On Fri, 4 Feb 2005 20:45:56 -0500, Thomas P. Gootee <
tomg@...>
wrote:
>
> Stephan,
> Yes. It does look like there's still room for better toner transfer
> performance, i.e. smaller and closer traces and pads.
> But yes, I DO have problems with toner spreading. But I usually EITHER
> use large-enough spacings for trace separation (2/
> 300ths-inch seems like about the minimum, to have basically no worries
> about developing a short between two 2/300ths-inch-
> wide traces),
that's 6.66mil
> OR only use 1/300th-inch spacing where it won't really matter too much
> if a short develops, such as when I
> have several parallel traces that all return to a common ground point,
> which might have small (1/300th-inch) spacing when
> they are getting close to their common connection point.
Well, i don't see the logic for that, either i have spacing or i have a
single track, but "dunno" seems of not much advantage to me.
> (Gee, I almost hope that someone asks me WHY I would want to run
> multiple ground traces, in parallel, when they're all going to the exact
> same place, anyway; heh heh.)
No, nobody wants to ask that as everybody knows it, but some might ask
what good it is if you are unsure if they are actually separate or not.
> I remember trying some surface-mount types/sizes of patterns, once, just
> as a test, and having some very close-together
> pads that I tried to run traces between, which really had problems from
> toner-spreading. I think I was using pads that
> were 7x14 dots, at 600 dpi, with 7 and 8 dots spacing tried, between
> some of them, and tried putting one and two traces
> between them (e.g. two one-dot-wide lines at dots 3 and 6 of an 8-dot
> space). I guess a solution might be to allow some
> space for the toner spreading, i.e. draw the pads narrower.
Yes, narrower pads help, but you didn't report definitive success here.
So, in the end you are doing 6.66mil traces with 6.66mil spacing reliably,
just like everybody else.
I bet your traces are closer to 8 mil and your spacing closer to 4mil in
the end.
Seems to me like this is a rather hard limit of TT.
I bought a 1200DPI printer only to find out it isn't real 1200 but 600
instead. Well, i hope i can at least get a bit better than the 300dpi
results.
There is a point where the process (transfer, spreading,...) is the limit
and not so much the printer resolution. I had hoped i can still gain much
by using a new printer, but i'm not so sure now...
The components aren't going to get bigger in the future.....
ST