PCB etching is cheap. A simple and cheap way to etch printed circuit boards

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 designed 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 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 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 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 agent, such as acetone or white spirit (as refined gasoline is called), and any dishwashing detergent, such as Ferry, can also be used.

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 edge 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 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 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 at this technological stage is useless.

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 100% 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	disadvantages
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 an etching solution 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 is 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 the 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 electric 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.

High-quality installation is the key to reliable and long-term operation of a device. In this article I will try to briefly and in detail explain the whole process of creating printed circuit boards. The LUT method is the most accessible of all existing ones, many have probably heard the name, and many are familiar with it, since more than half of people who are passionate about electronics use this particular technology to create printed circuit boards at home.

All you need to create fairly high-quality printed circuit boards at home is a laser printer, an iron - preferably domestic and, of course, a piece of foil fiberglass. A template with exact dimensions must be printed on a laser printer (namely, a laser printer), be sure to have the darkest possible shade, then carefully cut out the template.

At the same time, many advise printing the template on photo paper, but I personally have never used photo paper (and I don’t have a laser printer, I have to run to the nearest Internet club every time), in my case, plain A4 paper.

After this operation, you need to prepare the board, and for this, the first step is to cut the fiberglass to the size of your board, then carefully clean the surface of the foil with a fine sandpaper to a shine, then rinse the foil with a solvent or acetone. After that, we immediately begin the process.

Let's heat up our iron. Initially, I advised using domestic ones, the reason is quite simple - the bottom of branded irons is not smooth, and their weight is not very good, but domestic is what you need. We lay the template evenly on the board so that the toner looks at the side of the foil, then carefully begin to iron the board. Those who are doing the process for the first time, I advise you to fix the template relative to the board, so that in the end a curved board does not come out.

You need to iron for 90 seconds (I personally do this), after which we cut down the iron and let the board cool for one or two minutes, then we bring a vessel with water and throw the board there for a few minutes, after which we carefully remove paper.

The result is an almost finished semi-finished product, in places where the toner did not stick well or is completely absent - you can cover it with ordinary nail polish or manicure. To do this, take a varnish, a toothpick and finish the board. Let the manicure or varnish exhale for 15-30 minutes (depending on the specific varnish). Next, you need to prepare for the last stage - etching, and we'll talk about this further ...

After the template applied to the surface of the foil fiberglass, it's time to start the process of etching the board - this stage is the easiest. Someone uses copper sulfate for etching, others ferric chloride, in my area this is all a luxury, so I have to use an alternative method of etching printed circuit boards.
First, a little about the ingredients. All we need is a teaspoon of table salt, citric acid (2 bags of 40g), and hydrogen peroxide - 3% solution.

Where to get all this? Table salt can be stolen from your own kitchen, hydrogen peroxide is sold in 100mg bottles at any pharmacy (we need 2 bottles), and citric acid can be purchased at any grocery store.

Next, you need to look for a suitable vessel - plastic, glass or enameled. In this vessel, we mix all our components and add 20-50 ml of ordinary tap water to the solution. At the end, it remains to throw our board into the solution.

After 40-60 minutes, the board will be etched. The disadvantage of this solution is that it is enough for 2-3 boards the size of a pack of cigarettes, in fact, almost a one-time solution, but accessible to everyone.

All that remains next - you yourself know better than me - drilling holes for components, tinning the tracks (if you wish, but I advise you, the tin layer saves the copper tracks from oxidation) and the final assembly of electronic components.

The LUT method allows you to get fairly high-quality tracks with a thickness of up to 0.3-0.5 mm, therefore, it can be used to create printed circuit boards of almost industrial quality, but if you make a board, say for surface mounting (in the case of assembling digital devices of one kind or another ), where processors and integrated circuits with numerous small pins are involved, then the LUT method is not the best option, then a more modern and high-quality method for creating printed circuit boards, photoresist, comes to the rescue.

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 designed 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 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 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 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 agent, such as acetone or white spirit (as refined gasoline is called), and any dishwashing detergent, such as Ferry, can also be used.

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 edge 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 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 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 at this technological stage is useless.

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 100% 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	disadvantages
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 an etching solution 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 is 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 the 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 electric 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.

conditions using hydrogen peroxide. Everything is very simple and does not require much effort.

For work, we need the following list of tools:
- Program - layout 6.0.exe (other modification is possible)
- Photoresist negative (this is a special film)
- Laser printer
- Transparent film for printing
- PCB marker (if not, you can use nitro varnish or nail polish)
- Foil textolite
- UV lamp (if there is no lamp, we are waiting for sunny weather and using the sun's rays, I have done this many times, everything works out)
- Two pieces of plexiglass (you can use one, but I made two for myself) you can also use a CD box
- Stationery knife
- Hydrogen peroxide 100 ml
- Lemon acid
- soda
- Salt
- Smooth hands (required)

In the layout program, we make the layout of the board

We carefully check it so as not to confuse anything and put it on print

Be sure to put all the checkmarks on the left as in the photo. The photo shows that we have a drawing in a negative image, since we have a negative photoresist, those areas that UV rays hit will be paths, and the rest will be washed off, but more on that later.

Next, we take a transparent film for printing on a laser printer (available for sale), one of its sides is slightly matte and the other is glossy, so we put the film so that the pattern is on the matte side.

We take textolite and cut it to the size of the required board

Cut the photoresist to size (when working with photoresist, avoid direct sunlight, as they will ruin the photoresist)

We clean the textolite with an eraser and wipe it so that there is no debris left

Next, tear off the protective transparent film on the photoresist

And carefully glue it to the textolite, it is important that there are no bubbles. We iron well so that everything sticks well

Next, we need two pieces of plexiglass and two clothespins, you can use a CD box

We put our printed template on the board, be sure to put the template with the printed side on the textolite and clamp it between the two halves of the plexiglass so that everything fits snugly

After we need a UV lamp (or a simple sun on a sunny day)

We screw the light bulb into any lamp and set it above our board at a height of about 10-20 cm. And turn it on, the illumination time from such a lamp as in the photo at a height of 15 cm is 2.5 minutes. I do not advise longer, you can ruin the photoresist

After 2 minutes, turn off the lamp and see what happened. Paths must be clearly visible

If everything looks good, proceed to the next step.

We take the listed ingredients
- Peroxide
- Lemon acid
- Salt
- soda

Now we need to remove the non-exposed photoresist from the board, it must be removed in a solution of soda ash. If it doesn't exist, then you need to make it. Boil water in a kettle and pour into a container

Pour in plain baking soda. You don’t need much for 100-200 ml 1-2 tablespoons of soda and mix well, the reaction should begin

Let the solution cool down to 20-35 degrees (you can’t put the board in the hot solution right away, the entire photoresist will come off)
We take our board and remove the second protective film MANDATORY

And we put the board in the COOLED solution for 1-1.5 minutes

Periodically we take out the board and rinse it under running water, gently cleaning it with a finger or a soft kitchen sponge. When all the excess is washed away, such a fee should remain

The photo shows that it was washed off a little more than necessary, probably overexposed in the solution (which is not recommended)

But it's okay. just take a marker for printed circuit boards or nail polish and cover up all the missteps with it

Next, pour 100 ml of Peroxide into another container, 3-4 tablespoons of citric acid and 2 tablespoons of salt.

I don’t know about you, but I have a fierce hatred for classic circuit boards. A montage is such crap with holes where you can insert parts and solder, where all connections are made through wiring. It seems to be simple, but it turns out such a mess that it is very problematic to understand anything in it. Therefore, errors and burnt parts, incomprehensible glitches. Well fuck her. Only to spoil the nerves. It is much easier for me to draw a schematic in my favorite and immediately etch it in the form of a printed circuit board. Using laser-ironing method everything comes out for what that one and a half hours of easy work. And, of course, this method is great for making the final device, since the quality of printed circuit boards obtained by this method is very high. And since this method is very difficult for the inexperienced, I will gladly share my proven technology, which allows you to get printed circuit boards the first time and without any strain. with tracks 0.3mm and clearance between them up to 0.2mm. As an example, I will make a debug board for my controller tutorial. AVR. You will find the principal in the entry, and

There is a demo diagram on the board, as well as a lot of copper patches, which can also be drilled and used for your needs, like a regular circuit board.

▌Technology for manufacturing high-quality printed circuit boards at home.

The essence of the method of manufacturing printed circuit boards is that a protective pattern is applied to the foil textolite, which prevents etching of copper. As a result, after etching, traces of conductors remain on the board. There are many ways to apply protective drawings. Previously, they were drawn with nitro paint, using a glass tube, then they began to be applied with waterproof markers or even cut out of adhesive tape and pasted onto the board. Also available for amateur use photoresist, which is applied to the board, and then illuminated. Illuminated areas become soluble in alkali and washed off. But in terms of ease of use, low cost and speed of manufacture, all these methods lose a lot. laser ironing method(Further LUT).

The LUT method is based on the fact that the protective pattern is formed by toner, which is transferred to the textolite by heating.
So we need a laser printer, since they are not uncommon now. I am using a printer Samsung ML1520 with original cartridge. Refilled cartridges fit extremely poorly, as they lack the density and uniformity of toner delivery. In the print properties, you need to set the maximum density and contrast of the toner, be sure to turn off all saving modes - this is not the case.

▌Tool and materials
In addition to foil textolite, we also need a laser printer, iron, photo paper, acetone, fine sandpaper, a suede brush with metal-plastic pile,

▌Process
Then we draw a drawing of the board in any software convenient for us and print it. Sprint layout. Simple drawing for boards. To print normally, you need to set the colors of the layers to black on the left. Otherwise it will be bullshit.

Printout, two copies. You never know, suddenly we mess up one.

Here lies the main subtlety of the technology LUT because of which many people have problems with the release of high-quality boards and they quit this business. Through many experiments, it has been found that the best result is achieved when printing on glossy inkjet photo paper. I would call photo paper ideal LOMOND 120g/m2

It is inexpensive, sold everywhere, and most importantly, it gives an excellent and repeatable result, and does not burn with its glossy layer to the printer's stove. This is very important, as I have heard of cases where the printer oven was crap with glossy paper.

We load paper into the printer and boldly print on the glossy side. You need to print in mirror image so that after transferring the picture is true. How many times I made mistakes and made wrong prints, do not count :) Therefore, the first time it is better to print on plain paper for testing and check that everything is correct. At the same time, warm up the printer's oven.

After printing the picture, in no case can not be grabbed by hands and preferably protected from dust. So that nothing interferes with the contact of the toner and copper. Next, cut out the board pattern exactly along the contour. Without any stock - the paper is stiff, so everything will be fine.

Now let's deal with textolite. We will immediately cut out a piece of the desired size, without tolerances and allowances. As much as needs.

It needs to be well sanded. Carefully, trying to tear off all the oxide, preferably in a circular motion. A little roughness won't hurt - the toner will stick better. You can take not a skin, but an abrasive sponge "effect". Just need to take a new one, not greasy.

It is better to take the smallest skin you can find. I have this one.

After sanding, it must be carefully degreased in the same way. I usually rub a cotton pad from my wife and, having moistened it properly with acetone, I carefully walk over the entire surface. Again, after degreasing, in no case should you grab it with your fingers.

We impose our drawing on the board, naturally with the toner down. warm up iron to the max, holding the paper with your finger, press well and iron one half. It is necessary that the toner sticks to the copper.

Next, without allowing the paper to move, we iron the entire surface. We press with all our might, polish and iron the board. Trying not to miss a millimeter of the surface. This is the most important operation, the quality of the entire board depends on it. Don't be afraid to press with all your might, the toner won't float or smudge, as the photo paper is thick and perfectly protects it from spreading.

We iron until the paper turns yellow. However, this depends on the temperature of the iron. It almost doesn’t turn yellow on my new iron, but on the old one it almost charred - the result was equally good everywhere.

After that, you can let the board cool down a bit. And then, grabbing it with tweezers, we put it under the water. And keep some time in the water, usually two or three minutes.

Taking a brush for suede, under a strong stream of water, we begin to furiously lift the outer surface of the paper. We need to cover it with multiple scratches so that the water penetrates deep into the paper. In confirmation of your actions, there will be a manifestation of the drawing through thick paper.

And with this brush we dry the board until we remove the top layer.

When the whole drawing is clearly visible, without white spots, then you can start carefully, rolling the paper from the center to the edges. Paper lomond rolls great, leaving 100% toner and pure copper almost immediately.

Having rolled the whole pattern with your fingers, you can thoroughly scrape the entire board with a toothbrush to clean out the remnants of the glossy layer and scraps of paper. Don't be afraid, it's almost impossible to remove a well-seasoned toner with a toothbrush.

We wipe the board and let it dry. When the toner dries and turns gray, it will be clearly visible where the paper is left, and where everything is clean. Whitish films between the tracks must be removed. You can destroy them with a needle, or you can tear them with a toothbrush under running water. In general, it is useful to brush along the paths. Whitish gloss can be pulled out of narrow slots with electrical tape or masking tape. It sticks not as violently as usual and does not break off the toner. But the remnants of gloss tears off without a trace and immediately.

Under the light of a bright lamp, carefully examine the layers of toner for breaks. The fact is that when cooled, it can crack, then a narrow crack will remain in this place. The cracks gleam under the lamplight. These areas should be touched up with a permanent marker for CDs. Even if there is only a suspicion, it is still better to paint over. With the same marker, you can also draw low-quality tracks, if any. I recommend the marker Centropen 2846- it gives a thick layer of paint and, in fact, they can stupidly draw paths.

When the board is ready, you can bodyaze a solution of ferric chloride.

Technical digression, if you wish, you can skip it
In general, you can poison a lot of things. Someone poisons in blue vitriol, someone in acid solutions, and I in ferric chloride. Because it is sold in any radio store, poisons quickly and cleanly.
But ferric chloride has a terrible drawback - it just gets dirty with a scribe. It will get on clothes or any porous surface like wood or paper, everything, consider the stain for life. So dive your Dolce Gabana sweatshirts or Gucci boots into the safe and wrap three rolls of tape around them. And ferric chloride in the most cruel way destroys almost all metals. Especially fast aluminum and copper. So etching dishes should be glass or plastic.

I throw 250 gram package of ferric chloride per liter of water. And with the resulting solution, I poison dozens of boards until it stops poisoning.
The powder must be poured into the water. And make sure that the water does not overheat, otherwise the reaction proceeds with the release of a large amount of heat.

When the powder is all dissolved and the solution acquires a uniform color, you can throw a board there. It is desirable that the board float on the surface, copper down. Then the precipitate will fall to the bottom of the tank, without interfering with the etching of deeper layers of copper.
To prevent the board from sinking, you can stick a piece of foam to it on double-sided tape. That's exactly what I did. It turned out very convenient. I screwed in the screw for convenience, to hold on to it like a handle.

It is better to dip the board several times into the solution, and lower it not flat, but at an angle so that air bubbles do not remain on the copper surface, otherwise there will be jambs. Periodically it is necessary to get out of the solution and monitor the process. On average, the etching of the board takes from ten minutes to an hour. It all depends on the temperature, strength and freshness of the solution.

The etching process accelerates very sharply if you lower the hose from the aquarium compressor under the board and blow bubbles. The bubbles stir the solution and gently knock out the reacted copper from the board. You can also shake the board or container, the main thing is not to spill it, otherwise you won’t wash it off later.

When all the copper is etched, then carefully remove the board and rinse under running water. Then we look at the clearance, so that there is no snot and undergrass anywhere. If there is snot, then we throw another ten minutes into the solution. If the tracks are etched or there are breaks, then the toner is crooked and these places will need to be soldered with copper wire.

If all is well, then you can wash off the toner. To do this, we need acetone - a true friend of a drug addict. Although now it is becoming more difficult to buy acetone, because. some moron from the state drug control decided that acetone is a substance used to make drugs, which means that its free sale should be banned. Works well in place of acetone 646 solvent.

We take a piece of bandage and thoroughly wetting it with acetone, we begin to wash off the toner. You don’t need to press hard, the main thing is not to move too fast, so that the solvent has time to be absorbed into the pores of the toner, corroding it from the inside. It takes two or three minutes to flush the toner. During this time, even green dogs under the ceiling will not have time to appear, but it still does not hurt to open the window.

The washed board can be drilled. For these purposes, for many years I have been using a motor from a tape recorder, powered by 12 volts. The monster machine, though its resource is enough for about 2000 holes, after which the brushes burn out completely. And you also need to tear out the stabilization circuit from it by soldering the wires directly to the brushes.

When drilling, try to keep the drill strictly perpendicular. Otherwise, then you'll put the damn chip in there. And with double-sided boards, this principle becomes the main one.

The manufacture of a double-sided board also occurs, only here three reference holes are made, as small as possible in diameter. And after etching one side (the other at this time is sealed with adhesive tape so that it does not etch), the second side is combined through these holes and rolled. The first is sealed tightly with adhesive tape and the second is poisoned.

On the front side, you can apply the designation of radio components using the same LUT method, for beauty and ease of installation. However, I don’t bother like that, but comrade Woodocat from LJ community ru_radio_electric does so always, for which he has great respect!

Soon I will probably also publish an article on photoresist. The method is more confusing, but at the same time, it’s more fun for me to do it - I like to fool around with reagents. Although I still make 90% of the boards with LUT.

By the way, about the accuracy and quality of the boards made by the laser ironing method. Controller P89LPC936 in the building TSSOP28. The distance between the tracks is 0.3mm, the width of the tracks is 0.3mm.

Resistors on the top board 1206 . What is it?