How to prepare a board made in Eagle for production
Preparation for production consists of 2 stages: technology restrictions check (DRC) and generation of files in Gerber format
DRC
Every PCB manufacturer has technology restrictions on minimum trace widths, trace spacing, hole diameters, and so on. If the board does not meet these restrictions, the manufacturer refuses to accept the board for production.
When creating a PCB file, the default technology limits are set from the default.dru file in the dru directory. As a rule, these limits do not correspond to the limits of real manufacturers, so they need to be changed. You can set the limits just before generating the Gerber files, but it's better to do it right after the board file is generated. To set restrictions, press the DRC button
gaps
Go to the Clearance tab, where the gaps between the conductors are set. We see 2 sections: different signals and Same signals. different signals- defines gaps between elements belonging to different signals. Same signals- defines gaps between elements belonging to the same signal. When moving between input fields, the picture changes, showing the meaning of the input value. Dimensions can be specified in millimeters (mm) or thousandths of an inch (mil, 0.0254 mm).
Distances
The Distance tab defines the minimum distances between the copper and the edge of the board ( Copper/Dimension) and between the edges of the holes ( Drill/Hole)
Minimum dimensions
On the Sizes tab for double-sided boards, 2 parameters make sense: Minimum Width- minimum conductor width and Minimum Drill is the minimum hole diameter.
Belts
The Restring tab defines the sizes of the bands around the vias and pads of the output components. The width of the girdle is set as a percentage of the hole diameter, while you can set a limit on the minimum and maximum width. For double-sided boards, the parameters make sense Pads/Top, pads/bottom(pads on the top and bottom layers) and Via/Outer(through holes).
masks
On the Masks tab, the gaps from the edge of the pad to the solder mask are set ( stop) and solder paste ( Cream). Clearances are specified as a percentage of the smaller pad size, and you can set a limit on the minimum and maximum clearance. If the board manufacturer does not specify special requirements, you can leave the default values on this tab.
Parameter limit defines the minimum via diameter that will not be covered by the mask. For example, if you specify 0.6mm, then vias with a diameter of 0.6mm or less will be masked.
Running a check
After setting the restrictions, go to the tab file. You can save the settings to a file by clicking the button. Save as.... In the future, for other boards, you can quickly load the settings ( Load...).
Push button apply the set technology limits apply to the PCB file. It affects layers tStop, bStop, tCream, bCream. Also, vias and pads on output components will be resized to fit the constraints set on the tab. Restring.
Button press Check starts the constraint control process. If the board satisfies all restrictions, the program status line will display the message No errors. If the board does not pass control, a window appears DRC Errors
The window contains a list of DRC errors, indicating the error type and layer. By double-clicking on a line, the area of the board with the error will be shown in the center of the main window. Error types:
too little clearance
hole diameter too small
intersection of tracks with different signals
foil too close to board edge
After correcting the errors, you need to start the control again, and repeat this procedure until all errors are eliminated. The board is now ready to be output to Gerber files.
Gerber file generation
From the menu file choose CAM Processor. A window will appear CAM Processor.
The set of file generation parameters is called a task. The task consists of several sections. The section defines output parameters for a single file. Eagle comes with the gerb274x.cam task by default, but it has 2 drawbacks. Firstly, the lower layers are displayed in a mirror image, and secondly, the drill file is not displayed (one more task will have to be performed to generate the drill). Therefore, consider creating a task from scratch.
We need to create 7 files: board borders, copper top and bottom, silkscreen top, solder mask top and bottom, and drill.
Let's start with the borders of the board. In field Section enter the name of the section. Checking what's in the group style installed only pos. Coord, Optimize and Fill pads. From the list device choose GERBER_RS274X. In the input field file enter the name of the output file. It is convenient to place the files in a separate directory, so in this field we will enter %P/gerber/%N.Edge.grb . This means the directory where the board source file is located, the subdirectory gerber, the original board file name (without extension .brd) with added at the end .edge.grb. Note that subdirectories are not created automatically, so you will need to create a subdirectory before generating files gerber in the project directory. In the fields offset enter 0. In the list of layers, select only the layer Dimension. This completes the creation of the section.
To create a new section, press Add. A new tab appears in the window. Set the section parameters as described above, repeat the process for all sections. Of course, each section must have its own set of layers:
copper top - Top, Pads, Vias
copper bottom - Bottom, Pads, Vias
silkscreen on top - tPlace, tDocu, tNames
top mask - tStop
bottom mask - bStop
drilling - Drill, Holes
and the filename, for example:
top copper - %P/gerber/%N.TopCopper.grb
bottom copper - %P/gerber/%N.BottomCopper.grb
top silkscreen - %P/gerber/%N.TopSilk.grb
top mask - %P/gerber/%N.TopMask.grb
bottom mask - %P/gerber/%N.BottomMask.grb
drilling - %P/gerber/%N.Drill.xln
For a drill file, the output device ( device) should be EXCELLON, but not GERBER_RS274X
Keep in mind that some board manufacturers only accept files with names in the 8.3 format, that is, no more than 8 characters in the file name, no more than 3 characters in the extension. This should be taken into account when naming files.
We get the following:
Then open the board file ( File => Open => Board). Make sure the board file has been saved! Click Process Job- and we get a set of files that can be sent to the board manufacturer. Please note that in addition to the actual Gerber files, information files will also be generated (with extensions .gpi or .dri) - they do not need to be sent.
You can also display files only from individual sections by selecting the desired tab and pressing Process Section.
Before sending the files to the board manufacturer, it's a good idea to preview the output with a Gerber viewer. For example, ViewMate for Windows or for Linux. It can also be useful to save the board in PDF (in the board editor File->Print->PDF button) and upload this file to the manufacturer along with the gerberas. And then they are also people, this will help them not to make a mistake.
Technological operations that must be performed when working with photoresist SPF-VShch
1. Surface preparation.
a) cleaning with polished powder ("Marshalit"), size M-40, washing with water
b) decapitation with 10% sulfuric acid solution (10-20 sec), washing with water
c) drying at T=80-90 gr.C.
d) check - if within 30 seconds. a continuous film remains on the surface - the substrate is ready for use,
if not, repeat all over again.
2. Deposition of photoresist.
The photoresist is applied on a laminator with Tshafts = 80 gr.C. (See laminator operating instructions).
For this purpose, the hot substrate (after the drying cabinet) simultaneously with the film from the SPF roll is directed into the gap between the rolls, and the polyethylene (matt) film should be directed towards the copper side of the surface. After pressing the film to the substrate, the movement of the rollers begins, while the polyethylene film is removed, and the photoresist layer is rolled onto the substrate. Mylar protective film remains on top. After that, the SPF film is cut on all sides to fit the substrate and kept at room temperature for 30 minutes. Exposure is allowed for 30 minutes to 2 days in the dark at room temperature.
3. Exposure.
Exposure through a photomask is carried out on SKCI or I-1 installations with UV lamps of the DRKT-3000 or LUF-30 type with a vacuum of 0.7-0.9 kg/cm2. The exposure time (to obtain a picture) is regulated by the installation itself and is selected experimentally. The template must be well pressed against the substrate! After exposure, the workpiece is aged for 30 minutes (up to 2 hours is allowed).
4. Manifestation.
After exposure, the process of developing the picture is carried out. For this purpose, the upper protective layer, the lavsan film, is removed from the surface of the substrate. After that, the workpiece is lowered into a solution of soda ash (2%) at T=35 gr.C. After 10 seconds, the process of removing the unexposed part of the photoresist using a foam swab begins. The time of manifestation is selected empirically.
Then the substrate is removed from the developer, washed with water, decapitated (10 sec.) with a 10% solution of H2SO4 (sulfuric acid), again with water and dried in an oven at T=60°C.
The resulting drawing should not flake off.
5. The resulting drawing.
The resulting pattern (photoresist layer) is resistant to etching in:
- ferric chloride
- hydrochloric acid
- copper sulphate
- aqua regia (after additional tanning)
and other solutions
6. Shelf life of photoresist SPF-VShch.
Shelf life of SPF-VShch is 12 months. Storage is carried out in a dark place at a temperature of 5 to 25 gr. C. in an upright position, wrapped in black paper.
Sprint layout
The program with a simple and intuitive interface is designed for designing printed circuit boards with low complexity. It is used by amateurs of radio electronics when creating boards for electronic devices in order to automate the design process.
Eagle
A popular computer program specially designed for beginners and amateurs of radio electronics. Allows you to draw circuit diagrams and printed circuit boards of no higher than average complexity.
The domestic Russian-language program is intended for both professionals and radio amateurs. It is used to create boards in manual or automatic mode. Distributed in 2 versions - free (with restrictions) and paid.
A free, easy-to-learn and easy-to-use program is designed for manual design of boards of low to medium complexity. In addition to the built-in library of electronic components, it is possible to create your own database, which has made it popular among radio amateurs.
Altium Designer
Professional software for creating a wide range of electronic boards and devices of varying complexity. Allows you to carry out the development and design of printed circuit boards at a high level. It is used in many industries dealing with electronic devices.
FreePCB
A software product that is widely used by professionals in the development and design of printed circuit boards of varying complexity. It is distributed free of charge, which allows you to use the software in many enterprises of the national economy and in private companies that produce electronic devices.
Kicad
A free Russian-language professional program that allows you to design printed circuit boards and electrical circuits of small, medium and high complexity. You can create boards and place components on them manually and automatically.
DesignSpark PCB
A free program that allows you to design electrical circuits and printed circuit boards of electronic devices at a professional level. The program is equipped with a powerful library of electronic components and has an autorouting function.
PCB123
A software product with which amateurs and professionals can design and develop circuits and boards of any complexity with the creation of a three-dimensional image. The program is distributed free of charge.
TopoR
A paid high-performance program released by a domestic manufacturer is designed for designing and manufacturing boards of any complexity. The appearance of the resulting board can be clearly seen on a three-dimensional image that can be built in the same program.
EDWinXP
Paid professional software used for designing boards and developing electronic devices of varying complexity. The program can also be downloaded for free, but the duration of such a program is limited (14 days).
P-CAD
Powerful and one of the earliest professional PCB design software. Allows you to design boards of any complexity. Currently using the version of the program that was released in 2006.
Paid professional program designed to design both light and complex single-sided, double-sided and multilayer boards. The functions that are available in the program allow you to simulate, carry out various checks and fully prepare the board for production. There is a trial version of the program, which is limited to the number of days of its use (30).
The post contains photos, videos and diagrams.
The idea behind the photoresistive method is very simple. The copper on the printed circuit board is coated on top with a special substance. If light hits this substance, it then dissolves in the developer. If the light does not hit, then the substance remains a dye in the developer. The board manufacturing process consists of four parts:
1. Create a transparent mask on which it is marked what to connect with what
1. We shine on the board with the substance through this mask
2. We throw the board into the developer: only the places marked on the mask are painted on the board
3. We throw the board into the etchant: it will eat all the copper, except for the painted one
Schema creation
The first step in creating a printed circuit board is quite obvious: you need to create a diagram of what will be on the board. A fairly standard program for this is Eagle CAD. Despite the fact that the program is quite difficult to master (it seems to me that it is absolutely disgusting to use), Eagle CAD is used by a lot of people. There are so many users that parts manufacturers and suppliers sometimes create component libraries.As part of this post, we will be making a fairly simple device: a board that distributes contacts for ATTiny. So that you can plug a chip, power and programmer into the board.
First, let's draw a simple circuit, and then, by clicking "Switch to board", we will place the components on the board layout.
The scheme and layout of the board is possible.
Print layout
Let's prepare the layout for printing. You need to make sure that only layers with Bottom, Pads, Vias, Dimension are enabled. In the print menu, you need to enable Mirror and Black. Thus, the layout will be reflected and printed in black only. I don't know if there's a better way, but I printed the layout to PDF, converted the PDF to TIFF at a pretty decent resolution, and then duplicated the image in a text editor to fill the sheet:
I note that I printed two diagrams, one for today, and the other for later.
The document is ready. We print on transparent film. I used film from MG Chemicals. Although designed for laser printers, I used my Lexmark inkjet. Minus: the ink is easy to smear by hand.
Board preparation
Obviously, the photoresistive process requires a board coated with a special substance. You can buy this substance and cover the fee yourself, but I decided to buy ready-made. Cut out a piece from the board that matches the size of the circuit. I used a Dremel machine to cut:
Exposure
Everything is ready to expose the board. Experience shows that an inkjet printer may not give the desired density (that is, black in appearance will actually be riddled with small holes). It is not difficult to deal with this: you can combine two or three layers of the printout. Like this:
Let's remove the protective layer from the board (white thin film) and put it on the base (the book on electronics gives +3 to luck). We will cover the board with a film with a printout and press this case with glass:
The design should stand under a strong lamp for 10 minutes:
development
While the board is being exposed, let's dilute the developer. The proportion and recommended temperature are written on the developer box. I got the developer from MG Chemicals. It is diluted in any plastic container in a ratio of 1 to 10:
The developer is ready, ten minutes have already passed. We take the board and throw it into the developer:
Etching
We rinse the board in water and throw it into the etchant. I used ferric chloride from MG Chemicals. The recommended temperature is 50 ° C, but I poisoned at room temperature 25 ° C. It was poisoned for about 20 minutes:You will get something like this:
Cleanup
The remaining dye is easily removed with alcohol-coated rags:The result is a clean board:
holes
Holes are easy to punch. I used the same Dremel machine:It turns out almost ready-made board: 
Components
We attach the necessary components to the board and solder them to the copper base:
Result
The payment turned out to be what you need, at least show your friends:
However, you will not explain to all your friends what it is ...
Security
The process of manufacturing boards by this method involves working with any chemical rubbish.First, don't flush the chemical stuff down the sink or toilet. There is a lot of advice on the Internet about what to do with this rubbish.
Secondly, this chemical rubbish spoils clothes, leaves stains on the hands and does something completely terrible with the eyes. Please use safety equipment! For example, I used rubber gloves, goggles, and a shower curtain apron: 
I will be happy to answer questions, hear suggestions on how this process can be improved, and, of course, supplement the post with any information that was missed.
There are many methods creation of printed circuit boards. All of them have both pluses and minuses. The main criteria for choosing a method for creating a printed circuit board are simplicity, i.e. the ability to implement using what is at home or at work, and accuracy - how much you can reduce the distance between the tracks without compromising the circuit. Perhaps these criteria are not the most important, but for me, simplicity and accuracy have always been the most important.
The method I will describe here is called "plotter cutting method". The method is well known to those who are engaged in the field of outdoor advertising. In outdoor advertising, it is necessary to cut out letters, numbers, contours on adhesive paper. Of course, you can (like the Chinese) do everything manually, but where accuracy is needed, a plotter comes to the rescue. Instead of an ink cartridge on such a plotter, a cutter is installed, which makes cuts in the adhesive layer, leaving the paper substrate intact.
A plotter can be found in any printing house and for little money you can cut a printed circuit board with a very high track density. The printed circuit board drawing must be presented in vector form, the most preferred format for this is CorelDraw. That's it about creating a printed circuit board in the Corel Draw program and the conversation will go below.
First you need to decide on the pattern of the printed circuit board. There is enough material on the net to find a board drawing that is suitable in terms of completeness and quality of execution. Like all drawings, the file will have the extension: jpg, bmp, gif, tif…
We take a drawing of a printed circuit board. The quality of the picture can be either very good or not very good. For example, here's what I found.
The quality of the picture leaves much to be desired, so with the help of any graphic editor we ennoble the picture. The most common editor is Photoshop, but to work in this program you need skills and months of mastering, so you can go the long way and do the processing in the standard Windows program - Paint.
The purpose of processing is to increase the contrast of the tracks, remove unnecessary blackouts, and crop the image to the desired size. If all this succeeds, then you can immediately proceed to the installation of the CorelDraw program. I did all the processing on a very slow machine (800 MHz, 384 Mb), so the new versions of the program were not suitable for me, but CorelDraw Graphics Suite X3 was perfect.
For those who are not yet a virtuoso in Photoshop, but in Paint the processing results left much to be desired, I will describe what needs to be done with the picture to achieve the best result. Naturally, the image needs to be processed. The program for this is suitable Sprint-Layout. To work in this program, the original processed image must have a resolution of no more than 300 by 300 pixels, bmp extension and any quality. The resolution does not affect anything, then everything can be adjusted to the actual dimensions of the printed circuit board, it's just that the Layout program does not work with pictures larger than 300 by 300 pixels.
Sprint-Layout is a program for drawing one- and two-sided printed circuit boards, it allows you to copy printed circuit boards, so to speak, “from nature”. This last skill will be useful to us.
We launch the Sprint-Layout program.
"File - new file", select the dimensions of the future drawing of the printed circuit board.
"Options - background", open the view of the printed circuit board in bmp format.
Here you need to do a little magic with the dimensions of the original image. Although the maximum resolution is 300 by 300 pixels, but when adding an image of 300 by 150, the image turned out to be clearly cut off in length, so by increasing the dpi resolution, we adjust the image size. If this does not work out, you need to change the physical dimensions of the image in Photoshop.
We redraw the board using the program tools. The program is in Russian, and it is not so difficult to understand it. After drawing, save the resulting image in *.jpg format.
After all the processing, you should get something like this image, you just need to save the correct layer.
Adding the processed image to CorelDraw. Corel only needs to convert the image into a vector drawing that the plotter understands. For this:
1) open the program and click "create"
2) click "file - import" and select the processed image file, a black arrow appears indicating the place where you want to place the image, right-click on the screen - the image appears
3) you need to convert the image to a vector drawing. Select "Bitmaps - Trace Bitmap - High Quality Image"
4) if the window outlines are not visible, which happens when the desktop resolution is insufficient, press the “enter” button or press OK and we get something like this
5) on the color palette on the vertical bar on the right, with the LEFT mouse button, click on the WHITE color, and with the RIGHT mouse button - on the BLACK color. This will make the outline of the tracks black.
6) got two drawings superimposed on each other. One is the original image, the second is a vector drawing. We shift one relative to the other, holding the right mouse button, select the picture with dark tracks and delete it with the "delete" button, set the dimensions of the printed circuit board (in the program header - the size of the objects). You should get a vector drawing of the circuit board contours, suitable for cutting on a plotter
7) save the drawing in *.cdr format and send it for cutting
After cutting, the paper-based adhesive film has many thin lines that cut through the adhesive layer of the film and form tracks.
The next step is to remove the entire film between the tracks, leaving the tracks on the paper base. Carefully pick a place in the corner between the tracks with a sharp knife and gently pull towards the board and up. It is necessary to monitor the tracks so that none remains on the film being removed. If the track rises from the paper base, then it must be quietly returned to its place with a fingernail.
Do not touch the stripped film with areas of not yet stripped film and finished tracks. The films will stick together and be difficult to remove. If the cutting is done with high quality, and the tracks are large, then without special skills you can do this operation the first time.
On top of the tracks to transfer them from the paper base to the fiberglass base, we roll a transparent film with an adhesive layer and carefully remove the paper base, leaving the tracks glued to the transparent film. This film is available in printing houses and usually comes with an adhesive film. It turns out that the tracks on the colored side are glued to the transparent film, and on the side of the adhesive layer they simply hang in the air.
We are fully preparing the board for transferring tracks to it.
The board must be clean, without greasy spots, which may prevent the tracks from fixing properly, so we clean the board with sandpaper, degrease, and dry.
We roll the film with tracks to the foil part of the fiberglass. Rolling involves gentle but firm pressure on the tracks with a hard sponge that will not scratch the film. Then carefully remove the film so that all the tracks remain on the printed circuit board.
We warm up the film for better adhesion of the film to the board using a hair dryer or a fan heater, pickle, rinse, drill holes, remove the film tracks, clean the tracks with sandpaper and tin the tracks.
The preparation of the printed circuit board takes place in several stages:
1. Cut the foil fiberglass to the size of the printed circuit board, leaving gaps for fastening.
2. Clean the foil layer of fiberglass with fine sandpaper to a shine, degrease with “nefras” or another solvent that does not leave streaks and stains, and dry.
3. Apply the tracks of the future circuit in any suitable way.
4. Etch the board in a solution of ferric chloride.
5. Rinse and dry the printed circuit board.
6. Drill holes with a small drill.
7. Remove the protective layer of the tracks.
8. Clean, degrease, dry.
9. Apply a thin layer of solder to all tracks, leaving the holes unsoldered.
10. Solder the parts.
We print the payment.
Yes, that's right - we print.
Now we will talk about how to make a good printed circuit board using a laser printer and an iron. In general, let's talk about the now fashionable laser-ironing technology for manufacturing printed circuit boards.
The technology, as it turned out, is not only fashionable, but also very convenient and simple. To combine business with pleasure and not make some kind of abstract fee, let's take the scheme from our website as an example. We'll make a payment for her.
First of all, what do we need?
1.
Of course, foil fiberglass is one- or two-sided, it doesn’t matter. Now there are no problems with it - it is sold in any radio parts store or on the market.
2.
Any magazine on "glossy" paper.
3.
A tool for cutting textolite is best a cutter from a hacksaw blade.
4.
Sandpaper "zero" or a hard sponge for cleaning dishes made of steel wire.
5.
From chemistry: alcohol, acetone or solvent, liquid soldering flux, ferric chloride.
6.
And of course a computer, a laser printer, a soldering iron, good lighting and a lot of patience.
Look like that's it.
It is necessary to start, of course, with the design of this very board.
There are a great variety of programs that are engaged in tracing (that is, breeding tracks) printed circuit boards in manual and automatic mode. Personally, I have so far settled on the program dip trace domestic manufacturer. It allows you to draw not only boards, but also circuit diagrams and libraries of electronic components. But now we are only interested in boards.
This is how this program looks like and this is how the finished drawing of the board in it looks like.
Well, then we proceed directly to the manufacturing process and, so as not to get confused in it, we will go in small steps, so:
We need to print the board drawing on a laser printer. In principle, you can use an inkjet printer, but in this case you will need to make a photocopy of the drawing and use it already. The idea is simple - we need to print a drawing on paper made with toner (powder), which is used in laser printers or copiers. We need glossy paper - most often, it is used in computer magazines or various advertising booklets. I used a magazine that I love and respect very much for its content, and now also for the quality paper on which it is printed.
You don't need to clean anything - just tear out the page and print our drawing directly on top of the original text.
Print a couple of copies at once - suddenly come in handy.
Printed, in connection with which we move on.
We cut off the piece of textolite we need in size, prepare the skin (sponge) and acetone with a piece of cotton wool or cotton pads.
We take a skin or a sponge and begin to rub our workpiece from the side of the foil. It is not necessary to be especially zealous, but nevertheless, the surface should become even and brightly shiny, and not matte, as it was before. After we take a piece of cotton wool, dip it in acetone or solvent and wipe the freshly polished foil.
It should turn out something like this:
I must say that after the workpiece has been wiped with acetone, in no case should it be grabbed by the fingers of the foil - only by the edges, even better with two fingers by the corners. Otherwise, you will have to re-wipe the foil with acetone.
Let's move on to the next step.
Before performing this step, read its description to the end.
So, from the sheet on which the board drawing is printed, we cut out a piece directly with the drawing, while leaving rather large margins at the edges. After that, we carefully put our blank on the drawing (with foil to the printed tracks, of course), wrap the fields and fasten them, for example, with masking tape.
You should get an envelope like this:
Done? Great, let's move on to the most important step - ironing.
So, we take an iron - absolutely any.
Tefal, Bosch, Belarusian Tractor Plant, with a steamer, without a steamer. No difference.
We set the temperature regulator to the maximum (if you have the names of fabrics written on the iron, then on "linen"). We put the iron on the prepared envelope.
The envelope, of course, must be placed with tape down. We begin to iron gently. This is the most subtle part of the whole procedure and it is impossible to learn it except from your own experience. The pressure on the iron should not be strong - otherwise the toner will spread and smear over the foil, but not weak - otherwise the toner will not adhere well to the workpiece. In short - there is a wide field for experimentation. In any case, it is necessary to warm up the entire surface of the future board evenly and pay special attention to the edges - there is the greatest risk of non-heating and subsequent peeling of the toner. The same applies to the warm-up time, although this is easier.
Approximately the degree of readiness can be determined by the yellowing of the paper and by the appearance of the outlines of the tracks on it.
It's about the same as in the photo.
Well, let's say we decided that everything is ready. Turn off the iron and leave the board for about 10 minutes to cool down. Pour water into a suitable bowl. The temperature of the water should be such that it was just possible to hold a hand in it. Well, we throw our cooled billet there.
That's it, let's go smoke, drink tea, chase the cat - anything for 15 minutes. You can even 20. By the way, you can leave the water on so that it does not cool down.
We come back and begin to carefully separate the paper from the workpiece. Very carefully and slowly. The remaining pieces after this are rolled up with your fingers. In no case do we scrape the board with our claws, but gently, with fingertips, clean the foil from stuck paper. After that, we arm ourselves with a hairdryer and dry, dry, dry. In fact, everything is not so long, because it dries up in just a minute or two.
Well, we got such a bullshit
Ugh. Exhale and move on to the next step.
At this stage, we need to etch the board - that is, remove all unnecessary foil from the workpiece so that only the tracks we have drawn remain.
Why use ferric chloride? It is sold in jars - it is such a gruel of rusty color and terribly disgusting stink. It is diluted with warm water.
We dilute approximately at the rate of 100 grams of ferric chloride per 100 grams of water. Water can be less - the main thing is that the solution completely covers our workpiece. So, we dissolve the iron in water, mix it thoroughly and throw the future board there - now it doesn’t have long to be a blank.
During the etching process, it is harmless to stir the solution - either by stirring it with a non-metallic stick, or by shaking the bath from side to side. Again, you can put warm water under the bottom of the bath so that the solution does not cool down. The etching time depends on the size of the board and the concentration of the solution. Usually about 20 minutes. If during this time the board has not been pickled, then the concentration of ferric chloride is insufficient and it is worth adding more.
By the way! Did you know that used ferric chloride can be recovered? If you have been strangled by a large, green toad, the used solution can be reused. To do this, you need to restore it - that is, select from the solution all the copper that he ate from the printed circuit board. Look at the photo
Half of this nail has been soaked in a used ferric chloride solution. Thus, if you pour in a handful of nails, all the copper present in the solution will be deposited on them. What is characteristic is that the consumer qualities of nails will not suffer from this at all.
However, back to our sheep. Or rather, to our already almost finished board. She's already etched.
Now we thoroughly wash it, dry it and this is what happened:
Now again we take cotton wool, dip it in acetone and erase all the toner that now covers the tracks on the board.
Well, almost everything is ready - the last step remains.
Well, now it remains only to drill holes for the elements, and irradiate the tracks - that is, cover them with a thin layer of solder. We drill, you know, with a drill.
I used a drill with a diameter of 0.9 mm, which I recommend to you, unless of course you have large parts on the board. In general, of course, the diameter of the pins must be taken into account even at the stage of designing a printed circuit board, so that later you don’t bite your elbows and don’t redo everything.
As for tinning, everything is quite simple here - we cover the board with any liquid flux - the simplest is a 30% solution of rosin in alcohol. We warm up the soldering iron and taking the minimum amount of solder on the tip, we begin to drive it along the tracks of the board. Then we wipe the board with alcohol to remove excess flux.
