Hi John
Congratulations on that first board. But don't worry, some problems
happen to all of us from time to time.
I have been making PCBs at home for years and must have made hundreds of
them. But I screwed some up yesterday. Mostly I have it sorted. I'd run
out of photo board from my usual supplier and reluctantly bought some
from my local Maplin shop. The UV exposure time is completely different
to my normal boards and as a result I ended up binning the first one. I
did know this, I've run into it before, but guess I was on remote
control and hadn't engaged brain properly!
The etch time will depend on the concentration of the etchant, the
temperature and the amount of agitation. I usually aim to etch in 5 - 10
minutes but that is in a small heated bubble tank.
Plus if you have only put a small amount of etchant in the tray then it
may have become exhausted, particularly if you were etching large areas
of copper off the board. A solution (pun intended) is rather than to use
or make up a little at a time, to etch in a much larger quantity and to
keep it for the next boards. I mix up my etchant from ammonium
persulfate powder a litre at a time, etch with it, and then store the
solution. The stuff I etched with yesterday was made up in September (I
put a date on the bottle) and still worked fine.
Regards
Paul
On 12/05/2012 03:26, John wrote:
>
>
> After several false starts I got a board ready to etch. I went to Radio
> Shack and bought a bottle of etchant. It was a chilly(68 F), rainy day
> so I put enough etchant in a plastic dish to cover the board a quarter
> of an inch. I stirred it cautiously and it had barely started to etch in
> 15 minutes. I warmed it gently with a small heat gun up to a little over
> 100 F occaisionally. It took an hour and a half to etch. I may not have
> shook it up enough so my next attempt will be with the rest of the
> bottle in a bigger dish.
>
> For the moment, picking a broken drill bit out of one of the holes is
> the next challenge! We don't all have success the first time around.
>
> BTW, am I the only one to ever get the printer output to the wrong scale
> and not discover it until I drilled the board?
>
> I am getting closer!
>
>
>
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