====== Etchant recipe ======

I got this recipe from the [[https://www.youtube.com/watch?v=W4CvzLtyUXI|Bearded Engineer]] on YouTube who gave a great breakdown of different etchants and the chemistry behind them. Having tried Ferric Chloride I found it to be horrible stuff that makes a mess so I was really happy to come across this safer and cleaner approach.

Note when handling ANY chemicals I recommend you use gloves and safety glasses. I also tend to use an apron in case of splashes but that's more optional, it just saves clothes, gloves and glasses save you and your eyes! I also recommend having a well ventilated space some of these chemicals smell rather bad and are not good for you.

==== Ingredients ====
  * 100g Hydrogen Peroxide 3-6% (most pharmacies stock this)
  * 30g Citric Acid (you can get a powder of this on Amazon)
  * 5g Sodium Chloride (table salt will do)
  * 45g Bicarbonate of Soda (any supermarket has this)

==== Equipment ====
  * Nitrile gloves
  * Protective glasses
  * Something to mix the solution in (I recommend a 500ml Erlenmeyer Flask).
  * Something to stir the mix with (I recommend a glass rod).
  * Small glass bowl, to measure into.
  * A metal measuring spoon.
  * Scales, able to measure small amounts.
  * A tray or tank (I built an [[etching_tank|etching tank]] for this) for etching in.

==== Steps ====
  - Pour the hydrogen peroxide into your mixing jar, measure out the citric acid, the sodium chloride and add them to the hydrogen peroxide. Now mix it until the solution is clear.
  - Add the solution to your mixing tank then place your PCB in the mix. I put a bit of tape on the ends I added and use these to ensure the PCB is floating in the mix and not touching the sides so the solution can reach all of the copper it needs to remove.
  - I find the etching takes about 16 minutes.
  - Once all of the copper is remove you can rinse the board off with water.
  - The solution is good for a few boards use.

==== Disposal ====
I do NOT recommend poring this down your drain as it will wreak havoc with your copper pipes, you need to neutralize this first. I found that by SLOWLY adding a bit of the bicarbonate of soda a couple of grams at a time it will bring the PH to neutral. You add it slowly as it really fizzes up as it reacts with the acid, and if you go to fast it will overflow the flask you are using.