Homebrew PCBs

I have been off the group for a while and I'm sure this was covered.  
In the direction for making etchant from Hydrogen Peroxide and Muratic 
Acid, it says that you can regenerate with a bubbler.  How long does 
this take?  I know it will depend on the amount and the area that was 
etched, but is there a rule of thumb to make it work. I do have to day 
that I make a small bathch and it worked great on a sample board.

John Whitney
Wis X 1/9

I'm attempting to bootstrap my first batch of CuCl as I type, so 
this page is fresh off my bookmarks: 
http://pacificsun.ca/~robert/pcb/cucl.htm Pretty good  
page on CuCl. Lots of precision chemistry. 
 
I thought he also had the following seat-of-the-pants advice: if it 
hasn't regenerated overnight, add more acid, but glancing back, I 
see it must have been from somewhere else.   
  
Stan 
 
--- In Homebrew_PCBs@yahoogroups.com, "johnwhitneyfiat"  
<johnwhitneyfiat@y...> wrote:  
> I have been off the group for a while and I'm sure this was  
covered.    
> In the direction for making etchant from Hydrogen Peroxide and  
Muratic   
> Acid, it says that you can regenerate with a bubbler.  How long  
does   
> this take?  I know it will depend on the amount and the area that  
was   
> etched, but is there a rule of thumb to make it work. I do have to  
day   

> that I make a small bathch and it worked great on a sample board.  
>   
> John Whitney  
> Wis X 1/9

On Fri, 02 Sep 2005 02:07:31 +0200, johnwhitneyfiat  
<johnwhitneyfiat@...> wrote:

> I have been off the group for a while and I'm sure this was covered.
> In the direction for making etchant from Hydrogen Peroxide and Muratic
> Acid, it says that you can regenerate with a bubbler.  How long does
> this take?  I know it will depend on the amount and the area that was
> etched, but is there a rule of thumb to make it work. I do have to day
> that I make a small bathch and it worked great on a sample board.
> John Whitney
> Wis X 1/9


I personally never tried it, but i would say many hours, perhaps days.
My tank volume isn't that large, and that means if i run out of active  
etchant halfway through a board i have to do something, waiting very long  
until it is regenerated is not an option. So i just add a small amount of  
CuCl.
With the low price of that stuff and tiny amounts required.....


ST

johnwhitneyfiat wrote:
> I have been off the group for a while and I'm sure this was covered.  
> In the direction for making etchant from Hydrogen Peroxide and Muratic 
> Acid, it says that you can regenerate with a bubbler.  How long does 
> this take?  I know it will depend on the amount and the area that was 
> etched, but is there a rule of thumb to make it work. I do have to day 
> that I make a small bathch and it worked great on a sample board.
> 


Many factors involved, it could be 15 minutes or 2 days. Obviously the 
more air that contacts the solution the quicker all the Cu(1+) converts 
to Cu(2+). So more air, and smaller bubbles are two factors you can 
control to increase speed. My etching solution seems to foam a little, 
which *dramatically* increases the regeneration speed. Maybe add a drop 
of dishwashing detergent ?
If your doing air regeneration, then make sure fee HCl concentration is 
 > 1 Molar or 5% wt, and specific gravity is above 1.30 , which 
corresponds to about 140 grams/liter of dissolved copper. Having less of 
these two parameters and you compromise etch speed.

I tried to use CuCl over a period of 4 months.  I was never able to
regenerate it using a bubbler - even left it running for a week once.
  I added more acid but no regen.  However, adding H2O2 made a huge
difference.  My bubbles were fairly small so I think I was getting O2
into it.   I suspect there is more to it than just pumping oxygen into
the solution.

--- In Homebrew_PCBs@yahoogroups.com, "stan4312" <stanman@t...> wrote:

> I'm attempting to bootstrap my first batch of CuCl as I type, so 
> this page is fresh off my bookmarks: 
> http://pacificsun.ca/~robert/pcb/cucl.htm Pretty good  
> page on CuCl. Lots of precision chemistry. 
>  
> I thought he also had the following seat-of-the-pants advice: if it 
> hasn't regenerated overnight, add more acid, but glancing back, I 
> see it must have been from somewhere else.   
>   
> Stan 
>  
> --- In Homebrew_PCBs@yahoogroups.com, "johnwhitneyfiat"  
> <johnwhitneyfiat@y...> wrote:  
> > I have been off the group for a while and I'm sure this was  
> covered.    
> > In the direction for making etchant from Hydrogen Peroxide and  
> Muratic   
> > Acid, it says that you can regenerate with a bubbler.  How long  
> does   
> > this take?  I know it will depend on the amount and the area that  
> was   
> > etched, but is there a rule of thumb to make it work. I do have to  
> day   
> > that I make a small bathch and it worked great on a sample board.  
> >   
> > John Whitney  
> > Wis X 1/9

Are you sure you added enough acid *before* aerating ? How do you know 
what the acid concentration was after aerating ?

I find it hard to believe it wouldn't oxidize in that time.
I assume you are looking for the transparent green color to determine if 
the bath regeneration was completed.

Adam

Phil wrote:

> I tried to use CuCl over a period of 4 months.  I was never able to
> regenerate it using a bubbler - even left it running for a week once.
>   I added more acid but no regen.  However, adding H2O2 made a huge
> difference.  My bubbles were fairly small so I think I was getting O2
> into it.   I suspect there is more to it than just pumping oxygen into
> the solution.
> 
> --- In Homebrew_PCBs@yahoogroups.com, "stan4312" <stanman@t...> wrote:
> 
>>I'm attempting to bootstrap my first batch of CuCl as I type, so 
>>this page is fresh off my bookmarks: 
>>http://pacificsun.ca/~robert/pcb/cucl.htm Pretty good  
>>page on CuCl. Lots of precision chemistry. 
>> 
>>I thought he also had the following seat-of-the-pants advice: if it 
>>hasn't regenerated overnight, add more acid, but glancing back, I 
>>see it must have been from somewhere else.   
>>  
>>Stan 
>> 
>>--- In Homebrew_PCBs@yahoogroups.com, "johnwhitneyfiat"  
>><johnwhitneyfiat@y...> wrote:  
>>
>>>I have been off the group for a while and I'm sure this was  
>>
>>covered.    
>>
>>>In the direction for making etchant from Hydrogen Peroxide and  
>>
>>Muratic   
>>
>>>Acid, it says that you can regenerate with a bubbler.  How long  
>>
>>does   
>>
>>>this take?  I know it will depend on the amount and the area that  
>>
>>was   
>>
>>>etched, but is there a rule of thumb to make it work. I do have to  
>>
>>day   
>>
>>>that I make a small bathch and it worked great on a sample board.  
>>>  
>>>John Whitney  
>>>Wis X 1/9
> 
> 
> 
> 
> 
> 
> Be sure to visit the group home and check for new Links, Files, and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBs
> 
> If Files or Photos are running short of space, post them here:
> http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
> 
>

I may not have all the specifics right - it was about 6 months ago but
I did add 50 mL of 30% HCl and then aerated.  It stayed a dull green,
even after a week of aerating.  50 mL of 35% H2O2 brightened it to
emerald green and I was able to etch a board with it.  Total volume
was 2L + 100 mL.  I'm sure I was doing something wrong but I just
wanted to etch boards not fiddle f*rt around with chemicals. 

I love AP.  Its clear, clean, fast, reliable and very easy to use. 
Never had to fuss with it.  It just works. 

I still have 2.1 L of mystery etchant if some one wants it...  heh heh heh

--- In Homebrew_PCBs@yahoogroups.com, Adam Seychell <a_seychell@y...>
wrote:
> Are you sure you added enough acid *before* aerating ? How do you know 
> what the acid concentration was after aerating ?
> 
> I find it hard to believe it wouldn't oxidize in that time.
> I assume you are looking for the transparent green color to
determine if 
> the bath regeneration was completed.
> 
> Adam
> 
> Phil wrote:
> > I tried to use CuCl over a period of 4 months.  I was never able to
> > regenerate it using a bubbler - even left it running for a week once.
> >   I added more acid but no regen.  However, adding H2O2 made a huge
> > difference.  My bubbles were fairly small so I think I was getting O2
> > into it.   I suspect there is more to it than just pumping oxygen into
> > the solution.
> > 
> > --- In Homebrew_PCBs@yahoogroups.com, "stan4312" <stanman@t...> wrote:
> > 
> >>I'm attempting to bootstrap my first batch of CuCl as I type, so 
> >>this page is fresh off my bookmarks: 
> >>http://pacificsun.ca/~robert/pcb/cucl.htm Pretty good  
> >>page on CuCl. Lots of precision chemistry. 
> >> 
> >>I thought he also had the following seat-of-the-pants advice: if it 
> >>hasn't regenerated overnight, add more acid, but glancing back, I 
> >>see it must have been from somewhere else.   
> >>  
> >>Stan 
> >> 
> >>--- In Homebrew_PCBs@yahoogroups.com, "johnwhitneyfiat"  
> >><johnwhitneyfiat@y...> wrote:  
> >>
> >>>I have been off the group for a while and I'm sure this was  
> >>
> >>covered.    
> >>
> >>>In the direction for making etchant from Hydrogen Peroxide and  
> >>
> >>Muratic   
> >>
> >>>Acid, it says that you can regenerate with a bubbler.  How long  
> >>
> >>does   
> >>
> >>>this take?  I know it will depend on the amount and the area that  
> >>
> >>was   
> >>
> >>>etched, but is there a rule of thumb to make it work. I do have to  
> >>
> >>day   
> >>
> >>>that I make a small bathch and it worked great on a sample board.  
> >>>  
> >>>John Whitney  
> >>>Wis X 1/9
> > 
> > 
> > 
> > 
> > 
> > 
> > Be sure to visit the group home and check for new Links, Files,
and Photos:

> > http://groups.yahoo.com/group/Homebrew_PCBs
> > 
> > If Files or Photos are running short of space, post them here:
> > http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
> > Yahoo! Groups Links
> > 
> > 
> > 
> >  
> > 
> > 
> > 
> >

Dull green is ok, only when it becomes brown is the problem. If you 
dilute a bit of it and it turns bright green then its pretty much 
regenerated. But, this doesn't necessarily mean it'll etch ok.

I here a lot of people on this group that cannot get air re-generated 
cupric chloride to work, simply because they run their solutions too 
damn week. I have done a side by side comparison with fresh full 
strength ferric chloride (sp.gr 1.47), under exact same conditions and 
the cupric chloride (without any H2O2, ever) is only fractionally slower 
(7.5 minutes for FeCl and 9 minutes for CuCl for bubble etching, 35um 
thick copper at 15\ufffdC).

Adam

Phil wrote:

> I may not have all the specifics right - it was about 6 months ago but
> I did add 50 mL of 30% HCl and then aerated.  It stayed a dull green,
> even after a week of aerating.  50 mL of 35% H2O2 brightened it to
> emerald green and I was able to etch a board with it.  Total volume
> was 2L + 100 mL.  I'm sure I was doing something wrong but I just
> wanted to etch boards not fiddle f*rt around with chemicals. 
> 
> I love AP.  Its clear, clean, fast, reliable and very easy to use. 
> Never had to fuss with it.  It just works. 
> 
> I still have 2.1 L of mystery etchant if some one wants it...  heh heh heh
> 
> --- In Homebrew_PCBs@yahoogroups.com, Adam Seychell <a_seychell@y...>
> wrote:
> 
>>Are you sure you added enough acid *before* aerating ? How do you know 
>>what the acid concentration was after aerating ?
>>
>>I find it hard to believe it wouldn't oxidize in that time.
>>I assume you are looking for the transparent green color to
> 
> determine if 
> 
>>the bath regeneration was completed.
>>
>>Adam
>>
>>Phil wrote:
>>
>>>I tried to use CuCl over a period of 4 months.  I was never able to
>>>regenerate it using a bubbler - even left it running for a week once.
>>>  I added more acid but no regen.  However, adding H2O2 made a huge
>>>difference.  My bubbles were fairly small so I think I was getting O2
>>>into it.   I suspect there is more to it than just pumping oxygen into
>>>the solution.
>>>
>>>--- In Homebrew_PCBs@yahoogroups.com, "stan4312" <stanman@t...> wrote:
>>>
>>>
>>>>I'm attempting to bootstrap my first batch of CuCl as I type, so 
>>>>this page is fresh off my bookmarks: 
>>>>http://pacificsun.ca/~robert/pcb/cucl.htm Pretty good  
>>>>page on CuCl. Lots of precision chemistry. 
>>>>
>>>>I thought he also had the following seat-of-the-pants advice: if it 
>>>>hasn't regenerated overnight, add more acid, but glancing back, I 
>>>>see it must have been from somewhere else.   
>>>> 
>>>>Stan 
>>>>
>>>>--- In Homebrew_PCBs@yahoogroups.com, "johnwhitneyfiat"  
>>>><johnwhitneyfiat@y...> wrote:  
>>>>
>>>>
>>>>>I have been off the group for a while and I'm sure this was  
>>>>
>>>>covered.    
>>>>
>>>>
>>>>>In the direction for making etchant from Hydrogen Peroxide and  
>>>>
>>>>Muratic   
>>>>
>>>>
>>>>>Acid, it says that you can regenerate with a bubbler.  How long  
>>>>
>>>>does   
>>>>
>>>>
>>>>>this take?  I know it will depend on the amount and the area that  
>>>>
>>>>was   
>>>>
>>>>
>>>>>etched, but is there a rule of thumb to make it work. I do have to  
>>>>
>>>>day   
>>>>
>>>>
>>>>>that I make a small bathch and it worked great on a sample board.  
>>>>> 
>>>>>John Whitney  
>>>>>Wis X 1/9
>>>
>>>
>>>
>>>
>>>
>>>
>>>Be sure to visit the group home and check for new Links, Files,
> 
> and Photos:
> 
>>>http://groups.yahoo.com/group/Homebrew_PCBs
>>>
>>>If Files or Photos are running short of space, post them here:
>>>http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
>>>Yahoo! Groups Links
>>>
>>>
>>>
>>> 
>>>
>>>
>>>
>>>
> 
> 
> 
> 
> 
> 
> Be sure to visit the group home and check for new Links, Files, and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBs
> 
> If Files or Photos are running short of space, post them here:
> http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
>

I never got anything close to 9 minute etches with cucl.  Probably too
weak.  Dull green was more like olive drab.

By the way, I just added a new heater to my tank and did 6 pcbs.  I
got 5 minute etches on 1 oz, ds boards (2 at a time) with a not so
fresh solution of AP at 120 F.  not bad at all. 

--- In Homebrew_PCBs@yahoogroups.com, Adam Seychell <a_seychell@y...>
wrote:
> Dull green is ok, only when it becomes brown is the problem. If you 
> dilute a bit of it and it turns bright green then its pretty much 
> regenerated. But, this doesn't necessarily mean it'll etch ok.
> 
> I here a lot of people on this group that cannot get air re-generated 
> cupric chloride to work, simply because they run their solutions too 
> damn week. I have done a side by side comparison with fresh full 
> strength ferric chloride (sp.gr 1.47), under exact same conditions and 
> the cupric chloride (without any H2O2, ever) is only fractionally
slower 
> (7.5 minutes for FeCl and 9 minutes for CuCl for bubble etching, 35um 
> thick copper at 15°C).
> 
> Adam
> 
> Phil wrote:
> > I may not have all the specifics right - it was about 6 months ago but
> > I did add 50 mL of 30% HCl and then aerated.  It stayed a dull green,
> > even after a week of aerating.  50 mL of 35% H2O2 brightened it to
> > emerald green and I was able to etch a board with it.  Total volume
> > was 2L + 100 mL.  I'm sure I was doing something wrong but I just
> > wanted to etch boards not fiddle f*rt around with chemicals. 
> > 
> > I love AP.  Its clear, clean, fast, reliable and very easy to use. 
> > Never had to fuss with it.  It just works. 
> > 
> > I still have 2.1 L of mystery etchant if some one wants it...  heh
heh heh
> > 
> > --- In Homebrew_PCBs@yahoogroups.com, Adam Seychell <a_seychell@y...>
> > wrote:
> > 
> >>Are you sure you added enough acid *before* aerating ? How do you
know 
> >>what the acid concentration was after aerating ?
> >>
> >>I find it hard to believe it wouldn't oxidize in that time.
> >>I assume you are looking for the transparent green color to
> > 
> > determine if 
> > 
> >>the bath regeneration was completed.
> >>
> >>Adam
> >>
> >>Phil wrote:
> >>
> >>>I tried to use CuCl over a period of 4 months.  I was never able to
> >>>regenerate it using a bubbler - even left it running for a week once.
> >>>  I added more acid but no regen.  However, adding H2O2 made a huge
> >>>difference.  My bubbles were fairly small so I think I was getting O2
> >>>into it.   I suspect there is more to it than just pumping oxygen
into
> >>>the solution.
> >>>
> >>>--- In Homebrew_PCBs@yahoogroups.com, "stan4312" <stanman@t...>
wrote:
> >>>
> >>>
> >>>>I'm attempting to bootstrap my first batch of CuCl as I type, so 
> >>>>this page is fresh off my bookmarks: 
> >>>>http://pacificsun.ca/~robert/pcb/cucl.htm Pretty good  
> >>>>page on CuCl. Lots of precision chemistry. 
> >>>>
> >>>>I thought he also had the following seat-of-the-pants advice: if it 
> >>>>hasn't regenerated overnight, add more acid, but glancing back, I 
> >>>>see it must have been from somewhere else.   
> >>>> 
> >>>>Stan 
> >>>>
> >>>>--- In Homebrew_PCBs@yahoogroups.com, "johnwhitneyfiat"  
> >>>><johnwhitneyfiat@y...> wrote:  
> >>>>
> >>>>
> >>>>>I have been off the group for a while and I'm sure this was  
> >>>>
> >>>>covered.    
> >>>>
> >>>>
> >>>>>In the direction for making etchant from Hydrogen Peroxide and  
> >>>>
> >>>>Muratic   
> >>>>
> >>>>
> >>>>>Acid, it says that you can regenerate with a bubbler.  How long  
> >>>>
> >>>>does   
> >>>>
> >>>>
> >>>>>this take?  I know it will depend on the amount and the area that  
> >>>>
> >>>>was   
> >>>>
> >>>>
> >>>>>etched, but is there a rule of thumb to make it work. I do have
to  
> >>>>
> >>>>day   
> >>>>
> >>>>
> >>>>>that I make a small bathch and it worked great on a sample board.  
> >>>>> 
> >>>>>John Whitney  
> >>>>>Wis X 1/9
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>Be sure to visit the group home and check for new Links, Files,
> > 
> > and Photos:
> > 
> >>>http://groups.yahoo.com/group/Homebrew_PCBs
> >>>
> >>>If Files or Photos are running short of space, post them here:
> >>>http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
> >>>Yahoo! Groups Links
> >>>
> >>>
> >>>
> >>> 
> >>>
> >>>
> >>>
> >>>
> > 
> > 
> > 
> > 
> > 
> > 
> > Be sure to visit the group home and check for new Links, Files,
and Photos:

> > http://groups.yahoo.com/group/Homebrew_PCBs
> > 
> > If Files or Photos are running short of space, post them here:
> > http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
> > Yahoo! Groups Links
> > 
> > 
> > 
> >  
> > 
> > 
> >

----- Original Message ----- 

From: "Phil" <phil1960us@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Tuesday, September 06, 2005 1:11 AM
Subject: [Homebrew_PCBs] Re: Regenerating CuCl


>I tried to use CuCl over a period of 4 months.  I was never able to
> regenerate it using a bubbler - even left it running for a week once.
>  I added more acid but no regen.  However, adding H2O2 made a huge
> difference.  My bubbles were fairly small so I think I was getting O2
> into it.   I suspect there is more to it than just pumping oxygen into
> the solution.

I think the reaction needs some energy for it to to take place.

Leon
--
Leon Heller, G1HSM
leon.heller@...
http://www.geocities.com/leon_heller


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On Tue, 06 Sep 2005 05:46:55 +0200, Adam Seychell  
<a_seychell@...> wrote:

> Dull green is ok, only when it becomes brown is the problem. If you
> dilute a bit of it and it turns bright green then its pretty much
> regenerated. But, this doesn't necessarily mean it'll etch ok.
> I here a lot of people on this group that cannot get air re-generated
> cupric chloride to work, simply because they run their solutions too
> damn week. I have done a side by side comparison with fresh full
> strength ferric chloride (sp.gr 1.47), under exact same conditions and
> the cupric chloride (without any H2O2, ever) is only fractionally slower
> (7.5 minutes for FeCl and 9 minutes for CuCl for bubble etching, 35um
> thick copper at 15\ufffdC).
> Adam


i agree, you need a strong solution to do air-regeneration.
For H2O2, anything works, but as it grows denser the time between H2O2  
applications can be extended, wile at the beginning with a very weak  
solution you need to add it each time you etch, at least. Density, and a  
enough volume, are the key to air regeneration i think.


ST

Stefan Trethan wrote:
> On Tue, 06 Sep 2005 05:46:55 +0200, Adam Seychell  
> <a_seychell@...> wrote:
> 
> 
>>Dull green is ok, only when it becomes brown is the problem. If you
>>dilute a bit of it and it turns bright green then its pretty much
>>regenerated. But, this doesn't necessarily mean it'll etch ok.
>>I here a lot of people on this group that cannot get air re-generated
>>cupric chloride to work, simply because they run their solutions too
>>damn week. I have done a side by side comparison with fresh full
>>strength ferric chloride (sp.gr 1.47), under exact same conditions and
>>the cupric chloride (without any H2O2, ever) is only fractionally slower
>>(7.5 minutes for FeCl and 9 minutes for CuCl for bubble etching, 35um
>>thick copper at 15\ufffdC).
>>Adam
> 
> 
> 
> i agree, you need a strong solution to do air-regeneration.
> For H2O2, anything works, but as it grows denser the time between H2O2  
> applications can be extended, wile at the beginning with a very weak  
> solution you need to add it each time you etch, at least. Density, and a  
> enough volume, are the key to air regeneration i think.
> 
> 

Yes, the more copper the faster, and the more acid the faster. You are 
only limited by solubility, and HCl fuming. A good compromise I found is 
to run at sp.gr 1.38~1.45 and acid at 2~3 Molar. This will be almost 
fast as fresh undiluted ferric chloride. Unfortunately you have to 
invest in a hydrometer, and perform titration (using a 1 ml syringe) to 
determine acid concentration about every 20~30 PCBs or so etched.


Adam

On Tue, 06 Sep 2005 08:52:20 +0200, Phil <phil1960us@...> wrote:

> By the way, I just added a new heater to my tank and did 6 pcbs.  I
> got 5 minute etches on 1 oz, ds boards (2 at a time) with a not so
> fresh solution of AP at 120 F.  not bad at all.


yea, but still, what do you do with it when the AP is spent?

ST

Phil wrote:
> I never got anything close to 9 minute etches with cucl.  Probably too
> weak.  Dull green was more like olive drab.

If the sun is shining outside, then put it in a plastic tray and let it 
evaporate for a few days. Thats what I did.
Unfortunately you'll have to invest money in a hydrometer if you ever 
want to use CuCl again, otherwise your poking in the dark.


> By the way, I just added a new heater to my tank and did 6 pcbs.  I
> got 5 minute etches on 1 oz, ds boards (2 at a time) with a not so
> fresh solution of AP at 120 F.  not bad at all. 

I admit, its nice to see the PCB being etched when using AP. But I don't 
like fooling around with heaters/heating, so thats why I prefer a room 
temperature etchant. If I had to included the time to heat my tank to 
temperature, then it will take me a *lot* longer to etch a board.

On Tue, 06 Sep 2005 12:58:12 +0200, Adam Seychell  
<a_seychell@...> wrote:

>
> If the sun is shining outside, then put it in a plastic tray and let it
> evaporate for a few days. Thats what I did.
> Unfortunately you'll have to invest money in a hydrometer if you ever
> want to use CuCl again, otherwise your poking in the dark.
>


You can get a hydrometer for that range in the car parts store.
Simply get the meter for battery acid.
They sell the classic floating hydrometer variety (with hydrometer  
pipette) for a whopping eur1 or so.
There's also the "rotating indicator" version, but it is much less  
accurate.

The resolution isn't as good as with a lab meter, but it's plenty for CuCl.

Since i use H2O2 i don't really use is though...

ST

--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@g...> wrote:
> On Tue, 06 Sep 2005 08:52:20 +0200, Phil <phil1960us@y...> wrote:
> 
> > By the way, I just added a new heater to my tank and did 6 pcbs.  I
> > got 5 minute etches on 1 oz, ds boards (2 at a time) with a not so
> > fresh solution of AP at 120 F.  not bad at all.
> 
> 
> yea, but still, what do you do with it when the AP is spent?
> 
> ST

Put it in a jar, place jar on hotplate on low and let it evaporate
down to a pretty blue mass of crystals.  Dump crystals into a storage
jar and then take it to a household/toxic waste event that happens
every 3 months or so.  I've only done this once - it takes about 2
years to fill the storage jar at the rate I'm going.

To your point that disposal is an issue that should be factored in -
yes, I agree it's very attractive to never dispose.  If I were doing
hundreds of board year, I would have a different point of view.  Right
now, it is still less work for me to properly dispose AP than to
regenerate CuCl.

--- In Homebrew_PCBs@yahoogroups.com, Adam Seychell <a_seychell@y...>
wrote:
...
> I admit, its nice to see the PCB being etched when using AP. But I
don't 
> like fooling around with heaters/heating, so thats why I prefer a room 
> temperature etchant. If I had to included the time to heat my tank to 
> temperature, then it will take me a *lot* longer to etch a board.

My tank has a 1 L capacity so it doesn't take very long to heat up
with a hacked aquarium heater.  I'd estimate 20-30 mins depending on
ambient temp.  For me, fiddle f*rting with a heater and pump is
preferable to fiddle f*rting with chemicals.  ;)  For others it may be
the other way around.

It's not wasted time, though.  I set up the tank and heater, do the
toner transfer and prep the board for etch.   By then the tank is just
right and away I go.  Usually, I batch up multiple boards for a single
etch session so its even more efficient.

What it boils down is that there are lots of ways of getting the same
result with relatively the same level of efficiency.

One other thing I haven't seen discussed is the effect of etching
speed on pinholing with TT.  I think (though have no way to prove it)
that pinholing is proportional to etch time.  It seems to work out
that way.  The last batch (the one I mentioned) had almost no
pinholing at all.  I was very pleased with the result.  Even under the
microscope, it looked suprisingly clean for TT.

Phil wrote:

> What it boils down is that there are lots of ways of getting the same
> result with relatively the same level of efficiency.

yep, and each of us has a preferred choice on what system to use.


> One other thing I haven't seen discussed is the effect of etching
> speed on pinholing with TT.  I think (though have no way to prove it)
> that pinholing is proportional to etch time.  It seems to work out
> that way.  The last batch (the one I mentioned) had almost no
> pinholing at all.  I was very pleased with the result.  Even under the
> microscope, it looked suprisingly clean for TT.   
> 

As I understand the "pinholes" are just small voids in the toner coating 
the copper. How can this effect etching rate , which is governed by a 
chemical reaction ?

--- In Homebrew_PCBs@yahoogroups.com, Adam Seychell <a_seychell@y...>
wrote:
> Phil wrote:
...
> > One other thing I haven't seen discussed is the effect of etching
> > speed on pinholing with TT.  I think (though have no way to prove it)
> > that pinholing is proportional to etch time.  It seems to work out
> > that way.  The last batch (the one I mentioned) had almost no
> > pinholing at all.  I was very pleased with the result.  Even under the
> > microscope, it looked suprisingly clean for TT.   
> > 
> 
> As I understand the "pinholes" are just small voids in the toner
coating 
> the copper. How can this effect etching rate , which is governed by a 
> chemical reaction ?

The other way around - etch time affects pinholing.  Shorter time,
less pinholing.  At least that's what I have noticed.  

It may have to do with the fact that I suplimented, as usual, the
toner resist on the larger areas with an etch resist pen.  perhaps it
is this resist that breaks down in the etchant and the faster the
etching time, the less breakdown occurs.   However, even the areas
that i didn't supliment look amazingly good, too. 

What ever the reason, I am very happy with the latest results.

Phil

--- In Homebrew_PCBs@yahoogroups.com, "Phil" <phil1960us@y...> wrote:
> --- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
> <stefan_trethan@g...> wrote:
> > On Tue, 06 Sep 2005 08:52:20 +0200, Phil <phil1960us@y...> wrote:
> > 
> > > By the way, I just added a new heater to my tank and did 6 pcbs.  I
> > > got 5 minute etches on 1 oz, ds boards (2 at a time) with a not so
> > > fresh solution of AP at 120 F.  not bad at all.
> > 
> > 
> > yea, but still, what do you do with it when the AP is spent?
> > 
> > ST
> 
> Put it in a jar, place jar on hotplate on low and let it evaporate
> down to a pretty blue mass of crystals.  Dump crystals into a storage
> jar and then take it to a household/toxic waste event that happens
> every 3 months or so.  I've only done this once - it takes about 2
> years to fill the storage jar at the rate I'm going.
> 
> To your point that disposal is an issue that should be factored in -
> yes, I agree it's very attractive to never dispose.  If I were doing
> hundreds of board year, I would have a different point of view.  Right
> now, it is still less work for me to properly dispose AP than to
> regenerate CuCl.

Since the blue crystals are mostly Copper Sulfate, another option 
might be to electroplate out the Copper.  Of course, something
will have to be dissolved into the solution to bind to the sulfate
ions, but that can be a metal which isn't as toxic as Copper (Iron?).

I'll leave further discussion of this up to the chemists.

For additional speculation, would it be possible to electroplate
out the Copper from used Ferric Chloride solution (e.g., Copper
Chloride), and replace it with Iron, thus possibly regenerating the
Ferric Chloride?

Dave

On Wed, 07 Sep 2005 20:12:35 +0200, Dave <wa4qal@...> wrote:

>
> For additional speculation, would it be possible to electroplate
> out the Copper from used Ferric Chloride solution (e.g., Copper
> Chloride), and replace it with Iron, thus possibly regenerating the
> Ferric Chloride?
> Dave


i have heard about that before, i think it works...

ST

Dave wrote:

> 
> 
> Since the blue crystals are mostly Copper Sulfate, another option 
> might be to electroplate out the Copper.  Of course, something
> will have to be dissolved into the solution to bind to the sulfate
> ions, but that can be a metal which isn't as toxic as Copper (Iron?).
> 
> I'll leave further discussion of this up to the chemists.
> 
> For additional speculation, would it be possible to electroplate
> out the Copper from used Ferric Chloride solution (e.g., Copper
> Chloride), and replace it with Iron, thus possibly regenerating the
> Ferric Chloride?
> 
> Dave
I think people have tried this . I don't think its that easy. Plating 
copper out is one thing, but converting the solution back to its 
original state is another, Somehow Fe(+2) must go back to Fe(+3).
Often these reclaiming processes are only worthwhile on large scale.

As for sulfate based etchant (ammonium persulfate, sodium persulfate, 
peroxide-sulfuric), yes, possible. For copper refining they use lead 
sheet for anode material (positive, where oxygen gas evolves) and copper 
sheet for cathode (negative, where copper metal deposits).
Again not worth the effort for a few liters of solution.

There is one chemistry that is cable of recycling and etching 
simultaneous, see http://www.elo-chem.com/index.php?subid=2
It is alkaline ammonium copper sulfate. Needs heating, and smells.

A page about a hombrew spray etcher was brought to my attention.
Note that i do not intend to attempt one again any time soon, but it  
surely is highly interesting.

<http://www.modelbouw.gompy.net/etsbak/etsbak.htm>

Thanks Simon for pointing the page out to me, and also for providing a  
translation which i am allowed to use (see below).




Translation based on Simons, added to and edited by me:

Klik op de foto's om deze te vergroten.
Click the pictures to enlarge.

   Dopje boveaan de sproeipijp met lasdraadje voor bevestiging aan  
ventielslang
   Cap on the spraypipe with welding rod for attaching a hose.

   Sproeipijp gemaakt van 3/4 " PVC-buis met iedere 5 mm een gaat van 1 1/5  
mm
   spraypipe made of 3/4" PVC tube with a 1.5mm hole every 5mm

   Motorhuis PVC-pijp 32 mm met dop
   motor housing 32mm PVC pipe and cap

   Motor in huis
   motor in housing

   Ventielslang welke aan de sproeipijp komt vastlijmen met seconde lijm  
aan as
   Hose (valve hose?, see pic, rubber..) which is attached to spraypipe,  
glue with cyano glue.

   Stukje PVC in dopje van sproeibuis
   piece of PVC (welding rod) in cap of spraypipe

   Sproeibuis aan motor met ventielslang
   spraypipe attached to motor with hose

   Nogmaals
   again

   Iets dichterbij maar wat onscherp
   closeup but a bit blurry

   Sproeipijp hangend onder de deksel in dop 32 mm waarvan deel is  
uitgevijld.
   spraypipe hanging under the lid in cap (32mm) of which it fills  
partially. (i reckon it means there's some space)

   Deksel open
   lid open

   We draaien het nog koude draadje rond de pijp
   winding the welding rod 'round the pipe

   Vervolgens gaan we het verwarmen met de verfstripper
   afterwards it is heated with the hot air gun

   Even laten afkoelen
   letting it cool

   Draadje is nu spiraaltje geworden
   welding rod has now become a spiral

   Van dichtbij
   closeup

   Spiraal in pijp draaien !! niet drukken
   turn spiral into pipe, don't compress it!!

   Afknippen op ~4 mm zodat het uitsteekt
   cut it leaving 4mm protruding

   Spiraal zit nu in de pijp
   spiral is now in the pipe

Hieronder nog wat foto's van de complete etsbak
Here some pictures of the complete etcher



Deze bak is met twee motoren uitgevoerd zodat er ook dubbelzijdige printen  
in 1x gemaakt kunnen worden.
This etcher has two motors to allow etching doublesided boards in one go.

In het midden wel iets maken zodat de print rechtop blijft staan.
in the middle the PCB is helt upright and in place.



The spiral inside the spray tube is made of 3mm round PVC welding rod.
This spiral can be made by winding the rod around a 8mm copper tube, and  
either heating the rod while winding or heating it after it is fully wound  
with a hot air gun and letting it cool.

The sprayer tube is suspended in the etcher on a piece of hose of about  
5cm length, the idea behind this is that the sprayer tube can swing. If it  
were fixed you would see spray patterns on the PCB. When the tube can  
swing around, while the patters will still be there they will move around  
so have no effect.

-----

In the bottom plate is a hole of about 6 to 8 cm so that the spray-tube  
will not swing excesively when the motor turns.
It also serves as stand for the boards.


recommended is that the print is set a little higher, so that it does not  
stand in the etching fluid all the time.

Everything is glued with HARD-PVC glue of Bison

-----

The motor can be placed in a section of PVC tube with end cap. Every motor  
can  be used as long as it fits in the tube.
Do not use any mains voltage motors. This is dangerous with regard to the  
etching fluid.

With an adjustable DC power supply the revs of the motor can be adjusted  
so that the etching fluid does not spray out of the container.


Well, hope that is of help to someone, please put it in the links section  
i'm way too tired to face yahoo.
Sorry about my bad translation but my dutch is from a few months tv  
subtitles only....


ST