Fritz Schlunder
Guest
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 Posted:
Sat Jan 29, 2005 2:28 pm Post subject:
Re: Want to make PCB's. |
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"Richard Harris" <richard_harris_2@hotmail.com> wrote in message
news:cteh1o$1bm$1@hercules.btinternet.com...
Interesting read, but... For some possible suggestions on further process
refinement...
I think you may have a transparency brand/printer brand mismatch (even if
they claim to work with each other, they may still not be the best combo for
each other available). Not all inkjet transparencies are made the same, and
not all inkjet inks are made the same either. As a result some combinations
will produce terrible results for PCB making while others make superb
results in a single layer (one transparency). Others will be somewhere
inbetween.
Also... At least for the presensitized PCBs I use they claim you should
leave the photoresist on the finished board since it protects the traces
from oxidation while also serving as solder flux. If you really feel you
must remove it anyway I would recommend using a chemical approach (just
stick it back in the developer for awhile after you have fully etched it)
rather than mechanical. The mechanical approach is more work, requires more
equipment, and you run the risk of damaging and destroying the smallest
feature size traces and whatnot.
I can make minimum trace width and trace spacing and other feature sizes of
4 mils consistently with reasonably well defined edges using a single
transparency with an Epson 1440 dpi printer. I can play with 2 mil feature
sizes, but some non negligible distortion exists (ex: printer produces
slightly different quality for X oriented traces than Y oriented traces, and
printer resolution becomes an issue since 2 mils at 1440 dpi is less than
three droplets wide), so 2 mil gaps can't be made reliably. YMMV. |
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