Ferric Chloride VS Muriatic Acid + Hydrogen Peroxide for etching

[RafayAli]

Hey,
I am about to make my third PCB and a friend proposed me to look for the Hydrogen per oxide chemical for etching rather than going for the Ferric chloride one. I previously used Ferric Chloride but after using it to make one PCB I had to dispose it off. I read the procedure for the hydrogen per oxide one but in the comments I read that it too does not last for long but can be re-used.

Can somebody please suggest me what to do?
I am attaching the link which I found to make the Hydrogen per oxide solution.

https://www.instructables.com/id/Stop-using-Ferric-Chloride-etchant!--A-better-etc/?ALLSTEPS

 

[schmitt trigger]

Ferric Chloride is indeed a very nasty stuff, so I applaud your decision to go for an environmental friendly solution.

I haven't used the method described in the instructables, but it does appear to be chemically correct.

The only thing I would add is that you'll be dealing with nasty chemicals, make sure that you use rubber gloves, safety glasses and old clothes when dealing with the stuff.

Also, you'll be storing some poisonous chemicals. Make sure that they are completely away from children and pets, and labeled accordingly.

 

[Kick]

In my opinion Ferric chloride is best one. Last 1 year I am using that one only. Main disadvantage is you can't use it again.

 

[jpanhalt]

I don't know where the rumors that ferric chloride is environmentally unfriendly and can 't be uses multiple times come from.

First, ferric chloride is widely used in waste water treatment because it is environmentally friendly. If there is any problem with discarding it after etching copper, it is from the copper it contains. Anything you use for etching will contain the same amount of copper, assuming the etched patterns are the same.

Second, ferric chloride can be re-used many times. Just calculate the amount of copper that can be removed given a certain concentration of ferric chloride. That calculation nevers need to be done in practice, as one can tell from behavior of the solution when it is getting weak. It should also be noted that re-oxidation of the reduced iron (mostly ferrous) is not only practical but prolongs the life of the solution. Letting it sit exposed to air is adequate. Bubbling air through it hastens the re-oxidation. If you add additional HCl, the etching solution eventually (after many PCB's) becomes mostly cupric chloride, which is also an excellent etchant. In other words, it is a mixture of ferric and cupric chlorides that is renewable effectively forever. Here is a link to an article by Adam Seychell that descrivbes the cupric chloride method:

https://jimlaurwilliams.org/projects/seychellePaper/

And from Chemcut on the same subject: **broken link removed**

In fact, Chemcut has several nice reference articles here: https://www.chemcut.net/technical-info/

Third, ferric chloride and cupric chloride give better definition and less undercutting than peroxide/HCl.

Finally, in my experience the peroxide/HCl etchant many affect the resist you are using. I use a photoresist, and it is pitted by that reagent.

John

 

[RafayAli]

I don't know where the rumors that ferric chloride is environmentally unfriendly and can 't be uses multiple times come from.

First, ferric chloride is widely used in waste water treatment because it is environmentally friendly. If there is any problem with discarding it after etching copper, it is from the copper it contains. Anything you use for etching will contain the same amount of copper, assuming the etched patterns are the same.

Second, ferric chloride can be re-used many times. Just calculate the amount of copper that can be removed given a certain concentration of ferric chloride. That calculation nevers need to be done in practice, as one can tell from behavior of the solution when it is getting weak. It should also be noted that re-oxidation of the reduced iron (mostly ferrous) is not only practical but prolongs the life of the solution. Letting it sit exposed to air is adequate. Bubbling air through it hastens the re-oxidation. If you add additional HCl, the etching solution eventually (after many PCB's) becomes mostly cupric chloride, which is also an excellent etchant. In other words, it is a mixture of ferric and cupric chlorides that is renewable effectively forever. Here is a link to an article by Adam Seychell that descrivbes the cupric chloride method:

https://jimlaurwilliams.org/projects/seychellePaper/

And from Chemcut on the same subject: **broken link removed**

In fact, Chemcut has several nice reference articles here: https://www.chemcut.net/technical-info/

Third, ferric chloride and cupric chloride give better definition and less undercutting than peroxide/HCl.

Finally, in my experience the peroxide/HCl etchant many affect the resist you are using. I use a photoresist, and it is pitted by that reagent.

John

Hey thank you very much for the article. I will try this