Which is the best hobby do-it-yourself method for making PCB's?

[John Popelish]

OK, dumb question time - does this work with sodium bicarbonate
as well? Or is it maybe not recommended because of the H in NaHCO3?

(snip)

It works just fine. But you might be surprised how much a quart of
ferric chloride will consume, and how much gas it gives off. You can
but a big box of washing soda lots cheaper than the same amount of
neutralizing ability with bicarb. You can also use calcium carbonate
(limestone). With either sodium bicarbonate or sodium carbonate you
get salt (sodium chloride from the reaction. With limestone you get
calcium chloride, the stuff that is sold to melt ice from the sidewalks.

 

[John Popelish]

(snip)

It works just fine. But you might be surprised how much a quart of
ferric chloride will consume, and how much gas it gives off. You can
but a big box of washing soda...

Make that,
buy a big box of washing soda...

 

[John Larkin]

At that point, the proper thing to do would be to filter through some
paper towels, and throw the solids into the trash. Copper compounds are
extremely poisonous to fish and plants.

Roughly a ounce of copper, diluted by maybe a billion gallons of
water, won't harm anything. More copper is leached out of household
plumbing every day in any good-sized city than you can reasonably dump
from household pcb etching.

John

 

[Chuck Harris]

Roughly a ounce of copper, diluted by maybe a billion gallons of
water, won't harm anything. More copper is leached out of household
plumbing every day in any good-sized city than you can reasonably dump
from household pcb etching.

John

Of course, but if I routinely dump it, and you routinely dump it, and
someone else dumps their favorite stuff down the drain, sooner or later
it adds up. Like you, I truly doubt that there are enough hobbiests that
use ferric chloride to etch PCBs so ever make a difference in the ecology
of the sewage treatment plant.

As an interesting side note, WSSC, the local water and sewer company,
for a couple of years used ferric chloride as the flocculating agent
for their water purification process... and surprise!! after a couple
of years of doing that, the copper plumbed houses in their district started
getting pinhole leaks in long horizontal sections of the copper pipe.

Imagine!

-Chuck

 

[Chuck Harris]

Hence the need for pre-neutralization with washing soda. It will do
nothing to pipes after that, except, possibly line them with a bit of mud.

Yes, you already said that, and if you will notice, I wrote FeCl, not iron
or copper carbonate.

-Chuck

 

[Robert Latest]

["Followup-To:" header set to sci.electronics.design.]
On Mon, 28 Nov 2005 19:22:49 -0500,

I think the copper compound in spent etchant can kill the 'good'
bacteria in a septic tank system, for those out of reach of municipal
water-treatment systems.

Any municipal water treatment system I've ever heard of uses a
"biological" cleaning stage using bacteria -- so it applies here as
well. Yes, and it is the copper solution (the Cu++ ions) that are toxic.
I don't know just how insoluble the compunds are that you create by
adding soda. But if you indeed create some "mud" on the bottom of the
container, with the rest of the solution not having any greenish or
bluish tint, it's a good start.

robert

 

[John Popelish]

Any municipal water treatment system I've ever heard of uses a
"biological" cleaning stage using bacteria -- so it applies here as
well. Yes, and it is the copper solution (the Cu++ ions) that are toxic.
I don't know just how insoluble the compunds are that you create by
adding soda. But if you indeed create some "mud" on the bottom of the
container, with the rest of the solution not having any greenish or
bluish tint, it's a good start.

The water is very close to colorless when the mud settles.

According to this table, copper carbonate has a solubility constant of
about 1.4*10^-10 and iron carbonate has a solubility constant of about
3.2*10^-11. Both are essentially rock dust.
http://www.csudh.edu/oliver/chemdata/data-ksp.htm

 

[Rich Grise]

Rich Grise wrote:
(snip)

It works just fine. But you might be surprised how much a quart of
ferric chloride will consume, and how much gas it gives off. You can
buy a big box of washing soda lots cheaper than the same amount of
neutralizing ability with bicarb. You can also use calcium carbonate
(limestone). With either sodium bicarbonate or sodium carbonate you
get salt (sodium chloride from the reaction. With limestone you get
calcium chloride, the stuff that is sold to melt ice from the sidewalks.

Cool!

Thanks!
Rich

 

[samIam]

Wow! That really is a bad idea! FeCl is basically harmless to nature,

in small quantities, but put it in with oil, antifreeze, and other gork,
and you now have real toxic waste.

The folks that pick up this guy's waste are expecting certain contaminants
to be in the oil, but not FeCl. If they find out about the FeCl,
they will not be able to recycle the oil. They will have to send it, at
great cost, to a toxic waste disposal processor.

Chuck I read this and freaked out.
This afternoon I called up the Waste Treatment plant where this stuff is
headed (theres only two in the entire county one disposal and one
treatment plant... its a county of about 28k people or so ...)

They handle all sorts of chemicals including the stuff used to develope
pictures, etch boards, clean spills etc etc.

They were quite knowledgeable with FeCl ... at least they sounded like
they were (I am not a Chemical Engineer so sue me).

And as I pointed out the mechanic KNEW what FeCl was. When I pointed out
"hey be careful that stuff will eat through .." he replied "dont worry
I know what it is"

To get over the guilt trip youve got me on, I am going to HUG a tree on
my way home.

 

[Rich Grise, Plainclothes Hippie]

....
Chuck I read this and freaked out.
This afternoon I called up the Waste Treatment plant where this stuff is
headed (theres only two in the entire county one disposal and one
treatment plant... its a county of about 28k people or so ...)

They handle all sorts of chemicals including the stuff used to develope
pictures, etch boards, clean spills etc etc.

They were quite knowledgeable with FeCl ... at least they sounded like
they were (I am not a Chemical Engineer so sue me).

And as I pointed out the mechanic KNEW what FeCl was. When I pointed out
"hey be careful that stuff will eat through .." he replied "dont worry
I know what it is"

It only makes sense - they get paid for the recycled oil, they have to
pay to have the other poisons disposed of.

To get over the guilt trip youve got me on, I am going to HUG a tree on
my way home.

Do better than that - if you see any litter along the way, pick it up and
put it in the bin.

Cheers!
Rich

 

[Jasen Betts]

OK, dumb question time - does this work with sodium bicarbonate
as well? Or is it maybe not recommended because of the H in NaHCO3?

It should do, only it'll fizz a bit more than with washing soda.

I have a confession to make - I had enough of the RS stuff to be about
an inch deep in a 9" x 12" cake pan, and I just dumped it down the storm
drain, which leads to the ocean, so I feel so guilty I should probably
turn Liberal or something[1]. ;-P I had done one double-sided board, if
that makes any difference. And the only heat I used was to set the pan in
the driveway in the sun.

the ocean's got plenty of iron (from rusting ships etc) and heaps of chlorine
in it already, a little copper is unlikely to harm anything.

Bye.
Jasen

 

[Mike Young]

["Followup-To:" header set to sci.electronics.design.]
On Mon, 28 Nov 2005 19:22:49 -0500,

I think the copper compound in spent etchant can kill the 'good'
bacteria in a septic tank system, for those out of reach of municipal
water-treatment systems.

Any municipal water treatment system I've ever heard of uses a
"biological" cleaning stage using bacteria -- so it applies here as
well. Yes, and it is the copper solution (the Cu++ ions) that are toxic.
I don't know just how insoluble the compunds are that you create by
adding soda. But if you indeed create some "mud" on the bottom of the
container, with the rest of the solution not having any greenish or
bluish tint, it's a good start.

And all of them also use FeCl3 at one stage or another to kill said bacteria
and deodorize before it reaches your tap. Na2CO3 is a simple, cheap, and
effective disposal method.

 

[Barry Lennox]

However, ferric chloride is very easy to chemically alter, so it is
almost completely inert in the environment. Just neutralize it with
washing soda (sodium carbonate) till it quits fizzing. Then all iron
and copper chloride will have been converted to almost insoluble iron
and copper carbonate mud. Then you can flush it down the toilet.

I knew a small PCB house that used to mix used FeCl with ordinary
builders cement, and it did much the same.

Barry Lennox

 

[private]

"I'd like to add a suggestion about how to dispose of used etching
solution. Before you pour it in to the sink, pour it in a plastic tank
and drop there scrap of old steel nails, screws, small, nuts, bolts,
etc., and let it stay for a few days. It will turn the hazardous mix of
copper chloride and Ferric Chloride (FeCl3) into copper powder (sludge)
that settles on the bottom and a non-etching and non-corrosive solution
of FeCl2. It will save from corrosion, destruction and costly
replacement in the future your cast iron drain pipes and it will save
from killing bacteria in the septic tank or in sewer treatment plant.
They are very sensitive to copper chloride and Ferric Chloride. A
current law prohibits disposal of those chemicals in the sewer. For best
yet treatment, after separation of solution of FeCl2, mix it with
solution of soda (Na2CO3 used as detergent) in a flat tray lined with
plastic film. It will turn FeCl2 into Fe(CO3) (insoluble rusty mud) and
NaCl (harmless cooking salt). After drying outdoor whole dry rusty
powder could be wrapped in plastic film and disposed of in the normal
trash container." [From http://www.fullnet.com/u/tomg/gooteepc.htm]

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