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

 

[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

 

[Rich Grise]

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.

I still like the idea of neutralizing it, just so it's not corrosive or
toxic on the way down the pipe.

Plus which, it sounds kinda fun. ;-)

Cheers!
Rich

 

[[email protected]]

To apply the positive resist evenly on boards:

1. You need a variable speed quarter inch drill with a sanding
attachment, double sided masking tape and a cardboard box (and
posttive resist)

2. Poke a hole in the cardboard box( large enough so that your board
fits into the box not hitting the sides) so that the drill end sticks
through.

3. Attach the sanding attachment to the drill.

4, Tape your pc board tape the board using double sided masking tape
to a sanding attachment. Center (balance) it well.

5. Pour a "small" amount of the positive resist on the board. You'll
have to experiment to find the correct amount.

6. Place a cover over the open end of the box so that when you spin
the board (in the next step) the excess positive resist will not fly
out and coat unwanted objects (you among other things).

7 Slowly spin the board so that cetrifical force will spread the
resist over the board. You'll have to stop a few times to check this.

Lots of luck.

Harry
==================

 

[Chuck Harris]

To apply the positive resist evenly on boards:

1. You need a variable speed quarter inch drill with a sanding
attachment, double sided masking tape and a cardboard box (and
posttive resist)

2. Poke a hole in the cardboard box( large enough so that your board
fits into the box not hitting the sides) so that the drill end sticks
through.

3. Attach the sanding attachment to the drill.

4, Tape your pc board tape the board using double sided masking tape
to a sanding attachment. Center (balance) it well.

5. Pour a "small" amount of the positive resist on the board. You'll
have to experiment to find the correct amount.

6. Place a cover over the open end of the box so that when you spin
the board (in the next step) the excess positive resist will not fly
out and coat unwanted objects (you among other things).

7 Slowly spin the board so that cetrifical force will spread the
resist over the board. You'll have to stop a few times to check this.

Lots of luck.

I guess that's a way, but in industry, we did it a little differently.
We used a thin rectangular S.S. "bucket" that was just slightly larger
than the board we were coating, and dipped the board into the bucket
vertically, then after removing it, we let it hang to drip dry. This
was all done under yellow lights to keep from exposing the resist.

I did thousands of boards that way, and never had any coating thickness
problems.

-Chuck

 

[James T. White]

[email protected] wrote:

I guess that's a way, but in industry, we did it a little differently.
We used a thin rectangular S.S. "bucket" that was just slightly larger
than the board we were coating, and dipped the board into the bucket
vertically, then after removing it, we let it hang to drip dry. This
was all done under yellow lights to keep from exposing the resist.

I did thousands of boards that way, and never had any coating thickness
problems.

I've used the "dip method" as a hobyist, too. Not having a made to size
container usually meant finding something and pouring in more liquid
resist
in than I needed. When I was done, I had to decide if I wanted to risk
contaminating the resist still in the bottle with that that was in the
tray. For
a PCB shop the answer is simple, throw it out. For for the hobyist that
usually means saving it. I never had problems, but was always concerned
that eventually I would get dust/lint from the air in it or have
problems
with viscosity since some evaporation is unavoidable.

 

[Chuck Harris]

I've used the "dip method" as a hobyist, too. Not having a made to size
container usually meant finding something and pouring in more liquid
resist

Our container was made using a bending brake, and some sheet stainless steel.
You could easily make one using some pieces of plexiglass, and a little
glue.

in than I needed. When I was done, I had to decide if I wanted to risk
contaminating the resist still in the bottle with that that was in the
tray. For
a PCB shop the answer is simple, throw it out.

I don't recall ever actually dumping out the resist. We just kept
adding more KPR to the pot. It was quite an ugly mess what with the drips
drooling down the sides, turning brown and congealing. The pot had a simple
cover (also bent up with the brake) that we put over its top when it wasn't
in use.

For for the hobyist that

usually means saving it. I never had problems, but was always concerned
that eventually I would get dust/lint from the air in it or have
problems
with viscosity since some evaporation is unavoidable.

Our environment wasn't exactly clean, being as we were in an open room just
off of the machine shop. I don't recall dust being much of a problem.

We used the same KPR pot to make PCB's, brass shimstock painting stencils,
and ID tags for equipment.

-Chuck

 

[Anton Erasmus]

Our container was made using a bending brake, and some sheet stainless steel.
You could easily make one using some pieces of plexiglass, and a little
glue.


I don't recall ever actually dumping out the resist. We just kept
adding more KPR to the pot. It was quite an ugly mess what with the drips
drooling down the sides, turning brown and congealing. The pot had a simple
cover (also bent up with the brake) that we put over its top when it wasn't
in use.

For for the hobyist that


Our environment wasn't exactly clean, being as we were in an open room just
off of the machine shop. I don't recall dust being much of a problem.

We used the same KPR pot to make PCB's, brass shimstock painting stencils,
and ID tags for equipment.

It is of course possible to get a nice even coating as a hobbiest, but
unless one does this quite often, the effort saved by using pre-coated
boards are immense. The boards from bungard also comes with a
protective sheet which protects the coating from light and mechanical
damage. One can saw, drill, punch, file and basically go bananas
without damaging the coating. It is difficult to remove this
protective sheet accidentaly, but it is quite easy to remove on
purpose. Having good quality pre-coated boards also removes one more
variable. When starting out it is often good to have as few as
possible variables to play with.
Are there any other manufacturers that provide pre-coated PCBs, which
can be ordered via the internet ?

Regards
Anton Erasmus

 

[Chuck Harris]

Are there any other manufacturers that provide pre-coated PCBs, which
can be ordered via the internet ?

Regards
Anton Erasmus

Sure,

Go to http://WWW.digikey.com, or http://www.mouser.com. They each sell
precoated PCB's

-Chuck

 

[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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