lThis Project will explain how easy to make PCB by yourself at home
All you need is some stuff and time to make some experiment.
We can make PCB with low cost :
Please note that making these PCBs involves some potentialy hazardous chemicals and tools. It is your own resposibility to take suitable precautionary actions! If you do not know what these suitable precautionary actions are, DO NOT use these chemicals and tools.
I recommend wearing protective goggles, clothing, and chemical resistant gloves all the time when handling these chemicals, tools and PCBs!. In some countries the use of some of the tools and chemicals may be bound to restrictions, such as proper waste disposal and licenses, or may even be forbidden. It is your own resposibility to act according to your countries/states laws and regulations. A complete list of protective equipment and procedures nescessary or recommended is NOT included in this discription; it provides just some basic hints and reminders.
I want to make some points especially clear: both NaOH (caustic soda) and Iron Cloride are very unhealthy. Caustic soda dissolves your clothing, skin, and tissue (amongst others), and Iron Cloride permanently stains it yellow (amongst others). Do not use use NaOH in conjuction with metal (especially aluminium) containers or equipment. Do not use Iron Chloride in conjunction with metal, as this may dissolve/react or become stained. Iron Chloride etches stainless steel! Some plastics may dissolve in or react with Iron Chloride (e.g. POM) or Caustic soda (e.g. some floor coverings/LINOLEUM)
Find out what you need to do in case of an accident BEFORE THE ACCIDENT ACTUALLY HAPPENS. Find out what measures to take when your skin or eyes come in to contact with these chemicals, and find out what to do when they are ingested. Like any dangerous goods they should be kept out of reach of children, preferably in a locked cabinet.
Use safety caps. Mark bottles containing chemicals with their names, their "strength" (kg/L or Mol/L), their date of preparation, and with a notice stating that they are dangerous to skin & eyes and should never be ingested. Use strong chemical resistant PLASTIC containers, as glass may (more easily) break in case of chemical reactions, overheating or wrong handling. Make sure your labels and ink resist the chemicals as well!. Do not store the chemicals in a place where it may potentially become warm, such as a car or in direct sunlight.
Please note that the UV-light used to expose the UV-sesitive resin coated PCB's is not exactly healthy either. Wear suitable UV-protective glasses, UV-protective gloves, long sleeves, and keep skin and eye exposure times as short as possible, or even better prevent it altogether by using a light tight "UV-PCB-exposure-box". The exact type of light/lamp used determines how dangerous the UV light is; if the manufaturer does not explicitly state that the lamp is safe, don't assume it is. I've seen people use UV lamps designed to sterilize equipment.
Exposure of the eyes to UV light may lead to cataract.
The dust released during cutting and drilling PCBs is detrimental to your health as well, and may (amongst others) lead to skin irritation, sore eyes and various lung diseases. Avoid contact as much as possible. Never inhale the dust; wear a good quality dust protective mouth cover. I prefer to use a damp piece of cloth to wipe my work-area clean regulary. After use, before it dries up again, I dispose of this piece of cloth in a proper way.
Software Tools : Schematic and PCB Lay out program
To design PCB lay out, we need a software tool like : Protel, Orcad, PCB designer, eagle, CAM350 , Express PCB or else.
I prefer using protel to design PCB lay out.
At the first step, we make schematic diagram with protel.
After finish it, we must creat netlist, check the netlist report to make sure right. Open netlist report from PCB layout program, and now we must create route. There are 2 kinds of routes, manual and automatic.
I prefer use manual route, because i can design with my style optimally, but if you choose auto route, the result maybe become 2 layer .
The picture above is top layer, because there is SMD component.
Prepare the Board
Prepare the board, scrub it with a scotchbrite or "artificial steel wool" pad (nylon abrasive pad), equivalent to '0' steel wool.
The "scotchbrite" can removes oxidation, stains, scratches, etc, so the copper surface of the PCB is all uniformly nice and shiny. (You might have to press very hard, for this part.)
Don't Scrub with sandpaper.
Make sure the board was clean and shiny, before next process.
Print layout into the Board
To print lay out into the board, there are several methods :
1. UV Photoresist laminate
Print layout to transparant plastic film with laser printer
The dark area will be cooper and the transparent area will be spacing. I always print out two films and tape them on top of each other.
In this way the dark area will be really black so no UV light can pass later.
You must be accurate when you place the two films on top of each other. A small shift will give blurry lines of the board.
I place the films against a window, since a window is flat and you can see the light come through the films.
Preheat UV lamp for at least two minutes just prior to starting the exposure.
Spray the board with positiv 20 to covering board with postive resist, before exposure process.
- There is Board that have photo-positive coat on the copper, so you don't need this positive resist.
- Transparant film that has a positive photoresist, you can see at this site
Now placed the board with the 2 glasses under the UV-lamp.
Areas of the PCB exposed to the UV light (through the film) are turned into a protective plastic film.
you must experimented with different timing , for 3-4 minutes will give good results.
If you overexpose the board, the light will penetrate the black area and give bad results.
After 3-4 minutes, turn off the UV-lamp and remove the board to let it cool down.
It needs to cool down because it is quite hot (30-40 degree Celcius) and if you put a hot board into the developing liquid (water solution of NaOH) the reaction will got to fast and you loose the lines.
So, let the board cool down (shake it) and then put into the developing liquid.
When you buy the NaOH powder, you can read the label how much mixing water you need.
For me the developing phase takes about 1-2 minute then I shower the board with fresh water to remove NaOH remains.
- DP50 developer, 50 gram sachet mixes with 1 litre of water and can develop a minimum of 10 x 100x150mm PCBs.
- Silicate based product, which comes as a liquid concentrate. The name is sodium Metasilicate pentahydrate Na2SiO3*5H2O
2. Traditional Screen printing
This method involve applying a "mask" over the desired portions of the board ( copper side ), and using an acid or etchant that can't easily penetrate the mask material to remove the unwanted copper from the remainder of the surface.
Printing layout to transparant plastic film with laser printer, you must inverse / mirror the layout .
The dark area will be cooper and the transparent area will be spacing.
In this way the dark area will be really black so no UV sun light can pass later.
Make a thin layer emulsion in screen printing, and let it cool down for 10 minutes
Optional Screen emulsion :
- Ulano 133 ( oil base )
- Clean Glass
- Transparan negative film
- Screen printing ( T165 or T180 )
- Black Cloth
assemble them with that sequence, and then expose screen direct to sunshine.
You must experimented with different timing and weather for make good results. If the weather is blue sky, it takes 20-30 second, but if grey sky it takes 1 -2 minutes.
If you overexpose the screen, it will give bad results.
After that showering screen printing with water, The dark area will be solid and the other will be transparant.
Prepare clean board, Rakel ( handle made from a piece of wood, for sweep ink screen printing from top screen to board ), and ink screen printing ( photo sensitive etchant resistant material ).
Put screen printing on board, and drop the ink to screen, and start sweeping from up to down with rakel.
Now, you have PCB coated with the photo sensitive etchant resistant material ( ink screen printing ) and ready to ecth.
3. Toner Transfer Paper
Toner Transfer method is use of pressure / heat to transfer toner printed on papers by a laser printer or copier onto the PCB material
The type of paper used is the key, there is paper called press n peel sheet (PNP), but i suggest to try with different paper type to get good results.
- Print Artwork ( inverse image ) using the darkest laser printer setting to transfer paper.
- Cut the artwork out with scissors
- Heat up a normal household iron clothes(without the steam) with maximum temperature setting.
- Laying the board on a flat surface place the iron clothes on the board for a few seconds. Make sure it's not too hot.
Place the Transfer paper with artwork designs on the board with the image facing down.
Iron the paper to the board. Make sure that you get thorough with this using a circular motion with the iron. You can also place the iron flat on in for a few seconds. You will also see the image as it is being heated bleeding through the paper confirming that it is sticking to the board.
When you are pretty sure that it has been ironed on, let it cool down then carefully pull the paper away from the board. If you start to see that part of the image didn't stick to the board you can try applying more of the iron. I won't say exactly how hot the iron should be or how long you should apply it as you will have to experiment with that as different papers will probably vary in how they work.
4. Direct printing into the board
This method is using modification printer to print artwork direct into the board.
Now the board is ready to etch.
Several Etchant chemical:
FeCl3 (Ferric Chloride)
Caution disposal :
To dispose of used FeCL3. Before you pour it in to the sink, pour it in a plastic tank and drop there scrap of old steel nails, screws, small, nuts, bolts, etc., and let it stay for a few days. It will turn the hazardous mix of copper chloride and Ferric Chloride (FeCl3) into copper powder (sludge) that settles on the bottom and a non-etching and non-corrosive solution of FeCl2. It will save from corrosion, destruction and costly replacement in the future your cast iron drain pipes and it will save from killing bacteria in the septic tank or in sewer treatment plant. They are very sensitive to copper chloride and Ferric Chloride. A current law prohibits disposal of those chemicals in the sewer. For best yet treatment, after separation of solution of FeCl2, mix it with solution of soda (Na2CO3 used as detergent) in a flat tray lined with plastic film. It will turn FeCl2 into Fe(CO3) (insoluble rusty mud) and NaCl (harmless cooking salt). After drying outdoor whole dry rusty powder could be wrapped in plastic film and disposed of in the normal trash container.
The advantage use ammonium persulphate is more or less transparent, allowing you to see the progress of the etching, without removing the board from the etchant .
- Peroxide of hydrogen
Etching the board in a Tupperware style plastic food container, The copper side that coated will stay, and the part was not coated will remove.
After that take the board and shower with fresh water, scrub the board again to clean the ink or residue.
Use Small standing drill that accept small drills 0, 5 - 3 mms.
In the practice are used :
Drills 0,8 mms for the IC completed and drivers of elements
Drill 1 mm for pins big elements
Drills 1,5 mms for relay, switches, etc
Drills 3 mms for holes or spacer of support pcb.
Coat the PCB with Silver to reduce oxidation of copper.
You can use AgNo3 ( Silver Nitrat ) + Potasium + fresh water
Immerse the board +/- 5 second, and then scrub with metal brush ( the soft one ).
Now, The PCB is ready to use