Hydrogen peroxide, citric acid, salt for etching the printed circuit board

The printed circuit board is one of the main parts of any wiring diagram. Before you make this or that radio amateur design, a radio amateur thinks about how to create a printed circuit board. To date, there are many methods of creating boards that will not be different from the factory ones, for example, the LUT method using a laser printer. However, it is not available to everyone. The use of copper sulfate, ferric chloride and other etchants is difficult to reach for ordinary people, and these traces of mud leave enough. In this article we will look at how hydrogen peroxide, citric acid, salt, helps etch printed circuit boards, and also introduce you to a cleaner and affordable alternative method.

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Citric acid and hydrogen peroxide is a safe and generally available composition for etching copper

To prepare the solution, you will need:

• Hydrogen Peroxide( 3%), 100 ml. You can buy at any pharmacy.
• Citric acid, 80 g. The product can be bought at any store.
• Table salt, 1 tsp. The product should already be in your kitchen.

Important! This volume is sufficient for etching 100 cm2 of copper with a thickness of 35 μm.

Before preparing the mixture:

1. Draw and print the board.
2. Cut out a piece of textolite.
3. Transfer the toner to the textolite.
4. Leave to soak.

Now proceed with the preparation of the solution:

1. Take a glass or plastic container( not metallic only).
2. Preheat the peroxide. To do this, put the closed jar with the product on a water bath and leave until the temperature is leveled.
3. Pour the peroxide into the vessel( you do not need to dilute, since it is already 3%).
4. Pour citric acid into the container with peroxide.
5. Stir it.
6. Slowly add salt.

The result should be a clear liquid.

Important! While the solution has not cooled down, lower the fee there with the tracks down.

The etching time is approximately 40-50 minutes. The process itself largely depends on the temperature of the mixture. In the process of etching, it becomes green at first, and when all the acid reacts and becomes salt - it will be repainted in blue or blue.

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Useful advices:

• If the solution foams( bubbles), then hydrogen peroxide, citric acid and salt are taken in the wrong proportions. In particular, most likely you have touched with salt. Add a little peroxide and water to the mixture.
• Salt in the manufacture of the solution do not regret, as it plays the role of a catalyst, and in the process of etching is practically not consumed.
• After about 20 minutes of pickling, remove and inspect the board for sub-strikes, since after foaming, the material under the pattern or toner layer can begin to be etched.
• The more hydroperite, the faster the process will pass. But keep in mind that the solution is not stored, and it can not be reused, so if peroxide is too much, it will simply be overspent. Excess hydropyrites can be determined by abundant blistering during etching.
• To understand if the board is ready, without getting it, watch the solution. If he ceased to hiss and bubble, then either there is nothing to bait, or the remedy is exhausted. Get out and check.
• Remove toner with acetone.
• If after removing the toner the board is lowered into the remnants of the mixture, the copper tracks will turn pink and get rid of the oxides. To tinker such a processed board is much faster and easier.

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Advantages of Home Method:

1. High etching speed.
2. The process takes place at room temperature.
3. Availability.
4. Easy cooking.
5. The cheapest method of etching copper.
6. A solution of hydrogen peroxide, citric acid and salt is safe - for both body and clothing.
7. Citric acid and hydrogen peroxide do not leave dirty spots.

Disadvantage of

Average copper citrate is slightly soluble, which means it can precipitate, including the etching surface. To prevent the problem, do not save citric acid.

We hope that you have evaluated the alternative way of etching the board. They can be used to make schemes of any complexity. This method is environmentally friendly, safe, and most importantly - you will not get dirty due to the fact that there is nothing. Good luck to all radio amateurs!