Homebrew_PCBs

Hi to everyone.

OK, I am not new to the world of PCB making (using college equipment)
but now I want to make my own at home, staring simple with a PCB kit from
Maplin (UK).
My question is how to treat the ferric chloride I can get (liquid or
pellets) to get the most life out of it?
Also, how/where can I dispose of used ferric chloride in the UK?
I have read (on the web, so I am going to take it with a pinch of salt till
told otherwise) that it is possible to use the liquid as the base for
concrete, turn it into a lump'o rock and chuck it in the bin?

many thanx for your time,

PK

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On Mon, 17 May 2004 13:53:00 +0100, P K <oneNastyViper@...> wrote:

> Hi to everyone.
>
> OK, I am not new to the world of PCB making (using college equipment)
> but now I want to make my own at home, staring simple with a PCB kit from
> Maplin (UK).
> My question is how to treat the ferric chloride I can get (liquid or
> pellets) to get the most life out of it?

How to treat FeCl?
Some would say dump it, never use it ;-).

There are only a few tricks how you can prolong life, acids i think.
and electrolysis...
Not sure myself, not using the yellow from hell.

> Also, how/where can I dispose of used ferric chloride in the UK?
> I have read (on the web, so I am going to take it with a pinch of salt
> till
> told otherwise) that it is possible to use the liquid as the base for
> concrete, turn it into a lump'o rock and chuck it in the bin?
>

I've read that too... the concrete should neutralize it and the copper
is bound in the concrete then, not sure.

If you want my suggestion: don't use ferric cloride, use CuCl etchant,
it is much less of a pain in the ... .

look in the links section for more information.

ST

If you must use FeCl, don't get the pellets or powder. Its
exothermic (I think this is the right term) when it reacts with water
and produces a lot of heat and splashing if you aren't careful.
Makes a gawdawful mess. Nasty stuff.

I agree with Stefan, CuCl is a better way to go (cheap, easy
availability of components). Even Ammonium Persulfate is better than
FeCl (no staining and doesn't generate heat when mixed with water)
though relatively pricey.

Maplins has the hexahydrate, I thought there was two types:
hexahydrate and another anhydrous one?
Don't ask me if there is a difference, I haven't studied any chemistry
but on a website its said to use the hexahydrate not the anhydrous
one???
This etching chemistry is complicated...all I want to do is etch
small circuits in a little tub with the least amount of hassle with
easy availble and reasonably safe chemicals (ie I don't want to wipe
out a little part of swinton:-P)

PK

--- In Homebrew_PCBs@yahoogroups.com, "Phil" <phil1960us@y...> wrote:

> If you must use FeCl, don't get the pellets or powder. Its
> exothermic (I think this is the right term) when it reacts with

water

> The hydrated form doesn't generate very much heat or splash much. It
> should be added to the water rather than vice versa. The anhydrous
> form generates more heat. I've never had any problems with either
> type, though.
>
>
> Leon
>

Second that.

Heat was never a problem while i used it.

But it is very nasty stuff...

ST

On Tue, 18 May 2004 10:40:31 -0000, onenastyviper
<oneNastyViper@...> wrote:

--- In Homebrew_PCBs@yahoogroups.com, "leon_heller"
<leon_heller@h...> wrote:

> The hydrated form doesn't generate very much heat or splash much.

It

--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
<stefan_trethan@g...> wrote:

> On Tue, 18 May 2004 10:40:31 -0000, onenastyviper
> <oneNastyViper@h...> wrote:
>
> > Maplins has the hexahydrate, I thought there was two types:
> > hexahydrate and another anhydrous one?
> > Don't ask me if there is a difference, I haven't studied any

chemistry

> > but on a website its said to use the hexahydrate not the anhydrous
> > one???
> > This etching chemistry is complicated...all I want to do is etch
> > small circuits in a little tub with the least amount of hassle

with

> > easy availble and reasonably safe chemicals (ie I don't want to

wipe

> > out a little part of swinton:-P)
> >
> > PK
>
>
> The chemistry is not really complicated, if you want to maintain a

good

> etchant
> with least cost and no waste it is complicated.
> If you only want to make the occassional pcb and don't care if you

put in

> 5cent or 10cent worth of chemicals then you need not regard the

chemistry

> much.
>
> I still suggest using CuCl.
> A simple and effective etching tank is a tupperware container.
> The flat ones work just fine, the PCB need not be vertical and you

need

> much less etchant than in e.g. a cerial container.
> The lid is tight enough to prevent vapor escaping, and also

prevents a

> disaster
> if you knock the tank over while in storage.
> For single-sided pcbs a piece of tape makes a great pcb handle.
> For CuCl you only need HCl (Muriatic acid), and H2O2, which is both

easy

> to get
> hold of.
>
> The procedure when etching is to place the board in the ethant and

add a

> small
> amount of H2O2. Then it etches, you take the board out, put the

etchant

> away,
> and reuse next time again only adding a small amount of H2O2.
>
> If one day the etching stops and you see blue sludge on the copper

the HCl

> Interesting. I didn't notice 2 forms being sold. Not that it
> matters much as I dont intend to use FeCl unless desperate and I'll
> get the pre-mixed stuff from radio shack.
>
> And, yes, I added the dry stuff to the water but it still made a
> horrible mess splattering. Even small amounts caused problems. I
> did have several years of University Chem so I know the proper
> procedures.
>
> Phil
>
>
>
> ----------

I must have had the other kind then, a half-a-liter solution did just get
hand-warm.

ST

>
> NaHCO3 - baking soda
> NaCL- from HCL and NaHCO3 reaction
> Cu - copper
>
>
> and drop off at your local hazardous waste facility.
>
>
> Is my chemistry correct ?
>

you probably have no metallic copper, more like CuCl2 and CuCl....

the acid is definitely no problem, neutralize with anything...

The H2O2 degrades to pure water, the oxygen goes in the air in a matter of
hours/days.

As we have established before the copper compounds are the problem,
possibly killing
the bacteria in the wastewater plant.


Best idea in my opinion is neutralize, and then let evaporate without
danger.

Can lime be used for neutralizing it?
slaked lime like you use for construction i mean.....

ST

--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
<stefan_trethan@g...> wrote:

> >
> > NaHCO3 - baking soda
> > NaCL- from HCL and NaHCO3 reaction
> > Cu - copper
> >
> >
> > and drop off at your local hazardous waste facility.
> >
> >
> > Is my chemistry correct ?
> >
>
> you probably have no metallic copper, more like CuCl2 and CuCl....
>
> the acid is definitely no problem, neutralize with anything...
>
> The H2O2 degrades to pure water, the oxygen goes in the air in a

matter of

> hours/days.
>
> As we have established before the copper compounds are the problem,
> possibly killing
> the bacteria in the wastewater plant.
>
>
> Best idea in my opinion is neutralize, and then let evaporate

without

Stefan Trethan wrote:

>>NaHCO3 - baking soda
>>NaCL- from HCL and NaHCO3 reaction
>>Cu - copper
>>
>>
>>and drop off at your local hazardous waste facility.
>>
>>
>>Is my chemistry correct ?
>>
>
>
> you probably have no metallic copper, more like CuCl2 and CuCl....
>
> the acid is definitely no problem, neutralize with anything...
>
> The H2O2 degrades to pure water, the oxygen goes in the air in a matter of
> hours/days.
>
> As we have established before the copper compounds are the problem,
> possibly killing
> the bacteria in the wastewater plant.
>
>
> Best idea in my opinion is neutralize, and then let evaporate without
> danger.
>
> Can lime be used for neutralizing it?
> slaked lime like you use for construction i mean.....
>
> ST

Yep, I've used slaked lime a few times. its mostly calcium hydroxide
Ca(OH)2. You get CaCl2 which is soluble. Builders lime is 1/1000th cost of
bicarbonate soda from a food store.

If you want to remove copper then easiest approach is throw in some scrap
iron and/or aluminum while the etchant is still slightly acidic. The copper
precipitates as copper metal and aluminium/iron goes into solution.
After about 1 week the solution will be crystal clear with brown copper
sludge on the bottom. Syphon out most of the liquid being careful not to
disturb the sediment, neutralize the remaining sludge and leave few days to
dry to a dark crust. Works well with spent ammonium persulfate etchant and
CuCl. But I havn't tried treating FeCl3 etchant this way.

Adam

--- In Homebrew_PCBs@yahoogroups.com, Adam Seychell
<adam_seychell@y...> wrote:
...

> If you want to remove copper then easiest approach is throw in some

scrap

> iron and/or aluminum while the etchant is still slightly acidic. The

copper

> precipitates as copper metal and aluminium/iron goes into solution.
> After about 1 week the solution will be crystal clear with brown copper
> sludge on the bottom. Syphon out most of the liquid being careful

not to

> disturb the sediment, neutralize the remaining sludge and leave few

days to

> dry to a dark crust. Works well with spent ammonium persulfate

etchant and

Adam,
Thanks for the info on slaked lime.
But go with the iron: aluminum may be better at getting the copper out,
but when I asked a company that deals with powdered metals about the
toxic waste thing, they said that aluminum was considered more hazardous
then copper. They said there were no restriction on copper for them,
but there were aluminum restrictions.
But if you do use aluminum, treat it right. Small aluminum
powder/crystals are not a fire hazard directly, like phosphorus or
plutonium (phosphogenic?), but they are a combustion hazard. My father
told me that in Viet Nam, they used aluminum powder with a small starter
charge to blow up buildings, The small charge mixed the aluminum powder
with the air, and started it burning. Aluminum burns fairly slowly
(compared to explosives), so it's not a sharp explosion, just a big old
push that lifts the roof up and knocks the walls down. I expect that is
the case with most metallic powders. I don't know the powder volume
requirements to do damage, so be careful with it, or store it outside.
But even plate aluminum burns - that is, sustains a fire with no help
once started (USS Stark and M113s, for instance), while iron plate does
not. I guess Aluminum burning releases more KWatts per unit mass, and
has a lower ignition temperature then steel or iron.
Richard

I know that iron salts are safe to dump (in reasonable concentrations), but
that news about aluminum in the environment is good to know. So scrap iron
it is. Small pieces are faster because increased surface area, but metal
powder is definitely not required, steel food cans out of the trash bin do
a perfectly fine job. Over the years I have dumped many liters of this
neutralized precipitated etchant solution on my garden, with zero effect.

Steve,
I should try write up a web page someday on treating etchants with scrap
iron, but I would only doing this after getting more scientific results and
doing a few experiments. I suspect the copper concentration in the solution
after 1 week is under 100 ppm (%0.01 or 0.1 g/liter). I can test this by
adding excess ammonium hydroxide and so any copper dissolved in there will
form deep blue copper complex. Normally, in clear solutions a extreamily
faint blue tint is visible at Cu concentrations around 10ppm. But the
dissolved iron(II) ions forms cloudy yellow/brown iron(II) hydroxide with
the ammonium hydroxide and makes it difficult see the blue shade. The
ammonium hydroxide is only needed as a test to confirm the process is working.

Adam

Richard Mustakos wrote: