Todd,
Thank you for the advice.
If you use a tray for etching, how do you keep the temperature up for the sodium persulphate?
Or is it just a case of getting the water warm before you mix in the etchant?
It's possible that the agitator is too aggressive, especially as the etch time is taking so long.
Can there be a difference in the quality of the sodium persulphate? The current batch is from a difference source to the very first etching.
Thanks again,
Phil.
--- In Homebrew_PCBs@yahoogroups.com, "Todd F. Carney" <k7tfc@...> wrote:
>
> Either ammonium persulfate or sodium persulfate is used by commercial pcb
> manufacturers. They do not use ferric chloride, not for decades. Only
> hobbyists use the stuff. I'm using a peroxide-muriatic acid-sodium chloride
> etchant. It's very cheap, and the chemicals are available either in a drug
> store or at places such as Home Depot (for the acid). I use it "one-shot."
> I use just enough to do the board I'm etching and then toss it away. It's
> that cheap. This way, It works the same way--etch times, etc.--every time I
> use it.
>
> 73,
>
> Todd
> ------------------------------------------------------------------------------------
> K7TFC / Medford, Oregon, USA / CN82ni / UTC-8
> ------------------------------------------------------------------------------------
> QRP (CW & SSB) / EmComm / SOTA / Homebrew / Design
>
>
> On Tue, Feb 19, 2013 at 9:12 PM, tda7000 <Tda7000@...> wrote:
>
> > ∗∗
> >
> >
> >
> >
> > I have used the toner transfer method with the laminator described here:
> > http://ultrakeet.com.au/write-ups/superfuser
> >
> > I have not used Press-n-peel blue, just magazine paper. However I have not
> > had undercutting (that I ever noticed!). I used old Ferric Chloride and
> > later on the Hydrochloric acid and Hydrogen Peroxide mixture. Both worked
> > great.
> >
> > http://ultrakeet.com.au/write-ups/etchantComparison he describes Ammonium
> > Persulphate as being much worse than Ferric Chloride. I have never used
> > Ammonium Persulphate.
> >
> > I don't know if it's any different to Sodium Persulphate in terms of
> > undercutting, but if his article has any truth behind it I would probably
> > try something else.
> >
> >
> > --- In Homebrew_PCBs@yahoogroups.com, "phil.quinton@" wrote:
> > >
> > > Hi,
> >
> > First post, hopefully one of many..
> >
> > To cut a long
> > > story short, I'm having problems ∗after∗ etching with Sodium
> > > Persulphate
> >
> >
> >
> > In short, it appears to be etching ∗under∗ the
> > > toner somehow.
> >
> > My guess is that the etch tank is no
> > > longer getting to the right temperature ( ~ 45 degrees ) and I'm etching
> > > too long with the agitator on. I'm going to get myself a temperature
> > > probe to confirm.
> >
> > Has anyone had a similar experience ( Etch
> > > looking fine until the toner is removed )?
> >
> > Thanks in
> > > advance,
> > Phil.
> >
> > >
> >
> >
> >
>
>
> [Non-text portions of this message have been removed]
>