--- In
Homebrew_PCBs@yahoogroups.com, "Leon" <leon355@...> wrote:
>
> ----- Original Message -----
> From: "javaguy11111" <javaguy11111@...>
> To: <Homebrew_PCBs@yahoogroups.com>
> Sent: Monday, June 16, 2008 5:22 AM
> Subject: [Homebrew_PCBs] Re: photomask shortcuts
>
>
> >> >
> >> > "Leon" <leon355@> writes:
> >> >
> >> >> > ∗ Developer/stripper chemistry - is more concentrated ok? Not
> > optimal
> >> >> > from a cost point of view, but I'm thinking of
> > time-between-discards
> >> >> > and shelf life.
> >> >>
> >> >> What are you using? It's quite critical for NaOH.
> >> >
> >> > Whatever samples javaguy is selling - http://www.pcbhobbyist.com/
> >> >
> >> >> Should be used at room temperature.
> >>
> >> He recommends sodium carbonate, which isn't generally used. I use
> > about 12
> >> g/litre sodium hydroxide. Sodium metasilicate is popular, and has
> > much more
> >> latitude than NaOH. NaOH has unlimited shelf life and can be reused.
> > A more
> >> concentrated solution can be used for stripping resist.
> >
> >
> > Actually the datasheet for the resist recommends that you do not use
> > NaOH for developing. Instead Sodium or Potassium Carbonate is
> > recommended.
>
> It must be a different resist than is used on precoated boards. Is it
> negative?
>
> Leon
>
It is Dupont Riston. It is a dry film negative actiing resist.