Homebrew PCBs

On 3/27/06, aggie_672000 <aggie_672000@...> wrote:
> It is my understanding you tin plate the pcb after etching to
> protect the new copper trace from corrosion. TINNIT is the name of
> the material used to tin plate.

That's all true.  But I know I read the same thing that Matt did
(where did you see it, Matt?), that some commercial processes use tin
plate as an etch mask.  I don't remember why they did that.

Seems one could do that as a homebrew process:
1. Put toner or leave photoresist where you want to etch
2. Tin plate the areas you want to keep (TINNIT)
3. Remove the toner or photoresist
4. Etch

but I don't see what advantage that would have over the more common
homebrew processes.

Cheers,
- Jan

>
> --- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
> <stefan_trethan@...> wrote:
> >
> > On Mon, 27 Mar 2006 17:50:06 +0200, matt clement
> <buckeyes1997@...>
> > wrote:
> >
> > > I saw a process used by a fab house and they used a negative
> photo
> > >
> > > resist and then tin coated the board.  The tin only stuck to the
> > >
> > > places that had the bare copper.  Then the board was chemically
> etched
> > >
> > > and the tin protects the copper.  Would we possibly be able to
> come up
> > >
> > > with a similar system of printing a negative image and then tin
> > >
> > > plating before etching?  The toner would probably melt when you
> tried
> > >
> > > to tin the board with an iron, but maybe a chemical plating
> process?
> > >
> > >
> > > Does anyone know for sure if tin etches away with FeCl?  I might
> have
> > >
> > > to try it at lunch...haha.
> > >
> > >
> > > matt
> > >
> >
> >
> > I'm not sure about FeCl, those tin resist baths are usually
> Sulphuric acid
> > / peroxyde i think.
> > You could do things that way, but why do you want to?
> >
> > ST