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In this article we will talk about methods for manufacturing a printed circuit board and etching the board.

There are many ways to make a printed circuit board. The main way, which I personally use, is making a board from foil PCB (getinax), by applying a pattern with a drawing pen and etching in a chemical solution. It so happened that I started drawing circuit boards from the sixth grade of school (currently from the fifth), when computers were the size of entire rooms. It was at that time that I became “trained.” Therefore, I draw a board on a sheet of squared paper faster than on a computer, using special programs. True, the most voluminous board in terms of element base that I have ever drawn by hand was a board consisting of fourteen microcircuits and a couple of hundred simple elements.

Making a board by drawing a drawing with a drawing pen or, more often, Lately, LUT (laser ironing technology) and etching in a chemical solution consists of the steps listed below, the difference from other methods may differ slightly in the operations themselves and in their sequence:

1. Layout of placement of radio elements on the board and routing of conductors (tracks). Currently, there are many programs for developing radio boards. It's easier to use them. You can do development without using special programs, but this requires some perseverance and many times more time. In this case, for convenience, the board is drawn on a sheet of paper in a checkered pattern, and for redevelopment it is drawn again;

2. A board is cut from foil PCB or getinax required sizes. A more convenient material is textolite, which is essentially multilayer fiberglass, and foil adheres to it better than to getinax. Getinax is a sheet material made of pressed paper impregnated with bakelite varnish. Getinax is a lower quality material than PCB and has several properties that I personally don’t like:

- may delaminate;

— printed conductors bounce off faster from overheating than those of PCB, which makes it difficult to replace radio components without damaging the board if they fail;

— there are cases of overheating of radio components, which can cause the radio board to become “smoky.” The same happens when moisture gets into high-voltage circuits. Burnt getinax often turns into a conductor (something like graphite). The same thing happens with getinax when moisture accidentally gets into high-voltage circuits. The latter can bring you huge troubles;

But despite all this, it is significantly cheaper and can be cut with scissors. This can be useful when you need to make a quick single-sided board using SMD parts.

3. The ends of the board are processed from sharp corners and burrs with a file or sandpaper;

4. The cut out board is wrapped in a sheet with the board drawn on it. With a thin core and light blows of a hammer, holes are made (marking) for future holes in those places that were previously marked on the sheet;

5. In the marked places, holes are drilled for future radio components. For small parts - resistors, capacitors, thin-lead transistors, a 0.5 mm drill is used, for thicker leads - a 0.7 mm drill. If necessary, other sizes can be used. As a drill, it is more convenient to use a portable drilling machine, which can be purchased at a specialized radio store. You can also use a hand-held electric drill with some skill;

6. After drilling the holes, the board is sanded with sandpaper. All burrs formed as a result of drilling are cleared off, and the foil is cleaned for further application of track patterns and etching;

7. From an ordinary empty rod from ballpoint pen a drawing board is made. To do this, the rod is heated over the flame of a match (or lighter), and when the plastic melts, the rod is pulled out. After the plastic has hardened, the end of the drawing board is cut to obtain a hole with a diameter of approximately 0.2...0.4 mm;

8. A varnish (it’s more convenient to use nail polish) 2…5 cm in height is put into the drawing pen, after which the printed circuit board is drawn: soldering pads are made around the holes, and printed circuit board tracks are drawn between these pads. With a certain amount of skill and using rulers as guides, the quality of the drawing can be on par with factory radio boards;

9. After the varnish has dried, the unvarnished areas of the board are etched by placing the board in a ferric chloride solution. At the same time, the copper of the tracks protected by varnish is not etched, and the copper coating of the board not covered with varnish, entering into chemical reaction dissolves in ferric chloride. To speed up the etching process, the solution with the board can be heated in a water bath, or simply placed on a central heating radiator;

10. After etching, the board is washed with water and, using a cotton swab moistened with acetone or another solvent, the varnish is removed from the board, after which it is washed again under running water;

11. It is better to solder radio components using low-melting solder and flux - rosin dissolved in alcohol.

Should be added:

Can be used as a drawing board disposable syringe, in this case it is necessary to break the oblique cut of the needle and sharpen it so that there are no sharp scratching surfaces of the tip. Recently, there are many markers on sale, the dye of which is not washed off with water and provides a fairly durable protective layer, so they can also be used as a drawing pen.

Some craftsmen also tin after etching the board. Tinning is done in one of two ways:

1. Soldering iron;

2. The iron bath is filled with Rose or Wood alloy. The alloy, in order to avoid oxidation of the solder, is completely covered with a layer of glycerin on top. For tinning, the board is immersed in the melt for no more than five seconds. Heat the bath using an electric stove.

Recently, the printer method of transferring a radio board pattern has become increasingly widespread.

It consists of the following:

1. Using special programs, a radio board is designed and drawn;

2. A mirror image of the board is printed on a substrate using a laser printer. In this case, thin coated paper (covers from various magazines), fax paper, or film for laser printers is used as a substrate.

3. The substrate is applied to the prepared board with the front side (picture) and “rubbed” onto the board using a very hot iron. To evenly distribute the pressure of the iron on the substrate, it is recommended to lay several layers of thick paper between them. The toner melts and sticks to the board.

4. After cooling, there are two options for removing the backing: either the backing is simply removed after transferring the toner to the board (in the case of film for laser printers), or it is pre-soaked in water and then gradually peeled off (coated paper). The toner remains on the board. After removing the backing, in those places where the toner has separated, you can retouch the board manually.

5. The board is etched in a chemical solution. During etching, the toner does not dissolve in ferric chloride.

This method allows you to get a very beautiful printed montage, but you need to get used to it, because it may not work out the first time. The fact is that a certain high-temperature regime is required. There is only one criterion here: the toner must have time to melt enough to stick to the surface of the board, and at the same time it must not have time to reach a semi-liquid state so that the edges of the tracks do not flatten. Removing the paper sheet requires some softening with water, otherwise the paper sheet may come off along with the toner. Drilling holes in a printed circuit board is carried out after etching.

PCB etching

There are many compounds for chemically stripping copper from a printed circuit board. All of them differ in the speed of the reaction and the availability of the chemical reagents necessary for preparing the solution. Do not forget that any chemical is harmful to health, so do not forget to take precautions. Here are the chemical solutions for etching printed circuit boards that I personally used:

1. Nitric acid(HNO3)– the most dangerous and unpopular reagent. It is transparent, has a pungent odor, is highly hygroscopic, and also evaporates strongly. Therefore, it is not recommended for storage at home. Not used for etching pure form, and a solution with water in a ratio of 1/3 (one part acid to three parts water). Do not forget that it is not water that pours into acid, but rather the acid into water. The etching process takes no more than five minutes, with active gas release. “Nitrogen” also dissolves varnish, so before using it you need to let the varnish dry thoroughly. Then, during etching, it will not have time to soften and separate from the copper coating. Precautions must be strictly followed.

2. A solution of sulfuric acid (H 2 SO 4) and hydrogen peroxide (H 2 O 2). To prepare this solution, you need to add four tablets of hydrogen peroxide (pharmacy name - “Hydroperite”) to a glass of ordinary battery electrolyte (a solution of sulfuric acid in water). Ready solution should be stored in a dark container, not hermetically sealed, since the decomposition of hydrogen peroxide releases gas. The etching time for a printed circuit board is about one hour for a well-mixed fresh solution at room temperature. This solution after etching can be restored by adding hydrogen peroxide H 2 O 2. The required amount of hydrogen peroxide is assessed visually: a copper board immersed in the solution should be repainted from red to dark brown. The formation of bubbles in the solution indicates an excess of hydrogen peroxide, which leads to a slowdown in the etching reaction. Precautions must be strictly followed.

Attention: When using the two previously mentioned solutions, it is necessary to observe all precautions when working with caustic chemicals. All work must be carried out only on fresh air or under the hood. If the solution comes into contact with the skin, it must be washed immediately big amount water.

3. Ferric chloride (FeCl 3)- the most popular reagent for etching printed circuit boards. 150 g of ferric chloride powder is dissolved in 200 ml of warm water. The etching process in this solution can take from 15 to 60 minutes. The time depends on the freshness of the solution and temperature. After etching is complete, the board must be washed with plenty of water, preferably with soap (to neutralize acid residues). The disadvantages of this solution include the formation of waste during the reaction, which settles on the board and interferes with the normal course of the etching process, as well as the relatively low reaction rate.

4. Solution table salt(NaCl) and copper sulfate(CuSO 4) in water. Four tablespoons of table salt and two tablespoons of copper sulfate crushed into powder are dissolved in 500 ml of hot water (approximately 80 °C). The solution is ready for use immediately after cooling (when using heat-resistant paint, cooling is not necessary). Etching time is about 8 hours. To speed up the etching process, the solution with the board can be heated to 50 °C.

5. Solution citric acid in hydrogen peroxide (H 2 O 2). In a small bath (up to 100 ml), the printed circuit board is filled with a large volume of hydrogen peroxide, after which 1 tablespoon of citric acid is added. After which the process of etching the printed circuit board begins. It is actively accompanied by a change in the color of the liquid from transparent to blue. The edges turn out smooth and, if you first go over the foil fiberglass laminate with fine sandpaper, then everything will be etched very evenly.

Using this method, I was able to obtain boards with the following parameters:

The gap between the conductors is 0.2 mm.

With a set conductor thickness of 0.25 mm, in reality it turned out to be 0.2-0.22 mm.

Dimensions of boards up to 100x200 mm.

If you need to pickle faster, you can add a pinch of regular table salt. It will speed up the process, but be careful: During the etching process, thermal energy and usually the solution warms up quite well. Over my many years of experience working with this solution, it exploded twice and “smeared” everything around me. Of course, everything was wiped off very quickly with an ordinary rag and soda and there were no traces of it on clothes or things (unlike ferric chloride), but it was quite interesting to observe.

The average etching time is 20-30 minutes.

I did not use any other solutions for etching printed circuit boards. It is most pleasant to work with the last point, since the components can be obtained in any city.

If you need to do it well

In principle, a printed circuit board can also be ordered at a factory specialized for their production. Of course, it costs more than you would make it yourself, but the quality of workmanship will be many times better. If you have a lot of such prototypes, then I highly recommend watching a video on the production of printed circuit boards.

The point here is this. The factory takes money for 2 things: for preparation for production, during which it transfers your files from printed circuit board to its standard and manufactures the equipment, and for the manufacturing itself. The manufacturing itself is not an expensive thing: factories buy blanks for radio boards in large quantities and the production itself is cheaper, but they charge an average of 2-3 thousand rubles for preparation. For me, paying that kind of money for the production of one board does not make sense. But, if there are 10-20 of these boards, then this money for preparation is divided among all the boards and it turns out cheaper.

Since I'm studying to become an engineer, I often do projects at home with fairly simple electronic circuits and for this I often make printed circuit boards myself.

What is a printed circuit board?

A printed circuit board (PCB) is used to mechanically assemble radio components and connect them electrically using conductive patterns, pads and other components etched onto the copper layer of the laminated wafer.
The PCB contains pre-designed copper tracks. Properly designing connections through these traces reduces the amount of wire used and therefore the amount of damage caused by broken connections. The components are mounted on the PCB by soldering.

Creation methods

There are three main ways to make printed circuit boards with your own hands:

1. LUT printed circuit board manufacturing technology
2. Manually drawing tracks
3. Etching on a laser machine

The laser etching method is industrial, so I will tell you more about the first two manufacturing methods.

Step 1: Create a PCB Layout

Usually wiring is done by converting schematic diagram using special programs. There are many free programs publicly available, for example:

I created the layout using the first program.

Don’t forget to select DPIG 1200 in the image settings (File – Export – Image) for best quality Images.

Step 2: Board Materials

(text on photo):

• Magazines or advertising brochures
• Laser printer
• Regular iron
• Copper Laminate for PP
• Etching solution
• Foam sponge
• Solvent (eg acetone)
• Wire in plastic insulation

You will also need: permanent marker, sharp knife, sandpaper, paper towels, cotton wool, old clothes.
I will explain the technology using the example of manufacturing a PCB touch switch with IC555.

Step 3: Print the layout

Print the circuit layout on a sheet of glossy or A4 photo paper using a laser printer. Do not forget:

• You need to print the image as a mirror image.
• Select "Print All Black" in both your PCB design software and laser printer settings
• Make sure that the image will be printed on the glossy side of the sheet.

Step 4: Cut the board out of the laminate

Cut a piece of laminate the same size as the PCB layout image.

Step 5: Sanding the board

Use steel wool or the abrasive side of a dish sponge to scrub the foil side. This is necessary to remove the oxide film and photosensitive layer.
The image fits better on a rough surface.

Step 6: Circuit Manufacturing Options

Option 1:
LUT: transferring an image printed on a glossy layer of paper to a foil layer of laminate. Place the printed image on a horizontal surface with the toner side up. Place the copper layer on top of the board on top of the image. The image should be positioned evenly relative to the edges. Secure the laminate and the image on both sides with tape so that the paper cannot move; the sticky layer of tape should not get on the copper coating.

Option 2:
Drawing tracks with a permanent marker: using the printed layout as a guide, first draw the pattern onto the copper layer of a piece of laminate with a simple pencil, then trace with a permanent black marker.

Step 7: Iron the Image

• The printed image must be ironed. Preheat the iron to maximum temperature.
• put it on a flat surface wooden surface clean waste cloth, place the future board on it with the copper layer facing up with the image of the circuit pressed to it.
• On one side, press the board with a hand with a towel, on the other, press it with an iron. Hold the iron for 10 seconds, then begin ironing with the paper, pressing slightly, for 5-15 minutes.
• Iron the edges well - with pressure, slowly moving the iron.
• Pressing for a long time works better than constantly stroking.
• The toner should melt and stick to the copper layer.

Step 8: Cleaning the Board

After ironing, place it in warm water for about 10 minutes. The paper will become wet and can be removed. Remove the paper at a low angle and preferably without any residue.

Sometimes particles of tracks are removed from the paper.
The white rectangle in the photographs marks the place where the tracks were poorly transferred and then restored with a black permanent marker.

Step 9: Etching

You need to be extremely careful when etching.

• first put on rubber gloves or plastic coated gloves
• cover the floor with newspapers just in case
• fill plastic box water
• add 2-3 teaspoons of ferric chloride powder to water
• soak the board in the solution for about 30 minutes
• ferric chloride will react with copper and copper, not protected by a layer of toner, will go into solution
• to check how the etching of the internal parts of the board is progressing, remove the board from the solution with pliers; if the internal part has not yet been cleared of copper, leave it in the solution for some more time.

Stir the solution lightly to make the reaction more active. Copper chloride and ferric chloride are formed in the solution.
Check every two to three minutes to make sure all the copper has been removed from the board.

Step 10: Safety

Do not touch the solution with unprotected hands; be sure to use gloves.
The photo shows how the etching takes place.

Step 11: Disposing of the solution

The pickling solution is toxic to fish and other aquatic life.
Do not pour used solution down the sink; it is illegal and may damage the pipes.
Dilute the solution to reduce the concentration and only then pour it into the public sewer.

Step 12: Completing the Manufacturing Process

The photo shows for comparison two printed circuit boards made using LUT and a permanent marker.

Place a few drops of solvent (nail polish remover is fine) on a cotton swab and remove the remaining toner from the board, you should only have copper traces left. Proceed carefully, then dry the board with a clean cloth. Cut the board to the right size and sand the edges.

Drill mounting holes and solder all components onto the board.

Step 13: Conclusion

1. Laser ironing technology is a very effective way to make printed circuit boards at home. If you do everything carefully, each path will turn out clear.
2. Tracing with a permanent marker is limited by our artistic skills. This method is suitable for the simplest circuits; for something more complex, it is better to make a board using the first method.

I recently discovered it on the Internet new method etching of printed circuit boards, which differs from classical etching methods, moreover, this method does not have the inherent characteristics of traditional ferric chloride And ammonium persulfate shortcomings. Ferric chloride, with its unwashable stains on clothes and, as a result, damaged things, may not have suited many people for a long time. Also ammonium persulfate, not everyone has a separate table for etching at home - soldering, most likely most people, like me, do it in the bathroom. Sometimes, as a result of careless actions with ammonium persulfate and drops getting on clothes, small holes form over time and things become damaged.

Someone might say, I’m happy with persulfate because of its etching speed, but the new etching method makes it possible to etch boards, I think, at no less speed. Yesterday I etched the board in half an hour, the design was drawn on a quick fix marker, the narrowest paths were 1 mm wide, no undergrasses were noticed. The photo of the board is below, though after I tinned and soldered all the parts onto the board, just to show that even narrow traces are obtained without undercuts, I think this is enough. But I would like to immediately note that the drawing transferred to a printed circuit board using the LUT (laser ironing technology) is preserved better; according to people’s reviews, when etching with this method, even narrow paths 1 mm wide turn out consistently well.

Now let's get down to business. For the board measuring 35*25, which I etched, I used the following ingredients: bottle of pharmacy hydrogen peroxide 50 ml, cost 3 rubles and 1 sachet of 10 grams food grade citric acid, costing 3.5 rubles, salt teaspoon(used as a catalyst) of course free of charge, any you have in your kitchen will do, even iodized ones. Exact proportions are not necessary here; we make something like this: pour in enough hydrogen peroxide to cover the board by 5 mm, add 10 grams (in my case a bag) of citric acid and add a teaspoon of salt .

There is no need to add water, the liquid that is in the peroxide is used. If you plan to etch the board large sizes, then we increase the amount of ingredients in those proportions relative to hydrogen peroxide, as indicated above, also so that the board is hidden by 5 mm. By the end of etching, the solution will turn bluish. During etching, we move the board in the container, because gas bubbles will accumulate on the board, interfering with etching.

Towards the end of etching, remove the board from the solution with tweezers and inspect it. If we draw a picture with a marker, I recommend drawing in several layers to avoid small undercuts on narrow paths, but ferric chloride and ammonium persulfate will give us the same effect. The remaining solution from etching can be poured down the drain, followed by a large number of water. I don’t think anyone will store the solution for reuse; it’s always easier to make a new solution if necessary than to wait longer when etching with an old solution.

Saving time and money compared to old methods is obvious to everyone, I think. You can also use concentrated peroxide sold in hairdressing stores or hydroperite tablets, but here everyone will have to choose the ratio of ingredients themselves, since I haven’t experimented with them. As promised, I’m posting a photo of the board etched using this method; I made the board in a hurry, though.

A little more about this one useful thing, How vertical baths. If uniform and high-quality double-sided etching is required, vertical baths with solution mixing are convenient. Stirring is done by inserting a tube from an aquarium aerator into the bath. Also, a vertical bath has a minimal evaporation area. In addition, there will be no sticking dirt if the solution is old and littered. I wish you successful etching without any undercuts. I was with you AKV .

Discuss the article ETCHING PRINTED BOARDS

Today we will speak in a slightly unusual role; we will talk not about gadgets, but about the technologies that lie behind them. A month ago we were in Kazan, where we met the guys from Navigator Campus. At the same time, we visited a nearby (well, relatively close) factory for the production of printed circuit boards - Technotech. This post is an attempt to understand how those same printed circuit boards are produced.

So, how are printed circuit boards made for our favorite gadgets?

The factory knows how to make boards from start to finish - designing a board according to your technical specifications, manufacturing fiberglass laminate, producing single-sided and double-sided printed circuit boards, producing multilayer printed circuit boards, marking, testing, manual and automatic assembly and soldering of boards.
First, I'll show you how double-sided boards are made. Their technical process is no different from the production of single-sided printed circuit boards, except that during the manufacture of OPP they do not perform operations on the second side.

About board manufacturing methods

In general, all methods of manufacturing printed circuit boards can be divided into two large categories: additive (from the Latin additio-adding) and subtractive (from Latin subtratio-subtraction). An example of subtractive technology is the well-known LUT (Laser Ironing Technology) and its variations. In the process of creating a printed circuit board using this technology, we protect future tracks on a sheet of fiberglass with toner from a laser printer, and then bleed off everything unnecessary in ferric chloride.
In additive methods, on the contrary, conductive tracks are deposited on the surface of the dielectric in one way or another.
Semi-additive methods (sometimes also called combined) are a cross between classical additive and subtractive. During the production of PCBs using this method, part of the conductive coating may be etched off (sometimes almost immediately after application), but as a rule this happens faster/easier/cheaper than in subtractive methods. In most cases, this is a consequence of the fact that most of the track thickness is increased by electroplating or chemical methods, and the layer that is etched is thin and serves only as a conductive coating for electroplating.
I will show you exactly the combined method.

Manufacturing of two-layer printed circuit boards using the combined positive method (semi-additive method)

Manufacturing of fiberglass laminate

The process begins with the manufacture of foil fiberglass laminate. Fiberglass is a material consisting of thin sheets of fiberglass (they look like dense shiny fabric), impregnated with epoxy resin and pressed in a stack into a sheet.
The fiberglass sheets themselves are also not very simple - they are woven (like regular fabric in your shirt) thin, thin threads ordinary glass. They are so thin that they can easily bend in any direction. It looks something like this:

You can see the orientation of the fibers in the long-suffering picture from Wikipedia:


In the center of the board, the light areas are the fibers running perpendicular to the cut, the slightly darker areas are parallel.
Or for example on a microphotograph of tiberius, as far as I remember from this article:

So, let's begin.
Fiberglass fabric is supplied to production in the following reels:


It is already impregnated with partially cured epoxy resin - this material is called prepreg, from English pre-im preg nated - pre-impregnated. Since the resin is already partially cured, it is no longer as sticky as in its liquid state - the sheets can be picked up by hand without any fear of getting dirty with the resin. The resin will only become liquid when the foil is heated, and then only for a few minutes before completely solidifying.
The required number of layers along with copper foil is assembled on this machine:


And here is the roll of foil itself.


Next, the canvas is cut into pieces and fed into a press with a height of two human heights:


In the photo is Vladimir Potapenko, production manager.
The technology of heating during pressing is implemented in an interesting way: not parts of the press are heated, but the foil itself. A current is supplied to both sides of the sheet, which, due to the resistance of the foil, heats the sheet of future fiberglass. Pressing occurs at very low pressure to prevent the appearance of air bubbles inside the PCB


When pressed, due to heat and pressure, the resin softens, fills the voids, and after polymerization, a single sheet is obtained.
Like this:


It is cut into blanks for circuit boards using a special machine:


Technotech uses two types of blanks: 305x450 - small group blank, 457x610 - large blank
After this, each set of blanks is printed with route map, and the journey begins...


A route card is a piece of paper with a list of operations, information about the fee and a barcode. To control the execution of operations, 1C 8 is used, which contains all the information about orders, the technical process, and so on. After completing the next production stage, the barcode on the route sheet is scanned and entered into the database.

Drilling blanks

The first step in the production of single-layer and double-layer printed circuit boards is drilling holes. With multilayer boards it's more complicated, and I'll talk about that later. Blanks with route sheets arrive at the drilling section:


A package for drilling is assembled from the blanks. It consists of a substrate (plywood type material), from one to three identical printed circuit board blanks and aluminum foil. The foil is needed to determine if the drill touches the surface of the workpiece - this is how the machine determines whether the drill is broken. Every time he grabs the drill, he controls its length and sharpening with a laser.


After assembling the package, it is placed in this machine:


It is so long that I had to stitch this photo together from several frames. This is a Swiss machine from Posalux, unfortunately I don’t know the exact model. In terms of characteristics, it is close to this. It consumes three times three-phase power supply voltage of 400V, and consumes 20 kW during operation. The weight of the machine is about 8 tons. It can simultaneously process four packages using different programs, which gives a total of 12 boards per cycle (naturally, all workpieces in one package will be drilled the same way). The drilling cycle ranges from 5 minutes to several hours, depending on the complexity and number of holes. Average time is about 20 minutes. Technotech has three such machines in total.


The program is developed separately and downloaded over the network. All the operator needs to do is scan the batch barcode and place the package of blanks inside. Tool magazine capacity: 6000 drills or cutters.


Nearby there is a large cabinet with drills, but the operator does not need to control the sharpening of each drill and change it - the machine always knows the degree of wear of the drills - it records in its memory how many holes were drilled by each drill. When the resource is exhausted, he himself replaces the drill with a new one, the old drills will only have to be unloaded from the container and sent for re-sharpening.


This is what the inside of the machine looks like:


After drilling, a mark is made in the route sheet and base, and the board is sent stage by stage to the next stage.

Cleaning, activation of workpieces and chemical copper plating.

Although the machine uses its own “vacuum cleaner” during and after drilling, the surface of the board and holes still needs to be cleaned of dirt and prepared for the next technological operation. To begin with, the board is simply cleaned in a cleaning solution with mechanical abrasives


Inscriptions, from left to right: “Brush cleaning chamber top/bottom”, “Washing chamber”, “Neutral zone”.
The board becomes clean and shiny:


After this, the surface activation process is carried out in a similar installation. For each surface, a serial number is entered. Activation of the surface is preparation for the deposition of copper on inner surface holes to create vias between board layers. Copper cannot settle on an unprepared surface, so the board is treated with special palladium-based catalysts. Palladium, unlike copper, is easily deposited on any surface, and subsequently serves as crystallization centers for copper. Activation installation:

After this, successively passing through several baths in another similar installation, the workpiece acquires a thin (less than a micron) layer of copper in the holes.


Then this layer is increased by galvanization to 3-5 microns - this improves the layer’s resistance to oxidation and damage.

Application and exposure of photoresist, removal of unexposed areas.

Next, the board is sent to the photoresist application area. They didn’t let us in there because it was closed, and in general, it was a clean room, so we’ll limit ourselves to photographs through the glass. I saw something similar in Half-Life (I'm talking about pipes coming down from the ceiling):


Actually, the green film on the drum is the photoresist.


Next, from left to right (in the first photo): two installations for applying photoresist, then an automatic and manual frame for illumination using pre-prepared photo templates. The automatic frame has a control that takes into account alignment tolerances with reference points and holes. In a manual frame, the mask and board are aligned by hand. Silk-screen printing and solder mask are displayed on the same frames. Next is the installation of developing and washing the boards, but since we didn’t get there, I don’t have photos of this part. But there is nothing interesting there - approximately the same conveyor as in “activation”, where the workpiece passes successively through several baths with different solutions.
And in the foreground is a huge printer that prints these same photo templates:


Here is the board with it applied, exposed and developed:


Please note that photoresist is applied to areas where later will not copper - the mask is negative, not positive, as in LUT or homemade photoresist. This is because in the future the build-up will occur in the areas of future tracks.


This is also a positive mask:


All these operations take place under non-actinic lighting, the spectrum of which is selected in such a way as to simultaneously not affect the photoresist and provide maximum illumination for human work in a given room.
I love announcements whose meaning I don’t understand:

Galvanic metallization

Now it has come through Her Majesty - galvanic metallization. In fact, it was already carried out at the previous stage, when a thin layer of chemical copper was built up. But now the layer will be increased even more - from 3 microns to 25. This is the layer that conducts the main current in the vias. This is done in the following baths:


In which they circulate complex compositions electrolytes:


And a special robot, obeying the programmed program, drags boards from one bath to another:


One copper plating cycle takes 1 hour 40 minutes. One pallet can process 4 workpieces, but there can be several such pallets in a bath.

Deposition of metal resist

The next operation is another galvanic metallization, only now the deposited material is not copper, but POS - lead-tin solder. And the coating itself, by analogy with photoresist, is called metal resist. The boards are installed in the frame:


This frame goes through several already familiar galvanic baths:


And it is covered with a white layer of POS. In the background you can see another board, not yet processed:

Photoresist removal, copper etching, metal resist removal

Now the photoresist is washed off from the boards, it has fulfilled its function. Now on the still copper board there are traces covered with metal resist. At this installation, etching occurs in a tricky solution that etches the copper, but does not touch the metal resist. As far as I remember, it consists of ammonium carbonate, ammonium chloride and ammonium hydroxide. After etching, the boards look like this:


The tracks on the board are a “sandwich” of the bottom layer of copper and the top layer of galvanic POS. Now, with another even more cunning solution, another operation is carried out - the POS layer is removed without affecting the copper layer.


True, sometimes the PIC is not removed, but is melted in special furnaces. Or the board goes through hot tinning (HASL process) - where it is lowered into a large bath of solder. First, it is coated with rosin flux:


And it is installed in this machine:


He lowers the board into the solder bath and immediately pulls it back out. Air currents blow away excess solder, leaving only a thin layer on the board. The payment is like this:


But in fact, the method is a little “barbaric” and does not work very well on boards, especially multilayer ones - when immersed in molten solder, the board suffers a temperature shock, which does not work very well on internal elements multilayer boards and thin single- and double-layer tracks.
It is much better to cover with immersion gold or silver. Here is some very good information about immersion coatings if anyone is interested.
We did not visit the immersion coating site for a banal reason - it was closed, and we were too lazy to get the key. It's a pity.

Electrotest

Next, the almost finished boards are sent for visual inspection and electrical testing. An electrical test is when the connections of all contact pads are checked to see if there are any breaks. It looks very funny - the machine holds the board and quickly pokes probes into it. You can watch a video of this process on my instagram(by the way, you can subscribe there). And in photo form it looks like this:


That big machine on the left is the electrical test. And here are the probes themselves closer:


In the video, however, there was another machine - with 4 probes, but here there are 16 of them. They say it is much faster than all three old machines with four probes combined.

Solder mask application and pad coating

Next technological process- applying a solder mask. That same green (well, most often green. But in general it can be very different colors) coating that we see on the surface of the boards. Prepared boards:


They are put into this machine:


Which, through a thin mesh, spreads a semi-liquid mask over the surface of the board:


By the way, the application video can also be viewed in instagram(and subscribe too:)
After this, the boards are dried until the mask stops sticking, and are exposed in the same yellow room what we saw above. After this, the unexposed mask is washed off, exposing the contact patches:


Then they are coated with a finishing coating - hot tinning or immersion coating:


And markings are applied - silk-screen printing. These are white (most often) letters that show where which connector is and which element is located there.
It can be applied using two technologies. In the first case, everything happens the same as with a solder mask, only the color of the composition differs. It covers the entire surface of the board, then it is exposed, and the areas not cured by ultraviolet light are washed off. In the second case, it is applied by a special printer that prints with a tricky epoxy compound:


It's both cheaper and much faster. The military, by the way, does not favor this printer, and constantly states in the requirements for their boards that markings are applied only with photopolymer, which greatly upsets the chief technologist.

Manufacturing of multilayer printed circuit boards using the through-hole metallization method:

Everything that I described above applies only to single-sided and double-sided printed circuit boards (at the factory, by the way, no one calls them that, everyone says OPP and DPP). Multilayer boards (MPCs) are made on the same equipment, but using slightly different technology.

Manufacturing of kernels

The core is an inner layer of thin PCB with copper conductors on it. There can be from 1 such cores in a board (plus two sides - a three-layer board) to 20. One of the cores is called gold - this means that it is used as a reference - the layer on which all the others are set. The kernels look like this:


They are made in exactly the same way as conventional boards, only the thickness of the fiberglass laminate is very small - usually 0.5 mm. The sheet turns out so thin that it can be bent like thick paper. Copper foil is applied to its surface, and then all the usual stages occur - application, photoresist exposure and etching. The result of this is the following sheets:


After manufacturing, the tracks are checked for integrity on a machine that compares the board pattern against the light with a photomask. In addition, there is also visual control. And it’s really visual - people sit and look at the blanks:


Sometimes one of the control stages makes a verdict about the poor quality of one of the workpieces (black crosses):


This sheet of boards, in which a defect occurred, will still be manufactured in full, but after cutting, the defective board will go into the trash. After all layers are made and tested, the next technological operation begins.

Assembling kernels into a bag and pressing

This happens in a room called the “Pressing Area”:


The cores for the board are laid out in this pile:


And next to it is a map of the location of the layers:


After which a semi-automatic board pressing machine comes into play. Its semi-automatic nature lies in the fact that the operator must, at her command, give her the kernels in a certain order.


Transferring them for insulation and gluing with prepreg sheets:


And then the magic begins. The machine grabs and transfers sheets to the working field:


And then he aligns them along the reference holes relative to the gold layer.


Next, the workpiece goes into a hot press, and after heating and polymerization of the layers, into a cold one. After this, we receive the same sheet of fiberglass, which is no different from blanks for two-layer printed circuit boards. But inside it has a good heart, several cores with formed tracks, which, however, are not yet connected in any way and are separated by insulating layers of polymerized prepreg. Then the process goes through the same stages that I described earlier. True, with a slight difference.

Drilling blanks

When assembling a package of OPP and DPP for drilling, it does not need to be centered, and it can be assembled with some tolerance - this is still the first technological operation, and all others will be guided by it. But when assembling a package of multilayer printed circuit boards, it is very important to adhere to inner layers- when drilling, the hole must pass through all the internal contacts of the cores, connecting them in ecstasy during metallization. Therefore, the package is assembled on a machine like this:


It's x-ray drilling machine, which sees through the textolite internal metal reference marks and, based on their location, drills basic holes into which fasteners are inserted for installing the package into a drilling machine.

Metallization

Then everything is simple - the workpieces are drilled, cleaned, activated and metallized. The metallization of the hole connects all the copper heels inside the printed circuit board:


Thus, completing the electronic circuit of the insides of the printed circuit board.

Checking and polishing

Next, a piece is cut from each board, which is polished and examined under a microscope to make sure that all the holes turned out fine.


These pieces are called sections - transversely cut parts of the printed circuit board, which allows you to evaluate the quality of the board as a whole and the thickness of the copper layer in the central layers and vias. IN in this case, it is not a separate board that is allowed for grinding, but the entire set of via diameters specially made from the edge of the board that are used in the order. A thin section filled in transparent plastic looks like this:

Milling or scribing

Next, the boards that are on the group blank must be divided into several parts. This is done either on a milling machine:


Which cuts out the desired contour with a milling cutter. Another option is scribing, this is when the outline of the board is not cut out, but cut with a round knife. This is faster and cheaper, but allows you to make only rectangular boards, without complex contours and internal cutouts. Here is the scribed board:

And here is the milled one:


If only the production of boards was ordered, then this is where it all ends - the boards are put in a pile:


It turns into the same route sheet:


And waiting to be sent.
And if you need assembly and sealing, then there is still something interesting ahead.

Assembly

Then the board, if necessary, goes to the assembly area, where the necessary components are soldered onto it. If we're talking about manual assembly- then everything is clear, there are people sitting (by the way, most of them are women, when I went to them, my ears curled up from the song from the tape recorder “God, what a man”):


And they collect, they collect:


But if we talk about automatic assembly, then everything is much more interesting. This happens on such a long 10-meter installation, which does everything - from applying solder paste to soldering on thermal profiles.


By the way, everything is serious. Even the rugs are grounded there:


As I said, it all starts with the fact that an uncut sheet with printed circuit boards is installed together with a metal template at the beginning of the machine. Solder paste is thickly spread on the template, and the squeegee knife passing from above leaves precisely measured amounts of paste in the recesses of the template.


The template is raised and the solder paste is placed in the correct places on the board. Cassettes with components are installed in the following compartments:


Each component is inserted into its corresponding cassette:


The computer that controls the machine is told where each component is located:


And he begins to arrange components on the board.


It looks like this (video not mine). You can watch forever:

The component installation machine is called the Yamaha YS100 and is capable of installing 25,000 components per hour (one takes 0.14 seconds).
Then the board passes through the hot and cold zones of the stove (cold means “only” 140°C, compared to 300°C in the hot part). Having spent a strictly defined time in each zone with a strictly defined temperature, the solder paste melts, forming one whole with the legs of the elements and the printed circuit board:


The soldered sheet of boards looks like this:


All. The board is cut, if necessary, and packaged to soon go to the customer:

Examples

Finally, examples of what technotech can do. For example, design and manufacture of multilayer boards (up to 20 layers), including boards for BGA components and HDI boards:


C with all “numbered” military approvals (yes, each board is manually marked with a number and production date - this is required by the military):


Design, manufacturing and assembly of boards of almost any complexity, from our own or from customer components:


And HF, microwave, boards with a metalized end and a metal base (I didn’t take photos of this, unfortunately).
Of course, they are not a competitor to Resonit in terms of quick prototypes of boards, but if you have 5 or more pieces, I recommend asking them for the cost of production - they really want to work with civilian orders.

And yet, there is still production in Russia. No matter what they say.

Finally, you can catch your breath, look up at the ceiling and try to understand the intricacies of the pipes:

When available laser printer, radio amateurs use a technology for manufacturing printed circuit boards, which is called LUT. However, such a device is not available in every home, since even in our time it is quite expensive. There is also a manufacturing technology using photoresist film. However, to work with it you also need a printer, but an inkjet one. It’s already simpler, but the film itself is quite expensive, and at first it’s better for a novice radio amateur to spend the available funds on a good soldering station and other accessories.
Is it possible to make a printed circuit board of acceptable quality at home without a printer? Yes. Can. Moreover, if everything is done as described in the material, you will need very little money and time, and the quality will be very good. high level. Anyway electricity“will run” along such paths with great pleasure.

List of necessary tools and consumables

You should start by preparing the tools, devices and consumables that you simply cannot do without. To implement the most budget-friendly method for manufacturing printed circuit boards at home, you will need the following:

1. Software for drawing design.
2. Transparent polyethylene film.
3. Narrow tape.
4. Marker.
5. Foil fiberglass.
6. Sandpaper.
7. Alcohol.
8. Unnecessary toothbrush.
9. Tool for drilling holes with a diameter of 0.7 to 1.2 mm.
10. Ferric chloride.
11. Plastic container for etching.
12. Brush for painting with paints.
13. Soldering iron.
14. Solder.
15. Liquid flux.

Let’s go through each point briefly, since there are some nuances that can only be reached through experience.
Today there are a huge number of programs for developing printed circuit boards, but for a novice radio amateur the most simple option will Sprint Layout. The interface is easy to master, it is free to use, and there is a huge library of common radio components.
Polyethylene is needed to transfer the pattern from the monitor. It is better to take a stiffer film, for example, from old covers for school books. Any tape will be suitable for attaching it to the monitor. It’s better to take a narrow one - it will be easier to peel off (this procedure does not harm the monitor).
It’s worth looking at markers in more detail, as this is a sore subject. In principle, any option is suitable for transferring a design onto polyethylene. But to draw on foil fiberglass, you need a special marker. But there is a little trick to save money and not buy quite expensive “special” markers for drawing printed circuit boards. The fact is that these products are absolutely no different in their properties from ordinary permanent markers, which are sold 5-6 times cheaper in any office supply store. But the marker must have the inscription “Permanent”. Otherwise nothing will work.

You can take any foiled fiberglass laminate. It's better if it's thicker. For beginners, working with such material is much easier. To clean it, you will need sandpaper with a grit size of about 1000 units, as well as alcohol (available at any pharmacy). The last consumable can be replaced with nail polish mixing liquid, which is available in any house where a woman lives. However, this product smells quite nasty and takes a long time to dissipate.
To drill the board, it is better to have a special mini-drill or engraver. However, you can go a cheaper route. It is enough to buy a collet or jaw chuck for small drills and adapt it to a regular household drill.
Ferric chloride can be replaced with others chemicals, including those that you probably already have in your home. For example, a solution of citric acid in hydrogen peroxide is suitable. Information on how alternative compositions to ferric chloride are prepared for etching boards can be easily found on the Internet. The only thing worth paying attention to is the container for such chemicals - it should be plastic, acrylic, glass, but not metal.
There is no need to talk in more detail about the soldering iron, solder and liquid flux. If a radio amateur has come to the question of making a printed circuit board, then he is probably already familiar with these things.

Development and transfer of a board design to a template

When all of the above tools, devices and Consumables prepared, you can start developing the board. If the device being manufactured is not unique, then it will be much easier to download its design from the Internet. Even a regular drawing in JPEG format will do.

If you want to go a more complicated route, draw the board yourself. This option is often unavoidable, for example, in situations where you do not have exactly the same radio components that are needed to assemble the original board. Accordingly, when replacing components with analogues, you have to allocate space for them on fiberglass, adjust holes and tracks. If the project is unique, then the board will have to be developed from scratch. This is what the above-mentioned software is needed for.
When the board layout is ready, all that remains is to transfer it to a transparent template. The polyethylene is fixed directly to the monitor using tape. Next, we simply translate the existing pattern - tracks, contact patches, and so on. For these purposes, it is best to use the same permanent marker. It does not wear off, does not smear, and is clearly visible.

Preparation of foil fiberglass laminate

The next step is the preparation of fiberglass laminate. First you need to cut it to the size of the future board. It is better to do this with a small margin. To cut foil fiberglass laminate, you can use one of several methods.
Firstly, the material can be cut perfectly using a hacksaw. Secondly, if you have an engraver with cutting wheels, it will be convenient to use it. Thirdly, fiberglass can be cut to size using a utility knife. The principle of cutting is the same as when working with a glass cutter - a cutting line is applied in several passes, then the material is simply broken off.

Now it is imperative to clean the copper layer of fiberglass from the protective coating and oxide. The best way There is no better way to solve this problem than using sandpaper. The grain size is taken from 1000 to 1500 units. The goal is to obtain a clean, shiny surface. It is not worth sanding the copper layer to a mirror shine, since small scratches from sandpaper increase the adhesion of the surface, which will be needed later.
Finally, all that remains is to clean the foil from dust and fingerprints. To do this, use alcohol or acetone (nail polish remover). After processing, we do not touch the copper surface with our hands. For subsequent manipulations, we grab the fiberglass by the edges.

Combination of template and fiberglass

Now our task is to combine the pattern obtained on polyethylene with the prepared fiberglass laminate. To do this, the film is applied to Right place and positioned. Leftovers are wrapped on reverse side and are attached using the same tape.

Drilling holes

Before drilling, it is recommended to secure the fiberglass laminate with the template to the surface in some way. This will allow for greater accuracy and will also prevent sudden rotation of the material as the drill passes through. If you have a drilling machine for such work, then the problem described will not arise at all.

You can drill holes in fiberglass at any speed. Some work at low speeds, others at high speeds. Experience shows that the drills themselves last much longer if they are used at low speeds. This makes them more difficult to break, bend and damage the sharpening.
The holes are drilled directly through the polyethylene. Future contact patches drawn on the template will serve as reference points. If the project requires it, we promptly change drills to the required diameter.

Drawing tracks

Next, the template is removed, but not thrown away. We still try not to touch the copper coating with our hands. To draw paths we use a marker, always permanent. It is clearly visible from the trail it leaves. It is better to draw in one pass, since after the varnish, which is included in the permanent marker, has hardened, it will be very difficult to make edits.

We use the same polyethylene template as a guide. You can also draw in front of the computer, checking the original layout, where there are markings and other notes. If possible, it is better to use several markers with tips of different thicknesses. This will allow you to draw both thin paths and extensive polygons more efficiently.

After applying the drawing, be sure to wait some time necessary for the final hardening of the varnish. You can even dry it with a hairdryer. The quality of future tracks will depend on this.

Etching and cleaning marker tracks

Now comes the fun part - etching the board. There are several nuances here that few people mention, but they significantly affect the quality of the result. First of all, prepare the ferric chloride solution according to the recommendations on the package. Usually the powder is diluted with water in a ratio of 1:3. And here's the first piece of advice. Make the solution more saturated. This will help speed up the process, and the drawn paths will not fall off before everything necessary is etched out.

Immediately the second tip. It is recommended to immerse the bath with the solution in hot water. You can heat it in a metal bowl. Increasing the temperature, as has been known since school, significantly accelerates the chemical reaction, which is what etching our board is. Reducing the procedure time is to our advantage. The tracks made with a marker are quite unstable, and the less they sour in the liquid, the better. If at room temperature the board is etched in ferric chloride for about an hour, then warm water this process is reduced to 10 minutes.
In conclusion, one more piece of advice. During the etching process, although it is already accelerated due to heating, it is recommended to constantly move the board, as well as clean off the reaction products with a drawing brush. By combining all the manipulations described above, it is quite possible to etch out excess copper in just 5-7 minutes, which is easy excellent result for this technology.

At the end of the procedure, the board must be thoroughly rinsed under running water. Then we dry it. All that remains is to wash away the traces of the marker that are still covering our paths and patches. This is done with the same alcohol or acetone.

Tinning of printed circuit boards

Before tinning, be sure to go over the copper layer again with sandpaper. But now we do it extremely carefully so as not to damage the tracks. The simplest and most accessible method of tinning is the traditional one, using a soldering iron, flux and solder. Rose or Wood alloys can also be used. There is also so-called liquid tin on the market, which can greatly simplify the task.
But all these new technologies require additional costs and some experience, so for the first time it will be suitable classic method tinning. Liquid flux is applied to the cleaned tracks. Next, solder is collected onto the soldering iron tip and distributed over the copper remaining after etching. It is important to warm up the traces here, otherwise the solder may not “stick”.

If you still have Rose or Wood alloys, then they can be used outside the technology. They melt just fine with a soldering iron, are easily distributed along the tracks, and do not bunch up into lumps, which will only be a plus for a beginning radio amateur.

Conclusion

As can be seen from the above, budget technology making printed circuit boards at home is really affordable and inexpensive. You don't need a printer, an iron, or expensive photoresist film. Using all the tips described above, you can easily make the simplest electronic radios without investing a lot of money in it, which is very important in the first stages of amateur radio.