Yahoo Groups archive

Homebrew PCBs

Index last updated: 2026-04-28 23:05 UTC

Thread

[Homebrew_PCBs] Etching Problem

[Homebrew_PCBs] Etching Problem

2010-03-18 by Mark Lerman

I am using HCl (31%) + H2O2 (30%) + water in the ratio of 3:1:3 at 
room temperature with manual agitation (rocking) to etch some boards, 
but I'm having some problems. The boards seem to take a long time to 
etch (>15 minutes), and rather than etching evenly, the edges of the 
board etch first, then the perimeter of the non-etched area gradually 
decreases. I'm concerned that the etching from the edge will undercut 
the traces. What am I doing wrong? Other people report even etching 
in 1-5 minutes with this mixture, so I must be doing something wrong! 
Thanks for any help.

Mark

Re: [Homebrew_PCBs] Etching Problem

2010-03-18 by DJ Delorie

Is the H2O2 fresh?  It breaks down over time, a solution that's been 
mixed for a while won't have any H2O2 left in it, and HCl won't etch Cu 
without an oxidizer.

Are you sure you used 30% H2O2 and not the more common 3% ?

Re: [Homebrew_PCBs] Etching Problem

2010-03-18 by Mark Lerman

It's Claroxide 30, from a beauty supply, and should be fresh. Perhaps 
I'm using too little - I used 30 cc water +30cc HCl +10cc H2O2 for a 
ds board that measured about 4x2 inches. I don't know the thickness 
of the copper. The board was etched horizontal in a container with 
the etchant level only about .25 inches above the surface of the board.

Mark
\
At 12:35 PM 3/18/2010, you wrote:
Show quoted textHide quoted text
>Is the H2O2 fresh?  It breaks down over time, a solution that's been
>mixed for a while won't have any H2O2 left in it, and HCl won't etch Cu
>without an oxidizer.
>
>Are you sure you used 30% H2O2 and not the more common 3% ?
>
>
>------------------------------------
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>

Re: [Homebrew_PCBs] Etching Problem

2010-03-18 by DJ Delorie

By "Fresh" I meant how long since you'd mixed them.  As for amount, I 
mixed up four liters of etchant and just keep reusing it :-)

Re: Etching Problem

2010-03-18 by awakephd

Mark, I am a long way from being an expert, but until one of the experts chips in, I'll say that the proportions don't sound right to me. I use 1 part 30% HCl, and 2 parts 3% H2O2, and it etches quickly. So it would seem that you are using a way, way higher concentration of H2O2 to HCL -- ??

FWIW, even though this mixture etches quickly, it does etch from the outside edges in -- but that is true of every etching I have seen or done, not that that is a very large sample.

--- In Homebrew_PCBs@yahoogroups.com, Mark Lerman <mlerman@...> wrote:
Show quoted textHide quoted text
>
> It's Claroxide 30, from a beauty supply, and should be fresh. Perhaps 
> I'm using too little - I used 30 cc water +30cc HCl +10cc H2O2 for a 
> ds board that measured about 4x2 inches. I don't know the thickness 
> of the copper. The board was etched horizontal in a container with 
> the etchant level only about .25 inches above the surface of the board.
> 
> Mark
> \
> At 12:35 PM 3/18/2010, you wrote:
> >Is the H2O2 fresh?  It breaks down over time, a solution that's been
> >mixed for a while won't have any H2O2 left in it, and HCl won't etch Cu
> >without an oxidizer.
> >
> >Are you sure you used 30% H2O2 and not the more common 3% ?
> >
> >
> >------------------------------------
> >
> >Be sure to visit the group home and check for new Links, Files, and Photos:
> >http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
> >
> >
> >
>

Re: [Homebrew_PCBs] Etching Problem

2010-03-18 by Mark Lerman

DJ,

I mixed it immediately before using from sealed containers. When you 
mix the 4 L, do you keep it in an airtight (covered) etching tank, or 
do you pour it into a container and then back into the etching 
chamber when you want to etch a board? Do you mix it in the same 
proportion I do - 3 HCl +3 H2O + 1 H2O2?? Thanks!

Mark

At 04:36 PM 3/18/2010, you wrote:
Show quoted textHide quoted text
>By "Fresh" I meant how long since you'd mixed them.  As for amount, I
>mixed up four liters of etchant and just keep reusing it :-)
>
>
>------------------------------------
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>

Re: [Homebrew_PCBs] Re: Etching Problem

2010-03-18 by Mark Lerman

I'm using 30% H2O2, not 3%, but I have to do some calculations to 
compare the two.

Mark


At 05:11 PM 3/18/2010, you wrote:
Show quoted textHide quoted text
>Mark, I am a long way from being an expert, but until one of the 
>experts chips in, I'll say that the proportions don't sound right to 
>me. I use 1 part 30% HCl, and 2 parts 3% H2O2, and it etches 
>quickly. So it would seem that you are using a way, way higher 
>concentration of H2O2 to HCL -- ??
>
>FWIW, even though this mixture etches quickly, it does etch from the 
>outside edges in -- but that is true of every etching I have seen or 
>done, not that that is a very large sample.
>
>--- In Homebrew_PCBs@yahoogroups.com, Mark Lerman <mlerman@...> wrote:
> >
> > It's Claroxide 30, from a beauty supply, and should be fresh. Perhaps
> > I'm using too little - I used 30 cc water +30cc HCl +10cc H2O2 for a
> > ds board that measured about 4x2 inches. I don't know the thickness
> > of the copper. The board was etched horizontal in a container with
> > the etchant level only about .25 inches above the surface of the board.
> >
> > Mark
> > \
> > At 12:35 PM 3/18/2010, you wrote:
> > >Is the H2O2 fresh?  It breaks down over time, a solution that's been
> > >mixed for a while won't have any H2O2 left in it, and HCl won't etch Cu
> > >without an oxidizer.
> > >
> > >Are you sure you used 30% H2O2 and not the more common 3% ?
> > >
> > >
> > >------------------------------------
> > >
> > >Be sure to visit the group home and check for new Links, Files, 
> and Photos:
> > >http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
> > >
> > >
> > >
> >
>
>
>
>
>------------------------------------
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>

Re: [Homebrew_PCBs] Re: Etching Problem

2010-03-19 by Herbert E. Plett

are you sure it is 30%, and not 30 vol?
30% is very hard to get.
don't put any water in. to reuse add more H2O2, water enough...


--- On Thu, 3/18/10, Mark Lerman <mlerman@...> wrote:
Show quoted textHide quoted text
> I'm using 30% H2O2, not 3%, but I
> have to do some calculations to 
> compare the two.

Re: [Homebrew_PCBs] Etching Problem

2010-03-19 by DJ Delorie

I used 2 parts 3% H2O2 and 1 part 37% HCl.  After doing what boards I 
had ready for it, I added enough copper to convert it to a CuCl etchant, 
which is stable.  I keep it in a mostly-sealed (but not 100% airtight) 
container.

Re: [Homebrew_PCBs] Re: Etching Problem

2010-03-19 by mlerman@ix.netcom.com

Herbert,

Ah, it does say 30 vol - I assumed that was 30% by volume (I'm not by any means a chemist). Please educate me as to the difference and what it implies for my usage!

Mark


-----Original Message-----
Show quoted textHide quoted text
>From: "Herbert E. Plett" <cachureos@...>
>Sent: Mar 18, 2010 9:18 PM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: Re: [Homebrew_PCBs] Re: Etching Problem
>
>are you sure it is 30%, and not 30 vol?
>30% is very hard to get.
>don't put any water in. to reuse add more H2O2, water enough...
>
>
>--- On Thu, 3/18/10, Mark Lerman <mlerman@...> wrote:
>> I'm using 30% H2O2, not 3%, but I
>> have to do some calculations to 
>> compare the two.
>
>
>
>      
>
>
>------------------------------------
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>

Re: [Homebrew_PCBs] Re: Etching Problem

2010-03-19 by Herbert E. Plett

30 vol is 3%.
the vol indication is about how much O2 is produced from the product.
3% has water enough, don't need to add more.
what runs out is the O2 produced. you can regenerate it either with more H2O2 (more water) or with bubbling air.
the etchant will last (almost) for ever. if you leave it open, some of the water will evaporate (thats good)...



--- On Thu, 3/18/10, mlerman@... <mlerman@...> wrote:
Show quoted textHide quoted text
> 
> Ah, it does say 30 vol - I assumed that was 30% by volume
> (I'm not by any means a chemist). Please educate me as to
> the difference and what it implies for my usage!

Re: [Homebrew_PCBs] Re: Etching Problem

2010-03-19 by Mark Lerman

Thanks for the information - I knew I had to be doing something wrong!

Mark

At 10:23 PM 3/18/2010, you wrote:
Show quoted textHide quoted text
>30 vol is 3%.
>the vol indication is about how much O2 is produced from the product.
>3% has water enough, don't need to add more.
>what runs out is the O2 produced. you can regenerate it either with 
>more H2O2 (more water) or with bubbling air.
>the etchant will last (almost) for ever. if you leave it open, some 
>of the water will evaporate (thats good)...
>
>
>
>--- On Thu, 3/18/10, mlerman@... <mlerman@...> wrote:
> >
> > Ah, it does say 30 vol - I assumed that was 30% by volume
> > (I'm not by any means a chemist). Please educate me as to
> > the difference and what it implies for my usage!
>
>
>
>
>
>
>------------------------------------
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>

Move to quarantaine

This moves the raw source file on disk only. The archive index is not changed automatically, so you still need to run a manual refresh afterward.