Homebrew PCBs

Gun Blueing from your local hardware store.
Very slightly dampen a corner of a cloth with it, rub briskly.
You'll get a black sooty deposit if you put too much on / leave
it wet etc.; start with a less dampened corner of the cloth.
Keep rubbing....

Same deal as prep for etching / plating - clean.  Kitchen cleanser
like ajax etc.  Wash well.

Rubber gloves - it leaves a nasty odor that's hard to wash off.
Nothing terrible in the MSDS.

CHeaper than most of the brass-blackening compounds in the few
hobby shops that sell them.  Faster, too.
/mark

On Thu, 13 May 2004 07:24:08 -0700, Mark <mfraser@...> wrote:

> Gun Blueing from your local hardware store.
> Very slightly dampen a corner of a cloth with it, rub briskly.
> You'll get a black sooty deposit if you put too much on / leave
> it wet etc.; start with a less dampened corner of the cloth.
> Keep rubbing....
>
> Same deal as prep for etching / plating - clean.  Kitchen cleanser
> like ajax etc.  Wash well.
>
> Rubber gloves - it leaves a nasty odor that's hard to wash off.
> Nothing terrible in the MSDS.
>
> CHeaper than most of the brass-blackening compounds in the few
> hobby shops that sell them.  Faster, too.
> /mark
>
>

Never seen anywhere around, thought about it too...

I am on to something, left it immersed in strong NaOH solution mixed with 
sulphur overnight.
It got black, very black, but the copper was etched :-( . Might work just 
fine if
i only leave it for a short time.

ST

Stefan Trethan wrote:

> On Thu, 13 May 2004 07:24:08 -0700, Mark <mfraser@...> wrote:
> 
> 
>>Gun Blueing from your local hardware store.
>>Very slightly dampen a corner of a cloth with it, rub briskly.
>>You'll get a black sooty deposit if you put too much on / leave
>>it wet etc.; start with a less dampened corner of the cloth.
>>Keep rubbing....
>>
>>Same deal as prep for etching / plating - clean.  Kitchen cleanser
>>like ajax etc.  Wash well.
>>
>>Rubber gloves - it leaves a nasty odor that's hard to wash off.
>>Nothing terrible in the MSDS.
>>
>>CHeaper than most of the brass-blackening compounds in the few
>>hobby shops that sell them.  Faster, too.
>>/mark
>>
>>
> 
> 
> Never seen anywhere around, thought about it too...
> 
> I am on to something, left it immersed in strong NaOH solution mixed with 
> sulphur overnight.
> It got black, very black, but the copper was etched :-( . Might work just 
> fine if
> i only leave it for a short time.
> 

I though sulfur was insoluble and therefore wouldn't have an 
effect, but I'm no expert. I've seen copper site in some 50g/L 
NaOH photoresists stripper solution overnight and came back next 
morning to find a copper(II) oxide film ,i.e black.

The oxide will dissolve away in any acid.

Commercially they use sodium hypochlorite ("pool chlorine") mixed 
with NaOH to make black oxide film on PCB s prior to lamination 
of inner layers. Apparently the epoxy sticks a whole lot better 
to Cu oxide than to the metal. I've never tried it but I think 
the NaClO acts to massively speed up the oxidation rather than 
relying on dissolved atmospheric oxygen. Worth a try....

Adam

--- Adam Seychell <adam_seychell@...> wrote:

> Commercially they use sodium hypochlorite ("pool
> chlorine") mixed with NaOH to make black oxide film
> on PCB s prior to lamination of inner layers.
> Apparently the epoxy sticks a whole lot better 
> to Cu oxide than to the metal. 

How about a solution composed of NaOH and H2o2? 
You will get:

Cu(OH) Blue in color
Cu(OH)2 Black in color.

If you apply heat, the Cu(OH) will be oxidized to
Cu(OH)2.



Best regards

Marvin Dickens 

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> How about a solution composed of NaOH and H2o2?
> You will get:
>
> Cu(OH) Blue in color
> Cu(OH)2 Black in color.
>
> If you apply heat, the Cu(OH) will be oxidized to
> Cu(OH)2.
>
>
>
> Best regards
>
> Marvin Dickens
>
> ===


Thanks, that's worth a try....

The black i produced the other day didn't stick....

ST

Stefan Trethan wrote:
>>How about a solution composed of NaOH and H2o2?
>>You will get:
>>
>>Cu(OH) Blue in color
>>Cu(OH)2 Black in color.
>>
>>If you apply heat, the Cu(OH) will be oxidized to
>>Cu(OH)2.
>>
>>
>>
>>Best regards
>>
>>Marvin Dickens
>>
>>===
> 
> 
> 
> Thanks, that's worth a try....
> 
> The black i produced the other day didn't stick....
> 

Thats interesting.
I found this doing a google search
http://doc.tms.org/ezMerchant/prodtms.nsf/ProductLookupItemID/JEM-0306-558/$FILE/JEM-0306-558F.pdf


I was wrong before, its actually sodium hydroxide and sodium 
chlorite. Not sure where you get chlorites from. I thought all 
the chlorite, chlorate and perchlorates are ingredients in bomb 
making material so may be difficult to get in a useful form.
The order of oxidation power (lowest to highest) is

NaCl0   sodium hypochlorite
NaCl02  sodium chlorite
NaCl03  sodium chlorate
Na(Cl0) sodium perchlorate

Please note that you should have *total* respect for
the chlorite family of compounds:

> NaCl0   sodium hypochlorite

This is laundry bleach. Dangerous, but workable if you
respect it.

> NaCl02  sodium chlorite

Used in industrial processes, as a microcide and as a
pesticide.  More nasty/dangerous. Take nothing for
granted and always follow a carefully planned
handeling routine. Never deviate from the routine.

> NaCl03  sodium chlorate

Used in industrial processes (Mainly the manufacture
of paper) and as a herbacide. Nasty and dangerous. I
don't want around me or at my house/business.

> Na(Cl0) sodium perchlorate

Strong oxidizer and unstable. Spontaneous combustion
is possible. Don't drop it, it will probably explode.
Heat sensitive. As I recall, it's hygroscopic. Totally
nasty/dangerous. This stuff falls into my "I don't
want no parts of this sh!t" catagory.

Regards

Marvin Dickens

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> > a solution composed of NaOH and H2o2?
> > You will get:
> >
> > Cu(OH) Blue in color
> > Cu(OH)2 Black in color.
> >
> > If you apply heat, the Cu(OH) will be oxidized to
> > Cu(OH)2.

> Thanks, that's worth a try....

> ST

Hey Stefan,

Did you give the above a try? If so, what were the
results?


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On Sun, 16 May 2004 16:00:45 -0700 (PDT), mpdickens <md30022@...> 
wrote:

>> > a solution composed of NaOH and H2o2?
>> > You will get:
>> >
>> > Cu(OH) Blue in color
>> > Cu(OH)2 Black in color.
>> >
>> > If you apply heat, the Cu(OH) will be oxidized to
>> > Cu(OH)2.
>
>> Thanks, that's worth a try....
>
>> ST
>
> Hey Stefan,
>
> Did you give the above a try? If so, what were the
> results?
>
>

not yet...

i'll tell you then.

ST