Seven common methods of making PCB copper clad board

- Dec 26, 2019-

Seven common methods of making PCB copper clad board

    Now there are more and more people playing circuits. It is indispensable to play circuit boards to make circuit boards. If you want the board to look at the high-end atmosphere, you ca nt process it every time. It s better to make a PCB cover yourself. Copper plate.

Seven common methods of making PCB copper clad board

Here I will introduce the seven methods of PCB copper clad board for you.

Some of the following contents are collected and sorted by yourself, and some are summarized and summarized in combination with actual experience. Please excuse me for any irrationality.

I. Carving method:

   This method is the most direct. Copy the designed copper foil pattern to the copper foil surface of the copper-clad laminate, and use a special engraving tool made of a hacksaw blade to directly draw the copper foil directly along the edge of the copper foil pattern, cutting as far as possible, Then remove the unnecessary copper foil outside the pattern, and then drill with a power drill. The key to this method is: the intensity of the characterization should be enough; the excess copper foil should be removed starting from the edge of the board. When the operation is good, it can be gradually peeled off in pieces, and small needle-nose pliers can be used to complete this step. Some small circuit experimental versions are suitable for this method.

Second, the manual depiction method:

   Is to use a pen to directly draw the printed graphics on the copper-clad board, and then perform chemical etching and other steps. This method seems simple, and it is not easy to operate in practice! The current electronic components are small in size, and the pin spacing is smaller (millimeters). The copper foil traces are also very small, and the lines drawn are still difficult to modify. It is completely up to you to draw such a board. . The experience is that the choice of "paints" and brushes is critical. I myself used red nail polish in a medical syringe to paint circuit boards. The effect is good, but the tip of the needle needs to be properly processed. Some people have also introduced the use of a paint film to dissolve in anhydrous alcohol and use a duckbill to sketch. The specific method is as follows :

   Dissolve one piece of paint (ie shellac, available from chemical raw materials stores) in three parts of anhydrous alcohol and stir appropriately. After it is completely dissolved, add a few drops of medical purple potion (gentian violet) to make it It shows a certain color and can be used as a protective paint to paint circuit boards after being stirred evenly.

   First polish the copper-clad board with fine sandpaper, and then use the duckbill pen (or the ink duckbill on the compass to draw graphics) for drawing. The duckbill has a nut to adjust the stroke thickness and the stroke thickness. Adjustable, and can draw straight lines and triangles to draw very thin straight lines, and the drawn lines are smooth and uniform, without edge jagged, giving a smooth and fluent feeling; at the same time, it can also be in the free place of the circuit board Write the lines drawn by Chinese characters, English, pinyin, or symbols. If they are infiltrated to the surroundings, the concentration is too small, and you can add a little varnish. If you cannot drag the pen, it is too thick, and you need to drip a few drops of absolute alcohol . It doesn't matter if it is wrong, just use a small stick (matchstick) to make a small cotton swab, dipped in a little alcohol, you can easily wipe it off and redraw it. Once the circuit board is drawn, it can be etched in a ferric chloride solution. After the circuit board is corroded, it is also very convenient to remove the paint. You can wipe off the protective paint with a cotton ball dipped in anhydrous alcohol, and then dry it with a loose perfume.

   Because the alcohol evaporates quickly, the prepared protective paint should be placed in a vial (such as an ink bottle) and sealed. Do not forget to close the cap after use. If the concentration becomes thicker when you use it next time, just add an appropriate amount. An absolute alcohol is sufficient.

Third, the map method:

  ①Precut symbol method

There is a "standard pre-cut symbol and tape" available in electronics stores. Common specifications for pre-cut symbols are D373 (0D-2.79, ID-0.79), D266 (0D-2.00, ID-0.80), D237 (OD-3.50, ID-1.50) and other types, it is best to buy paper-based materials (black), plastic-based (red) materials are not used as much as possible. Common specifications of tape are 0.3, 0.9, 1.8, 2.3, 3.7 and so on. The units are millimeters. According to the layout of the circuit design, the corresponding symbols and tape can be selected and pasted on the copper foil surface of the copper-clad plate. Tap the stickers with a softer hammer, such as smooth rubber, plastic, etc., to make them fully adhere to the copper foil. Focus on the turn and overlap of the line. In cold weather, it is best to warm the surface with a heater to enhance the adhesion effect. After posting, the corrosion process can be performed.

  ② Sticker paper mapping method (recommended)

Use Protel or PADS and other design software to draw the printed board. Use a dot-matrix printer to output the paper to the self-adhesive paper. Paste the self-adhesive paper to the copper-clad board that has been cleaned. , Tear off the part of the paper that needs to be corroded. Put it into the ferric chloride solution for corrosion, clean it, and put it into use after drying. This method is similar to the engraving method, but saves a lot of effort than the engraving method, and can ensure the beauty and accuracy of the printed wire!

As everyone knows from experience, the corrosion of ferric chloride solution is very slow. The author used dilute nitric acid to do this experiment. The corrosion speed is amazing, and it can be done in about five minutes. The quality is no different from that of trichloride. Diy is recommended Try it! But this method is more dangerous, remind the producers to pay attention, do not let any part of the body touch the corrosive fluid, otherwise the consequences are disastrous! Remember! Remember!

Fourth, mimeograph method:

Put the wax paper on the steel plate, use a pen to engrav the circuit diagram on the wax paper 1: 1, and cut the circuit diagram engraved on the wax paper according to the size of the circuit board, and place the cut wax paper on the printed copper plate. Take a small amount of paint and talcum powder to make a thick and suitable printing material, dip the printing material with a brush, apply it evenly on wax paper, repeat it several times, and the circuit can be printed on the printed board. This stereotype can be used repeatedly and is suitable for small batch production. Tip: Using a photoelectric stamper, you can automatically make 1: 1 wax paper according to the design drawings.

 

V. Hot Melt Plastic Plate Making Method:

This method is collected from online articles. The feasibility has not been verified for reference.

  ①Print the circuit board drawing on 80g copy paper on the printer in the ratio of 1: 1. It is also possible to draw by hand, but the paper should be flat.

  ② Find a fax machine, remove the fax paper from the machine, and replace it with a hot-melt plastic film. Put the circuit diagram in the entrance of the facsimile machine, and use the copy key of the facsimile machine to copy the circuit diagram on the thermoplastic film. At this time, the "print manuscript" of the printed circuit board is ready.

  ③ Use double-sided tape to affix the plastic film on the drawing to the copper-clad board. Pay attention to be flat, do not wrinkle, and the tape cannot cover the melting part, otherwise it will affect the production effect of the circuit board.

  ④ Use the paint brush to paint the paint evenly on the plastic film. Note: You can't brush back and forth, you can only brush in one   direction, otherwise the plastic film will wrinkle together, and the lines on the copper plate will overlap. After the circuit diagram is completely brushed, carefully remove the plastic film. At this point, a printed circuit board is printed. After drying, it is ready for corrosion.

If you want to print multiple pieces, you can make a wooden frame larger than the circuit board, and apply the silk screen on the wooden frame to fix it. Then use double-sided tape to paste the plastic film fixed under the screen. Place the copper-clad board on the table, close the wire mesh rack (the printed picture and the copper-clad board should be aligned left and right), and use a paint brush to brush the paint in one direction and remove the wire rack. The printed circuit board is printed. If there are defects, they can be modified with paint and bamboo.

 

Attention must be paid to the above process. When painting, the hand should be applied with appropriate strength. If the paint film is too heavy, the lines will be laced, and the lines that are too light will be broken. The plastic film must face up.

 

6. Use pre-coated photosensitive copper-clad board:

   Using a special copper-clad board, the surface of the copper platinum layer is pre-coated with a layer of photosensitive material, so it is called "pre-coated photosensitive copper-clad board", also called "photosensitive board". The production method is as follows:

Print the circuit diagram 1: 1 on a relatively transparent (thin) paper with at least one side that is smooth and flat, and print the mirror image on the flat side.

    Then put the smooth side of the paper close to the photosensitive circuit board (clamped with glass), and place it under the sun for 2-8 minutes. The length of time depends on the strength of the sun. It can be irradiated for about 20 minutes on a cloudy day. Note: The above is the reference time for transparencies. Use white paper to extend the time according to the light transmittance of the paper. During this process, do not move the relative position of the paper and the circuit board, and keep it close.

   Then put the circuit board under the developer to develop underwater (wash away the unnecessary photosensitizer), the remaining developer will prevent the copper from reacting with the next step of ferric chloride. This process typically takes 1-3 minutes. The time is inversely proportional to the degree of exposure. If the exposure is excessive, the development time will be short. If the exposure is insufficient, the development time will be long, even longer than 10 minutes. In addition, it is also related to the concentration of the developing water. However, it is strongly recommended that the exposure should not be excessive, and it is better to have a longer development time, so that no errors will occur and 100% success can be guaranteed.

The final corrosion by ferric chloride takes about 10-60 minutes.

    Since the above process directly determines the retention of the copper sheet, the accuracy can be very high. Therefore, the skilled person can generally make a high-precision circuit board within 30 minutes, and the thermal transfer paper can also be used for exposure after printing without the need to heat the transfer process. The effect is better. The price should be a lot more expensive, but it is generally acceptable.

    ①Single panel production: Print the PCB drawing made by the computer, and print the 1: 1 black and white 720dpi drawing (component side) with inkjet special paper. If you use a laser printer to output the drawing, you can. Take a photosensitive board that is the size of the drawing and remove the protective film. Use a glass plate or a plastic transparent plate to compress the drawing with the photosensitive PCB board, and expose it to sunlight for 5-10 minutes. Use the accompanying developer 1:20 for water development. When the exposed part (unwanted copper clad) is completely exposed, rinse it with water to etch with ferric chloride. After skilled operation, you can produce a trace with an accuracy of 0.1mm!

    ② The production of double-sided circuit boards: the steps refer to the single-sided board. The double-sided board is mainly positioned on both sides to be accurate. Both sides can be exposed separately, but the time should be the same, and one side should be protected with black paper when the other side is exposed.

 

Seven, thermal transfer method:

hardware:

1: A printout device for producing a high-precision plastic toner solder resist layer, such as a laser printer or a copier (if a copier requires a copy of the original, the original can be printed with an inkjet printer).

2: A working iron.

3: A smooth backing paper with a sticker.

4: A certain amount of ferric chloride corrosion solution, depending on the size of the board. In addition, it is better to have a digital thermometer with a range of 0 to 200 degrees, and the high-end digital multimeter comes with it.

software:

A lower version of PROTEL, such as PROTEL 2.5 Chinese version of a higher version of PROTEL, such as PROTEL 99SE Chinese version, is even just a drawing program that comes with WIN. In short, it is a software that can draw pictures.

step:

The first step: use some software that can generate images to generate some image files, such as using a lower version of PROTEL to organize the SCH, and then use the netlist to generate the corresponding PCB drawing, or use PowerPCB to directly draw the PCB drawing (without PROTEL, PowerPCB, or even WINDOWS brush program is also available) for printing.

Step 2: Print the PCB drawing on thermal transfer paper (the thermal transfer paper referred to by JS is the yellow backing of adhesive paper!).

Step 3: Lay the printed PCB transfer paper on the copper-clad board and prepare for transfer.

Step 4: Use an electric iron to heat (to be very hot) and press the black plastic powder on the transfer paper against the copper clad plate to form a high-precision anti-corrosion layer.

Step 5: The effect of electric iron heating and pressing after successful transfer! If you do it often and become proficient, it is easy to succeed.

Step 6: Prepare the ferric chloride solution for corrosion.

Step 7: The effect is pretty good! Be careful not to corrode excessively, the corrosion is over, and prepare to weld.

Step 8: Clean out the pad part, the remaining part is used for solder mask.

Step 9: Install the required originals and weld them.

 

note:

1: Do not overheat or cool the iron. The optimal temperature is between 140 and 170. Within this temperature range, the transfer characteristics of plastic toner are the best.

2: After the temperature is lower, peel off the transfer paper, and then slowly peel it off. If you find that the transfer is not good, please cover it again, and heat and pressurize it again for heat transfer.

3: For some really problematic parts (such as broken wires), please use oily carbon pen or nail polish, paint or something to remedy, but this is not a lot.

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