Quick question about etching PCB - why is it not working!?

[Ibanezsr500]

Hey guys,

I'm trying to etch a small board with Hydrochloric Acid and Hydrogen Peroxide (at a ratio of 1:2, respectively), but it's not etching away the copper. Its been sitting in the etchant for  40 minutes now and NOTHING is happening, no bubbles or no dicolouration of the copper, it might as well be sitting in water. The etchant etches alluminium or any other little flakes of metal I throw in there, but not the copper on the board. Any suggestions?

Btw, I got my copper clad board from Jaycar if it matters.

[jogina111]

you can try a 1:1 ratio for a stronger solution..see if that works out..

[Ibanezsr500]

Cool, just tried it, didn't seem to make much (if any) of a difference. Thanks, for the suggestion, anything helps at this point.

I wonder if its the etchant or the board thats the problem. The etchant etches alluminium shavings like crazy, but does nothing to the copper...

[Mustachio]

I've only been using ferric chloride but I think most etching solutions work better when their warm. I usually fill up a small tub with hot water and leave the bottle of etchant in it to warm up before I use it. (and yeah like he said 1:1 might be better)

Good luck, wear safety gear chicks dig it!

[Minion]

It will take a while to etch if the board is just soaking in the liquid , it needs to be agitated ...... I use those air tight tupperware containers with the locks on them and put them in a zip lock and shake the hell out of it and get a board etched in about 3 minutes .......

[Ibanezsr500]

...work better when their warm...

shake the hell out of it...

Thanks guys, tried both, still no success. I think that it might be the copper board, not sure why it would make a difference, but weirder things have happened! Heating the etchant up sure makes a difference!  The little alluminium flakes (left over from drilling enclosures) I've been throwing in the etchant disolved almost instantly!

[Minion]

maybe there is some sort of coating ober the copper stopping it from oxidizing ...... try a small piece of PCB and scrub the surface with steel wool or fine sand paper then see if it the copper dissolves ....

[jogina111]

yeah, scrub your pcb with steel wool or heat it up to dissolve the coating...but you have to put transfer again : (

the solution needs a substance from copper. I think its called carbide.. Try etching some copper from other pcb or wires. Is it green? It should be green...

[Ibanezsr500]

Thanks guys, I'll give both of those ideas a go and let you know how things turn out.

[Jdansti]

If you used photo paper for the transfer, make sure that there's not a remaining layer material from the paper.

Maybe someone can answer this question: when you use hydrogen peroxide, do you use the drug store strength, or an industrial concentration like 10% or greater? 

[jogina111]

both works but we need to change the ratio. Its 2
parts peroxide to 1 part HCl...using 10%peroxide requires 3 parts of HCl to 1part of peroxide..

I guess he added the peroxide to acid...which is wrong. It should be the other way around. Acid to peroxide.

[jogina111]

both works but we need to change the ratio. Its 2
parts peroxide to 1 part HCl...using 10%peroxide requires 3 parts of HCl to 1part of peroxide..

I guess he added the peroxide to acid...which is wrong. It should be the other way around. Acid to peroxide.

[jogina111]

both works but we need to change the ratio. Its 2
parts peroxide to 1 part HCl...using 10%peroxide requires 3 parts of HCl to 1part of peroxide..

I guess he added the peroxide to acid...which is wrong. It should be the other way around. Acid to peroxide.

[Tony Forestiere]

Hmmm. Wondering if you bought photo-sensitized PCB material?

[Keppy]

If it dissolves aluminum then there's nothing wrong with the solution. Clean the board with steel wool or a scotch brite pad as suggested, re-transfer and try again.

One other note: Use fresh peroxide. It degrades as it sits, particularly if it's been opened or stored in the light. I don't think this is your problem, since the aluminum's dissolving, but it's worth noting. My last etches were horrible due to old peroxide.

[Ibanezsr500]

If you used photo paper for the transfer...

...the drug store strength, or an industrial concentration like 10% or greater? 

Nah, didn't use photopaper this time, I used Press 'n Peel. The peroxide was 3%. Hydrochloric was 38%.

both works but we need to change the ratio. Its 2
parts peroxide to 1 part HCl...using 10%peroxide requires 3 parts of HCl to 1part of peroxide..

I guess he added the peroxide to acid...which is wrong. It should be the other way around. Acid to peroxide.

yep, mixed it 2:1, peroxide (3%) to hydrochloric (38%) respectivley. And no, I poured the Acid into the peroxide. I don't think that it would make any difference chemically though, it's just a safty thing so you don't splash acid everywhere.

Hmmm. Wondering if you bought photo-sensitized PCB material?

Pretty sure I got the normal stuff, unless the dude at Jaycar stuffed up, but that doesn't happen often.

If it dissolves aluminum then there's nothing wrong with the solution...

One other note: Use fresh peroxide...I don't think this is your problem, since the aluminum's dissolving...

This is my conclusion, so I'm not sure whats wrong. The peroxide was old, but as I mentioned, it ate the alluminium pretty quick.

Thanks for all your help guys, it's really apreciated. I think I'm just gonna go buy some ammonium persulphate and see if that solves my problem. Or maybe some more copper board...probably both, just to be sure.

I'm still curious as to why the solution won't etch copper, but will still etch alluminium. I even threw some copper wire into the etchant and it didn't do anything either!

[Jdansti]

You probably don't have any nitric acid, but that would do it - maybe too well.

Something you might want to try is heating the etchant. When I heat ferric chloride, I use a water bath so I don't have to heat it on the stove or microwave. I put hot tap water in a plastic container, and I set another container with the enchant in it in the hot water.  The enchant never comes into contact with the hot water. You can then immerse the boards in the enchant while the etchant is being heated by the water bath.

[jogina111]

since you'll go shopping,go buy ferric chloride, its a sure shot...