Brad,
I looked at your artwork scans. WOW. Has anyone suggested that
you might be a glutton for punishment?
I noticed that the first two scans are much cleaner than the
others. If you have access to the pages that they were scanned
from, you should re-scan with the lines square to the scanning
direction. This will produce much cleaner results.
Before you invest too much time is trying to make clean artwork
using the scans as a basis, make sure that the scanning process
didn't distort the dimensions in one direction or the other. I
have found small differences in the scaling between the x and y
axes that make assembly of 40 pin ICs, or long connectors
impossible.
These boards will be difficult to etch. The combination of large
open spaces and very narrow traces may make it difficult to keep
the traces from over etching.
To answer your question about plated through holes, they can be
done, but it is a bit involved. There are a number of tutorials on
making plated through holes on YouTube. Here are two of them:
Process 1:
https://www.youtube.com/watch?v=KTNuTv_IQp4
Process 2:
https://www.youtube.com/watch?v=s3GY-j4Gh0E
https://www.youtube.com/watch?v=9rME-XGCcCo
I have not tried either of these processes, but they do seem
possible.\ufffd The difficulty I see with your boards is the sheer
number of holes. The possibility that one or more of the holes,
especially the small via holes, not getting plated through is very
great. Finding an open would be very difficult, not to mention
time consuming.
One thing to remember: The holes are drilled and plated before
the board is etched. This means that the holes need to be
protected during the etching process. It seems to me that the best
process for doing this would be the photoresist process. The
photomask used for resist exposure would need to have the drill
holes omitted, so the resist will tent over the holes during
etching. Drilling before photomasking has the benefit that it
makes the mask easier to align. I would suggest that some extra
pads with holes should be included on the masks to assist with
alignment. These pads would include the drill holes. This also
improves the probability that two sided boards would have proper
alignment between sides.
Harvey
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\ufffd
My TV Typewriter project is getting
close to the finish line so I\ufffdm working on lining up a
new project.
\ufffd
What I\ufffdd like to do next is a replica
of the SOL terminal prototype that appeared in Popular
Electronics in July of 1976.\ufffd I have the artwork for it
here:
\ufffd
http://www.sol20.org/articles/img/PE_SOL.pdf
\ufffd
As you can see, the quality of the
scan is pretty lousy.\ufffd There\ufffds no other sources for this
that I\ufffdve found.\ufffd I can clean it up manually with
Photoshop or Illustrator (and in fact have started on
the former) but that will take hours (months,
probably).\ufffd I\ufffdm wondering if there\ufffds a better technique
than endlessly using the rectangle tool to remake the
traces and remote the \ufffdnoise\ufffd.
\ufffd
I expect there will be other
challenges, being that this is a double sided board.\ufffd
There *isn\ufffdt* a way for a home PCB maker to do
thru-plate without third party help is there?\ufffd I don\ufffdt
want to send this off to a board house because of the
likely cost but also because that\ufffds not how a hobbyist
would have done it back then.\ufffd Since this artwork was
sent to those that wrote in for it, I\ufffdm assuming they
just created it as a two sided board the usual way and
then soldered in the connections between sides via ICs,
jumper wire, etc.
\ufffd
I also don\ufffdt want to completely
redraw the thing.\ufffd For me, that would lose the spiritual
connection to the original artwork.\ufffd I\ufffdm trying to leave
as much of it as original as possible.
\ufffd
Anyway, thoughts and suggestions here
are most welcome.
\ufffd