In a message dated 2/16/2004 9:31:08 PM Central Standard Time,
joshdewinter@... writes:
Now I have another question...just as I was about to submit my
circuits to a board house...I need a method to align my top and
bottom sides. Is there anything anyone does that works especially
well? I have looked through the messages from the group and have
heard of people taping both top and bottom on, and running them
through at the same time. That sounds like it would work, but how do
you align them accurately?
Drill the holes FIRST.
Or, if you MANUALLY drill all the holes (and break more $$ worth of bits than
having the PC professionally-etched would cost!), and you MUST have the
"copper pattern" present for drilling, then, using a light-box, place the negatives
for top/bottom together, emulsion "inside", and tape them together along TWO
sides, being careful to keep the "targets" aligned while taping. THEN, just
SLIP the sensitized blank between, clamp in a contact-printing-frame, and
expose. Remove, reverse, and repeat. Now develop and etch.
But, if redundant, if the holes are there FIRST, you could use the negatives
"one at a time", and be CERTAIN of registration. Yes, I realize drilling
first would require either a home-brew CNC drilling rig, or the use of some kind
of, say, self-adhesive pattern showing all the hole-centers. And, sadly, most
photo-copy machines will NOT sufficiently accurately copy a pattern for this
purpose. If you "draw" your pattern with an ink-jet printer, then print a
copy on Avery 5265 (etc.) full-sheet adhesive-backed label-stock, and stick that
to your blank, and drill. The paper helps a tiny bit to "center" the bits as
they enter the work. A slow and kludgy method, but possible when the wallet
is so severely challenged. Jan Rowland
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