Homebrew_PCBs

----- Original Message -----
From: "Bruno St-Laurent" <bsl88k@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Tuesday, January 03, 2006 2:48 PM
Subject: [Homebrew_PCBs] CUCL Temperature , etch time ?????


> Hi guys I'm new using the homebrew mix of HCL 30% and H2O2 3%, and
> would like to know what is the best temperature for good etch time??? ,
> right now when i do a fresh mix, the etch time is really fast around 5
> minutes , but if a week later i want to reuse that mix now clear green
> color my etch time goes up to more than 30 minutes!!!!!!

It should be blue for proper etching. You need to add some concentrated
H2O2, to oxidise the green cuprous chloride to cupric chloride. Adding the
3% H2O2 will make the solution too dilute. Or, just mix it fresh each time.

Leon

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>
> On Tue, 03 Jan 2006 15:48:13 +0100, Bruno St-Laurent <bsl88k@n...>
> wrote:
>
> > Hi guys I'm new using the homebrew mix of HCL 30% and H2O2 3%, and
> >
> > would like to know what is the best temperature for good etch

> >
> > right now when i do a fresh mix, the etch time is really fast

> >
> > minutes , but if a week later i want to reuse that mix now clear

> >
> > color my etch time goes up to more than 30 minutes!!!!!!
> >
> >
> > Thanks
> >
> >
> > Bruno
>
> It is problematic to heat this etchant because HCL will boil at

> or something, and already below this temperature the amount of

> fumes will increase greatly. So there probably isn't much to heat

> room temperature before things get nasty.
>
> Use a bubbler.
>
> You do know that you need fresh H2O2 each time, as long as your Cu

----- Original Message -----
From: "Stefan Trethan" <stefan_trethan@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Tuesday, January 03, 2006 4:17 PM
Subject: Re: [Homebrew_PCBs] CUCL Temperature , etch time ?????


> On Tue, 03 Jan 2006 16:24:52 +0100, Leon Heller
> <leon.heller@...> wrote:
>
>> It should be blue for proper etching. You need to add some concentrated
>>
>> H2O2, to oxidise the green cuprous chloride to cupric chloride. Adding
>> the
>>
>> 3% H2O2 will make the solution too dilute. Or, just mix it fresh each
>> time.
>>
>>
>> Leon
>
>
> NO, not BLUE! It should be green. If it is blue you have no HCl and it
> can't etch.

You are right, of course. I just checked some of mine and it is green.

Leon

>

> wrote:
>
> >
> >
> > I do use a bubbler !!!, ok, then i need to get concentrated

> >
> > it easily available ???
>
>
> Yes, and not very expensive either. You want some around 30%.
> I was afraid the london bombings might cause more restrictions on

>
> On Tue, 03 Jan 2006 16:37:32 +0100, Bruno St-Laurent <bsl88k@n...>
> wrote:
>
> >
> >
> > I do use a bubbler !!!, ok, then i need to get concentrated

> >
> > it easily available ???
>
>
> Yes, and not very expensive either. You want some around 30%.
> I was afraid the london bombings might cause more restrictions on

----- Original Message -----
From: "Bob_xyz" <bob_barr@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Tuesday, January 03, 2006 4:37 PM
Subject: [Homebrew_PCBs] Re: CUCL Temperature , etch time ?????


> H2O2 is available at beauty supply stores in concentrations up to
> 40%. (It's hair bleach.) It's sold in 1 quart bottles for US$5 or
> so. I get mine at Sally Beauty Supply. Some beauty supply shops only
> sell to licensed hair stylists but some, like Sally, do sell to the
> general public.
>
> Buying in small quantities shouldn't raise any red flags. I don't
> think I'd want to try buying a 55 gallon drum of it, though. :=)

Mixed with acetone at freezing point it makes triacetone triperoxide. It's
popular with suicide bombers.

Leon

>
> On Tue, 03 Jan 2006 17:40:03 +0100, Bruno St-Laurent <bsl88k@n...>
> wrote:
>
> >
> >
> > Stefan how much H2O2 do i add ????
> >
> >
> > Bruno
>
>
> Of the 30% stuff just a little bit. A spoon full or two (DO NOT

> METAL), 5ml or less i'd say. Basically the smallest amount i can

> my H2O2 bottle. This regenerate enough etchant for one, maybe two

> Wow really small quantity !!! last question, Can it be regenarate for
> ever , or should be dispose after some H2O2 addition ???
>
> Thanks
>
> Bruno

>
>
> > Wow really small quantity !!! last question, Can it be regenarate

> > ever , or should be dispose after some H2O2 addition ???
> >
> > Thanks
> >
> > Bruno
>
> You can use it indefinitely. Of course HCl is also used up, so you

> add that too after a while. You can either go by feel and add when

> doesn't help to add H2O2, or you see any blue sludge on the PCB, or

> can look in the links section on how to measure the molarity of HCl

> etchant. Look for the method with the two eyedroppers it is the

> sufficiently simple IMO. You might also want to get a hydrometer.

> used to measure density (amount of copper per volume). You can get

> cheap and easy in the car tools store, it is used to measure

> fluid. Should cost well under 10$. Go for the type with the

> hydrometer in a large glass pipette, not the small plastic

> pointer one. But that's really only if you are curious about the

> it is not a requirement to make it work.
>
> Now if we only keep to add stuff to the etchant it will of course

> volume. This is very slow and is good because it dilutes the copper

> more etchant, otherwise you will reach a point where the specific

> gets too high. Should you get too much etchant at one point you'll

> dispose of some, but unless you make really many boards regularly

> growth is barely noticeable.
>
>
> You will find if you keep using your etchant it will gradually turn

> HCl+H2O2 etching to CuCl etching, that means instead of "instantly"

> and needing H2O2 to etch the H2O2 can be used to regenerate

> in the etchant. What that means for you is that once there is

> you do not necessarily need to add H2O2 each time. You only add it

> the etchant turns from a bright green to a darker, brownish color.

> there is enough bright green regenerated etchant for the board

> do not need to add any H2O2, even if you last etched months ago.

> will not help to add too much H2O2 - once all the etchant is bright

> it does no good and will just decompose to useless oxygen that has

> to regenerate and is released into the air.
>
>
> *********
>
> > If it fizzes, you added too much. It won't actually do any harm

> > put too much in. I normally fill the cap of the bottle up and

> > in. It seems to be about right for my tank.
> > Les
>
> if it fizzes it creates loads of nasty fumes that are corrosive.

>
> On Tue, 03 Jan 2006 20:06:54 +0100, Bruno St-Laurent <bsl88k@n...>
> wrote:
>
> >
> >
> > Thanks a lot for all these info !!!!, right now mine is bright

> >
> > green but etch really slowly, so i'll get H2O2 30% !!!!
> >
> >
> > Thanks
> >
> >
> > Bruno
> >
>
>
> As long as there is not enough cucl in the tank even when bright

> will not etch well. But it will etch, very slowly, until it gets

----- Original Message -----
From: "Stefan Trethan" <stefan_trethan@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Friday, January 06, 2006 12:40 AM
Subject: Re: [Homebrew_PCBs] Re: CUCL Temperature , etch time ?????


> On Thu, 05 Jan 2006 23:33:14 +0100, Bruno St-Laurent <bsl88k@...>
> wrote:
>
>>
>>
>> Stefan about the H2O2 30% , you really mean 30% not volume 30 ????
>>
>>
>> cause today i found H2O2 volume 30, it's only 9%!!!!!
>>
>>
>> Bruno
>>
>
>
> i dunno for sure, but i think it is 30% by volume not weight.

I think 30 vols means that it produces 30 x its volume as oxygen gas.

Leon

>

>
> --- In Homebrew_PCBs@yahoogroups.com, "Leon Heller"

> wrote:
> >
> <snip>
> >
> > I think 30 vols means that it produces 30 x its volume as oxygen

> >
>
> Exactly. I just found that out today. Volume 20 is 6% H2O2, volume

> is 9%, and volume 40 is 12%.
>
> It's a bit better than the drugstore 3% strength but not by all