Homebrew PCBs

I used some phosphoric acid and 3% hydrogen peroxide to etch some 
boards. I warmed it the a hot water bath and it produced a green 
tint to the solution after etching and did an excellent job. Has 
anyone had experience with this combination???

On Tue, 06 Apr 2004 14:33:38 -0000, dsv1486 <darrell.vandenberg@...> 
wrote:

> I used some phosphoric acid and 3% hydrogen peroxide to etch some
> boards. I warmed it the a hot water bath and it produced a green
> tint to the solution after etching and did an excellent job. Has
> anyone had experience with this combination???

interesting...

would be interesting to compare it to the hydrocloric and sulphuric 
etchants...

What about fumes? are there any? the clor smell is not especially nice..
what about maintaining it in an etching state?
what happens if there is too much copper and you cool it?


i know it is added in some drink, like cola..., what does it cost?

ST

The biggest problem with phosphoric acid is it's low vapor pressure at room
temperature,i.e. when heated it evaporates, vaporizes very readily. (faster
than water)   This result in more irritating fumes than most other etches,
and is probably the reason very few people use it as such.



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

From: "dsv1486" <darrell.vandenberg@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Tuesday, April 06, 2004 10:33 AM
Subject: [Homebrew_PCBs] Phosphoric Acid Etch


> I used some phosphoric acid and 3% hydrogen peroxide to etch some
> boards.

On Wed, 7 Apr 2004 08:29:56 -0400, Jeremy Taylor <jt@...> wrote:

> The biggest problem with phosphoric acid is it's low vapor pressure at 
> room
> temperature,i.e. when heated it evaporates, vaporizes very readily. 
> (faster
> than water)   This result in more irritating fumes than most other 
> etches,
> and is probably the reason very few people use it as such.
>
>

nothing for me then..

ST

It was very inexpensive as I purchased it from a hydroponics shop 
that was closing. It was $5 for 5 gallons of 89% concentration. I 
did not notice the evaporation issue and while etching I did not 
notice any smell. Does anyone know what chemical reaction is going 
on?? I think it is making copper phosphate. I will try another test 
and let everyone know how it went.

It was very inexpensive as I purchased it from a hydroponics shop 
that was closing. It was $5 for 5 gallons of 89% concentration. I 
did not notice the evaporation issue and while etching I did not 
notice any smell. Does anyone know what chemical reaction is going 
on?? I think it is making copper phosphate. I will try another test 
and let everyone know how it went.

http://www.efma.org/publications/guidance/section16.asp

"Release of phosphorus oxides (toxic) from thermal decomposition and of
hydrogen from reaction with metals."

" 10.3 Materials to avoid
Bases, aluminium, copper, mild steel, brass, bronze"

It is likely that The ph control product used in hydroponics does contain a
bit of sulfuric. But its seems that the phosphorus does react independently
with the copper.

This is probably way more in-depth than you want but
http://dragon.klte.hu/~gasparv/reprints/jpc_chaos_control.pdf

JT
http://www.soundclick.com/jtsound
----- Original Message ----- 

From: "dsv1486" <darrell.vandenberg@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Wednesday, April 07, 2004 12:46 PM
Subject: [Homebrew_PCBs] Re: Phosphoric Acid Etch


> It was very inexpensive as I purchased it from a hydroponics shop
> that was closing. It was $5 for 5 gallons of 89% concentration. I
> did not notice the evaporation issue and while etching I did not
> notice any smell. Does anyone know what chemical reaction is going
> on?? I think it is making copper phosphate. I will try another test
> and let everyone know how it went.
>
>
>
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
> Yahoo! Groups Links
>
>
>
>
>

In a message dated 4/7/2004 7:26:25 AM Central Standard Time, 
stefan_trethan@... writes:
i know it is added in some drink, like cola

Only a FRACTION of 1% ! ! !


[Non-text portions of this message have been removed]

Jeremy Taylor wrote:
> The biggest problem with phosphoric acid is it's low vapor pressure at room
> temperature,i.e. when heated it evaporates, vaporizes very readily. (faster
> than water)   This result in more irritating fumes than most other etches,
> and is probably the reason very few people use it as such.
> 

I always thought a substance of low vapor pressure would 
evaporate less than a substance of high vapor pressure. I can 
tell you concentrated phosphoric acid (80% wt) at room temp is 
orderless, even when taking a sniff from the bottle. The stuff is 
concentrated by evaporation so I don't know it can evaporate 
faster than water. Its also not extremely dangerous to spill on 
you. As a comparison I would say NaOH is a lot more corrosive you 
your skin than con. H3P04. It takes a few minutes to start 
feeling the pain, and I have sensitive skin.


Adam.

Jeremy Taylor wrote:
> The biggest problem with phosphoric acid is it's low vapor pressure at room
> temperature,i.e. when heated it evaporates, vaporizes very readily. (faster
> than water)   This result in more irritating fumes than most other etches,
> and is probably the reason very few people use it as such.
> 

I always thought a substance of low vapor pressure would 
evaporate less than a substance of high vapor pressure. I can 
tell you concentrated phosphoric acid (80% wt) at room temp is 
orderless, even when taking a sniff from the bottle. The stuff is 
concentrated by evaporation so I don't know it can evaporate 
faster than water. Its also not extremely dangerous to spill on 
you. As a comparison I would say NaOH is a lot more corrosive you 
your skin than con. H3P04. It takes a few minutes to start 
feeling the pain, and I have sensitive skin.


Adam.

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

From: "Stefan Trethan" <stefan_trethan@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Wednesday, April 07, 2004 12:49 PM
Subject: Re: [Homebrew_PCBs] Phosphoric Acid Etch


> On Tue, 06 Apr 2004 14:33:38 -0000, dsv1486 <darrell.vandenberg@...>
> wrote:
>
> > I used some phosphoric acid and 3% hydrogen peroxide to etch some
> > boards. I warmed it the a hot water bath and it produced a green
> > tint to the solution after etching and did an excellent job. Has
> > anyone had experience with this combination???
>
> interesting...
>
> would be interesting to compare it to the hydrocloric and sulphuric
> etchants...
>
> What about fumes? are there any? the clor smell is not especially nice..
> what about maintaining it in an etching state?
> what happens if there is too much copper and you cool it?
>
>
> i know it is added in some drink, like cola..., what does it cost?

It's also used in rust removers.

Leon