Documentation

Making a board without etching

"Documentation" - Technical information by application electronic components, features of construction of various radio engineering And electronic circuits, as well as documentation on the features of working with engineering software and regulatory documents (GOST).

The method of manufacturing a printed circuit board by cutting has long been known and has many supporters, since it does not require computer equipment and a home chemical laboratory. You only need a simple cutter, which can be easily made from a piece of hacksaw blade.

Rice. 1

To develop this method, I want to offer a more advanced tool and, of course, a different cutting technique. I make the cutter on a sharpener from an old MZ tap (or M3.5, M4). The cutter drawing is shown in Fig. 1. On it, thin solid lines show the contours of the tap before it is processed, and thin dashed lines show the invisible bottom of the remaining (upper in the picture) groove.

After turning, the cutter must be inserted into the handle, for which an old felt-tip pen or fountain pen will do. The cutter shank is heated in the flame of a gas stove to a temperature at which the plastic of the future handle melts, and, held with pliers, inserted into a previously prepared hole. The cutting edge is sharpened and finished using fine-grained sandpaper.

The design is applied to the foil of the board blank in any way, even with a pencil. Using the described tool is completely different from working with a traditional cutter and is more reminiscent of the techniques of a linocut maker using a graver. A groove in the foil to the base material of the board is cut by moving away from you, and not towards you, turning the handle left and right around the longitudinal axis.

Rice. 2

The decisive factor in the work is the choice of the optimal cutting angle a (Fig. 2). If the angle is too large, the cutter penetrates into the material, begins to require more and more force and stops completely, and if it is too small, it “jumps out” of the material. At the optimal angle - it is determined experimentally - the edge cuts off a narrow strip of foil, slightly gripping the base layer.

Each cut is made in one pass, and not several, like with a conventional cutter, so even with little skill, the speed of making the board is very high. I spend about half an hour on a board measuring 100x60 mm.

Publication date: 06.12.2007

Readers' opinions

• Alfred / 06/18/2012 - 05:31
  This is the ideal awensr. Everyone should read this
• EvgEniy / 05/22/2012 - 12:10
  I had never thought about this method before... Thanks for the interesting idea! Now I want to make an electronically controlled machine that will do this itself (a la plotter)
• 000 / 24.12.2011 - 00:48
  Well, you can, of course, disable a simple board, but if something is more serious, alas, this method will look like masochism
• Zvezdochet / 04/13/2011 - 14:11
  To be honest, this is the first time I’ve heard of this method. And I can’t imagine a cutting technique with any other tool, but what is described in the article is an ingenious and simple method!

Pickling is the process of cleaning and processing a metal workpiece. Chemical, acidic, alkaline, electrochemical - there are many ways to perform this technological operation. Where is metal etching used, why is it used in industry, what are the processing methods using this technology, all these issues are discussed in detail in the article below.

What is etching

This is a technology for removing the top layer from the surface of a metal part. The technology is used to clean workpieces from scale, rust, oxides and remove the top layer of metal. Using this method, the top layer is removed to search for internal defects and study the macrostructure of the material.

Using etching, they clean the part and increase surface adhesion. This is done for the subsequent connection of the metal surface with another workpiece, before applying paint, enamel, galvanic coating and other protective coatings.

The method allows you not only to quickly clean the part, but also to create the desired pattern on the metal surface. Using this method, the finest channels and complex images are cut out on a metal surface. You can clean large parts or rolled products. The processing depth is adjustable with an accuracy of several microns, which makes it possible to produce complex parts with small grooves and other complex elements.

Application of etching in industry

1. For cleaning parts made of carbon, low-alloy and high-alloy steel, titanium and aluminum from oxide film.
2. To improve adhesion before applying galvanic and other types of protective coatings.
3. To prepare steel surfaces for hot-dip galvanizing.
4. To conduct macroanalysis to detect the formation of intergranular corrosion in stainless steels.
5. This technology is used to process small metal parts, such as watch gears.
6. Copper processing is used to make semiconductor chips and printed circuit boards in electronics. This method applies a conductive pattern to the microcircuit.
7. For quick cleaning of hot rolled metal products, heat-treated parts, from oxides.
8. In the aircraft industry, this technology is used to reduce the thickness of aluminum sheets to reduce the weight of the aircraft.
9. In the manufacture of metal inscriptions and drawings. Etching produces relief images drawn by removing a layer of metal according to a specific stencil.

Types of etching

The main types of metal processing used in industry:

• electrolytic - there are cathode and anodic;
• chemical;
• plasma.

Electrolytic etching

Electrolytic or galvanic metal processing is used to quickly clean parts, apply engravings and produce grooves. Metal parts are immersed in an acid or salt electrolyte. The part becomes a cathode - a negative electrode or an anode - a positive electrode. Therefore, two types of electrolytic etching are classified - cathodic and anodic.

1. Cathodic etching. The method is used to remove scale from the surface of carbon steel products after hot rolling or oil quenching. In cathodic etching, the material for the anode is lead, and the electrolyte is a solution of hydrochloric, sulfuric acid or an alkali metal salt. During the electrolysis process, hydrogen gas is actively released at the cathode, which interacts with iron and removes scale. During the cathode method, the metal surface is actively saturated with hydrogen, which increases the fragility of the workpiece. Therefore, the cathode method is not used for thin-walled products.
2. Anodic electrochemical cleaning. This is the most common method in mechanical engineering. The process involves mechanically tearing off the oxide film on the anode with oxygen and mixing metal molecules with the electrolyte. An electrolyte is a solution of acids or salts of the metal being processed. Lead, copper and other metals are used as the cathode. During anodic treatment, the surface of the product becomes clean, with slight roughness, and the metal dissolves in the electrolyte. With this method, there is a risk of reducing the thickness of the workpiece and over-etching.

Chemical etching

The chemical treatment method is used to clean the surface of a part from oxide film, scale and rust for workpieces made of the following materials:

• ferrous metals;
• stainless and heat-resistant steels;
• titanium and its alloys;
• aluminum

For etching, sulfuric, hydrochloric or nitric acid is used. The workpiece is immersed in an acid or alkaline solution, molten salt and kept for the required time interval. The required cleaning time can range from 1 to 120 minutes.

The cleaning process occurs due to the release of hydrogen when the acid interacts with the metal. Acid molecules penetrate through pores and cracks under the oxide film. There they interact with the metal surface and hydrogen is released. The released gas tears off the oxide film and cleans the part.

Simultaneously with the oxides, the metal being treated dissolves in the acid. To prevent this process, corrosion inhibitors are used.

Plasma etching

With the ion-plasma method, cleaning and removal of the surface layer occurs by bombarding the part with ions of inert gases that do not react chemically with the molecules of the material being processed. Allows you to make high-precision notches and grooves with an accuracy of up to 10 nm. The technology is used in microelectronics.

The plasma-chemical method involves excitation of plasma in a chemically active medium, which causes the formation of ions and radicals. Active particles falling on a metal surface cause a chemical reaction. In this case, light compounds are formed, which are removed from the surrounding air by vacuum pumps.

The method is based on chemical reactions that occur when using reactive gases, such as oxygen, which are highly reactive. These gases actively interact in the gas discharge plasma. Unlike plasma treatment in inert gases, with this cleaning method, the active gas reacts only with certain molecules.

The disadvantage of this method is the lateral expansion of the grooves.

Etchants

Pickling of carbon steels is carried out in an 8-20% solution of sulfuric or 10-20% hydrochloric acid. With the obligatory addition of corrosion inhibitors (KS, ChM, UNIKOL) to eliminate the fragility of the material and reduce the possibility of over-etching.

Products made of stainless or heat-resistant steel are processed using a solution consisting of: 12% hydrochloric, 12% sulfuric, 1% nitric acid. If required, processing is done in several stages. The first is that scale is loosened in 20% hydrochloric acid. The second stage is immersion in a 20-40% nitric acid solution to completely remove surface contaminants.

The thick layer of scale that forms on stainless steel is removed during its production by 75-85% molten caustic soda with 20-25% sodium nitrate. After which, complete removal of oxides is carried out in 15-20% nitric acid.

Processing of aluminum and alloys based on it involves removing the refractory oxide film from the surface of the workpiece. For this purpose, alkaline or acidic solutions are used. Usually 10-20% alkali is used, at a temperature of 50-80 ºС, the etching procedure takes less than 2 minutes. The addition of sodium chloride and sodium fluoride to the alkali makes this process more uniform.

The purification of titanium and its alloys, carried out after heat treatment, is carried out in several stages. At the first stage, scale is loosened in concentrated caustic soda. Then the scale is removed in a solution of sulfuric, nitric or hydrofluoric acid. To remove the remaining pickling sludge, use hydrochloric or nitric acid with the addition of a small amount of hydrofluoric acid.

When processing copper and its alloys, etchants from hydrogen peroxide, chromic acid and the following salts are used:

• copper chloride;
• ferric chloride;
• ammonium persulfate.

This information material describes in detail the pickling process used in metallurgical plants. The method allows you to quickly clean the metal surface from oxides, scale, rust and other contaminants. Thanks to etching, it is possible to apply various designs to metal, create complex microcircuits and make microscopic channels of the desired shape.

Metal etching sometimes replaces casting and engraving; it makes the whole process much simpler. You can get a design that is both concave - relief, and convex - bas-relief. Metal etching at home can be chemical or galvanic. The first option is more toxic when used at home, so for starters we will use the second, it is also called electrochemical.

Equipment

You need to take a power supply or transformer that can output from 4 to 7 V. In addition, you will need a dielectric bath; it must contain the necessary part and a second metal object that is connected to the anode.

To etch a pattern on metal, you must use iron sulfate. If the design is needed on a copper or brass surface, then use it. You can also use it. The main thing is that the water is distilled.

Preparing the part for etching

In order for the etching to be uniform and in the right places, the part must be cleaned of dirt and also degreased. For more convenient work, copper wire is soldered onto the part with tin; it will be convenient to hold the object by it. To clean the surface, you need to dip the object to be converted into 10% sodium hydroxide, the temperature of which is 50°C, then into a 15% sulfuric acid solution and hold it there for two minutes, then rinse it in hot water. When the procedure is completed, the surfaces of the object will be completely cleaned, and of course, you cannot touch them with your hands.

Electrochemical etching of metal

We need to protect areas that should not be etched. To do this, you need to apply a special mastic to these surface areas. It is made from three parts of wax and two parts of rosin, they are melted in a tin can, stirring. After everything turns into a homogeneous mass, it is allowed to cool and divided into fragments. Each of them is placed in gauze so that later, when pressed, as much mastic as necessary can seep through it. After this, the workpiece that we will etch heats up. Now we take the created mixture, which was placed in gauze, and rub the surface with an even layer.

After cooling, the mastic becomes hard. The top is coated with light water-soluble paint. This can be watercolor or gouache white. After which the coating should dry. Then you can apply the design; it will stick well to the paint. It can be depicted using a pencil or translated using carbon paper. Then this outline needs to be scratched with a needle all the way to the metal.

Now the etching of the metal by electrolysis begins, we connect one rod to the anode - plus, the other to the cathode - minus. We connect the part on which the image will be applied to the first, and any steel plate to the second. After this, the process of etching the metal begins where the image was scratched.

If you need to create a multi-level drawing, everything is done in the same way as described above. Only the contours are checked each time, and when the smallest of them have been etched to the required depth, the part is removed and painted over with heated mastic using a brush. When it hardens, everything is repeated again until the next level of the drawing. In this process, an image is gradually created.

In this way, metal is etched at home, after which the surface is washed with turpentine and then polished, giving the product a finished look.

Chemical etching

Now let's look at how to create a pattern on a metal surface without the use of electrical devices. To do this, we need chemicals that are freely sold in hardware stores. So, let's begin. For etching we need:

• "White Spirit";
• paint that does not dissolve in White Spirit;
• acetone;
• resin, which is used to cover roofs;
• table salt;
• copper sulfate.

Cleaning the part

To begin with, the part where the image is planned is cleaned with fine sandpaper and degreased. When the surface is ready, you need to seal the place where the design will be applied with adhesive tape or something similar. After this, the entire remaining surface, where chemical etching should not affect the metal, is painted over. It can be of any color, as long as it is resistant to White Spirit.

Once the paint is dry, you can remove the adhesive tape. Beneath it is clean metal, ready to create a design on it. Now you need to apply an image onto this “mini-canvas”. It is made using resin, which is dissolved in White Spirit until it becomes liquid, like paint. Use it to paint the desired image using a brush. What’s good about this kind of improvised paint is that if something doesn’t work out in the drawing, you can remove it by moistening a cloth or cotton swab in White Spirit. If there are very small details in the drawing that did not turn out well with a brush, they can be corrected with a needle, scraping off the excess after drying.

In this way, you can etch a knife, keys, in general, any metal object. Now that the drawing is completely ready, you can begin the etching itself.

Etching solution

We need a liter of water, in which we need to dissolve 100 g of copper sulfate, and then add salt. It needs to be sprinkled until it stops dissolving. The resulting mixture will have a blue color. However, after a metal object is immersed in it, the color will begin to change to green.

So, let's dive into the detail. The chemical process begins immediately. In all this production, no substances harmful to health are released, so this metal etching at home is safe.

Actions during a chemical reaction

During the reaction, a plaque forms, which will become more and more numerous. It slows down the whole process, so you need to periodically wash it off with water. You should not do this using various brushes, brushes and other tools, because you can damage the paint. But it seems to hold the entire design, and it would be a shame if, while etching a knife, for example, you inadvertently damage the design on it. This is a very delicate work that requires a steady hand and patience.

The depth of the pattern directly depends on the time during which the metal remains in the solution. There are no exact criteria, so each master must observe the progress of the chemical reaction himself. And only after doing this several times will it be possible to say with confidence how much time is needed to develop the desired pattern to the intended depth.

Advantages and disadvantages of electrochemical and chemical etching

The advantages of electrochemical etching of metal at home include the fact that the created pattern is clearer, this is clearly visible if you look at it with magnification. However, the downside is that this method requires an electrical device, which not everyone may have.

The advantages of chemical etching include the fact that everything you need can be bought at a hardware store. These ingredients are cheap, and, most importantly, you don’t need to look anywhere for a power supply or other devices capable of delivering from 4 to 7 V. However, the disadvantage is the imperfect edges of the pattern.

As you know, metal is quite difficult to process at home without special skills and tools, especially if it is such a hard metal as steel. However, you can call on chemistry to help: there is such a chemical process - electrolysis. It flows on the electrodes when an electric current passes through electrolyte solutions. Those. If you take a metal workpiece as an electrode and use ordinary salt water as an electrolyte, then when a current passes through it, the metal will begin to be etched off; in other words, atoms from the surface of the metal will begin to “fly away.” Thus, metal processing does not always require any special skills and tools, because electricity can do everything for us.

In this article we will look at how to etch an inscription or design on a metal plate. For this you will need:

• Plastic or glass container.
• Salt.
• Metal plate.
• Power supply 5 - 12 volts.
• Connecting wires.

Electrochemical engraving on metal

Step 1. Cut out a rectangular piece from a metal plate, on which the inscription will be etched in the future. You can get a metal plate 1-2 mm thick at any hardware store; I bought the cheapest steel eye.

A piece cut from it:

Step 2. Carefully sand the surfaces of the workpiece, first with coarse sandpaper, then with fine sandpaper. The surface should become shiny, covered with many small scratches. You also need to sand the edges and edges of the plate with sandpaper. After sanding, the metal must be degreased with alcohol, solvent, or simply washed thoroughly with hot water and soap. After this, you should not touch surfaces with oily hands.

Step 3. Using a laser printer, print out the design that will be immortalized on the metal and transfer it to the metal using laser-iron technology, which has been described more than once on the Internet. You need to print it in a mirror image. If you don't have a laser printer at hand, you can just as easily draw a design with nail polish or a permanent marker. The painted area will remain untouched, and the bare metal will undergo electrolysis, i.e. it will simply get poisoned.

Step 4. Now that the workpiece is completely ready for etching, you need to take a non-metallic container, pour water into it and add salt. The speed of etching greatly depends on the concentration of salt; the more salt, the faster the process. If the etching speed is too high, there is a risk of damage to the protective layer of varnish or toner from the printer, and the drawing will not be of high quality. The optimal ratio is a tablespoon of salt per glass of water.
The anode must be secured in the container, i.e. the metal workpiece itself and the cathode - a simple piece of metal. The larger its area, the higher the etching rate will be. The etching installation is clearly shown in the picture below:

The plus from the power source (anode) is connected to the workpiece, and the minus (cathode) is connected to the solution. In this case, it is advisable to install several negative contacts on all sides of the workpiece, then the etching will take place evenly on all sides.

A few words about the power source. I use a computer power supply, or rather its 12-volt line. The higher the voltage, the higher the etching speed. You can also use a regular cell phone charger; its output is 5 volts, this voltage will be quite enough. You should not increase the voltage above 12 volts, otherwise the process will be too active, the protective layer of varnish will fall off, and the solution will overheat.
Having correctly connected all the wires, turn on the power supply. Bubbles will immediately start coming from the negative contact (cathode), this means that the process is in progress. If bubbles begin to come from the workpiece, then you need to change the polarity of the power supply.

After several minutes of etching, a nasty yellow-green foam forms on the surface of the solution.

After 30-40 minutes, the workpiece can be removed from the solution, having first turned off the power. It will be completely covered with a black coating, this is normal.

Step 5. Now all that remains is to clean the metal from plaque, wipe off the toner or varnish, and, if desired, sand the surface again. Black deposits can be easily removed under running plain water; the varnish or toner is washed off with acetone or nail polish remover. Now it is clearly visible that the letters on the metal have become embossed, and the metal surface itself has become matte after etching.

Pickling is a metal processing process in which a layer of a certain thickness is removed from the surface under the influence of active chemicals (acids or salts with an acidic reaction), as well as direct current in an electrolyte bath.

Metal etching can serve various purposes and be used in industry and at home. The surface of an item subjected to etching receives a number of technological and decorative properties and allows one to examine its microstructure in a metallographic microscope, remove scale and other non-metallic inclusions from the surface, obtain the necessary jewelry ornament or prepare it for soldering.

Etching, also called electrochemical engraving, is most often used at home or in the garage to obtain relief images on various objects with decorative functions. Most often, it is used on steels with high hardness, the processing of which with conventional engraving tools requires great effort. This process is not very difficult even in the absence of artistic skills, if you follow its technology.

Metal surface preparation

In order for the etching process to proceed at a high speed and the thickness of the removed layer to be the same, all dirt and traces of oils should be removed from the surface of the product. For this purpose, ordinary detergents and cleaning products used for washing dishes and warm water are suitable. After washing and drying, the surface should be wiped with fiber soaked in a solvent, which, in addition to degreasing, helps remove residual moisture.

Separately, it is worth mentioning the quality of surface treatment. Mirror polishing is subsequently guaranteed to give a good contrasting pattern even with a small etching depth. But if its implementation is impossible for some reason, the surface can be treated with sandpaper so that the risks from it go in one direction. This will also give a good optical effect.

Drawing

To apply a design to metal, you can use a lot of different methods that work according to the same mechanism: areas that are not subject to etching are protected from exposure to an aggressive environment or electrolyte.

Method No. 1

The most affordable way is to apply regular nail polish to the protected areas. However, it has a number of significant disadvantages:

• The viscosity of the varnish does not allow the lines to be thin enough to obtain highly complex patterns;
• Good ability in visual arts required;
• Correcting inaccurate lines is difficult.

Method No. 2

First you need to apply a protective layer to the entire surface of the product. To do this, you can use primers GF-021, XV-062 or bitumen varnish, available in auto parts and household goods stores. After the coating has completely dried, you can use a gel pen or a thin marker to draw the contours of the future image. An experienced artist can be hired for this task.

Next, from a copper (or brass) wire or rod, the diameter of which is selected based on the ease of holding in the hand, you need to make a needle with a pointed end and scratch the primer along the image lines to the metal. Harder needle material may damage the polish on the surface of the product.

Already at this stage you can evaluate the relief of the future ornament. To obtain areas with different depths of metal etching, for example, contours and penumbra, this process can be carried out in two or more cycles.

Important! The primer should not chip off during the process. Before applying the design, you should experiment and make sure that it is suitable for the job.

Method No. 3

You will need a laser printer, glossy paper, image processing software and an iron. The selected picture must be formatted (adjusted to size, mirrored) and printed. The most affordable source of glossy paper is women's magazines.

The printed image is applied to the surface, covered with a regular landscape sheet (to protect the iron) and ironed. After cooling, the paper is washed off under running water, and the toner layer remains on the metal surface.

This method is often used for etching printed circuit boards. Its main drawback is that the design is applied only to a straight surface.

Important! The gloss is difficult to see under water. After drying, you need to make sure that it does not remain on the product.

Care must be taken to protect all surfaces of the product. Various substances can be used for this. You can cover the back surface with ordinary plasticine: it is a good dielectric.

Metal etching methods

The choice of a specific method depends on many factors: the chemical activity of the metal, the availability of chemical reagents and safety considerations.

Chemical etching

It is performed in a container with the active substance. For carbon steels, solutions of weak acids may be suitable: citric, acetic. Hydrochloric acid works well. Pickling in battery electrolyte, nitric acid and rust converter should be treated very carefully: the process can release toxic gaseous substances, so it is better not to work with such reagents in the absence of a fume hood and good ventilation.

One of the safest substances is a saturated solution of ferric chloride. It can be bought in stores that sell radio components. The advantages of the solution are its almost unlimited service life (when working with iron alloys) and the coloring of the etched surface in an even gray color.

The process time is selected experimentally depending on the concentration of the reagent used and the activity of the metal.

Electrochemical etching

Many stainless and acid-resistant steels, for example, 40Х13, 95Х18, 08Х10Н18, 03Х12Н14М2, do not react to acids, so an electrochemical method is used for etching them.

It will require an electrolyte bath made of plastic or glass, wires, terminals and a direct current source. A saturated solution of table salt will work as an electrolyte. When choosing a container for it, you should remember that the process can proceed quite violently, so its volume should be 2 times larger than that of the electrolyte.

You can use rechargeable batteries as a current source, but it is better to use a charger (3 - 10A) with an ammeter and the ability to adjust the current parameters to select their optimal value. The workpiece is connected to the anode (positive contact) using terminals and a conductor; any stainless plate placed in the bath parallel to the front surface of the workpiece can be used as a cathode. After this, the device is connected to the network.

The entire process can take from two minutes to half an hour, depending on the current strength and the area of ​​the pattern. The etching depth should be controlled by periodically removing the part from the bath. At the same time, do not forget to turn off the power.

At the end of the process, the protective coating can be removed with a suitable solvent and the results of the work can be assessed. Thanks to good adhesion of the etched surface, it is possible to create a colored pattern.

To do this, the entire surface of the product is blown out of a cylinder with nitro-enamel, and after it dries, it is wiped with a piece of clean leather, felt or other non-abrasive material. The paint is removed from the polished surface, remaining only in the depressions.

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