Homebrew PCBs

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Hi all

The new vertical tank is finally in use and i am pretty satisfied with the 
handling.
it features a pcb clamp that can acceept all thicknesses, and this clap 
can be opened/closed
with the same hand which also holds the lid/holder itself.
I used a plastic rod which is spring loaded and pressed on with the thumb 
to open the clamp.
this means i can feed the pcb and also afterwards drop it into the water 
tank without ever touching
etchant-exposed parts or washing any part of the pcb holder.
the visibility of the vertical glass tank is also great.


But to my questions:

With CuCl analysis, the initial amount of water does not play a major role 
i think?
the instructions call for 5ml of water, then 10 drops of etchant, 1 drop 
of indicator,
and then n drops of 1mol NaOH which are the etchant molarity*10.

Is it necessatry to measure this initial amount of water?
Is it correct that the only important thing is the equal size of 
etchant/NaOH drops?

I guess it would also be possible to make a "ready to use" 
water/methylorange solution?


The molarity of the etchant i used in the old tank was over 3, so i 
diluted it with water
to get 1.5. of course the etching is now terribly slow, because i have 
nearly no copper in.
i will dissolve some copper to get the density up (the hygrometer is off 
range, 1.6 would be
the lowest value)

Next question is about rubber. i have used a piece of bicycle hose to make 
the spring action of
the clamp. will it hold up inside the etchant tank? it is not immersed but 
exposed to the fumes all the
time. any experiences?

thanks

ST

> i will dissolve some copper to get the density up (the hygrometer is off
> range, 1.6 would be
> the lowest value)

make that 1.16 would be the lowest value. 1.6 is of course too much.

ST

--- In Homebrew_PCBs@yahoogroups.com, "Zoran A. Scepanovic"
<zasto@y...> wrote:
> 
> 
> Download a useful conversion calculator and terminology application
at http://www.engnetglobal.com/tips/toolsapp/

Added to Links under Conversion Software.

Thanks!

Steve

Yes, the exact amount of initial water for titration is not important. The 
water is generally required so you have more solution volume to look at. 10 
drops of solution would be difficult to see and properly mix, since if a 
small bit splashed on the side of the glass it may not get mixed and give 
false reading.

3 molar HCl is not too high. The only problem with high acid is fumes. If 
HCl fumes are not a problem then you could of left it at 3 molar. 
Concentrated HCl is about 12 molar.
http://www.howe.k12.ok.us/~jimaskew/cabconc.htm
I found more copper is needed get get faster etching, I think the SG of my 
solution was around 1.25 to 1.30 . Remember HCl is consumed during etching 
so adding more copper means even less acid in your solution.


Stefan Trethan wrote:

> Hi all
> 
> The new vertical tank is finally in use and i am pretty satisfied with the 
> handling.
> it features a pcb clamp that can acceept all thicknesses, and this clap 
> can be opened/closed
> with the same hand which also holds the lid/holder itself.
> I used a plastic rod which is spring loaded and pressed on with the thumb 
> to open the clamp.
> this means i can feed the pcb and also afterwards drop it into the water 
> tank without ever touching
> etchant-exposed parts or washing any part of the pcb holder.
> the visibility of the vertical glass tank is also great.
> 
> 
> But to my questions:
> 
> With CuCl analysis, the initial amount of water does not play a major role 
> i think?
> the instructions call for 5ml of water, then 10 drops of etchant, 1 drop 
> of indicator,
> and then n drops of 1mol NaOH which are the etchant molarity*10.
> 
> Is it necessatry to measure this initial amount of water?
> Is it correct that the only important thing is the equal size of 
> etchant/NaOH drops?
> 
> I guess it would also be possible to make a "ready to use" 
> water/methylorange solution?
> 
> 
> The molarity of the etchant i used in the old tank was over 3, so i 
> diluted it with water
> to get 1.5. of course the etching is now terribly slow, because i have 
> nearly no copper in.
> i will dissolve some copper to get the density up (the hygrometer is off 
> range, 1.6 would be
> the lowest value)
> 
> Next question is about rubber. i have used a piece of bicycle hose to make 
> the spring action of
> the clamp. will it hold up inside the etchant tank? it is not immersed but 
> exposed to the fumes all the
> time. any experiences?
> 
> thanks
> 
> 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
> 
> 
> 
>  
>

On Sun, 25 Apr 2004 10:09:23 +1000, Adam Seychell 
<adam_seychell@...> wrote:

> Yes, the exact amount of initial water for titration is not important. 
> The
> water is generally required so you have more solution volume to look at. 
> 10
> drops of solution would be difficult to see and properly mix, since if a
> small bit splashed on the side of the glass it may not get mixed and give
> false reading.
>

Yea i love it. I tried several times and found the reading is really the 
same,
even with the eyedroppers...

> 3 molar HCl is not too high. The only problem with high acid is fumes. If
> HCl fumes are not a problem then you could of left it at 3 molar.
> Concentrated HCl is about 12 molar.
> http://www.howe.k12.ok.us/~jimaskew/cabconc.htm

Too high HCl attacks the steadtler RED, i want to keep it low enough.

> I found more copper is needed get get faster etching, I think the SG of 
> my
> solution was around 1.25 to 1.30 . Remember HCl is consumed during 
> etching
> so adding more copper means even less acid in your solution.

yes i know that and i have left a bit of room to the "ideal" fill height 
for additional acid.
Today it looks much more colored already, but the hydrometer is still way 
off range..

(is my assumption correct that i need to dissolve 200gram copper to raise 
the density by 0,2?
in a 1l container...)

I'll try to get more copper in, and i also decided i need some of these 
eyedropper bottles.
then i can keep one filled with 1mol NaOH and use the other (equal-sized) 
eyedropper for the etchant.

ST

Stefan Trethan wrote:

> 
> (is my assumption correct that i need to dissolve 200gram copper to raise 
> the density by 0,2?
> in a 1l container...)
> 
> I'll try to get more copper in, and i also decided i need some of these 
> eyedropper bottles.
> then i can keep one filled with 1mol NaOH and use the other (equal-sized) 
> eyedropper for the etchant.
> 


Also add some hydrometers to your shopping list to cover the 
range 1.00 to 1.30  I find hydrometers with 0.10 range are plenty 
  good. Standard laboratory hydrometers have a range of 0.05.

Looking at the commercial CuCl etchant ( 
http://www.oxfordvue.com/TechInfo/how_does_it_work.html ), they 
run at  s.g 1.35 to 1.4 and have about 220 g/liter of copper.

I think this is too high, I found 1.25 to 1.30 better for room 
temp etching. CuCl2 etching without chemical oxidizers (H2O2, 
Cl2, NaClO3 etc) should etch 35um copper foil in 20 minutes at 
20\ufffdC with bubble agitation. Keep HCl plentiful.

A hydrometer is floating already....

>
> Also add some hydrometers to your shopping list to cover the
> range 1.00 to 1.30  I find hydrometers with 0.10 range are plenty
>   good. Standard laboratory hydrometers have a range of 0.05.
>
> Looking at the commercial CuCl etchant (
> http://www.oxfordvue.com/TechInfo/how_does_it_work.html ), they
> run at  s.g 1.35 to 1.4 and have about 220 g/liter of copper.
>
> I think this is too high, I found 1.25 to 1.30 better for room
> temp etching. CuCl2 etching without chemical oxidizers (H2O2,
> Cl2, NaClO3 etc) should etch 35um copper foil in 20 minutes at
> 20\ufffdC with bubble agitation. Keep HCl plentiful.
>
>
>
>
>
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
> Yahoo! Groups Links
>
>
>
>
>