Need some etching advice...

[Giglawyer]

Soo..I am toying around with etching...so far I have succeeded in ruining the first box I used.

I am using Muriatic Acid (31.5%) and Hydrogen Peroxide (40%).  The solution I brewed up was a 1:1 mix.  It didn't do much for a while, but I patiently kept moving the box around to get the process going, and then...a few minutes in...it starts a boiling.  Like something out of a James Bond movie. The box starts getting hot enough to feel through the gloves, so I pull it out.  Ugh...  Its a disaster.

Now, I may have left it in way too long.  I mean, I am sure of that.  But, I am also pretty sure that the mix I am using is way too powerful.  Any advice as to the ratio of Muriatic Acid to Hyrdogen Peroxide at these concentrations???

[italianguy63]

I do it this way too...

You will kill a couple enclosures until you figure it out.

I use 1:1:1 mix (Acid/Peroxide/Water).

I put the enclosure in about 15 to 30 seconds at a time.  I use an old toothbrush to lightly brush the etched areas-- breaking the black gunk free.

Then I dip in a water bath.

REPEAT.  I usually end up going 2.5 to 3 minutes total etch time.  This is the part that takes practice.

If you go too long, the mask will deteriorate, you will get shadows and pitting.

it's a hard balance-- longer (deeper) etch is better, but too long is not.

Keep trying!  MC

[Maik]

And check the water temp. Must be around 20 degrees Celsius/68 F.
If it´s too warm it will be too strong, every 10 degrees double acid power.

With 1:1:1 (acid30%, H2O2 30%) and a temp of 20 degrees it takes ca 2min to etch a box and 1,5-2,5min to etch a pcb.
For controling the etch or finishing the etchingput the box/pcb in water with some pril (dish soup) in it.

FIRST OF ALL: First water then acid or you get a lot of problems! And wear savety glasses and rubber gloves.
A fail will give you a heck full of pain (as I know, had a wound half of my hand, very painfull!)

[R.G.]

It takes the lives of ten thousand soldiers to make one good general.

[Giglawyer]

Thanks Guys, I will try again.

[thelonious]

You will kill a couple enclosures until you figure it out.

...but they can still make great prototyping enclosures for you (or some other guy) 

And wear savety glasses and rubber gloves.

...and a respirator, and do it in a well-ventilated area. Seriously. I once stupidly tried to use that particular mix of chemicals in the winter in a bathroom with the fan on (hey, a bathroom fan is ventilation, right?). I never did it again, since I started feeling strange and learned later I had been breathing chlorine gas. It's only Ferric Chloride for this guy from then on!

[davent]

Hexjibber's etches are second to none, he uses caustic soda.

His tutorial here.

http://diy-guitar-effects.tumblr.com/etching

[Arcane Analog]

You will have much more control of the etching process using feric chloride and your preferred temperature.

[italianguy63]

I do it OUTSIDE as well, in case of a spill.  This will eat through the floor like Alien blood.

I bought some caustic soda (Lye) to try.. haven't done it yet.

MC

[davent]

Mark where did you find the lye as on another forum people were having a difficult time tracking it down, (for use as presensitized PCB developer).
dave

[italianguy63]

Here you are!  Enjoy:

http://www.ebay.com/itm/2-Lb-Sodium-Hydroxide-Caustic-Soda-Lye-NaOH-/261666331662?pt=LH_DefaultDomain_0&hash=item3cec875c0e#ht_1696wt_956

It's even Kosher! 

MC

[davent]

Thanks Mark, My bagels and pretzels are gonna be special now!

[Pettol]

+1 on NaOH (caustic soda). Easier to work with, cleaner etch and doesn't affect the mask. I finally found a paint (for touch ups) that seems to resist it - Humbrol enamel.

[Arcane Analog]

I do it OUTSIDE as well, in case of a spill.  This will eat through the floor like Alien blood.

Another benefit of Ferric - it will not eat through your floor unless your floor is metal.

[Keppy]

Mark where did you find the lye as on another forum people were having a difficult time tracking it down, (for use as presensitized PCB developer).
dave

I don't know about Canada, but in the US hardware stores stock it as a drain cleaner. That's where I got it.

[davent]

Yeah that's what i assumed as well. The grocery store i worked in during my school years sold it but can't say i've noticed it in the years since. The person that was trying to track it down on the other forum works for one the big box home improvement giants i believe in North Carolina and was having no luck finding it locally and didn't want to buy on line.

I did find a soap making supplier not to far from me who sells it for  a pretty good price with shipping, didn't notice whether it's food grade or not.

[WhiskeyMadeMeDoIt]

+1 on NaOH (caustic soda). Easier to work with, cleaner etch and doesn't affect the mask.

I have been using a negative photo resist film for box etching.  Yoau cannot use NaOH because it will dissolve the mask! I use the cupric chloride etchant after I make my boards. 

[Pettol]

+1 on NaOH (caustic soda). Easier to work with, cleaner etch and doesn't affect the mask.

I have been using a negative photo resist film for box etching.  Yoau cannot use NaOH because it will dissolve the mask! I use the cupric chloride etchant after I make my boards. 

True. That's the drawback of photo resist films and sprays.

[italianguy63]

didn't notice whether it's food grade or not.

I wouldn't eat it.     (Kosher or not)

[Hexjibber]

Sounds like this muratic based one is relatively complicated when compared to using Ferric or NaOH, I followed Pettol's advice and used NaOH and have never looked back, give it a whirl man!