Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Ferric chloride question

Status
Not open for further replies.

hk3432

New Member
I am new to making my own PCBs and just got a bottle of Ferric chloride and would like to give this a try but have two questions about safety/disposal. I have seen many articles about this stuff (and videos) most were not wearing a respirator and some were doing it indoors, should I use a mask even while outside? What about proper disposal of Ferric chloride water that has been used for rinsing, is this safe to poor down the drain? (Not the actual acid bath)

Thanks.
 
Ferric chloride, if heated, will release HCl. It is unlikely your respirator will block that, unless you have something with activated carbon. In this day and age it is impossible to tell someone not to take a safety precaution. I do not and have never worn a respirator when dealing with ferric chloride indoors or out. Your material is in solution as well. That reduces the risk from the dust considerably. Eye protection is important. Be sure not to omit that.

As for disposal, just consider that the major use of ferric chloride is for sewage and water treatment. It is also used in many areas to kill roots that invade sewage lines. The risk in sewage is not from the ferric chloride, but from the copper salts that are produced during etching. To that end, I minimize the amount of copper that is removed by using copper pours.

Finally, ferric chloride etchant will last a very long time. There is no need to dispose of it after each use. I use cupric chloride (similar chemistry). It never wears out and never has to be discarded, unless the volume gets too great. Ferric chloride can equally be reused. It will eventually turn into a mixed cupric chloride and ferric chloride bath after a lot of use.

John
 
Last edited:
From what I understand, you don't want to pour ferric chloride down your drain, unless you absolutely, positively know that there isn't any copper pipe or fittings, or other metal piping/fittings along the way (most sewage pipe nowadays is ABS, I believe). Only because you don't want your pipes prematurely eaten away (to be sure, with enough dilution, this probably won't be a real issue).
 
Dilution is a key. A toilet is rarely connected with copper pipe even in the olden days. I should have added that detail.

BTW, ABS may be common in Arizona, but it is not that common in many places in the US. PVC is most often used for drain/waste/vent systems. I believe in the US, PVC is code in every locale; ABS is not.

John
 
HCl is hardly likely to kill you in moderate quantities. It's stomach acid. The vapour from Ferric Chloride will start surface rust on steel, but so will sea water.

If you want to neutralise Ferric Chloride, drop some iron filings or wire wool into it. Either will use up what remains fairly quickly. You would really have to try to eat through a copper drain pipe with waste Ferric Chloride, as what sits in a pipe wouldn't be enough to attack much of the pipe, and it would get washed away. Copper pipe is probably 100 times thicker than the copper on a circuit board.
 
when i started making boards i brought the ferric chloride balls you get off ebay, i mixed with water and the tray sat next to me on the bench for weeks and weeks no ill affects. but it always seemed to etch realy realy slow, so i went and got some concentrated liquid ferric chloride that i think was top strengh at around 40 BOM(i think thats what its called). a small amount was mixed with 30% water by volume as per recomendations from supplier, it sat on the bench in the tray as before...........within days i had horendous headaches and felt sick as a dog from the fumes! so it got put out the workshop into another building where it now lives!
 
BTW, ABS may be common in Arizona, but it is not that common in many places in the US. PVC is most often used for drain/waste/vent systems. I believe in the US, PVC is code in every locale; ABS is not.

ABS is used here in the States in sub-standard applications such as mobile homes (the cheaper ABS is loved by mobile home manufacturers). ABS degrades quickly when exposed to UV. PVC is the preferred material for waste lines. I've noticed from watching HGTV that Canada seems to be consumed by ABS waste lines. Maybe ABS is code there. Dunno.
 
I've given up ferric chloride, in part because of its staining characteristics.

I now use muriatic acid, (HCL), from the hardware store and hydrogen peroxide from the drug store. One part acid with two parts peroxide does a good job. It turns green as the copper is dissolved. Use it in an open area as it gives off a small amount of chlorine gas and heat. I use the left over compound to kill moss as it includes copper chloride.
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top