In the construction of electronic circuits, you can use the universal printed circuit board with holes without tracks, but it is more convenient to use a printed circuit board made according to this scheme.
Eat different ways manufacturing printed circuit boards, but in this article the photoresistive method will be considered.
This method, of course, is more expensive than LUT, but the result is almost always perfect, the main thing is to “fill your hand”. And in aesthetic terms, the photoresist has all the advantages.
A photoresist is a light-sensitive substance (in our case, it is a varnish), which changes its properties under the influence of light. The photoresist is superimposed with a photomask and illuminated, after which the illuminated (or unexposed) areas of the photoresist are washed off with a special solvent, which is usually caustic soda (NaOH).
All photoresists are divided into two categories: positive and negative. For positive photoresists, the track on the board corresponds to a black area on the photomask, and for negative ones, accordingly, it is transparent. Many enterprises work with negative photoresists, but we will use the positive one, as it is the most widely used in the free market. Let us dwell in more detail on the use of positive photoresists in aerosol packaging.
In the manufacture of printed circuit boards, especially complex ones, the most suitable method is when using a photoresist. Its main advantage is
high-contrast pattern on textolite with a resolution of 0.1mm (0.1mm is ideal, but 0.25mm works great) when made at home. In addition, sometimes when manufacturing a printed circuit board, an important requirement relates to aesthetic design. finished product, especially if the PCB is in the "open" position or packaged in a transparent thermal tube.
Detailed description of PCB manufacturing
Textolite preparation
To make a printed circuit board with minimal material costs, you need to carefully prepare the textolite before applying varnish.
We mean that the textolite is sawn into approximate size future printed circuit board with a margin of 5mm on each side. Usually copper grouting is started with special abrasive pastes, but in the absence of one, a mixture of dishwashing gel and detergent cleaning powder will come off. We grout with a metal mesh for washing dishes, thereby removing oxides, dirt from the surface of the textolite, and the mesh, in turn, will scratch the foil, which will further increase the adhesion of the varnish (photoresist) to the surface.
Grouting is carried out depending on the degree of contamination of the surface until
the surface will not have a uniform even hue, in fact golden.
Chemical stains on the textolite can be removed before applying the photoresist by dipping the textolite into a solution of hot ferric chloride, if the foil on the textolite has become uniformly red, then in principle future etching will go without problems, the board after this method should be thoroughly rinsed hot water and re-polish with an abrasive to a golden hue.
Now we wash the cleaned textolite with hot water and try to
do not touch the surface...
Now dry at a temperature of 60-70 ° C for a minute until the surface takes on a slight pinkish tint. If during this process frost has formed on the surface, then it must be removed with a napkin. There should be no fluff on the surface!
For drying, an ordinary hair dryer is suitable ...
Photo template preparation
While the textolite is cooling down, we are preparing a photomask ... In this case, there are several ways to make it, but I strongly recommend using an inkjet printer with a black print resolution of at least 1200 dpi. We will print on a transparent film (for inkjet printers it has a pile, for laser printers without a pile there is a special thermal film).
We draw attention to a typical mistake during the first independent
PCB manufacturing - we usually forget to “mirror” front side
printed circuit board.
Attention! The front side of the printed circuit board must be mirrored when printing! Reverse is not mirrored!
Thus, after printing, the pattern on the film will be turned upside down from the working side of the film (for inkjet, this is the fleecy side). And when we project the picture onto the textolite, the film will be applied with the working side to it and the projected picture will be correct (no longer mirrored). In order not to make a mistake when printing, I recommend applying, for example, the letters of your initials to the photomask.
I recommend making a couple of copies of photomasks for rational use
film and elimination of errors during the development of photoresist ... Ie. make more than one seal, but for example, two at the same time (if they are not large), then choose the highest quality and etch in ferric chloride.
We check the photomask (positive) printed in this way for transparency, ideally the working pattern (printed conductors) should be absolutely black!
We cut off the photomask from the film and try to make it smoother, the remaining piece of film can be used again (for printing another project).
In my example, I divided the photomask into two, and I will do two at the same time
fees...
Application of photoresist
Since it has cooled during this time, it's time to apply a photosensitive varnish on it. It is recommended to do this in a dark room with low light in order to see what layer of photoresist we have applied.
This process is one of the most important, namely, it should be quickly applied
a uniform layer of varnish with a faint purple tint without bubbles and streaks!
It is recommended, of course, to spray the photoresist on a centrifuge, but in the absence of one, you can do it “with your hand full” as in the photo above. Immediately evaluating approximately the shade by eye, we draw the following conclusion - whether it is worth moving on to the next phase of the operation or not. The hue should be pale purple, transparent, i.e. copper (scratches on it from a metal mesh) should be visible! Do not be afraid that the photoresist has such a thin layer after application - the main thing is that we isolated copper before etching.
It is usually recommended to dry the photoresist for an hour, but I dry at a relatively high 60-70ºC for 3-5 minutes. Then I leave the textolite to cool until it cools completely. When drying, do not overheat the board, the varnish may peel off, do not cool it sharply either! It is better to wait an extra 5 minutes, but then the result will be excellent ... in this matter, the main thing is not to rush!
Do not forget, of course, that we perform this entire procedure in low light.
(weak energy-saving lamp or Fluorescent Lamp somewhere behind us will not bring much harm).
After drying the photoresist, carefully inspect the surface
of the varnish applied by us, there should not be any sagging on the edges of the board, it is better to just carefully tear them off, it is for this that the textolite is recommended to be cut with a margin of 5 mm along the edges. Usually, sagging is formed on one edge, see the photo above, the board is specially tilted before applying varnish so that the photoresist, or rather its excess, flows down to one of the edges of the board. When spraying on a centrifuge, this option is practically excluded.
Exposure
This process is not complicated and short-term, it consists in preparing a photomask on the surface of the photoresist and then illuminating it with a mercury lamp (ultraviolet spectrum).
I use medical irradiators for disinfection of premises (UFO-1, UFO-2 and the like). UFO-1 contains a 100 W mercury quartz lamp paired with an incandescent spiral in quartz tubes (they act as a resistor and are, as it were, infrared lamps with strong heat release). Since the times of the USSR, many have had similar emitters in their apartments ... We only need this from this emitter:
If this is not there either, a 500 W spotlight for garages, parking lots, etc., for example, from Cosmos, is suitable, I used to illuminate them, I don’t remember the illumination time, I’ll have to select it experimentally, and the illumination distance is at least 30 cm ( heat spotlight will damage the photoresist, it will stick to the template).
Quickly on the deposited photoresist lays the photomask with its working side on
film and cover with a piece of thin glass (for example, from a photo frame). And we illuminate the photomask from a distance of at least 25 cm, but not more than 35 cm when using UFO-1 for exactly 2 minutes 15 seconds, if the photoresist has a slightly purple tint:
After illumination, we remove the board in a dark place for 5-8 minutes, such as for
fixing photoresist...
Solution preparation
While we have a photoresist fixed, we prepare a solution for its etching. It is recommended that German and Belgian manufacturers use caustic soda for developing, it is also caustic soda, coarse-grained powder white color, not transparent, and in the truest sense of the word - caustic. That is, it would be necessary to work in rubber gloves.
We interfere with 7 grams of this substance per liter of warm water until the powder is completely dissolved, the precipitate can be removed. If mixed in hot water, the precipitate will also dissolve. We take a container, for example, a plastic container. We lower our illuminated board into it. (The solution should not be hot, just warm is better!).
Rinse the board thoroughly immediately after development. warm water flushing the residue caustic soda. In my photo, this process took less than a minute, since my solution is not 7 grams per liter of water, but a little more ... Initially, the solution of caustic soda in water is transparent, then it will change color - it will become purple (seen in the photo above), because It has lacquer dissolved in it.
You can use the solution repeatedly, I happened up to five times with a weekly
The photoresist showed at intervals, the solution was already dark purple in color.
Board etching
Well, actually now we poison in a solution of ferric chloride in water in a ratio of 1: 3
As you can see in the photo, my varnish is transparent, copper is perfectly visible ... After etching
wash off the varnish with ferric chloride with acetone or other solvent (646, 647, 650).
You can pickle with other solutions, for example, copper sulfate with salt or citric acid.
Cut the board to size and process along the contour.
All! Payment is ready!
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.
Searching the Internet different kinds breadboards that you can make with your own hands and from available materials, came across a few interesting options, one of which 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 you can make 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 0.9 mm:
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 2Pushpins 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. 
I don’t know about you, but I have a fierce hatred for classic circuit boards. A montage is such crap with holes where you can insert parts and solder, where all connections are made through wiring. It seems to be simple, but it turns out such a mess that it is very problematic to understand anything in it. Therefore, errors and burnt parts, incomprehensible glitches. Well fuck her. Only to spoil the nerves. It is much easier for me to draw a schematic in my favorite and immediately etch it in the form of a printed circuit board. Using laser-ironing method everything comes out for what that one and a half hours of easy work. And, of course, this method is great for making the final device, since the quality of printed circuit boards obtained by this method is very high. And since this method is very difficult for the inexperienced, I will gladly share my proven technology, which allows you to get printed circuit boards the first time and without any strain. with tracks 0.3mm and clearance between them up to 0.2mm. As an example, I will make a debug board for my controller tutorial. AVR. You will find the principal in the entry, and
There is a demo diagram on the board, as well as a lot of copper patches, which can also be drilled and used for your needs, like a regular circuit board.
▌Technology for manufacturing high-quality printed circuit boards at home.
The essence of the method of manufacturing printed circuit boards is that a protective pattern is applied to the foil textolite, which prevents copper from etching. As a result, after etching, traces of conductors remain on the board. There are many ways to apply protective drawings. Previously, they were drawn with nitro paint, using a glass tube, then they began to be applied with waterproof markers or even cut out of adhesive tape and pasted onto the board. Also available for amateur use photoresist, which is applied to the board, and then illuminated. Illuminated areas become soluble in alkali and washed off. But in terms of ease of use, low cost and speed of manufacture, all these methods lose a lot. laser ironing method(Further LUT).
The LUT method is based on the fact that the protective pattern is formed by toner, which is transferred to the textolite by heating.
So we need a laser printer, since they are not uncommon now. I am using a printer Samsung ML1520 with original cartridge. Refilled cartridges fit extremely poorly, as they lack the density and uniformity of toner delivery. In the print properties, you need to set the maximum density and contrast of the toner, be sure to disable all saving modes - this is not the case.
▌Tool and materials
In addition to foil textolite, we also need a laser printer, iron, photo paper, acetone, fine sandpaper, a suede brush with metal-plastic pile,
▌Process
Then we draw a drawing of the board in any software convenient for us and print it. Sprint layout. Simple drawing for boards. To print normally, you need to set the colors of the layers to black on the left. Otherwise it will be bullshit.
Printout, two copies. You never know, suddenly we mess up one.
Here lies the main subtlety of the technology LUT because of which many people have problems with the release of high-quality boards and they quit this business. Through many experiments, it was found that the most best result achieved when printing on glossy photo paper for inkjet printers. I would call photo paper ideal LOMOND 120g/m2
It is inexpensive, sold everywhere, and most importantly, it gives an excellent and repeatable result, and does not burn with its glossy layer to the printer's oven. This is very important, as I have heard of cases where the printer oven was crap with glossy paper.
We load paper into the printer and boldly print on the glossy side. You need to print in mirror image so that after transferring the picture is true. How many times I made mistakes and made wrong prints, do not count :) Therefore, the first time it is better to print on plain paper for testing and check that everything is correct. At the same time, warm up the printer's oven.
After printing the picture, in no case can not be grabbed by hands and preferably protected from dust. So that nothing interferes with the contact of the toner and copper. Next, cut out the board pattern exactly along the contour. Without any stock - the paper is stiff, so everything will be fine.
Now let's deal with textolite. Cut out a piece right size, without permits and allowances. As much as needs.
It needs to be well sanded. Carefully, trying to tear off all the oxide, preferably in a circular motion. A little roughness won't hurt - the toner will stick better. You can take not a skin, but an abrasive sponge "effect". Just need to take a new one, not greasy.
It is better to take the smallest skin you can find. I have this one.
After sanding, it must be carefully degreased in the same way. I usually rub a cotton pad from my wife and, having moistened it properly with acetone, I carefully walk over the entire surface. Again, after degreasing, in no case should you grab it with your fingers.
We impose our drawing on the board, naturally with the toner down. warm up iron to the max, holding the paper with your finger, press well and iron one half. It is necessary that the toner sticks to the copper.
Next, without allowing the paper to move, we iron the entire surface. We press with all our might, polish and iron the board. Trying not to miss a millimeter of the surface. This is the most important operation, the quality of the entire board depends on it. Don't be afraid to press as hard as you can, the toner won't float or smudge, as the photo paper is thick and perfectly protects it from spreading.
We iron until the paper turns yellow. However, this depends on the temperature of the iron. It almost does not turn yellow on my new iron, but on the old one it almost charred - the result was equally good everywhere.
After that, you can let the board cool down a bit. And then, grabbing it with tweezers, we put it under the water. And keep some time in the water, usually two or three minutes.
Taking a brush for suede, under a strong stream of water, we begin to furiously lift the outer surface of the paper. We need to cover it with multiple scratches so that the water penetrates deep into the paper. In confirmation of your actions, there will be a manifestation of the drawing through thick paper.
And with this brush we dry the board until we remove the top layer.
When the whole drawing is clearly visible, without white spots, then you can start carefully, rolling the paper from the center to the edges. Paper lomond rolls great, leaving 100% toner and pure copper almost immediately.
Having rolled the entire pattern with your fingers, you can thoroughly scrape the entire board with a toothbrush to clean out the remnants of the glossy layer and scraps of paper. Don't be afraid, it's almost impossible to remove a well-seasoned toner with a toothbrush.
We wipe the board and let it dry. When the toner dries and turns gray, it will be clearly visible where the paper is left, and where everything is clean. Whitish films between the tracks must be removed. You can destroy them with a needle, or you can tear them with a toothbrush under running water. In general, it is useful to brush along the paths. Whitish gloss can be pulled out of narrow slots with electrical tape or masking tape. It sticks not as violently as usual and does not break off the toner. But the remnants of gloss tears off without a trace and immediately.
Under the light of a bright lamp, carefully examine the layers of toner for breaks. The fact is that when cooled, it can crack, then a narrow crack will remain in this place. The cracks gleam under the lamplight. These places need to be painted. permanent marker for CDs. Even if there is only a suspicion, it is still better to paint over. With the same marker, you can also draw low-quality tracks, if any. I recommend the marker Centropen 2846- it gives a thick layer of paint and, in fact, they can stupidly draw paths.
When the board is ready, you can bodyaze a solution of ferric chloride.
Technical digression, if you wish, you can skip it
In general, you can poison a lot of things. Someone is poisoning blue vitriol, someone in acid solutions, and I in ferric chloride. Because it is sold in any radio store, poisons quickly and cleanly.
But ferric chloride has a terrible drawback - it just gets dirty with a scribe. It will get on clothes or any porous surface like wood or paper, everything, consider the stain for life. So dive your Dolce Gabana sweatshirts or Gucci boots into the safe and wrap three rolls of tape around them. And ferric chloride in the most cruel way destroys almost all metals. Especially fast aluminum and copper. So etching dishes should be glass or plastic.
I throw 250 gram package of ferric chloride per liter of water. And with the resulting solution, I poison dozens of boards until it stops poisoning.
The powder must be poured into the water. And make sure that the water does not overheat, otherwise the reaction proceeds with the release a large number heat.
When the powder is all dissolved and the solution acquires a uniform color, you can throw a board there. It is desirable that the board float on the surface, copper down. Then the precipitate will fall to the bottom of the tank, without interfering with the etching of deeper layers of copper.
To prevent the board from sinking, you can stick a piece of foam to it on double-sided tape. That's exactly what I did. It turned out very convenient. I screwed in the screw for convenience, to hold on to it like a handle.
It is better to dip the board several times into the solution, and lower it not flat, but at an angle so that air bubbles do not remain on the copper surface, otherwise there will be jambs. Periodically it is necessary to get out of the solution and monitor the process. On average, the etching of the board takes from ten minutes to an hour. It all depends on the temperature, strength and freshness of the solution.
The etching process accelerates very sharply if you lower the hose from the aquarium compressor under the board and blow bubbles. The bubbles stir the solution and gently knock out the reacted copper from the board. You can also shake the board or container, the main thing is not to spill it, otherwise you won’t wash it off later.
When all the copper is etched, then carefully remove the board and rinse under running water. Then we look at the clearance, so that there is no snot and undergrass anywhere. If there is snot, then we throw another ten minutes into the solution. If the tracks are etched or there are breaks, then the toner is crooked and these places will need to be soldered with copper wire.
If all is well, then you can wash off the toner. To do this, we need acetone - a true friend of a drug addict. Although now it is becoming more difficult to buy acetone, because. some idiot from the state drug control decided that acetone is a substance used to make drugs, which means that its free sale should be banned. Works well in place of acetone 646 solvent.
We take a piece of bandage and thoroughly wetting it with acetone, we begin to wash off the toner. You don’t need to press hard, the main thing is not to move too fast, so that the solvent has time to be absorbed into the pores of the toner, corroding it from the inside. It takes two or three minutes to flush the toner. During this time, even green dogs under the ceiling will not have time to appear, but it still does not hurt to open the window.
The washed board can be drilled. For these purposes, for many years I have been using a motor from a tape recorder, powered by 12 volts. The monster machine, though its resource is enough for about 2000 holes, after which the brushes burn out completely. And you also need to tear out the stabilization circuit from it by soldering the wires directly to the brushes.
When drilling, try to keep the drill strictly perpendicular. Otherwise, then you'll put the damn chip in there. And with double-sided boards, this principle becomes the main one.
The manufacture of a double-sided board also occurs, only here three reference holes are made, as small as possible in diameter. And after etching one side (the other at this time is sealed with adhesive tape so that it does not etch), the second side is combined through these holes and rolled. The first is sealed tightly with adhesive tape and the second is poisoned.
On the front side, you can apply the designation of radio components using the same LUT method, for beauty and ease of installation. However, I don’t bother like that, but comrade Woodocat from LJ community ru_radio_electric does so always, for which he has great respect!
Soon I will probably also publish an article on photoresist. The method is more confusing, but at the same time, it’s more fun for me to do it - I like to fool around with reagents. Although I still make 90% of the boards with LUT.
By the way, about the accuracy and quality of the boards made by the laser ironing method. Controller P89LPC936 in the building TSSOP28. The distance between the tracks is 0.3mm, the width of the tracks is 0.3mm.
Resistors on the top board 1206 . What is it?
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 width conductor 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, a hot substrate (after drying cabinet) simultaneously with the film from the SPF roll is directed into the gap between the shafts, and the polyethylene (matte) 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 polyethylene film 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 according to the size of the substrate and kept at room temperature within 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 the solution 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.
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, take a transparent film for printing on laser printer(available for sale) one side 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 straight lines) sun rays, 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 happens. 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 fee and remove the second protective film NECESSARILY
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 into another container Peroxide 100 ml, 3-4 tablespoons citric acid and 2 tablespoons of salt.
