Consider the process of manufacturing printed circuit boards at home using a specific example. You need to make two boards. One is an adapter from one type of housing to another. The second is the replacement of a large microcircuit with a BGA package with two smaller ones, with TO-252 packages, with three resistors. Board sizes: 10x10 and 15x15 mm. There are several options for making printed circuit boards at home. The most popular - with the help of photoresist and "iron-laser technology".

Instructions for making printed circuit boards at home

You will need

• personal computer with a program for tracing printed circuit boards;
• laser printer;
• thick paper;
• fiberglass;
• iron;
• hacksaw;
• acid for etching the board.

1 Project preparation printed circuit board

Preparing a PCB project. I use the DipTrace program: convenient, fast, high quality. Developed by our compatriots. Very convenient and pleasant user interface, in contrast to the generally recognized PCAD. Free for small projects. Libraries of cases of radio-electronic components, including 3D models. There is a conversion to PCAD PCB format. Many domestic firms have already begun to accept projects in the DipTrace format.

PCB project

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

2 markup fiberglass

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

3 Project output on a laser printer

We output the project on a laser printer in a mirror image in the highest possible quality, without skimping on toner. Through long experiments, the best paper for this was chosen - thick matte paper for printers. You can try using photo paper or buy special thermal paper.

4 Transferring a project on fiberglass

Clean and degrease the board blank. If there is no degreaser, you can walk on the copper foil of fiberglass with an ordinary eraser. Next, using an iron, we “weld” the toner from the paper to the future printed circuit board. I hold for 3-4 minutes under slight pressure, until the paper turns slightly yellow. I set the heat to max. I put another sheet of paper on top for more even heating, otherwise the image may “float”.

An important point here is the uniformity of heating and pressure and the heating time. If the iron is underexposed, then the print will be washed off during etching, and the tracks will be corroded by acid. If overexposed, then nearby conductors can merge with each other.

5 We remove the paper from the workpiece

After that, put the blank with the paper stuck to it in the water. You can not wait until the textolite cools down. Photo paper gets wet quickly, and after a minute or two, you can carefully remove the top layer.

In places where there is a large accumulation of our future conductive tracks, the paper sticks to the board especially strongly. We haven't touched it yet. We give the board a couple more minutes to get wet. Now the rest of the paper is removed with an eraser or rubbing with a finger. You should get a beautiful clean blank with a clearly printed pattern.

We remove the remnants of paper from the blank of the printed circuit board

6 Board preparation to pickling

We take out the workpiece. We dry. If somewhere the tracks turned out to be not very clear, you can make them brighter with a thin CD marker or nail polish, for example (depending on what you are going to etch the board with).

It is necessary to ensure that all tracks come out clear, even and bright. It depends on the:

• uniformity and sufficiency of heating the workpiece with an iron;
• accuracy when removing paper;
• quality of textolite surface preparation;
• good luck with paper.

Experiment with different types of paper, different heating times, different types of fiberglass surface cleaning to find the best option in terms of quality. By choosing an acceptable combination of these conditions, in the future you will be able to produce printed circuit boards at home faster and with better quality.

7 Etching printed circuit board

We put the resulting workpiece with future conductor tracks printed on it in acid, for example, in a solution of ferric chloride. We'll talk more about other types of etching. We poison 1.5 or 2 hours. While we are waiting, we will cover the bath with a lid: the fumes are quite caustic and toxic.

8 flushing printed circuit board

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

8 Tinning printed circuit board

We process manufactured printed circuit boards. We wash off the remains of the flux with gasoline or an alcohol-gasoline mixture.

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

conclusions

With a certain skill, the “laser-ironing method” is suitable for the manufacture of simple printed circuit boards at home. Conductors from 0.2 mm and thicker are clearly obtained. The time for preparation, experiments with the selection of the type of paper and temperature of the iron, etching and tinning takes about 2 to 5 hours. When you find the optimal combination, the time spent on making the board will be less than 2 hours. This is much faster than ordering boards from a company. Cash costs are also minimal. In general, for simple budget amateur radio projects, the method is recommended for use.

There is a factory breadboard of the following type:

I don't like her for two reasons:

1) When installing parts, you have to constantly turn back and forth in order to first put the radio component, and then solder the conductor. On the table behaves unstable.

2) After dismantling, the holes remain filled with solder, before the next use of the board, they have to be cleaned.

After searching the Internet for various types of breadboards that you can make with your own hands and from available materials, I came across several interesting options, one of which I decided to repeat.

Option number 1

Quote from the forum: « For example, for many years I have been using these homemade breadboards. They are assembled from a piece of fiberglass, into which copper pins are riveted. Such pins can either be bought on the radio market, or made yourself from copper wire with a diameter of 1.2-1.3 mm. Thinner pins bend too much, and thicker pins take too much heat when soldering. This "dummy" allows you to reuse the most shabby radio elements. Connections are best made with a wire in fluoroplastic insulation MGTF. Then once made ends will last a lifetime.

I think this option suits me best. But fiberglass and ready-made copper pins are not available, so I'll do it a little differently.

Copper wire was extracted from the wire:

I cleaned the insulation and, using a simple limiter, made pins of the same length:

Pin diameter — 1 mm.

For the basis of the board took plywood thickness 4 mm (the thicker, the stronger the pins will hold):

In order not to suffer with the markup, I pasted lined paper on the plywood with adhesive tape:

And drilled holes with a pitch 10 mm drill diameter 0.9mm:

We get even rows of holes:

Now you need to hammer the pins into the holes. Since the diameter of the hole is smaller than the diameter of the pin, the connection will be tight and the pin will be tightly fixed in the plywood.

When driving the pins under the bottom of the plywood, you need to put a metal sheet. The pins are clogged with light movements, and when the sound changes, it means that the pin has reached the sheet.

So that the board does not fidget, we make legs:

We glue:

The breadboard is ready!

Using the same method, you can make a board for surface mounting (photo from the Internet, radio):

Below, for completeness, I will give a few suitable designs found on the Internet.

Option number 2

Pushpins with a metal head are hammered into a piece of the board:

It remains only to tin them. Copper-plated buttons are tinned without problems, but with steel ones.

What is a printed circuit board

A printed circuit board (English printed circuit board, PCB, or printed wiring board, PWB) is a dielectric plate, on the surface and / or in the volume of which electrically conductive circuits of an electronic circuit are formed. The printed circuit board is designed for electrical and mechanical connection of various electronic components. Electronic components on a printed circuit board are connected with their leads to the elements of the conductive pattern, usually by soldering.

In contrast to surface mounting, on a printed circuit board, the electrically conductive pattern is made of foil, entirely located on a solid insulating base. The printed circuit board contains mounting holes and pads for mounting pin or planar components. In addition, printed circuit boards have vias for electrical connection of foil sections located on different layers of the board. From the outside, the board is usually coated with a protective coating (“solder mask”) and markings (an auxiliary figure and text according to the design documentation).

Depending on the number of layers with an electrically conductive pattern, printed circuit boards are divided into:

single-sided (SPP): there is only one layer of foil glued to one side of the dielectric sheet.

double-sided (DPP): two layers of foil.

multilayer (MPP): foil not only on two sides of the board, but also in the inner layers of the dielectric. Multilayer printed circuit boards are obtained by gluing several single or double sided boards together.

As the complexity of the designed devices and the density of mounting increase, the number of layers on the boards increases.

The basis of the printed circuit board is a dielectric, the most commonly used materials are fiberglass, getinaks. Also, a metal base coated with a dielectric (for example, anodized aluminum) can serve as the basis for printed circuit boards; copper foil tracks are applied over the dielectric. Such printed circuit boards are used in power electronics for efficient heat removal from electronic components. In this case, the metal base of the board is attached to the radiator. As a material for printed circuit boards operating in the microwave range and at temperatures up to 260 ° C, fluoroplastic reinforced with glass fabric (for example, FAF-4D) and ceramics are used. Flexible boards are made from polyimide materials such as Kapton.

What material will we use for the manufacture of boards

The most common, affordable materials for the manufacture of circuit boards are Getinaks and Steklotekstolit. Getinax paper impregnated with bakelite varnish, fiberglass textolite with epoxy. We will definitely use fiberglass!

Foiled fiberglass is sheets made on the basis of glass fabrics impregnated with a binder based on epoxy resins and lined on both sides with copper electrolytic galvanic-resistant foil 35 microns thick. The maximum allowable temperature is from -60ºС to +105ºС. It has very high mechanical and electrical insulating properties, lends itself well to machining by cutting, drilling, stamping.

Fiberglass is mainly used one or two-sided with a thickness of 1.5mm and with copper foil with a thickness of 35μm or 18μm. We will use a 0.8mm thick single-sided fiberglass with a 35µm thick foil (why will be discussed in detail later).

Methods for making printed circuit boards at home

Boards can be manufactured chemically and mechanically.

With the chemical method, in those places where there should be tracks (drawing) on ​​the board, a protective composition (lacquer, toner, paint, etc.) is applied to the foil. Next, the board is immersed in a special solution (ferric chloride, hydrogen peroxide, and others), which "corrodes" the copper foil, but does not affect the protective composition. As a result, copper remains under the protective composition. The protective composition is subsequently removed with a solvent and the finished board remains.

The mechanical method uses a scalpel (for manual production) or a milling machine. A special cutter makes grooves on the foil, eventually leaving islands with foil - the necessary pattern.

Milling machines are quite expensive, as well as the cutters themselves are expensive and have a small resource. So, we will not use this method.

The simplest chemical method is manual. With a risograph varnish, tracks are drawn on the board and then we etch with a solution. This method does not allow making complex boards with very thin traces - so this is not our case either.

The next method for making boards is with a photoresist. This is a very common technology (boards are made by this method at the factory) and it is often used at home. There are a lot of articles and methods for manufacturing boards using this technology on the Internet. It gives very good and repeatable results. However, this is also not our option. The main reason is rather expensive materials (photoresist, which also deteriorates over time), as well as additional tools (UV lamp, laminator). Of course, if you have a bulk production of boards at home - then the photoresist is out of competition - we recommend mastering it. It is also worth noting that the equipment and technology of photoresist allows the production of silk-screen printing and protective masks on circuit boards.

With the advent of laser printers, radio amateurs began to actively use them for the manufacture of circuit boards. As you know, a laser printer uses "toner" to print. This is a special powder that sinters under temperature and sticks to paper - as a result, a pattern is obtained. The toner is resistant to various chemicals, which allows it to be used as a protective coating on the copper surface.

So, our method is to transfer the toner from the paper to the surface of the copper foil and then etch the board with a special solution to obtain a pattern.

Due to its ease of use, this method has earned a very wide distribution in amateur radio. If you type in Yandex or Google how to transfer the toner from paper to the board, you will immediately find such a term as "LUT" - laser ironing technology. Boards using this technology are made as follows: a pattern of tracks is printed in a mirror version, paper is applied to the board with a pattern to copper, we iron this paper on top, the toner softens and sticks to the board. The paper is further soaked in water and the board is ready.

There are "a million" articles on the Internet about how to make a board using this technology. But this technology has many disadvantages that require direct hands and a very long attachment to it. That is, you have to feel it. Payments do not come out the first time, they are obtained every other time. There are many improvements - to use a laminator (with alteration - in the usual one there is not enough temperature), which allow to achieve very good results. There are even methods for building special heat presses, but all this again requires special equipment. The main disadvantages of LUT technology:

overheating - the tracks spread out - become wider

underheating - tracks remain on paper

the paper is “cooked” to the board - even when it is soaked, it is difficult to leave - as a result, the toner may be damaged. There is a lot of information on the Internet about which paper to choose.

Porous toner - after removing the paper, micropores remain in the toner - the board is also etched through them - corroded tracks are obtained

repeatability of the result - excellent today, bad tomorrow, then good - it is very difficult to achieve a stable result - you need a strictly constant toner warm-up temperature, you need a stable board pressure.

By the way, this method did not work for me to make a board. Tried to do both on magazines and on coated paper. As a result, he even spoiled the boards - copper swelled from overheating.

For some reason, there is undeservedly little information on the Internet about another method of toner transfer - the method of cold chemical transfer. It is based on the fact that toner does not dissolve with alcohol, but with acetone. As a result, if you choose such a mixture of acetone and alcohol, which will only soften the toner, then it can be “re-pasted” onto the board from paper. I really liked this method and immediately paid off - the first board was ready. However, as it turned out later, I could not find detailed information anywhere that would give a 100% result. We need a method by which even a child could make a payment. But for the second time, the payment did not work out, then again it took a long time to select the necessary ingredients.

As a result, after a long time, a sequence of actions was developed, all components were selected that give, if not 100% then 95% of a good result. And most importantly, the process is so simple that the child can make the payment completely on his own. This is the method we will use. (Of course, it can be further improved to the ideal - if it works out better for you, then write). The advantages of this method:

all reagents are inexpensive, available and safe

no additional tools are needed (irons, lamps, laminators - nothing, although not - you need a pan)

there is no way to spoil the board - the board does not heat up at all

paper moves away by itself - you can see the result of the transfer of toner - where the transfer did not come out

there are no pores in the toner (they are sealed with paper) - accordingly, there are no mordants

do 1-2-3-4-5 and always get the same result - almost 100% repeatability

Before we start, let's see what boards we need, and what we can do at home with this method.

Basic requirements for manufactured boards

We will make devices on microcontrollers, using modern sensors and microcircuits. Microcircuits are getting smaller and smaller. Accordingly, the following requirements must be met:

boards must be two-sided (as a rule, it is very difficult to separate a single-sided board, it is rather difficult to make four-layer boards at home, microcontrollers need a ground layer to protect against interference)

the tracks should be 0.2mm thick - this size is quite enough - 0.1mm would be even better - but there is a possibility of pickling, track departure during soldering

the gaps between the tracks - 0.2mm - this is enough for almost all circuits. Reducing the gap to 0.1mm is fraught with merging of tracks and difficulty in monitoring the board for short circuits.

We will not use protective masks, nor will we do silkscreening - this will complicate the production, and if you are making the board for yourself, then this is not necessary. Again, there is a lot of information on the Internet on this topic, and if you wish, you can make a “marafet” yourself.

We will not tinker with the boards, this is also not necessary (unless you are making a device for 100 years). For protection, we will use varnish. Our main goal is to quickly, efficiently, cheaply make a board for the device at home.

This is what the finished board looks like. made by our method - tracks 0.25 and 0.3, distances 0.2

How to make a double-sided board from 2 single-sided

One of the problems with making double-sided boards is aligning the sides so that the vias line up. Usually a "sandwich" is made for this. 2 sides are printed on a sheet of paper at once. The sheet is bent in half, the sides are precisely aligned with the help of special marks. Double-sided textolite is inserted inside. With the LUT method, such a sandwich is ironed and a double-sided board is obtained.

However, in the cold transfer toner method, the transfer itself is carried out with the help of a liquid. And therefore it is very difficult to organize the process of wetting one side simultaneously with the other side. Of course, this can also be done, but with the help of a special device - a mini press (vice). Thick sheets of paper are taken - which absorb the toner transfer liquid. The sheets are wetted so that the liquid does not drip and the sheet holds its shape. And then a “sandwich” is made - a wetted sheet, a sheet of toilet paper to absorb excess liquid, a sheet with a pattern, a double-sided board, a sheet with a pattern, a sheet of toilet paper, again a wetted sheet. All this is clamped vertically in a vise. But we will not do this, we will do it easier.

A very good idea slipped through the board manufacturing forums - what a problem it is to make a double-sided board - we take a knife and cut the textolite in half. Since fiberglass is a puff material, it is not difficult to do this with a certain skill:

As a result, from one double-sided board with a thickness of 1.5 mm, we get two one-sided halves.

Next, we make two boards, drill and that's it - they are perfectly aligned. It was not always possible to cut the textolite evenly, and as a result, the idea came up to immediately use a thin one-sided textolite with a thickness of 0.8 mm. Then you can not glue the two halves, they will be held by soldered jumpers in vias, buttons, connectors. But if necessary, you can glue it with epoxy glue without any problems.

The main advantages of this trip:

Textolite with a thickness of 0.8 mm is easily cut with scissors on paper! In any shape, that is, it is very easy to cut to fit the body.

Thin textolite - transparent - by shining a lantern from below, you can easily check the correctness of all tracks, short circuits, breaks.

Soldering one side is easier - the components on the other side do not interfere and you can easily control the soldering of microcircuit pins - you can connect the sides at the very end

You need to drill twice as many holes and the holes may slightly misalign.

The rigidity of the structure is slightly lost if you do not glue the boards, and gluing is not very convenient

One-sided fiberglass 0.8mm thick is difficult to buy, mostly 1.5mm is sold, but if you can’t get it, you can cut a thicker textolite with a knife.

Let's move on to the details.

Necessary tools and chemistry

We will need the following ingredients:

Now that all this is there, let's do it step by step.

1. Layout of board layers on a sheet of paper for printing using InkScape

Automatic collet set:

We recommend the first option - it is cheaper. Next, you need to solder wires and a switch to the motor (preferably a button). It is better to place the button on the body, so that it is more convenient to quickly turn the motor on and off. It remains to choose a power supply, you can take any power supply for 7-12V with a current of 1A (or less), if there is no such power supply, then charging via USB at 1-2A or a Kron battery may be suitable (you just need to try - not all chargers like motors, the motor may not start).

The drill is ready, you can drill. But it is only necessary to drill strictly at an angle of 90 degrees. You can build a mini machine - there are various schemes on the Internet:

But there is an easier solution.

Drill jig

To drill exactly at 90 degrees, it is enough to make a drilling jig. We'll do something like this:

It is very easy to make it. We take a square of any plastic. We put our drill on a table or other flat surface. And we drill a hole in the plastic with the right drill. It is important to ensure a smooth horizontal displacement of the drill. You can lean the motor against a wall or rail and plastic too. Next, use a large drill to drill a hole for the collet. On the reverse side, drill or cut off a piece of plastic so that the drill can be seen. A non-slip surface can be glued to the bottom - paper or an elastic band. Such a conductor must be made for each drill. This will ensure perfectly accurate drilling!

This option is also suitable, cut off the top part of the plastic and cut off the corner from the bottom.

Here is how drilling is done with it:

We clamp the drill so that it sticks out 2-3 mm when the collet is fully immersed. We put the drill in the place where it is necessary to drill (when etching the board, we will have a mark where to drill in the form of a mini hole in copper - in Kicad we specially set a checkbox for this, so that the drill will get up there by itself), press the conductor and turn on the motor - the hole ready. For illumination, you can use a flashlight by placing it on the table.

As we wrote earlier, you can only drill holes on one side - where the tracks fit - the second half can be drilled without a jig along the first guide hole. This saves some power.

8. Tinning board

Why tin boards - mainly to protect copper from corrosion. The main disadvantage of tinning is overheating of the board, possible damage to the tracks. If you do not have a soldering station - definitely - do not tin the board! If it is, then the risk is minimal.

It is possible to tin the board with ROSE alloy in boiling water, but it is expensive and difficult to obtain. It is better to tin with ordinary solder. To do this qualitatively, a very thin layer must be made a simple device. We take a piece of braid for soldering parts and put it on the sting, fasten it with a wire to the sting so that it does not come off:

We cover the board with a flux - for example, LTI120 and a braid too. Now we collect tin into the braid and we drive it along the board (we paint it) - we get an excellent result. But with use, the braid falls apart and copper fibers begin to remain on the board - they must be removed, otherwise there will be a short circuit! It is very easy to see this by shining a flashlight on the back of the board. With this method, it is good to use either a powerful soldering iron (60 watts) or ROSE alloy.

As a result, it is better not to tin the boards, but varnish them at the very end - for example, PLASTIC 70, or a simple acrylic varnish bought in auto parts KU-9004:

Fine tuning of the toner transfer method

There are two points in the method that are amenable to tuning, and may not work right away. To set them up, you need to make a test board in Kicad, tracks in a square spiral of different thicknesses, from 0.3 to 0.1 mm and at different intervals, from 0.3 to 0.1 mm. It is better to immediately print several of these samples on one sheet and adjust.

Possible issues we will be fixing:

1) tracks can change geometry - spread, become wider, usually not very much, up to 0.1mm - but this is not good

2) the toner may not adhere well to the board, move away when removing the paper, it may not adhere well to the board

The first and second problems are interrelated. I solve the first, you come to the second. We must find a compromise.

The tracks can spread for two reasons - too much clamping weight, too much acetone in the composition of the resulting liquid. First of all, you need to try to reduce the load. The minimum load is about 800g, you should not reduce it below. Accordingly, we put the load without any pressure - we just put it on top and that's it. Be sure to have 2-3 layers of toilet paper for good absorption of excess solution. You must ensure that after removing the load, the paper should be white, without purple smudges. Such smudges indicate a strong melting of the toner. If it was not possible to adjust the load with the load, the tracks still blur, then we increase the proportion of nail polish remover in the solution. Can be increased to 3 parts liquid and 1 part acetone.

The second problem, if there is no geometry violation, indicates an insufficient weight of the cargo or a small amount of acetone. Again, it's worth starting with the load. More than 3 kg does not make sense. If the toner still does not adhere well to the board, then you need to increase the amount of acetone.

This problem mostly occurs when you change your nail polish remover. Unfortunately, this is not a permanent and not a pure component, but it was not possible to replace it with another one. I tried to replace it with alcohol, but apparently the mixture is not homogeneous and the toner sticks with some inclusions. Also, nail polish remover may contain acetone, then it will need less. In general, you will need to carry out such tuning once until the liquid runs out.

Board ready

If you do not immediately solder the board, then it must be protected. The easiest way to do this is to coat with alcohol rosin flux. Before soldering, this coating will need to be removed, for example, with isopropyl alcohol.

Alternatives

You can also make a payment:

Additionally, a custom board manufacturing service is now gaining popularity - for example, Easy EDA. If a more complex board is needed (for example, a 4-layer board), then this is the only way out.

Andreev S.

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

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

First way

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

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

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

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

Second way

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

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

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

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

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

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

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

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

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

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

Third way

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

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

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

PCB etching

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Well, the board is ready.

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, it is necessary 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 exposure 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.