Label：Homemade PCBs, Etching, Solder Mask
Jan 21, 2021960
The PCBs can be single-layer (one copper layer), double-layer (two copper layers) or multilayer. The conductors on different layers are connected with plated through holes called vias. Advanced PCBs may contain components embedded in the substrate-capacitors, resistors or active devices.
Have you ever thought about making PCBs at home? After reading this article, I hope it will increase your confidence in self-made PCBs.
Step 1. Design
Before trying to make it by hand, please remember that we need a good circuit design first.
1. Draw circuit schematics on graph paper or simulation programs such as MultiSim or Eagle CAD. The schematic should contain detailed descriptions of all components. Remember that the basic form of the schematic will be drawn on the circuit board. For the drawing of the schematic, you can refer to the article we published earlier.
2. If you are using a simulation program, test the circuit thoroughly in a simulation environment. If you are not using a simulation program, you can assemble and test the circuit on a breadboard. The breadboard is very easy to use and allows people to view the results of the circuit in real time without the need for soldering or permanent etching.
3. Make sure the circuit board functions in the breadboard or simulation software.
Step 2. Drawing
1. Obtain the circuit board. The circuit boards are about one dollar each and are just the copper layer on the insulator. The typical size is usually 3.5 inches by 5 inches. The drawing is simple; all that is needed is an indelible mark, such as Sharpie.
2. Use Sharpie to draw circuits on the circuit board. Remember, there can be no copper between the components. For example, if LEDs are connected, there must be a copper gap between the positive and negative points of the connection. Without gaps, current will flow around the LED instead of through it. Remember the law of electricity, all circuits must end with negative or ground, otherwise no current will flow.
Step 3. Etching
You need to prepare:
Non-metallic basin, deep enough to immerse the circuit board
Vinyl or latex gloves
Non-metallic device (rod) for stirring circuit boards
Hydrochloric acid about 30% (Muriatic Acid)
Hydrogen peroxide 3%
Acetone or mineral spirits
1. Put on goggles and gloves. Always remember safety first.
2. Make sure the area is well ventilated before mixing. These chemicals can produce harmful fumes.
3. Use non-metallic basins. Add a few drops to check if it can withstand acid.
4. Gently pour one unit of hydrochloric acid into every two units of hydrogen peroxide (add water and acid). When mixed, they become severely irritating to the skin and produce toxic chlorine gas.
5. Gently put in the circuit board and stir for about ten to fifteen minutes. Remember not to bring your face too close!
6. Continue stirring until all the copper is dissolved and the solution is light green.
7. When cleaning up, make sure to wear gloves. Rinse in cold water to remove the etching solution. Then dry it thoroughly with a paper towel or cloth. Put it aside. Make sure there is no solution in the work area or container, then remove the gloves and goggles.
8. When cleaning up, make sure to wear gloves. Rinse in cold water to remove the etching solution. Then dry it thoroughly with a paper towel or cloth. Put it aside. Make sure there is no solution in the work area or container, then remove the gloves and goggles.
9. Mix a certain proportion of acetone and rubbing alcohol. Take a piece of paper towel, soak it in the solution, and gently wipe the board surface. The permanent mark will begin to fall off. Continue rubbing until all marks disappear. You will see that your circuit is now engraved on the copper wire.
Step 4. Assembly
You need to prepare:
Handheld drilling machine or drilling machine
Various drill bits
1. Find all the positions of the through-hole components before drilling. Because copper powder is toxic, you need to wear a dust mask.
2. Drill a bit of width on the circuit board to accommodate any parts that need to be placed in that location. Remember not to make the hole too wide, otherwise welding will be very difficult.
3. Place the component in the designated position on the circuit board. Gently bend the feet of the assembly to the underside of the board to secure the parts in place. Make sure that the parts with polarities are arranged correctly and have corresponding positive and negative poles. Check and carefully check the position of all parts before welding. Welding is a skill that requires practice, although it is not difficult in itself.
4. Test the board before installing it in the device. If possible, use a multimeter to diagnose connection problems. Desoldering gun can be used for small switch and maintenance.
Step 5. Waste disposal
The etching solution is toxic to fish and other aquatic life. When you are done, do not pour it into the sink. Doing so is illegal and may damage your pipeline. You can reuse the solution by adding a little hydrogen peroxide during the next etching and a little acid when the solution stops working (every 4 or 5 etchings). If it must be disposed of, label it and hand it to a chemical waste treatment facility.