In this post, I will analyze popular methods for creating printed circuit boards yourself at home: LUT, photoresist, hand drawing. And also what programs are best for drawing PP.
Once upon a time, electronic devices were mounted using wall-mounted. Nowadays, only tube audio amplifiers are assembled this way. Printed editing is in widespread use, which has long turned into a real industry with its own tricks, features and technologies. And there are a lot of tricks there. Especially when creating PCBs for high-frequency devices. (I think I’ll do a review of the literature and features of designing the location of PP conductors someday)
The general principle of creating printed circuit boards (PCBs) is to apply tracks on a surface made of non-conducting material that conduct this current. The tracks connect the radio components according to the required circuit. The output is electronic device, which can be shaken, carried, sometimes even wet without fear of damaging it.
IN general outline The technology for creating a printed circuit board at home consists of several steps:
- Select a suitable foil fiberglass laminate. Why textolite? It's easier to get. Yes, and it turns out cheaper. Often this is enough for an amateur device.
- Apply a printed circuit board design to the PCB
- Bleed off excess foil. Those. remove excess foil from areas of the board that do not have a conductor pattern.
- Drill holes for component leads. If you need to drill holes for components with leads. This is obviously not required for chip components.
- Tin the current-carrying paths
- Apply solder mask. Optional if you want to make your board look closer to the factory ones.
Another option is to simply order the board from the factory. Nowadays, many companies provide printed circuit board production services. You will receive an excellent factory printed circuit board. They will differ from amateur ones not only in the presence of a solder mask, but also in many other parameters. For example, if you have a double-sided PCB, then the board will not have metallization of the holes. You can choose the solder mask color, etc. There are a lot of advantages, just have time to slobber on the money!
Step 0
Before making a PCB, it must be drawn somewhere. You can draw it the old fashioned way on graph paper and then transfer the drawing to the workpiece. Or you can use one of the many programs for creating printed circuit boards. These programs are called in general terms CAD (CAD). Some of the options available to a radio amateur include DeepTrace (free version), Sprint Layout, Eagle (you can, of course, also find specialized ones like Altium Designer)
Using these programs, you can not only draw a PCB, but also prepare it for production in a factory. What if you want to order a dozen scarves? And if you don’t want to, then it’s convenient to print such a PP and make it yourself using LUT or photoresist. But more on that below.
Step 1
So, the workpiece for PP can be divided into two parts: a non-conductive base and a conductive coating.
There are different blanks for PP, but most often they differ in the material of the non-conductive layer. You can find such a substrate made of getinax, fiberglass, a flexible base made of polymers, compositions of cellulose paper and fiberglass with epoxy resin, there is even a metal base. All these materials spill over with their physical and mechanical properties. And in production, the material for PP is selected based on economic considerations and technical conditions.
For home PP, I recommend foil fiberglass. Easy to get and reasonably priced. Getinaks are probably cheaper, but personally I can’t stand them. If you have disassembled at least one mass-produced Chinese device, you have probably seen what the PCBs are made of? They are brittle and stink when soldered. Let the Chinese smell it.
Depending on the device being assembled and its operating conditions, you can choose the appropriate textolite: single-sided, double-sided, with different thicknesses foil (18 microns, 35 microns, etc., etc.
Step 2
To apply a PP pattern to a foil base, radio amateurs have developed many methods. Among them are the two most popular at the present time: LUT and photoresist. LUT is an abbreviation for laser ironing technology. As the name suggests, you will need a laser printer, an iron and glossy photo paper.
LUT
A mirrored image is printed onto photographic paper. Then it is applied to foil PCB. And it warms up well with an iron. When exposed to heat, toner from glossy photo paper sticks to the copper foil. After warming up, the board is soaked in water and the paper is carefully removed.
The photo above shows the board after etching. The black color of the current paths is due to the fact that they are still covered with hardened toner from the printer.
Photoresist
This is a more complex technology. But with its help you can get a better result: without mordants, thinner tracks, etc. The process is similar to LUT, but the PP design is printed on transparent film. This creates a template that can be used over and over again. Then a “photoresist” is applied to the PCB—an ultraviolet-sensitive film or liquid (photoresist can be different).
Then a photomask with a PP pattern is firmly fixed on top of the photoresist and then this sandwich is irradiated with an ultraviolet lamp for a clearly measured time. It must be said that the PP pattern on the photomask is printed inverted: the paths are transparent and the voids are dark. This is done so that when the photoresist is exposed to light, the areas of the photoresist not covered by the template react to ultraviolet radiation and become insoluble.
After exposure (or exposure, as the experts call it), the board “develops” - the exposed areas become dark, the unexposed areas become light, since the photoresist there has simply dissolved in the developer (ordinary soda ash). Then the board is etched in a solution, and then the photoresist is removed, for example, with acetone.
Types of photoresist
There are several types of photoresist in nature: liquid, self-adhesive film, positive, negative. What is the difference and how to choose the right one? In my opinion, there is not much difference in amateur use. Once you get the hang of it, you’ll use that type. I would highlight only two main criteria: price and how convenient it is for me personally to use this or that photoresist.
Step 3
Etching of a PP blank with a printed pattern. There are many ways to dissolve the unprotected part of the PP foil: etching in ammonium persulfate, ferric chloride, . I like the last method: fast, clean, cheap.
We place the workpiece in the etching solution, wait 10 minutes, remove it, wash it, clean the tracks on the board and move on to the next stage.
Step 4
The board can be tinned with either Rose or Wood alloy, or simply cover the tracks with flux and go over them with a soldering iron and solder. Rose and Wood alloys are multicomponent low-melting alloys. And Wood's alloy also contains cadmium. So, at home, such work should be carried out under a hood with a filter. It is ideal to have a simple smoke extractor. You want to live happily ever after? :=)
Step 6
I will skip the fifth step, everything is clear there. But applying a solder mask is quite an interesting and not the easiest step. So let's study it in more detail.
A solder mask is used in the process of creating a PCB in order to protect the board tracks from oxidation, moisture, fluxes when installing components, and also to facilitate the installation itself. Especially when SMD components are used.
Usually, to protect PP tracks without a mask from chemicals. and to avoid exposure, seasoned radio amateurs cover such tracks with a layer of solder. After tinning, such a board often doesn’t look very nice. But what’s worse is that during the tinning process you can overheat the tracks or hang “snot” between them. In the first case, the conductor will fall off, and in the second, such unexpected “snot” will have to be removed in order to eliminate the short circuit. Another disadvantage is the increase in capacitance between such conductors.
First of all: solder mask is quite toxic. All work should be carried out in a well-ventilated area (preferably under a hood), and avoid getting the mask on the skin, mucous membranes and eyes.
I can’t say that the process of applying the mask is quite complicated, but it still requires a large number of steps. After thinking about it, I decided that I would give a link to more or less detailed description applying a solder mask, since it is currently not possible to demonstrate the process independently.
Get creative, guys, it's interesting =) Creating PP in our time is akin to not just a craft, but an entire art!
Since I'm studying to be 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?
The printed circuit board (PCB) is used for mechanical installation radio components and electrically connecting them using conductive patterns, pads and other components etched into 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:
- LUT printed circuit board manufacturing technology
- Manually drawing tracks
- 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 by using special programs. There are many free programs V open access, 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. Don't 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 sample, draw the diagram onto the copper layer of a piece of laminate, first with a simple pencil, then trace it 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
- Laser ironing technology is quite effective way making printed circuit boards at home. If you do everything carefully, each path will turn out clear.
- 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.
Terms on specific example. For example, you need to make two boards. One is an adapter from one type of case to another. The second is replacing a large microcircuit with a BGA package with two smaller ones, with TO-252 packages, with three resistors. Board sizes: 10x10 and 15x15 mm. There are 2 options for manufacturing printed circuit boards: using photoresist and the " laser iron". Let's use the "laser iron" method.
The process of making printed circuit boards at home
1. Preparing a printed circuit board design. I use the DipTrace program: convenient, fast, high quality. Developed by our compatriots. Very convenient and pleasant user interface, unlike the generally accepted PCAD. There is a conversion to PCAD PCB format. Although many domestic companies have already begun to accept DipTrace format.
In DipTrace you have the opportunity to see your future creation in volume, which is very convenient and visual. This is what I should get (the boards are shown in different scales):
2. First, we mark the PCB and cut out a blank for the printed circuit boards.
3. We display our project in a mirror image in the highest possible quality, without skimping on toner. After much experimentation, the paper chosen for this was thick matte photo paper for printers.
4. Don’t forget to clean and degrease the board blank. If you don’t have a degreaser, you can go over the copper of the fiberglass with an eraser. Next, using an ordinary iron, we “weld” the toner from the paper to the future printed circuit board. I hold it for 3-4 minutes under slight pressure until the paper turns slightly yellow. I set the heat to maximum. I put another sheet of paper on top for more even heating, otherwise the image may “float”. Important point here - uniformity of heating and pressure.
5. After this, after allowing the board to cool a little, we place the workpiece with the paper stuck to it in water, preferably hot. Photo paper quickly gets wet, and after a minute or two you can carefully remove the top layer.
In places where there is a large concentration of our future conductive paths, the paper sticks to the board especially strongly. We're not touching it yet.
6. Let the board soak for a couple more minutes. Carefully remove the remaining paper using an eraser or rubbing with your finger.
7. Take out the workpiece. Dry it. If somewhere the tracks are not very clear, you can make them brighter with a thin CD marker. Although it is better to ensure that all tracks come out equally clear and bright. This depends on 1) the uniformity and sufficient heating of the workpiece with the iron, 2) accuracy when removing the paper, 3) the quality of the PCB surface and 4) successful selection of paper. You can experiment with the last point to find the most suitable option.
8. Place the resulting workpiece with future conductor tracks printed on it in a ferric chloride solution. We poison for 1.5 or 2 hours. While we wait, let’s cover our “bath” with a lid: the fumes are quite caustic and toxic.
9. We take the finished boards out of the solution, wash and dry. Toner from a laser printer can be easily washed off the board using acetone. As you can see, even the thinnest conductors with a width of 0.2 mm came out quite well. There is very little left.
10. We tin the printed circuit boards made using the “laser iron” method. We wash off the remaining flux with gasoline or alcohol.
11. All that remains is to cut out our boards and mount the radio elements!
Conclusions
With some skill, the “laser iron” method is suitable for making simple printed circuit boards at home. Short conductors from 0.2 mm and wider are quite clearly obtained. Thicker conductors turn out quite well. Time for preparation, experiments with selecting the type of paper and iron temperature, etching and tinning takes approximately 3-5 hours. But it’s 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.
conditions using hydrogen peroxide. Everything is very simple and does not require much effort.
To work we will need the following list of tools:
- Program - layout 6.0.exe (other modification is possible)
- Negative photoresist (this is a special film)
- Laser printer
- Transparent film for printing
- Marker for printed circuit boards (if not, you can use nitro polish or nail polish)
- Foil PCB
- UV lamp (if there is no lamp, wait sunny weather and use the sun’s rays, I’ve done this many times and everything works out)
- Two pieces of plexiglass (you can do one, but I made two for myself), you can also use a CD box
- Stationery knife
- Hydrogen peroxide 100 ml
- Citric acid
- Soda
- Salt
- Smooth hands(this is required)
In the layout program we do the board layout
We check it carefully so as not to confuse anything and print it
Be sure to check all the boxes on the left as shown in the photo. The photo shows that our drawing is in a negative image, since our photoresist is negative, those areas that are hit by UV rays will be tracks, and the rest will be washed off, but more on that a little later.
Next, we take a transparent film for printing on a laser printer (available for free sale), one side is slightly matte and the other is glossy, and so we place the film so that the design is on the matte side.
We take the PCB and cut it to the size of the required board
Cut the photoresist to size (when working with photoresist, avoid direct sunlight, as it will damage the photoresist)
We clean the textolite with an eraser and wipe it so that there is no debris left
Next, we tear off the protective transparent film on the photoresist.
And carefully glue it to the PCB, it is important that there are no bubbles. Iron it well so that everything sticks well.
Next we need two pieces of plexiglass and two clothespins, you can use a CD box
We place our printed template on the board, be sure to place the template with the printed side on the PCB and clamp it between the two halves of plexiglass so that everything fits tightly
Afterwards we will need a UV lamp (or a simple sun on a sunny day)
We screw the light bulb into any lamp and place it above our board at a height of about 10-20 cm. And turn it on, the illumination time from such a lamp as in the photo at a height of 15 cm for me is 2.5 minutes. I don’t recommend it for longer, you might ruin the photoresist
After 2 minutes, turn off the lamp and see what happens. Paths must be clearly visible
If everything is clearly visible, proceed to the next step.
Take the listed ingredients
- Peroxide
- Citric acid
- Salt
- Soda
Now we need to remove unexposed photoresist from the board; it needs to be removed in solution soda ash. If it doesn't exist, then you need to make it. Boil water in a kettle and pour it into a container
Pour plain soda into it. You don’t need much for 100-200 ml, 1-2 tablespoons of soda and mix well, a reaction should begin
Let the solution cool to 20-35 degrees (you can’t put the board directly into a hot solution, all the photoresist will peel off)
We take our payment and remove the second one protective film NECESSARILY
And put the board in the COOLED solution for 1-1.5 minutes
Periodically, we take out the board and wash it under running water, carefully cleaning it with your finger or a soft kitchen sponge. When all the excess is washed off, there should be a board like this left:
The photo shows that a little more was washed off 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 mistakes with it
Next, pour 100 ml peroxide, 3-4 spoons into another container citric acid and 2 tablespoons of salt.
It seems that overclockers are approaching difficult times. Manufacturers, as if by agreement, began to limit the possibility of overclocking their products. I don't know if this is for good or for bad. I am not a principled opponent of overclocking, but I am pragmatic about it. If there is any benefit from it, for God's sake. But from my own experience, I was convinced that overclocking by itself does not give much. Well, I overclocked my processor by 40%, overclocked the video card a little and... I saw almost no differences in real work, with the exception of processor temperature. It was 38, now it’s 52, I don’t know what, but not degrees. He shrugged his shoulders and returned everything to its place. True, I have a fairly powerful computer even without overclocking. So, overclocking seems to provide only moral satisfaction. Yes, and this is debatable. Actually, what is the merit of an overclocker? Is it because he got a well-used processor or was he lucky with a specific video card?
But there have always been, are and will be people for whom it is not enough to buy good thing and just use it. So anti-overclocking measures from Intel, AMD, ATI and Nvidia can help direct the energy of people who feel itchy hands in a more promising direction.
advertising
In my opinion, modding is much more useful both from a practical point of view and for obtaining moral satisfaction. But not simple decoration, but changes and additions that increase functionality and ease of use. So, offhand, you can offer, for example, multichannel electronic thermometer, for rapid and independent of the arbitrariness of biowriters temperature control at all critical points, a built-in 6-8 channel amplifier for passive speakers (wow, I’m sick of the wheezing of cheap Chinese goods!), devices for hardware switching of hard drives (useful for placing several conflicting ones on one computer operating systems and archive protection from viruses), electronic system water cooling control, etc.Here I would like to note the articles “Everything you wanted to do by hand, but were afraid to ask...” and “HDD loading indicator”. They can be considered as the first signs of this, in my opinion, extremely promising approach.
There are even more of those who could repeat the finished development. The problem is technology. Making high-quality printed circuit boards at home is quite problematic, and ordering them from specialized companies expensive and time-consuming. And some of the buzz is lost.
Media selection
advertising
As it turns out, only special film can be used as an image carrier. laser printers. Any type of paper is not suitable. The film should be thin and have a paper backing. Expensive types of films have a special sublayer to firmly fix the image and are also unsuitable. IN lately I use EMTEK film, because Xerox film has disappeared from sale here, but Xerox is better. It warps less when heated. It is better to use low-melting toner. At first I used the original Samsung ML-1250 toner cartridge. It provides a very good dense image. After refilling the cartridge with Xerox 8T toner, as I was advised at the service center, the image became worse and the boards stopped working altogether, which prompted me to do research. But, having improved the technology, I achieved excellent results and with this toner.
Preparation of the workpiece
To obtain a good result, the surface preparation of the workpiece is crucial. The surface must be perfectly clean and smooth. Wiping with alcohol, acetone or any cleaning agents is not sufficient. The surface preparation procedure is as follows. First, we clean the surface from coarse dirt with Pemolux powder. We rinse the workpiece with a cotton swab without touching the surface with your fingers. Place it in a ferric chloride solution for 10-15 seconds. In this case, the thin top layer is etched off along with all contaminants. We rinse the workpiece under running water with a cotton swab. Shake off the water and dry without touching the surface with anything. If everything is done correctly, you should end up with a dark pink matte surface, possibly with slight streaks. The main thing is that there should be no shiny areas. If they are, repeat the procedure.
Rolling a pattern
It is usually recommended to place the workpiece, the carrier on it and iron it with an iron. IN ideal conditions this is possible and will pass, but in reality both the surface of the workpiece and the sole of the iron are not completely smooth and it will not be possible to obtain uniform pressing of the hot medium to the surface of the workpiece. In addition, the process cannot be controlled and you have to rely on luck. So I fix the iron with the sole up, put it on it blank slate paper so as not to accidentally damage the sole and the workpiece on it. The iron should be heated to a temperature at which the paper does not yet turn yellow, but no less. I lay a film with a printed pattern on top and roll it with a special device made from a tape recorder pressure roller. Rolling should begin from the center, squeezing the air from under the film to the sides. After the film adheres tightly to the surface of the workpiece, we increase the rolling force and carefully go over the entire board. Remove the workpiece from the iron and cool it. You can remove the film from the workpiece only after it has completely cooled. If done correctly, all the toner will transfer to the board, leaving faint pinkish marks on the film. The film cannot be reused.
Pin a picture
Despite the fact that the design looks almost perfect in appearance, you cannot etch the board right away. The toner layer becomes porous. If you immediately etch the board, and then look at the resulting conductors under a microscope or a strong magnifying glass, the etched points are clearly visible, and the edges of the conductor turn out to be uneven. To avoid this, cover the design on the board with a 10% solution of rosin in alcohol and place it on the iron again. The temperature should be set to the maximum so that the paper turns yellow and smokes. Let stand for 10 minutes. In this case, the toner fuses with rosin, forming a very durable, uniform, shiny layer. Let the board cool and develop the design with a swab of alcohol. Rosin fused with toner does not dissolve in alcohol, and the remains of unevaporated rosin from gap areas can be removed without much difficulty. When wiping, you can apply considerable force. The alloy of toner and rosin holds very firmly, even with sandpaper it is difficult to remove it. If somewhere the drawing is damaged, then this is its fate. It is better to detect a poorly rolled conductor at the wiping stage than after etching. If unsuccessful, wash off the drawing with acetone and repeat everything from the very beginning. This happens rarely.
Board etching
We carry out etching in a solution of ferric chloride. The solution can be heated to a temperature of 50-60 degrees. There are no special features. After etching, rinse the board with water and wash off protective coating acetone.
Results achieved
Using the technology described above, single-sided printed circuit boards measuring up to 100x150 mm were produced. The technology allows one conductor to be routed between the legs of microcircuits in DIP packages, so I have not yet encountered the need for double-sided boards. I have an idea about modifying the technology for double-sided boards, but have not tried it yet. The entire board manufacturing cycle takes about two hours, excluding the time spent on wiring. The payment is received on the first try in 9 cases out of 10.
P.S. This is my first article for you. If this topic is of interest to you, I will send more. I have a lot of materials.
Sincerely, S. Veremeenko.