Homebrew PCBs

I wonder if the amount of etch solution could influence the result -- as I 
would like to use a smaller plastic container with a transparent lid (less 
etchant, easier heated and less mess).

To put it in another way:
Would, say, 2 dl of etchant solution work as efficiently as 1 liter (10 dl)?

[that would be 7 and 34 ounces (2 pints) for all non-metrics]

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Hermod Pedersen, HCDX Web Editor
<http://www.hard-core-dx.com/>

On Sun, 24 Apr 2005 23:56:15 +0200, Hermod Pedersen  
<hermod.pedersen@...> wrote:

>
> I wonder if the amount of etch solution could influence the result -- as  
> I
> would like to use a smaller plastic container with a transparent lid  
> (less
> etchant, easier heated and less mess).
> To put it in another way:
> Would, say, 2 dl of etchant solution work as efficiently as 1 liter (10  
> dl)?
> [that would be 7 and 34 ounces (2 pints) for all non-metrics]


Depends on etching solution (which one) and board size, copper thickness,  
area, ...
IF there is not enough etchant, so that it all gets almost used before the  
board is ready, you will see a significant change in etching time. OTOH i  
used to etch with something like 3-4mm etchant height over the board in a  
container not much bigger than the board with CuCl, but need to regenerate  
several times during etch.

It appears to me that if you have a etchant that can not be regenerated,  
and doesn't keep, it is best to use just enough. If it keeps and can be  
regenerated there is no reason not to use more.

ST

In a message dated 4/24/2005 8:51:45 P.M. Central Daylight Time,  
hermod.pedersen@... writes:


I  wonder if the amount of etch solution could influence the  result


Of course, but the "absolute amount" is irrelevant.  It only matters  that 
you have enough to etch the amount of copper involved!  One rule of  thumb I 
have seen published is cover a board laying flat with 6 mm of  etchant.  That 
assumes the container is about the same size/shape as the  board.  If a larger 
container, you could cover with less, or even "shlosh"  it carefully and 
continuously until done.  (Such shloshing is necessary  anyway!)
 
"Professional etching" is done with the boards vertical.  This means  special 
container shapes and board-holders, but a 18 mm wide container  large enough 
to hold the board involved is MORE than enough to etch one board at  the time. 
 
 
Now the total NUMBER of boards you etch with that same etchant in  whichever 
container is a function of the TYPE of etchant, the "ounce value" of  the 
board (copper-thickness), how much copper is removed for the particular  pattern 
involved, and the temperature of the liquid.  This is a matter you  will have 
to learn via your own  experience.              Jan  Rowland


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

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

From: "Hermod Pedersen" <hermod.pedersen@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Sunday, April 24, 2005 10:56 PM
Subject: [Homebrew_PCBs] PCB Etching Solution Amount


>
>
> I wonder if the amount of etch solution could influence the result -- as I
> would like to use a smaller plastic container with a transparent lid (less
> etchant, easier heated and less mess).
>
> To put it in another way:
> Would, say, 2 dl of etchant solution work as efficiently as 1 liter (10 
> dl)?
>
> [that would be 7 and 34 ounces (2 pints) for all non-metrics]

I use a relatively small amount of etchant in a plastic food container. It 
works very well.

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

Leon Heller wrote:
>I use a relatively small amount of etchant in a plastic food container. It
>works very well.

That was my aim -- alas, I failed at my first attempt with photo resist.
Being unsure whether the board was exposed long enough, I got another 
board, fired at it a lot longer with the bulb, only to get the same result: 
very little in way of etching.

Mixing a new brew of etchant solved that -- it all etched in a few minutes.
Proves what Jan  Rowland wrote:

>Now the total NUMBER of boards you etch with that same etchant in  whichever
>container is a function of the TYPE of etchant, the "ounce value" of  the
>board (copper-thickness), how much copper is removed for the 
>particular  pattern
>works very well.involved, and the temperature of the liquid.  This is a 
>matter you  will have
>to learn via your own  experience.

To err on the "big hammer" side, this time I put the tiny board into a big 
bucket of etchant...
I am confident, thanks to all your enlightening comments, that I will be 
able to scale down towards my newly bought food container turned etch bowl.
By the way, for the time being I think I'll stick to natriumperoxidisulfat 
(forgot to mention that). Even though it seems to wear out faster, to me it 
feels somewhat nicer than ferric chloride or hydrochloric acid.

Best of all, I made two boards on the same piece. All this chemical stuff 
may seem messy (it kept me away for a looong time), but it really isn't 
that difficult once you get started. A lot of your postings here have been 
of great help and encouragement.

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Hermod Pedersen, HCDX Web Editor
<http://www.hard-core-dx.com/>