For amateur PCB production, thermal transfer printing and UV exposure are two commonly used methods.
The equipment that needs to be used in the thermal transfer method is: copper clad laminate, laser printer (must be a laser printer, inkjet printer, dot matrix printer and other printers are not allowed), thermal transfer paper (can be replaced by the backing paper behind the sticker) , but ordinary A4 paper cannot be used), thermal transfer machine (can be replaced by electric iron, photo laminator), oil-based marker pen (must be oil-based marker pen, its ink is waterproof, and water-based ink pens are not allowed) , Corrosive chemicals (generally use ferric chloride or ammonium persulfate), bench drill, water sandpaper (the finer the better).
The specific operation method is as follows:
Roughen the copper-clad surface of the copper-clad board with water sandpaper, and grind off the oxide layer, and then rinse the copper powder produced by the grinding with water, and dry it.
Use a laser printer to print the left and right mirror image of the drawn PCB file onto the smooth side of the thermal transfer paper, and the wiring is black and the other parts are blank.
Lay the thermal transfer paper on the copper clad surface of the copper clad board (the printing side faces the copper clad side, so that the copper clad board completely covers the printing area), and fix the thermal transfer paper to ensure that the paper does not Movement will occur.
The thermal transfer machine is turned on and preheated. After the preheating is completed, insert the copper-clad laminate fixed with the thermal transfer paper into the rubber roller of the thermal transfer machine, and repeat the transfer for 3 to 10 times (depending on the performance of the machine, some thermal transfer Some machines can be used after 1 pass, and some require 10 passes). If you use an electric iron to transfer, please adjust the electric iron to the highest temperature, and repeatedly iron the copper-clad board on which the thermal transfer paper is fixed, and iron it evenly to ensure that every part will be pressed by the iron. A copper clad laminate is very hot and cannot be touched for a long time before ending.
Wait for the copper clad laminate to cool naturally, and when it cools down to the point where it is no longer hot, carefully peel off the thermal transfer paper. Note that you must wait for complete cooling before tearing off, otherwise the plastic film on the thermal transfer paper may adhere to the copper clad board, resulting in failure of production.
Check whether the transfer is successful. If some traces are incomplete, you can use an oil-based marker to complete them. At this time, the marks left by the oil-based marker pen on the copper-clad board will remain after the corrosion. If you want to make a handwritten signature on the circuit board, you can directly write it on the copper-clad board with an oil-based marker at this time. At this time, a small hole can be punched on the edge of the PCB and a rope can be tied to facilitate the corrosion in the next step.
Put an appropriate amount of corrosive medicine (take ferric chloride as an example) into a plastic container, and pour hot water to dissolve the medicine (do not add too much water, it can be completely dissolved, too much water will reduce the concentration), and then transfer to Soak the printed copper clad laminate in the solution of corrosive chemicals, with the copper clad side up, to ensure that the corrosive solution is completely submerged in the copper clad laminate, and then keep shaking the container containing the corrosive solution, or shake the copper clad laminate. Well, the pump of the corrosion machine will stir the corrosion liquid. During the corrosion process, please always pay attention to the changes of the copper clad laminate. If the transferred carbon film or the ink written by the marker pen falls off, please stop the corrosion immediately and take out the copper clad laminate and rinse it, and then fill the fallen line with an oily marker pen again. Recorrosion. After all the exposed copper on the copper clad board is corroded, remove the copper clad board immediately, wash it with tap water, and then use water sandpaper to wipe off the printer toner on the copper clad board while cleaning.
After drying, drill a hole with a bench drill and it’s ready to use.
To make PCB by UV exposure, you need to use these equipment:
Inkjet printer or laser printer (other types of printers cannot be used), 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 ( The area should be larger than the circuit board to be made), ultraviolet lamp (you can use ultraviolet lamp tubes for disinfection, or ultraviolet lamps used in nail salons), sodium hydroxide (also called “caustic soda”, which can be bought in chemical supply stores), carbonic acid Sodium (also called “soda ash”, edible flour alkali is the crystallization of sodium carbonate, which can be replaced by edible flour alkali, or sodium carbonate used in chemical industry), rubber protective gloves (recommended), oily marker pen, corrosion medicine, bench drill , Water sandpaper.
First, use a printer to print the PCB drawing on film or sulfuric acid paper to make a “negative film”. Note that the left and right mirror images are required when printing, and the white is reversed (that is, the wiring is printed in white, and the place where copper foil is not required is black).
Roughen the copper-clad surface of the copper-clad board with water sandpaper, and grind off the oxide layer, and then rinse the copper powder produced by the grinding with water, and dry it.
If photosensitive oil is used, use a small brush to evenly paint the photosensitive oil on the surface of the copper clad laminate and let it dry. If you use a photosensitive film, paste the photosensitive film on the surface of the copper clad board at this time. There is a protective film on both sides of the photosensitive film. First tear off the protective film on one side and then stick it on the copper clad board. Do not leave air bubbles. Another layer of protective film Don’t be in a hurry to tear it off. Whether it is photosensitive film or photosensitive oil, please operate in a dark room. If there is no dark room, you can close the curtains and turn on low-power lighting to operate. The processed copper clad laminate should also be kept away from light.
Put the “negative film” on the copper-clad laminate that has undergone photosensitive treatment, press the glass plate, and hang the ultraviolet lamp above to ensure that all positions can receive uniform ultraviolet radiation. After placing it, turn on the ultraviolet lamp. Ultraviolet rays are harmful to humans. Do not look directly at the light emitted by the ultraviolet lamp with your eyes, and try to avoid exposure to the skin. It is recommended to use a cardboard box to make a light box for exposure. If you are exposed in the room, please evacuate the room after turning on the light. The length of the exposure process is related to many factors such as the power of the lamp and the material of the “negative film”. Generally, it ranges from 1 to 20 minutes. You can turn off the light regularly for inspection. If there is a very obvious color difference in the photosensitive film (where it is exposed to ultraviolet light) The color becomes darker, and the color in other places remains unchanged), then the exposure can be stopped. After the exposure is stopped, it is still necessary to store it in the dark until the development operation is completed.
Prepare a 2% concentration of sodium carbonate solution, soak the exposed copper clad laminate in the solution, wait for a while (about 1 minute), and you can see that the photosensitive film on the light-colored part that has not been exposed begins to turn white and swell. There was no significant change in the exposed dark areas. At this time, you can use a cotton swab to gently wipe off the unexposed parts. Developing is a very important process, which is equivalent to the thermal transfer step of making PCB by thermal transfer method. If the unexposed area is not completely washed off (not fully developed), it will cause corrosion in that area; and if the If the exposed areas are washed off, the produced PCB will be incomplete.
After the development is over, you can leave the darkroom at this time and proceed under normal light. Check whether the wiring of the exposed part is complete. If it is not complete, it can be completed with an oil-based marker pen, just like the heat transfer method.
Next is etching, this step is exactly the same as etching in thermal transfer method, please refer to above.
After the corrosion is finished, demoulding is carried out. Prepare 2% sodium hydroxide solution, immerse the copper clad laminate in it, wait for a while, the photosensitive material remaining on the copper clad laminate will automatically fall off. Warning: Sodium hydroxide is a strong alkali and highly corrosive. Please be careful when handling it. It is recommended to wear protective gloves and goggles. Once it touches the skin, please rinse it with water immediately. Solid sodium hydroxide must have strong hygroscopic properties, and it will deliquesce quickly when exposed to the air, please keep it airtight. Sodium hydroxide solution can react with carbon dioxide in the air to form sodium carbonate, which will lead to failure, please prepare it now.
After demoulding, wash off the residual sodium hydroxide on the PCB with water, let it dry and then punch holes.
Post time: Mar-15-2023