. But in other publications, and especially on the Internet, everything is not so smooth.

If there is a paper image in a different scale, it must be enlarged or reduced accordingly, for example, by copying on a copier with scaling. Or scan to a computer into a graphic file and in some graphic editor (for example, in Adobe Photoshop) bring the dimensions to 1:1 and print on the printer. The same applies to drawings of boards obtained from the Internet.

So, there is a 1:1 paper drawing from the side of the tracks. We take a blank made of foil fiberglass, sand the foil a little with a “zero”, put a paper pattern on the blank, attach it so that it does not move, for example, with adhesive tape. And with an awl or tap we pierce the paper at the points where there should be holes, and so that a clearly visible, but shallow mark on the foil remains.

The next step is to remove the paper from the workpiece. In the marked places, we drill holes of the required diameter. Then, looking at the track pattern, draw printed tracks and mounting pads with an indelible marker. We start drawing from the mounting pads, and then connect them with lines. Where thick lines are needed, draw a marker several times. Or we draw the outline of a thick line, and then densely paint over inside. Etching will be discussed later.

Second way

Radio amateurs called the second method "laser iron". The method is popular, but very capricious. Necessary tools - a laser printer with a fresh cartridge (a refilled cartridge, in my experience, is generally not suitable for this business), an ordinary household iron, very tricky paper.

So, preparation of the drawing. The drawing must be black (without halftones, colors), on a scale of 1:1, and moreover, it must be in a mirror image. All this can be achieved by processing the picture on a PC in some graphics editor. The above Adobe Photoshop will do fine, although even the simplest Paint program from the standard Windows set allows you to make a mirror image.

The result of the preparation of the drawing should be a graphic file with an image on a scale of 1: 1, black and white, without halftones and colors, which can be printed on a laser printer.

Another issue, important and subtle, is about paper. The paper should be dense and at the same time thin, so-called coated paper (the usual “for copier” does not give good results). Where to get it? Here is the main question. On sale, it is only thick - for photographs. And we need thin. Look in your mailbox! A lot of advertising booklets are made exactly on such paper - thin, smooth, glossy. Do not pay attention to the presence of color pictures - they will not interfere with us in any way. However, no, if the print is of poor quality, that is, the pictures get your fingers dirty, then such promotional products will not suit us.

Then we print our file on this paper and see what happens. As I said above, the printer must be with a fresh cartridge (and drum, if the drum is separate from the cartridge). In the printer settings, you need to select the print mode with the highest print density, in different printers this mode is called differently, for example, “Brightness”, “Dark”, “Contrast”. And no economical or draft (in the sense, "draft") modes.

All this is necessary because a dense and uniform pattern is needed, with the tracks depicted by a fairly thick layer of toner without interruptions, light stripes that may occur during the operation of a worn cartridge drum. Otherwise, the pattern will be uneven in the thickness of the toner, and this will lead to the fact that there will be track interruptions on the finished board in these places.

We print the pattern, cut it out with scissors so that there is a little extra on the edges, apply the pattern to the blank with toner to the foil, and wrap the excess under the board so that these parts are pressed by the board lying on the table and prevent the pattern from moving. We take an ordinary iron without steaming, heat it up to the maximum temperature. Smoothly smooth, avoiding displacement of the pattern.

Do not overdo it, as excessive pressure will smear the toner and some of the tracks will merge. Poorly finished edges on the workpiece will also prevent the toner from being well aligned to the workpiece.

In general, the essence of the process is that the laser printer toner melts and, when melted, sticks to the foil. Now we wait until the workpiece cools down. When it cools down, put it in a bowl of warm water for 10-15 minutes. The coated paper softens and begins to lag behind the board. If the paper does not lag behind, gently try to roll the paper with your fingers under running water.

On the workpiece, the wiring covered with a thin layer of shaggy paper will be visible. It is not necessary to try hard to roll up all the paper, since you can also tear off the tuner from the foil with such diligence. It is important that the rags of paper do not hang, and there should not be any paper between the tracks.

Third way

The third method is photo exposure on a photoresist layer. Photoresist is sold in radio parts stores. Usually instructions are included. Following this instruction, you need to apply a photoresist to the workpiece, and when it is ready to expose the layout of the board layout to it. Then process with a special solution - developer. The illuminated areas will be washed away, and a film will remain on the unlit areas.

The drawing should be prepared in the same way as for the "laser iron", but you need to print on a transparent film for the printer. This film is applied to the workpiece treated with photoresist (toner to the workpiece) and exposed according to the instructions. This method is complicated, requires the presence of a photoresist, a developing solution and strict adherence to the instructions, but it allows you to get wiring of almost factory quality.

In addition, the printer does not have to be a laser printer - an inkjet one is also suitable, provided that you will print on a transparent film for inkjet printers. When exposing the film, you always need to put the toner side on the workpiece, press it with glass for even fit. If the fit is loose, or if you put the film on the other side, the image will turn out to be of poor quality, as the tracks will blur due to out-of-focus.

PCB etching

Now about pickling. Despite the many alternative methods of etching, the good old "ferric chloride" is the most effective. It used to be impossible to get it, but now it is sold in jars in almost any radio parts store.

It is necessary to make a solution of ferric chloride, on the jar there is usually an instruction how much the contents of the jar are for how much water. Practically it turns out four teaspoons with a slide of powder per glass of water. Mix well. This can generate a lot of heat and even effervesce on the surface and spatter, so proceed with caution.

It is most convenient to etch in a bath for photo printing, but it is also possible in an ordinary ceramic plate (in a metal bowl it is impossible in any case!). The board must be located with the tracks down and be in a suspended state. I simply put four small fragments of ordinary building bricks specially prepared with a file, so that the board lies with its corners on them in a plate or bath.

Now it remains only to pour the solution into this container and carefully place the board on these supports. Some people prefer to lay the board on the surface of the solution so that it is held by the surface tension of water, but I do not like this method because the board is heavier than water and will sink with even a slight shaking.

Depending on the concentration and temperature of the solution, etching takes from 10 minutes to 1 hour. To speed up the etching process, you can create vibration, for example, put a working electric motor next to the table. And you can heat the solution with an ordinary incandescent lamp (putting a bath under a table lamp).

It should be noted that chalk residues (from coated paper) on the toner react with ferric chloride solution, bubbles are formed that prevent etching. In this case, you need to periodically remove the board and rinse with water.

In addition to the most convenient and effective, in my opinion, method of etching in a solution of ferric chloride, there are other options. For example, etching in nitric acid. Etching occurs very quickly, and with the release of heat. The nitric acid solution should be no more than 20% concentration. After etching, in order to neutralize the acid, it is necessary to wash the board with a solution of baking soda.

The method gives fast etching, but it also has many disadvantages. Firstly, if the workpiece is slightly overexposed, there may be strong undercutting of the tracks. And secondly, and most importantly, the method is very dangerous for health. In addition to the fact that nitric acid itself can cause chemical burns when it comes into contact with the skin, it also releases a poisonous gas, nitric oxide, when etched. So I don't recommend this method.

Another way is pickling in a solution of a mixture of copper sulfate and common salt. This method was actively used in the “before perestroika times”, when ferric chloride, like many other things, was not commercially available, but fertilizers for the garden were relatively affordable.

The sequence of preparing the solution is as follows - first pour water into a plastic or glass, ceramic bath. Then pour two tablespoons of table salt into a glass of water. Stir with a non-metallic stick until the salt is completely dissolved, and add copper sulfate at the rate of one tablespoon per glass of water. You stir again. Immerse the board in the solution.

In fact, pickling occurs in common salt, and copper sulfate works as a catalyst. The main disadvantage of this method is a very long etching, which can be from several hours to up to a day. You can slightly speed up the process by heating the solution to 60-70 ° C. It often turns out that one serving is not enough for the entire board and the solution has to be poured out and prepared again and again. This method is inferior in all respects to etching in ferric chloride, and it can only be recommended if ferric chloride cannot be obtained.

Etching in electrolyte for car batteries. The electrolyte of standard density must be diluted with water one and a half times. Then add 5-6 tablets of hydrogen peroxide. Etching occurs in speed approximately the same as in a solution of ferric chloride, but there are all the same disadvantages as in etching in nitric acid, since the electrolyte is an aqueous solution of sulfuric acid. Contact with skin causes burns, poisonous gas is released during the etching process.

After etching, the ink, photoresist, or toner must be removed from the surface of the printed tracks. Drawing with a marker is easily removed with almost any solvent for paints, or with alcohol, gasoline, cologne. Photoresist can be removed with white spirit or acetone. But the toner is the most resistant to chemistry material. Just clean it off mechanically. In this case, it is necessary not to damage the tracks themselves.

Cleaned from paint (toner, photoresist), the workpiece must be washed with water, dried and proceed to drilling holes. The diameter of the drill depends on the diameter of the desired hole. Drills - for metal.

It is most convenient for me personally to check with a compact cordless drill-driver. At the same time, I place the board vertically, screwing it with screws to a wooden block fixed in a vice. I move the drill horizontally, resting my hand on the table. But on a small drilling machine, of course, it will be better. Many people use miniature engraving drills, but I do not have such equipment.

By the way, you can also power a drill driver from a laboratory power source, after removing the battery, applying voltage directly to the contacts (“crocodiles”). This is convenient because without a battery, the drill is much lighter, well, plus the battery does not run out or you can use a tool with a faulty battery.

Well, the board is ready.

Printed circuit board- this is a dielectric base, on the surface and in the volume of which conductive paths are applied in accordance with the electrical circuit. The printed circuit board is intended for mechanical fastening and electrical connection between each other by soldering the leads of electronic and electrical products installed on it.

The operations of cutting a workpiece from fiberglass, drilling holes and etching a printed circuit board to obtain current-carrying tracks, regardless of the method of drawing a pattern on a printed circuit board, are performed using the same technology.

Manual application technology
PCB tracks

Template preparation

The paper on which the PCB layout is drawn is usually thin and for more accurate drilling of holes, especially when using a handmade home-made drill, so that the drill does not lead to the side, it is required to make it denser. To do this, you need to glue the printed circuit board pattern onto thicker paper or thin thick cardboard using any glue, such as PVA or Moment.

Cutting a workpiece

A blank of foil-coated fiberglass of a suitable size is selected, a printed circuit board template is applied to the blank and outlined around the perimeter with a marker, a soft simple pencil, or drawing a line with a sharp object.

Next, fiberglass is cut along the marked lines using metal scissors or cut with a hacksaw. Scissors cut faster and no dust. But it must be taken into account that when cutting with scissors, fiberglass is strongly bent, which somewhat worsens the strength of gluing copper foil, and if re-soldering of the elements is required, the tracks may peel off. Therefore, if the board is large and with very thin tracks, then it is better to cut it off with a hacksaw.

A printed circuit board pattern template is glued onto the cut-out blank using Moment glue, four drops of which are applied to the corners of the blank.

Since the glue sets in just a few minutes, you can immediately start drilling holes for radio components.

Hole drilling

It is best to drill holes using a special mini drilling machine with a 0.7-0.8 mm carbide drill. If a mini drilling machine is not available, then you can drill holes with a low-power drill with a simple drill. But when working with a universal hand drill, the number of broken drills will depend on the hardness of your hand. One drill is definitely not enough.

If the drill cannot be clamped, then its shank can be wrapped with several layers of paper or one layer of sandpaper. It is possible to wind tightly coil to coil of a thin metal wire on the shank.

After drilling is completed, it is checked whether all holes have been drilled. This is clearly visible if you look at the printed circuit board through the light. As you can see, there are no missing holes.

Drawing a topographic drawing

In order to protect the places of the foil on the fiberglass, which 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 tracks, it is better to pre-mark them with a soft, simple pencil or marker.

Before marking, it is necessary to remove traces of Moment glue, which glued 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 with a rag with any means, such as acetone or white spirit (as refined gasoline is called), and you can use any dishwashing detergent, such as Ferry.

After marking the tracks of the printed circuit board, you can begin to apply their pattern. Any waterproof enamel is well suited for drawing tracks, for example, alkyd enamel of the PF series, diluted to a suitable consistency with a white spirit solvent. You can draw tracks with different tools - a glass or metal drawing pen, a medical needle and even a toothpick. In this article, I will show you how to draw PCB tracks using a drawing pen and a ballerina, which are designed to be drawn on paper with ink.

Previously, there were no computers and all the drawings were drawn with simple pencils on whatman paper and then transferred with ink to tracing paper, from which copies were made using copiers.

Drawing a picture 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 drawer of the ballerina to the required line width and to set the diameter of the circle, adjust the second screw by moving the drawer from the axis of rotation.

Next, the drawer of the ballerina for a length of 5-10 mm is filled with paint with a brush. For applying a protective layer on a printed circuit board, paint of the PF or GF brand is best suited, as it dries slowly and allows you to work calmly. NC brand paint can also be used, but it is difficult to work with it, as it dries quickly. The paint should lay down well and not spread. Before drawing, the paint must be diluted to a liquid consistency, adding a suitable solvent to it little by little with vigorous stirring and trying to draw on scraps of fiberglass. To work with paint, it is most convenient to pour it into a nail polish bottle, in the twist of which a solvent-resistant brush is installed.

After adjusting the drawer of the ballerina and obtaining the required line parameters, you can begin to apply 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.

With the correct setting of the drawing pen and the desired consistency of paint around the holes on the printed circuit board, circles of perfectly round shape are obtained. When the ballerina begins to draw poorly, the remnants of dried paint are removed from the drawer gap with a cloth and the drawer is filled with fresh paint. to outline 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.

When the round contact pads on the board are drawn, you can start drawing conductive tracks using a manual drawing pen. The preparation and adjustment of a manual drawing pen is no different from the preparation of a ballerina.

The only thing that is additionally needed is a flat ruler, with pieces of rubber glued on one of its sides along the edges, 2.5-3 mm thick, 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 support for the hand when drawing a printed circuit board.

So that the printed circuit board does not slip when drawing tracks, it is advisable to place it on a sheet of sandpaper, which is two sandpaper sheets riveted together with paper sides.

If, when drawing paths and circles, they touched, then no action should be taken. It is necessary to allow the paint on the printed circuit board to dry to a state where it will not stain when touched, and use the tip of a knife to remove the excess part of the pattern. In order for the paint to dry faster, the board must be placed in a warm place, for example, in winter, on a radiator. In the summer season - under the rays of the sun.

When the pattern on the printed circuit board is completely applied and all defects are corrected, you can proceed to etching it.

Printed circuit board drawing technology
using a laser printer

When printing on a laser printer, the image formed by the toner is transferred electrostatically from the photo drum, on which the laser beam painted 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 texture of the paper. After cooling, 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 the toner is used to transfer the image of current-carrying tracks to a printed circuit board at home.

After the file with the printed circuit board drawing is ready, it is necessary to print it using a laser printer on paper. Please note that the image of the printed circuit board drawing for this technology must be viewed from the side of the installation of parts! An inkjet printer is not suitable for these purposes, as it works on a different principle.

Preparing a paper template for transferring a pattern to a printed circuit board

If you print a printed circuit board pattern on ordinary paper for office equipment, then due to its porous structure, the toner will penetrate deep 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 with 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, such as photographic paper, a substrate from self-adhesive films and labels, tracing paper, pages from glossy magazines.

As the paper for printing the PCB design, I use tracing paper from old stock. Tracing paper is very thin and it is impossible to print a template directly on it, it jams in the printer. To solve this problem, before printing on a piece of tracing paper of the required size, apply a drop of any glue in the corners and stick it on a sheet of A4 office paper.

This technique allows you to print a printed circuit board pattern even on the thinnest paper or film. In order for the toner thickness of the pattern 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 roughest type of paper, such as cardboard or something like that. It is quite possible that you will not get a good print the first time, and you will have to experiment a little, choosing the best print mode for a laser printer. In the resulting print of the pattern, the tracks and contact pads of the printed circuit board must be dense without gaps and smearing, since retouching is useless at this technological stage.

It remains to cut the tracing paper along the contour and the template for the manufacture of the printed circuit board will be ready and you can proceed to the next step, transferring the image to the fiberglass.

Transferring a pattern from paper to fiberglass

Transferring the PCB pattern 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 the fiberglass and pressed with great effort. 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 pattern remains on the printed circuit board.

Some craftsmen suggest transferring a pattern 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 the desired temperature and evenly press the paper against the entire surface of the printed circuit board when the toner solidifies. As a result, the pattern is not completely transferred and there are gaps in the pattern of PCB tracks. It is possible that the iron did not heat up enough, although the regulator was set to the maximum heating of the iron. I did not want to open the iron and reconfigure the thermostat. Therefore, I used another technology that is less laborious and provides a hundred percent result.

On a printed circuit board cut to size and degreased with acetone, a blank of foil fiberglass was glued to the corners of a tracing paper with a pattern printed on it. On top of the tracing paper put, for a more uniform pressure, heels of sheets of office paper. The resulting package was placed on a sheet of plywood and covered with a sheet of the same size on top. This whole sandwich was clamped with maximum force in the clamps.

It remains to heat the made 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 for cooling.

If an electric oven is not available, then you can also use a gas oven by adjusting the temperature with the gas supply knob according to the built-in thermometer. If there is no thermometer or it is faulty, then women can help, the position of the regulator knob, at which pies are baked, will do.

Since the ends of the plywood were warped, just in case, I clamped them with additional clamps. 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 the printed circuit boards, tighten the plates with screws and nuts. M10 will be enough.

After half an hour, the design has cooled down enough for the toner to harden, the board can be removed. At the first glance at the removed printed circuit board, it becomes clear that the toner transferred from the tracing paper to the board perfectly. The tracing paper fit snugly and evenly along the lines of the printed tracks, the rings of the pads and the marking letters.

The tracing paper easily came off almost all tracks of the printed circuit board, the remains of the tracing paper were 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 of the printer or remaining dirt or corrosion on the fiberglass foil. Gaps can be filled with any waterproof paint, nail polish or retouched 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.

Etching a printed circuit board at home is best in a solution of ferric chloride or hydrogen peroxide with citric acid. After etching, the toner from the printed tracks is easily removed with a swab dipped in acetone.

Then holes are drilled, conductive paths and contact pads are tinned, and radioelements are soldered.

This form was taken by a printed circuit board with radio components installed on it. The result was a power supply and switching unit for an electronic system that complements an ordinary toilet bowl with a bidet function.

PCB etching

To remove copper foil from unprotected areas of foil fiberglass in the manufacture of printed circuit boards at home, radio amateurs usually use a 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.

Etching solution recipes

Depending on the availability of components, radio amateurs use one of the solutions shown in the table below. Etching solutions are listed in order of popularity for their use by radio amateurs in the home.

Solution name	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% hydrogen peroxide solution	Availability of components, high pickling rate, 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	Dissolve ferric chloride in warm water	Sufficient etching rate, 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 pickling rate, reusable	Requires high precision
	Hydrochloric acid (HCl)	200 ml
Aqueous solution of copper sulphate	Water (H2O)	500 ml	In hot water (50-80 ° C), dissolve table salt, and then blue vitriol	Component Availability	The toxicity of copper sulfate and slow etching, up to 4 hours
	Copper sulfate (CuSO 4)	50 g
	Salt (NaCl)	100 g

Etch printed circuit boards in metal utensils are not allowed. To do this, use a container made of glass, ceramic or plastic. It is allowed to dispose of the spent pickling solution into the sewer.

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 listed solutions, by all criteria, this is the best.

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 the form of crystals 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 pickling solution is enough to remove 35 µm thick copper foil from a 100 cm2 printed circuit board. The spent solution is not stored and cannot be reused. By the way, citric acid can be replaced with acetic acid, but because of its pungent smell, you will have to pickle the printed circuit board in the open air.

Pickling solution based on ferric chloride

The second most popular pickling solution is an aqueous solution of ferric chloride. Previously, it was the most popular, since ferric chloride was easy to get at any industrial enterprise.

The etching solution is not picky about the temperature, it etchs rather quickly, 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 the preparation of an etching solution.

If the used solution of ferric chloride is stored in an airtight container, then it can be used repeatedly. To be regenerated, it is enough to pour iron nails into the solution (they will immediately be covered with a loose layer of copper). Leaves hard-to-remove yellow spots upon contact with any surface. At present, a solution of ferric chloride for the manufacture of printed circuit boards is used less frequently due to its high cost.

Etching solution based on hydrogen peroxide and hydrochloric acid

Excellent pickling solution, provides high pickling speed. Hydrochloric acid, with vigorous stirring, is poured into a 3% aqueous solution of hydrogen peroxide in a thin stream. Pouring hydrogen peroxide into acid is unacceptable! 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 gets on. For this reason, an etching solution with hydrochloric acid at home is not recommended.

Etching solution based on copper sulphate

The method of manufacturing printed circuit boards using copper sulphate is usually used if it is impossible to manufacture etching solutions based on other components due to their unavailability. Copper sulfate is a pesticide and is widely used for pest control in agriculture. In addition, the PCB etching time is up to 4 hours, while it is necessary to maintain the temperature of the solution at 50-80°C and ensure that the solution is constantly changed at the etched surface.

PCB etching technology

For etching the board in any of the above etching solutions, glass, ceramic or plastic utensils, such as dairy products, are suitable. If there was no suitable container size at hand, then you can take any box made of thick paper or cardboard of a suitable size and line its inside with plastic wrap. An etching solution is poured into the container and a printed circuit board is carefully placed on its surface with a pattern down. Due to the forces of the surface tension of the liquid and the low weight, the board will float.

For convenience, a cork from a plastic bottle can be glued to the center of the board with glue. The cork will simultaneously serve as a handle and a float. But there is a danger that air bubbles form on the board and in these places the copper will not corrode.

To ensure uniform etching of copper, you can put the printed circuit board on the bottom of the tank with the pattern up and periodically shake the bath with your hand. After a while, depending on the pickling 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 final dissolution of copper in the pickling solution, the printed circuit board is removed from the bath and thoroughly washed under running water. The toner is removed from the tracks with a rag soaked in acetone, and the paint is well removed with a rag soaked in a solvent that was added to the paint to obtain its desired consistency.

Preparing the printed circuit board for the 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 must be processed in a circular motion with fine sandpaper. You don’t need to get carried away, because the copper tracks are thin and can be easily grinded off. Just a few passes with a low-pressure abrasive is sufficient.

Further, the current-carrying tracks and contact pads of the printed circuit board are covered with an alcohol-rosin flux and tinned with soft solder with an eclectic soldering iron. so that the holes on the printed circuit board are not tightened with solder, you need to take a little of it on the soldering iron tip.

After completing the manufacture of the printed circuit board, all that remains is to insert the radio components into the intended positions and solder their leads to the sites. Before soldering, the legs of the parts must be moistened with alcohol-rosin flux. If the legs of the radio components are long, then they must be cut with side cutters before soldering to a protrusion length of 1-1.5 mm above the surface of the printed circuit board. After completing the installation of the parts, it is necessary to remove the remains of rosin using any solvent - alcohol, white spirit or acetone. They all successfully dissolve rosin.

It took no more than five hours to implement this simple capacitive relay circuit from the PCB traces to the production of a working sample, much less than the layout of this page.