Homebrew PCBs

I've used up my Ammonium Perchlorate so I got HCl and H2O2.  I
understand that I need to use a bubbler to regenerate the etchant and
have seen references to letting it run a long time.  How long should I
expect - hours? days?  

Currently, my bubbler is a piece of vinyl tubing that I drilled #70
holes in,  This produces somewhat large bubbles.  I'll try it but do
those of you that use CuCl recommend something different, like an
aquarium airstone?

I'll be using about 3 Liters and doing a number of double sided boards
in the 10x15 CM size range, 1 oz copper.  I have an aquarium heater
that will bring the temp up to about 100F (about 38C) if that matters.

Thanks
Phil

On Sun, 19 Sep 2004 21:17:25 -0000, Phil <phil1960us@...> wrote:

> I've used up my Ammonium Perchlorate so I got HCl and H2O2.  I
> understand that I need to use a bubbler to regenerate the etchant and
> have seen references to letting it run a long time.  How long should I
> expect - hours? days?
>

You need no bubbler with H2O2.
The H2O2 is the "quick" version to get the oxygen in.
The slow and nasty fumes version is to keep it bubbling for hours,
then it takes the oxygen from the air.
So you see, no bubbler required. You can keep it and see if it speeds up
etching because of the agitation.


> Currently, my bubbler is a piece of vinyl tubing that I drilled #70
> holes in,  This produces somewhat large bubbles.  I'll try it but do
> those of you that use CuCl recommend something different, like an
> aquarium airstone?

As said if you use H2O2 for regeneration it isn't needed.
The big bubbles will be fine for agitation though.


>
> I'll be using about 3 Liters and doing a number of double sided boards
> in the 10x15 CM size range, 1 oz copper.  I have an aquarium heater
> that will bring the temp up to about 100F (about 38C) if that matters.

NO DO NOT USE A HEATER!!!!!
The boiling point of HCl is VERY low, and even below the fumes increase
dramatically with heat. I experimented with that and don't want to repeat
the experience. Use a bubbler or mecanical movement/oscillation of the  
board.
I'm still wondering if high frequency vibrations or even ultrasonic would  
be a
good idea.



Quick guide for getting started:
Dilute the HCl to 10% or so. Put the board in and add a small amount of  
H2O2.
You should see a reaction on the board and the etchant coloring slowly.
tiny bubbles are ok, but bigger, fast rising bubbles indicate too much  
H2O2.
You must avoid that condition.

The H2O2 needs replenishing when the etchant turns from bright green to  
dark green.
The HCl will need replenishing when you see blue "sludge" on the board and  
the
etchant also gets slightly bluish. It is better to measure the HCl  
molarity than
just using the blue sludge as a sign. see links section for a simple mehod
using two eyedroppers.


At the beginning you will need H2O2 each time. After enough boards there
is enough copper in to etch with CuCl only. Then you only regenerate with  
H2O2
when the color turns. (note: H2O2 is lost if there is nothing to  
regenerate left,
so don't add too much).


If you observe the things described it is a very good and cheap etchant.

Possible problems:
resist attacked (especially touch-up markers): reduce HCl, measure molarity

long etch times: not enough Cu solved yet, not enough H2O2.

etching stops suddenly but etchant is bright green, H2O2 doesn't do  
anything:
HCl used up completely, add some, see the blue sludge on the board.

I hope i covered the most important things.
I really should write that up some day....


ST

P.S.: We MUST RESEARCH effects of vibrating the board and using ultrasonic  
sound.
Could please someone use a ultrasonic cleaner (with water) and see if the  
toner
comes off?

Thanks Stefan.  This is the first time I've heard not to use a heater.
 I recall reading somewhere to heat the CuCl solution so its a little
confusing.  I looked for the page that said that but couldn't find it
since I didn't bookmark it.  It might have been one that talked about
using CuCl salt, though.

I guess technically, this is HCl etching at first and then CuCl.

A How-To for HCl and H2O2 etching would be very useful.

Phil

--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@g...> wrote:
...
> 
> NO DO NOT USE A HEATER!!!!!
> The boiling point of HCl is VERY low, and even below the fumes increase
> dramatically with heat. I experimented with that and don't want to
repeat
> the experience. Use a bubbler or mecanical movement/oscillation of the  
> board.
> I'm still wondering if high frequency vibrations or even ultrasonic
would  
> be a
> good idea.

On Sun, 19 Sep 2004 22:53:27 -0000, Phil <phil1960us@...> wrote:

>
> Thanks Stefan.  This is the first time I've heard not to use a heater.
>  I recall reading somewhere to heat the CuCl solution so its a little
> confusing.  I looked for the page that said that but couldn't find it
> since I didn't bookmark it.  It might have been one that talked about
> using CuCl salt, though.
>
> I guess technically, this is HCl etching at first and then CuCl.
>
> A How-To for HCl and H2O2 etching would be very useful.
>
> Phil
>

you are right there, first Cl only, then CuCl.
the heating is no good. only a little is possible and that isn't helping  
much.
HCl vapor is bad business, very bad.

Tomorrow i will try using pool-supply Clorine to regenerate. curious and
have a pool. 'night.

ST

Hi all,

i was thinking the whole HCl H2O2 business is just for
getting Cl into the etchant to attach to the Cu, right?

So i thought maybe there are other ways to get this done.

Pool clorine.

There are two types, anorganic and organic.

the organic version is for long-term, it is cyanuric cloride.
(it is a acid).
I had that so i put a few shavings of a tablet in a small amount of used  
CuCl.
No regeneration could be observed but there was severe gassing and clorine  
gas smell.
I diluted that and disposed of it. (was only a tiny sample).

The anorgainc clorine used in pools is calcium hypochlorite.
it is used to quickly kill everything if the water is already half green.
It is not used for long durations (it doesn't stay in the water).
I'm not sure if i have that variety somewhere to try. I would guess
it is potentially better useful for CuCl etcants, because using another  
acid seems
not the solution to simplify the process.


I do not have the chemistry knoweledge to find out what is going on there,
but i'd like to know what you think of using other forms of clorine than  
HCl
as clorine source.

Could calcium hypoclorite potentially work? could sodium hypoclorite  
(bleach)
potentially work? Why not?

Could someone summarize the chemical reactions in CuCl / HCl / H2O2  
etchants
in simple terms, so that i might understand it too?

Well, thanks a lot.

ST

at tha classic CuCl page:

<http://users.rcn.com/rexa/Projects/CuCl_ech.html>

I found

> It should be noted that in commercial high-volume applications  
> regeneration of cupric > chloride by air oxidation is too slow to be  
> completely practical, so faster methodsare used to reverse the reaction,  
> such as direct chlorination, electrolytic action, or > intense oxidation  
> with hydrogen peroxide or sodium hypochlorite.

see, sodium hypochlorite! that's bleach, well, one kinds of bleach.
I wonder if calcium hypochlorite does the same.


ST

I'm going back 15 years or so, when cupric chloride etching was becoming a 
common system.  I don't remember anyone replenishing their etchants with 
anything other than hydrogen peroxide and hydrochloric acid.  These are 
cheap chemicals and the waste can be easily converted to copper oxide 
(hydroxide) and sent off for reclaimation.  A production etch line was 4 ft 
wide and ran 4 to 6 ft per minute with 18 x 24" boards spaced 2" apart. 
That's a lot of copper going into solution so the etchant had to be 
replenished at a high rate.  For the hobbist who etches a board once a week, 
simply bubbling air through CuCl etchant and adding a bit of HCl is the 
easiest method to regenerate the etchant.  If you want to run bigger batches 
of boards, get a bigger sump of etchant and let it regenerate for a few 
days.  One of the links on the list suggested using a picnic cooler as an 
etch tank - IMHO a good idea.

The addition of any additional salt content, either sodium or calcium, can 
be a problem.  I'd have to dig way back to get the details, but in general, 
its a good policy to avoid adding stuff to a chemical system if it can be 
avoided.  There are side reactions that can be really bad news - like 
hydrogen gas generation that can cause big BOOMS.

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

From: "Stefan Trethan" <stefan_trethan@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Monday, September 20, 2004 4:03 AM
Subject: [Homebrew_PCBs] CuCl pool stuff


> at tha classic CuCl page:
>
> <http://users.rcn.com/rexa/Projects/CuCl_ech.html>
>
> I found
>
>> It should be noted that in commercial high-volume applications
>> regeneration of cupric > chloride by air oxidation is too slow to be
>> completely practical, so faster methodsare used to reverse the reaction,
>> such as direct chlorination, electrolytic action, or > intense oxidation
>> with hydrogen peroxide or sodium hypochlorite.
>
> see, sodium hypochlorite! that's bleach, well, one kinds of bleach.
> I wonder if calcium hypochlorite does the same.
>
>
> ST
>
>
>
>
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
> Yahoo! Groups Links
>
>
>
>
>
>

Earl T. Hackett, Jr. wrote:
> 
> The addition of any additional salt content, either sodium or calcium, can 
> be a problem.  I'd have to dig way back to get the details, but in general, 
> its a good policy to avoid adding stuff to a chemical system if it can be 
> avoided.  There are side reactions that can be really bad news - like 
> hydrogen gas generation that can cause big BOOMS.
> 

I agree. Its best to keep the chemistry simple, and air is not something 
that you can add too much of. I found that air regeneration of CuCl 
depends greatly on bubble size. The finer the bubbles the faster the 
regeneration. If the bubbles are extra fine then the regeneration rate 
is fast enough to cause noticeable heating. A 1 or 2 inch layer of 
foaming on top of the etchant makes it work very fast , in one or two 
hours or so compared to several days.  If anyone is getting problems 
with HCl fumes then they have too much acid. Air generated CuCl etches 
ok with almost zero acid. The important thing is to keep the tank 
relatively sealed because of mist produced from bursting bubbles will 
eventually cover everything in the surrounding area with microscopic 
droplets of etchant.