How to make pcb circuit board

If you do PCB in your spare time, there are two common methods: thermal transfer and ultraviolet exposure.

The equipment required for thermal transfer method includes: copper clad laminate, laser printer (laser printer is required, but inkjet printer, needle printer and other printers are not allowed), thermal transfer paper (backing paper behind adhesive can be used to replace ordinary A4 paper), thermal transfer machine (electric iron and photo sealer can be used instead), and oily marker pen (oily marker pen must be used, and water-based ink pen is not allowed).

The specific operation method is as follows:

Roughen the copper-clad surface of the copper-clad plate with water sandpaper, and grind off the oxide layer, then rinse the copper powder produced by grinding with water and dry it.

Using a laser printer, the printed PCB file is printed on the glossy surface of thermal transfer paper with black lines and other parts blank.

Spread the thermal transfer paper flat on the copper-clad surface of the copper-clad plate (the printing surface faces the copper-clad surface, so that the copper-clad plate completely covers the printing area), and fix the thermal transfer paper to ensure that the paper will not move during the transfer.

Start the thermal transfer machine for preheating. After preheating, insert the copper clad laminate fixed with the heat transfer paper into the cots of the heat transfer machine, and repeat the heat transfer for 3~ 10 times (depending on the performance of the machine, some heat transfer machines can be used after 1 0 times, and some have to pass 10 times). If the electric iron is used for transfer printing, please adjust the electric iron to the highest temperature, and iron the copper clad laminate with the heat transfer paper fixed repeatedly and evenly to ensure that every part will be pressed by the iron, and wait for a long time for the whole copper clad laminate to be too hot to touch.

Wait for the copper clad laminate to cool naturally until it is no longer hot. Carefully uncover and tear off the heat transfer paper. Be careful not to tear it off before it is completely cooled, otherwise the plastic film on the heat transfer paper may stick to the copper clad laminate, leading to production failure.

Check whether the transfer was successful. If part of the transfer is incomplete, you can make it up with an oily marker. At this point, the traces left by the oily marker on the copper clad laminate will remain after corrosion. If you want to hand-write your signature on the circuit board, you can write it directly on the copper clad laminate with an oily marker. At this time, a small hole can be punched on the edge of PCB and tied with a rope to facilitate the next corrosion.

Put a proper amount of corrosive drugs (taking ferric chloride as an example) into a plastic container, pour in hot water to dissolve the drugs (don't add too much water, it can be completely dissolved, and too much water will reduce the concentration), then soak the transferred copper clad laminate in the solution of corrosive drugs, with the copper clad laminate facing upward to ensure that the corrosive liquid does not completely pass through the copper clad laminate, and then shake the container filled with corrosive liquid or shake the copper clad laminate continuously, which is better if etching machine is used. Please always pay attention to the changes of copper clad laminate during corrosion. If the transferred carbon film or ink written by the marker falls off, please stop the corrosion immediately, remove the copper clad plate and clean it, then repair the fallen lines with an oily marker and corrode it again. When all the exposed copper on the copper-clad plate is corroded, immediately take out the copper-clad plate, rinse it with tap water, and wipe off the printer toner on the copper-clad plate with water sandpaper.

After drying, drill a hole with a bench drill and you can use it.

When using ultraviolet exposure to make PCB, you need to use these devices:

Ink-jet printer or laser printer (other types of printers are not allowed), copper clad laminate, photosensitive film or photosensitive oil (available online), printing film or sulfuric acid paper (film is recommended for laser printers), glass plate or plexiglass plate (larger than the manufactured circuit board), ultraviolet lamp (ultraviolet lamp for disinfection or ultraviolet lamp for nail salon), sodium hydroxide (also called "caustic soda"), which can be bought in chemical stores) Edible flour alkali is the crystal of sodium carbonate, which can be replaced by edible flour alkali or sodium carbonate for chemical purposes), rubber protective gloves (recommended), oily marker, corrosive drugs, bench drill, water sandpaper.

First, print PCB drawings on film or sulfuric acid paper with a printer to make a "negative". Note that when printing, you need to mirror the left and right, and turn white (that is, the wiring is printed in white, and the place where copper foil is not needed is black).

Roughen the copper-clad surface of the copper-clad plate with water sandpaper, and grind off the oxide layer, then rinse the copper powder produced by grinding with water and dry it.

If photosensitive oil is used, brush the photosensitive oil evenly on the surface of copper clad laminate with a small brush and dry it. If photosensitive film is used, it should be pasted on the surface of copper clad laminate at this time. The photosensitive film has protective films on both sides. Tear off a protective film first, and then stick it on the copper clad laminate, leaving no bubbles. Don't tear off another protective film in a hurry. Please operate in a dark room, whether it is photosensitive film or photosensitive oil. If there is no darkroom, you can block the curtains and turn on the low-power lighting to operate. Please keep the treated copper clad laminate away from light.

Put the "negative film" on the photosensitive copper clad laminate, press the glass plate, and hang the ultraviolet lamp above it to ensure that all positions can receive uniform ultraviolet radiation. After placing, turn on the ultraviolet light. Ultraviolet rays are harmful to people. Don't look directly at the light emitted by the ultraviolet lamp, and try to avoid the skin. It is suggested to use cartons as light boxes for exposure. If exposed indoors, please turn on the light and leave the room. The exposure process is related to many factors, such as the power of lamps, the material of "negative film" and so on. It usually takes 1~20 minutes, so you can turn off the lights regularly for inspection. If the photographic film has obvious chromatic aberration (the color becomes darker where ultraviolet rays are irradiated, and the color remains unchanged elsewhere), the exposure can be stopped. After stopping exposure, it should be stored in a dark place before the development operation is completed.

Prepare 2% sodium carbonate solution, soak the exposed copper clad laminate in the solution and wait for a moment (about 1 min). It can be seen that the unexposed light-colored part of the photosensitive film begins to whiten and swell, while the exposed dark part has no obvious change. At this time, you can gently wipe off the unexposed part with a cotton swab. Development is a very important process, which is equivalent to the thermal transfer step of making PCB by thermal transfer method. If the unexposed part is not completely washed away (under-developed), it will lead to corrosion of that part. And if the exposed place is washed away, the PCB will be incomplete.

After development, you can leave the darkroom at this time and do it under normal illumination. Check whether the wiring of the exposed part is complete. If it is incomplete, it can be completed with an oily marker, just like the thermal transfer method.

Next is etching, which is exactly the same as etching in thermal transfer printing. Please refer to the above.

Demoulding after corrosion is completed. Prepare 2% sodium hydroxide solution, immerse the copper clad laminate in it, wait a moment, and the photosensitive substance remaining on the copper clad laminate will automatically fall off. Warning: Sodium hydroxide is a strong alkali and extremely corrosive. Please be careful when operating. Protective gloves and goggles are recommended. Once in contact with skin, please rinse with water immediately. Solid sodium hydroxide must have strong moisture absorption characteristics and will deliquesce quickly when exposed to air. Please keep it sealed. Sodium hydroxide solution can react with carbon dioxide in the air to produce sodium carbonate, which leads to failure. Please prepare it now.

After demoulding, rinse the residual sodium hydroxide on the PCB with water and dry it to make holes.