Homebrew PCBs

Hi,

has anyone ever tryed electro-etchig for PCBs ? 
What chemicals/ setup should be used? what pros and contras are in it?

thank you,
mihai

mihai_hagianu wrote:
> 
> 
> 
> 
> Hi,
> 
> has anyone ever tryed electro-etchig for PCBs ? 
> What chemicals/ setup should be used? what pros and contras are in it?
> 
> thank you,
> mihai
> 
> 

We had some discussion sometime ago in Homebrew_PCB. The consensus was 
it is probably achievable but not practice for just the occasional PCB. 
There is an extra tank to setup, while I think the cost of etchant in 
normal etching is small in the scheme of things.

Sulfuric acid would the electrolyte of my choice, probably 100 g/L to 
200 g/L. With bubble agitation, I'd expect you could get a current 
density at the anode (PCB) of over 5 A/dm^2.

Adam

--- In Homebrew_PCBs@yahoogroups.com, "mihai_hagianu"
<mihai_hagianu@y...> wrote:
> 
> 
> 
> 
> Hi,
> 
> has anyone ever tryed electro-etchig for PCBs ? 
> What chemicals/ setup should be used? what pros and contras are in it?
> 
> thank you,
> mihai

I tried EDM on PCB's a year ago and while you can do very fine traces
( for BGAs and the like ), it is a VERY slow process, even when you
use post process etching to remove large copper areas.

TT and H202 enhanced CuCl is the way to go!

Curt

Hi,

I have been using CuCl etchant for a while now. Before etching I add a
tablespoon of 100 volume H2O2 and away I go. Recently something has
changed. When adding the H2O2 the soulution used to bubble slightly and
change colour from muddy green to a nice blue-green. Recently when I add
the H2O2 it bubbles violently and nothing else happens. Has anyone else
had this problem?

Perhaps I should just dump the solution and start again.

Les

On Fri, 17 Dec 2004 23:19:59 +0000, Les Newell <lesnewell@...>  
wrote:

> Hi,
> I have been using CuCl etchant for a while now. Before etching I add a
> tablespoon of 100 volume H2O2 and away I go. Recently something has
> changed. When adding the H2O2 the soulution used to bubble slightly and
> change colour from muddy green to a nice blue-green. Recently when I add
> the H2O2 it bubbles violently and nothing else happens. Has anyone else
> had this problem?
> Perhaps I should just dump the solution and start again.
> Les


You have forgotten to add HCl.
You did check the molarity from time to time, right? ;-)


ST

>From: Les Newell <lesnewell@...>
>Reply-To: Homebrew_PCBs@yahoogroups.com
>To: Homebrew_PCBs@yahoogroups.com
>Subject: [Homebrew_PCBs] CuCl wierdness
>Date: Fri, 17 Dec 2004 23:19:59 +0000
>
>
>Hi,
>
>I have been using CuCl etchant for a while now. Before etching I add a
>tablespoon of 100 volume H2O2 and away I go. Recently something has
>changed. When adding the H2O2 the soulution used to bubble slightly and
>change colour from muddy green to a nice blue-green. Recently when I add
>the H2O2 it bubbles violently and nothing else happens. Has anyone else
>had this problem?

Try adding some HCl.

Leon

I'm told micro toner is used by Banks to get a raised feel to check 
printing. Assuming more toner is deposited, is it a good choice for the 
toner transfer method?
TM

Hi Curt,
Do you have more detailed info on EDM how it is done and with *home* 
built gear, I am interested in learning how to build and use EDM for 
PCB. Happy to receive info offline if not on list.
Bengt

--- In Homebrew_PCBs@yahoogroups.com, "curt_rxr" <cwrxr@e...> wrote:
> 
> I tried EDM on PCB's a year ago and while you can do very fine 
traces
> ( for BGAs and the like ), it is a VERY slow process, even when you
> use post process etching to remove large copper areas.

--- In Homebrew_PCBs@yahoogroups.com, "Bengt" <tecnoconsult@t...> wrote:
> 
> Hi Curt,
> Do you have more detailed info on EDM how it is done and with *home* 
> built gear, I am interested in learning how to build and use EDM for 
> PCB. Happy to receive info offline if not on list.
> Bengt

Hi Bengt,

Basically I used a modified HP Deskjet 500 to "print" my artwork onto
the board.  My thinking was that I could easily transfer any image
that could be scanned or generated by any Windoze program.  I mounted
a plastic tray in place of the paper magazine into which the board was
placed and covered with distilled water.  The tool was the carbide
point from a hand scriber which was carried in place of the ink
cartridge.  The tray was supported by ball bearings in vee groves such
that the friction wheels moved it instead of the paper.  ( This worked
better than I thought it might needing only to aligned properly during
setup and then kept CLEAN. )  I used a lower power version of the
sparker outlined at:  

http://cscott.net/Projects/FabClass/final/edsign1.html


  And it worked as far as it went, since I could use PCL commands to
control everything, but.....   ( you knew there was a but! ) It is
very slow.  It takes seven hours to do a single side, 4 inch by eight
inch board.  The problem is that for good resolution you are stuck
with a very small spot which is also the increment you move the head
between sparks.  

All in all it's not ready for prime time, since you can use TT and
CuCl etch and have a finished board in a fraction of the time it takes
to EDM one.  

What might be a useful line of investigation would be to convert a
plotter.  That way you could control line width by choosing a
different "pen" ( electrode ) instead of making multiple passes.  Also
vector graphics should allow for speedier positioning.

If there is interest I'll take some photographs of the beast and work
my notes into readable form after the holidays.

Merry Christmas one and all

Curt

--- In Homebrew_PCBs@yahoogroups.com, Terry Mickelson <tmdslca@t...> 
wrote:
> 
> I'm told micro toner is used by Banks to get a raised feel to check 
> printing. Assuming more toner is deposited, is it a good choice for 
the 
> toner transfer method?
> TM

I think you are referring to MICR toner.  This stands for Magnetic 
Ink Character Recognition.  This type of toner is used to print 
routing symbols, acccount numbers and amounts on checks that are 
printed on a computer.  The advantage to the user is that they need 
only stock one blank check form.  The remainder of the required 
information on the check is printed xerographically.

Banks use check readers that read the magnetic ink coded characters 
directly from the checks; no manual keying is necessary.

This toner no doubt has a blend of traditional toner elements 
combined with some magnetic metal (I don't know what metal).

It is also likely this toner would become reactive to the etchant, 
defeating the purpose of the toner as an etch resist.  

I also do not believe the MICR characters are raised.  Feel along the 
bottom of one of your checks where the MICR printing is. The MICR 
printing consists of the block style numbers.

I would be interested in knowing how print shops do raised letter 
business cards that mimic true engraved raised letter printing. 

RTurley

The way it used to be done (at least 10 years ago, that's as current as 
I can give you :-)  ) is it's printed in black in some 'normal' manner, 
then it gets a clear plastic powder that melts at temperature.  The page 
is flashed with some energy that is absorbed by the ink, which heats up 
and melts the plastic powder, and the rest of the powder is (hopefully) 
recycled.
Richard

>I would be interested in knowing how print shops do raised letter 
>business cards that mimic true engraved raised letter printing. 
>  
>

Rusty-

One process which raises letters, such as those on cards, is known as
"bakerizing". Sveral homebrew appraoches are outlined by Don Lancaster:

www.tinaja.com/glib/spotcolr.pdf

Grant

--- In Homebrew_PCBs@yahoogroups.com, "rustyturley" <rturley@a...> wrote:
[snip]

> I would be interested in knowing how print shops do raised letter 
> business cards that mimic true engraved raised letter printing. 
> 
> RTurley

>
>This toner no doubt has a blend of traditional toner elements
>combined with some magnetic metal (I don't know what metal).

Iron, like the black ink in US currency.

>It is also likely this toner would become reactive to the etchant,
>defeating the purpose of the toner as an etch resist.

It would probably be most amusing.

>I also do not believe the MICR characters are raised.  Feel along the
>bottom of one of your checks where the MICR printing is. The MICR
>printing consists of the block style numbers.

They aren't raised, that would be a disaster. They are read with a magnetic 
head that looks exactly like what you'd find in a 1/4" tape deck.  There 
are differences, but that gets a bit esoteric.