The cost is not the problem since the carbon dispersion should be available
free from one of the large colorant producers. The dye is similarly
available. I got 20 kg of dispersion paste for $130 AU. This is enough to
make about 1000 liters of solution. I've used about 100 grams so far. The
cost will be in building or setting up your chemical tanks. Plating copper is
easy but trying to plate uniform smooth copper on to your PCB takes a lot
more effort. I would say the carbon black process is simple relative to
copper plating. In other words, if you can get successful copper plating then
I'm sure the carbon black process will be easy for you. The success rate for
plating holes is just about perfect, but it has taken me a long time to get
at this stage. The guide I described is a good start. The only concern I have
is that a different carbon black dispersion concentrate may give different
results.
Adam
j_hallows wrote:
> This sounds good. I assume that this is just for hole activation and
> standard electroplating is done next to build up the holes. What is
> the success rate at home? And estimated costs? I don't want to dive
> into something that would be so hard to replicate. Thanks for the
> Info Adam.
>
> --- In Homebrew_PCBs@y..., Adam Seychell <adam_seychell@y...> wrote:
> > The BLACKHOLE processes is fast, cheaper and safer to run than
> conventional
> > electroless copper. This is expected since its aim is to replace the
> > electroless copper line in the PCB fabrication plant. The low
> toxicity is the
> > reason I choose to develop a carbon black processes myself at home.
> However
> > the chemistry of BLACKHOLE is a trade secret and your not going to
> replicate
> > the same results at home. BLACKHOLE SP is the latest process from
> MacDermid
> > and performs many times better than the process explained below. Of
> course
> > the hobbyist doesn't need the reliability of a multimillion dollar
> plant
> > producing a hundreds of panels a day. Its taken me about 6 months
> of fiddling
> > around with carbon black dispersions, conditioning solutions and
> circuit
> > board material to get a working process suitable for home use.
> Basically my
> > process can be written down as follows;
> >
> > 1) drill PCB
> > 2) clean copper surface with week solution of detergent/NaOH and
> 600 emery
> > paper.
> > 3) rinse well with tap water
> > 4) immerse in a "hole wall conditioner" 1 min
> > 5) rinse well with with tap water
> > 6) immerse in "carbon dispersion" 1 min
> > 7) sponge off excess dispersion with sponge, so all holes are fully
> empty.
> > 8) hot air dry
> > 9) repeat steps 4 to 8
> > 10) immerse in "activator" for 1 minute
> > 11) rinse well with with tap water
> > 12) microetch in a conventional non-chloride etching solution
> > 13) spray rinse with with tap water to remove all traces of carbon
> on copper
> > surface.
> > 14) air dry (optional)
> >
> >
> > Bath compositions/conditions;
> >
> > hole wall conditioner:
> > 5 to 10 g/l gelatine
> > 0.04 to 0.06 g/l CuSO4.5H20 (as a biocide)
> > temperature between 26°C and 32°C
> > agitation: unnecessary
> >
> >
> > carbon dispersion:
> > 2 to 4% (w/w) of non-ionic surfactant based
> > conductive carbon black dispersion paste∗
> > 6 to 10 g/l acetic acid
> > room temperature
> > agitation: unnecessary
> >
> >
> > activator:
> > 1 g/l of dye D&C Green No.5 , C.I 61570.
> > room temperature
> > agitation: not known
> >
> > non-chloride etchant:
> > 100 to 200 g/l ammonium persulfate
> > or
> > 1% hydrogen peroxide
> > 10% sulfuric acid.
> > both baths may be used at room temperature.
> >
> >
> > ∗ The carbon black dispersion paste is FLEXOBRITE BLACK 258/86
> manufactured
> > by Degussa Coatings & Colorants.
> >
> > You will have to phone around and get a 500g sample for aqueous
> based
> > non-ionic surfactant conductive carbon black dispersion. Many of
> the colorant
> > manufactures will have these. 500g will last you forever. There is
> still a
> > whole range of information I left out, either because I haven't
> worked it out
> > yet or I missed it. The D&C Green No5 is available from food, drug
> & cosmetic
> > dye suppliers, either as a sample or in small volume (1 kg). Good
> luck
> >
> > Adam
>
>
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