Homebrew_PCBs

On Wed, 07 Sep 2005 15:57:41 +0200, lcdpublishing
<lcdpublishing@...> wrote:

> 1) I am working with the powder, according to the directions, I add
> the powder to the water - 1 pound / 1/2 gallon. They caution to add
> it slowly as it could react and bubble up or get very warm. Any
> other worries at this point?

seems about right. watch those stains!!
if you mix it fresh before your first etch you can use the heat in the
etchant i guess. Wasn't too dramatic.

> 2) I will be using a small fish tank pump and bubbler rocks to
> create a wide spread of bubbles. This will be my first time etching
> with bubbles - I expect that this will speed up the etching process?

yes, similar to mechanic agitation or brushing.

> 3) I also have a fish tank heater. I am not sure if I will use this
> or not the first time around. However, I have read the comments " I
> am using a hacked fish tank heater to warm the solution ". This
> creates two questions for me.
> 3a) How hot do you need to make the solution?

i remember something a small bit below 50C for ideal speed.

> 3b) Do you really need to modify the heater to obtain the heat
> desired or can you use it without modification?

The fish would die, if there was no safety limit. many heaters can be
hacked by removing some sort of mechanical stop.
Please keep in mind ferric chloride is about as conductive as liquids get,
so take care with the electrics.

> 4) I suspect if I use any form of metal clip to hang the circuit
> board in the tank, it will probably corrode away and "waste" the
> ferric chloride. So, I am thinking of hanging the circuit boards
> with wire (insulated), is this a good idea?

all but titanium will be etched, i think. You can use a plastic clamp, a
strip of sticky tape, a hole and some cord, .....

> 5) based on the above descriptions ( and any modifications you folks
> add), how long does etching take using this process? I don't want
> to over etch, and trying to see though that brown solution isn't
> very good. I will of course have to lift out the circuit board to
> check it's progress, but if someone can provide an approximate time
> that would be helpful in that I could detect if something is wrong.

you must lift out the circuit board to check from time to time, it is in
the minutes range under good conditions up to hours under bad ones.

good luck, and i hope you bought the stain remover too, for any accidents
;-)

ST