Etching the board with hydrogen peroxide and citric acid is a recipe that is especially popular with ham enthusiasts. This is not only a quick, but also a safe way to get a canvas ready for soldering elements of the future device.
How have boards been poisoned in the past?
Previously, it took a lot of effort to make a circuit board . First, the scheme was bred on paper, then holes were made in the workpiece, after which the tracks were transferred to foil textolite or getinax, using paints and varnishes. After drying, the coating was peeled off, and the board was immersed in a container with a meadow for etching.
The hardest thing was to poison the board. Since for these purposes a meadow based on ferric chloride was used. In the radio circle, such a tool was not scarce, but at home I had to look for an alternative, which most often was copper sulfate.
Processing the board carried another secret: the board was etched unevenly. Some paths were corroded, and in some places the surface was not etched. All due to the inexperience of craftsmen or the repeated use of tin solution.
Modern board processing methods
Etching the board with hydrogen peroxide and citric acid is not new. Many have heard of this method before. By choosing this option for preparing the board, you will discover more than one advantage over etching in ferric chloride. For example, the quality of processing, safety and environmental friendliness of peroxide in combination with an oxidizing agent.
Home Board Processing Recipe
Everything that is necessary in order to etch the circuit board with hydrogen peroxide and citric acid, you will find in your medicine cabinet and in the kitchen you can purchase without any problems. Another indisputable advantage of processing boards in this way is the cost of the ingredients for creating the solution. Here is another advantage of the hydrogen mixture - it will cost much cheaper than ferric chloride.
Component composition
- 3% hydrogen peroxide - 100 ml.
- Citric acid - 30 grams.
- Salt - 5 grams (as an auxiliary component of the reaction).
- Water (if necessary).
Important! A solution prepared in such a proportion is enough to etch a copper foil with a thickness of 35 microns and an area of 100 square meters. cm.
Board preparation
- Draw and print a board.
- Cut the required size piece of PCB.
- Transfer the toner to the textolite and leave to soak, then remove.
How to prepare a solution?
- Preheat hydrogen peroxide: place the bottle in a water bath and wait until the temperatures of the two substances equalize.
- Take a cup. Any suitable, but not metal.
- Pour the heated peroxide into a clean, dry dish and pour in citric acid.
- Stir the mixture thoroughly.
- While stirring, add salt, which in the solution plays the role of a catalyst.
How to poison the board?
To etch the board with hydrogen peroxide and citric acid faster, you can use two containers. Simply place a smaller meadow container in a larger container and pour hot water into it. This will speed up and strengthen the process.
The etching of the board in the hydrogen peroxide solution is performed as follows: the board is placed in the meadow with the side on which the paths are drawn down so that the decomposition products easily sink to the bottom of the tank. To make the reaction more even, the solution needs to be stirred slightly from time to time. The whole process takes no more than 10 minutes.
At the end of the weed, the board must be neutralized and rinsed under running water.
This method of processing the board is completely safe. Boards can now be made at work, at home, and in the office, and working with unsafe reagents is not necessary at the same time.
Important! If the solution foams a lot, then you have added too much salt. Pour more peroxides, otherwise the reaction will go too active, the tracks may be damaged.
If during the reaction you pull out the board and take a look at it, you will not be able to notice the differences, compared to how the printed circuit board is etched in the ferric chloride, they simply do not exist. The main difference is a quick reaction and a less dangerous process for humans.
How to understand that the board has already been etched?
In a hydrogen-acid medium, the reaction proceeds according to the formula: Cu + H3Cit + H2O2 → H [CuCit] + 2H2O. Etching of the circuit board in hydrogen peroxide can be considered complete if any reactions have stopped in the solution: it no longer sizzles and does not bubble.
The finished board is cleaned and washed with water. The toner or ink is washed with acetone. After that, the board is thoroughly wiped and degreased.
Important! Check the tracks for integrity after processing the board. A damaged circuit will not work.
As you can see, etching the board with hydrogen peroxide at home is not only possible, but also safe. It will not be difficult to find the necessary components for the preparation of the etching composition, and the process itself will take no more than 15 minutes. Today, any amateur radio operator, thanks to simple and accurate advice, will be able to experiment at home without harming themselves and others.