Homebrew PCBs

i tried for the first time to use ammonium persulphate instead of 
ferric chloride. i built a nice etcing tank with a heater at about 
50 degree celcius and an air pump. i used about 1kg of ammonium 
persulphate with 2 litre of water (at the first place i used much 
less ammonium persulphate, but when i saw nothing is happening i put 
more).
help!!!!!!!!!!!!! i need it very urgent!
thanks a lot,
mumin.

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

From: "mumin55555" <mumin55555@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Monday, April 12, 2004 12:57 PM
Subject: [Homebrew_PCBs] help!!! my ammonium persulphate doesent
work!!!!!!!!!!


> i tried for the first time to use ammonium persulphate instead of
> ferric chloride. i built a nice etcing tank with a heater at about
> 50 degree celcius and an air pump. i used about 1kg of ammonium
> persulphate with 2 litre of water (at the first place i used much
> less ammonium persulphate, but when i saw nothing is happening i put

Many years ago when I used ammonium persulpahate I added a small amount of
salt (NaCl) to speed it up. Lots of nasty chlorine was given off, but it was
very fast. Mercuric chloride was used commercially instead of salt- I think
it acted as a catalyst - but it's very toxic and difficult to get hold of.

Leon

mumin55555 wrote:
> i tried for the first time to use ammonium persulphate instead of
> ferric chloride. i built a nice etcing tank with a heater at about
> 50 degree celcius and an air pump. i used about 1kg of ammonium
> persulphate with 2 litre of water (at the first place i used much
> less ammonium persulphate, but when i saw nothing is happening i put
> more).
> help!!!!!!!!!!!!! i need it very urgent!
> thanks a lot,
> mumin.

I get good results with ammonium persulphate, I use 1 part crystals to 5
parts hot water (75 deg C) as per the directions on the bottle I have. Your
agitation and heating should help speed the etching. Don't make it too
strong. Give it some time, don't just start throwing in more crystals.

Hope that helps
Dean

the container I have says 250 g/Liter H20 so you should have used 
500g.  I'd expect you to have a strong etching action with that temp 
and concentration.

Phil

--- In Homebrew_PCBs@yahoogroups.com, "Dean Thompson" <deanthom@d...> 
wrote:
> mumin55555 wrote:
> > i tried for the first time to use ammonium persulphate instead of
> > ferric chloride. i built a nice etcing tank with a heater at about
> > 50 degree celcius and an air pump. i used about 1kg of ammonium
> > persulphate with 2 litre of water (at the first place i used much
> > less ammonium persulphate, but when i saw nothing is happening i 
put
> > more).
> > help!!!!!!!!!!!!! i need it very urgent!
> > thanks a lot,
> > mumin.
> 
> I get good results with ammonium persulphate, I use 1 part crystals 
to 5
> parts hot water (75 deg C) as per the directions on the bottle I 
have. Your
> agitation and heating should help speed the etching. Don't make it 
too
> strong. Give it some time, don't just start throwing in more 
crystals.

> 
> Hope that helps
> Dean

Can you describe more of what you are seeing ?
Is the copper changing appearance ? Copper that has been rubbed down with a 
mild abrasive like Scotch Brite looks more like a reddish copper color with 
fine scratches visible on the surface. When immersed in the etchant the 
copper should turn pink color in the first 10~30 seconds (due to 
microscopic roughening) and after a minute the fine surface scratches 
should disappear. Are you seeing this ? If not then I suspect you don't 
have ammonium persulfate or your copper is heavily contaminated on the 
surface thus protecting it from the etchant. Surface residue is common with 
negative dryfilm photoresists that have been on the copper for a long time 
(>6 months).

Your too strong, as other has said the normal makeup of (NH4)2S2O8 is 
approximately 200 g/L.

Adam

mumin55555 wrote:

> i tried for the first time to use ammonium persulphate instead of 
> ferric chloride. i built a nice etcing tank with a heater at about 
> 50 degree celcius and an air pump. i used about 1kg of ammonium 
> persulphate with 2 litre of water (at the first place i used much 
> less ammonium persulphate, but when i saw nothing is happening i put 
> more).
> help!!!!!!!!!!!!! i need it very urgent!
> thanks a lot,
> mumin.
> 
> 
> 
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs 
> Yahoo! Groups Links
> 
> 
> 
>  
>