Etching the board with hydrogen peroxide and citric acid is a recipe that is especially popular with radio amateurs. This is not only a fast, but also a safe way to get a canvas ready for soldering the elements of a future device.
How have boards been poisoned in the past?
It used to be a lot of effort to make a PCB. First, the scheme was drawn on paper, then holes were made in the workpiece, after which the tracks were transferred to foil textolite or getinax, using paintwork products. After the coating had dried, it was torn off, and the board was immersed in a container with a meadow for etching.
The hardest thing was to poison the fee. Since for these purposes a meadow based on ferric chloride was used. In the radio circle, such a tool was not in short supply, but at home they had to look for an alternative, which was most often copper sulfate.
The processing of the board carried another secret: the board was etched unevenly. Somethe tracks were corroded, and in some places the surface was not etched. All due to the inexperience of the craftsmen or the repeated use of the puddle solution.
Modern board processing methods
Etching boards with hydrogen peroxide and citric acid is not new. Many have heard of this method before. By choosing this board preparation option, you will discover many advantages over ferric chloride etching. For example, the processing quality, safety and environmental friendliness of peroxide in combination with an oxidizing agent.
Recipe processing board at home
Everything you need to etch the board with hydrogen peroxide and citric acid, you will find in your first aid kit and in the kitchen, or you can easily purchase it. Another undeniable advantage of processing boards in this way is the cost of the ingredients to create the solution. Here is another advantage of the hydrogen mixture - it will cost much less than ferric chloride.
- Hydrogen peroxide 3% - 100 ml.
- Citric acid - 30 grams.
- Table s alt - 5 grams (as an auxiliary component of the reaction).
- Water (if needed).
Important! A solution prepared in this proportion is enough to etch copper foil with a thickness of 35 microns and an area of 100 square meters. see
Preparing the board
- Draw and print the board.
- Cut out a piece of textolite to the required size.
- Transfer the toner to the textolite andleave to soak, then remove.
How to prepare the solution?
- Heat the hydrogen peroxide: place the bottle in a water bath and wait until the temperatures of the two substances are equal.
- Take a cup. Any, but not metal, will do.
- Pour the heated peroxide into a clean, dry bowl and pour in the citric acid.
- Stir the mixture thoroughly.
- Stir while adding s alt, which acts as a catalyst in the solution.
How to poison the board?
To make the etching of the board with hydrogen peroxide and citric acid faster, you can use two containers. Simply place the smaller bowl of meadow into the larger container and pour hot water into it. This will speed up and strengthen the process.
Etching the board in 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 decay products easily sink to the bottom of the container. In order for the reaction to proceed more evenly, the solution should be stirred slightly from time to time. The whole process takes no more than 10 minutes.
After weeding is complete, the board must be neutralized and rinsed under running water.
This board processing method is completely safe. It is now possible to make boards at work, at home, and in the office, and it is not at all necessary to work with unsafe reagents.
Important! If the solution foams a lot, then you poured too much s alt. Pour more peroxide, otherwise the reactionwill be too active, the tracks may be damaged.
If you pull the board out and look at it during the reaction, you won't be able to tell the difference compared to ferric chloride etching, there just isn't. The main difference is a fast passing 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 a printed circuit board in hydrogen peroxide can be considered complete if any reactions have stopped in the solution: it no longer hisses or bubbles.
The finished board is cleaned and washed with water. Toner or paint can be removed 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 radio amateur, thanks to simple and accurate advice, will be able to experiment at home without harming himself or others.