Would superglue work? I have various types of adheasives but don't want to
really test them out(stuff like that always turns into a mess).
Right. I'm only interested in creating a double sided board so I don't have
to use wire traces and just for fun for testing. I have a lot of single
sided boards so I thought I'd give it a shot as it would be easier than
running a but of wire traces. on the back side of the board... Ok, not sure
if it would be easier or not but...
Use epoxy. It has better rigidity and better thermal characteristics
than some other adhesive would.
I would also work out the traces, and etch the boards BEFORE joining
them, as you do not want the etchant to migrate between them at all.
You should also do all your drilling, as punching through from the other
side will rip off traces. All drilling should be done through the copper
first, and very carefully using a sharp bit (plural for high hole count).
Fiberglass is harder than steel, and that is the predominate cause of
damage to boards by cheap PCB houses that are too damned scrooged up to
replace their bits at the right interval to keep the holes nice and
clean. You could do all your drilling prior to any etch cycle too, so
that you can insure match-ups between "layers".
I would take the finished boards (etched, drilled, etc.), add solder to
any traces that you feel need additional current carrying capacity,and
laminate strips of a cheap roll of 1" Kapton tape over those traces, or
the hole board if you want. This acts as a solder mask, AND insulated
traces from contact by components, etc. The only thing left exposed
would be the pads, annular rings and vias. The rest would have a nice
blanket over it. However... BEFORE your tape it up, take the ready
board with the HASLd traces
and clean it very good in aqueous bath
if the flux was water clean, or hot alcohol if it was RMA flux. I would
not use no clean for any work other than spot level rework sessions.
ANYWAY, the idea is to get VERY clean boards *before* you laminate them
together. Final clean is in fresh, hot 99% alcohol, then BAKE the PCBs
for an hour in a minimum 60°C dry oven. PCB media is VERY hygroscopic,
so you want any and all trapped water out of the boards before you go
slapping them together for keeps.
After that final bake start using gloves to handle them.
Liquid nails sounds like a good choice, but you may want a good two
part construction epoxy. That way, YOU initiate the polymerization.
Liquid nails and off-the-shelf single part glues may not cure right.
OK, put epoxy on both mating faces. ALMOST squeegee off all of it from
both. Just don't push hard on the squeegee, which can be any clean line
edge on a piece of plastic. A plastic milk carton (jug) wall. Cut the
straight squeegee edge in one motion so it is a clean squeegee face.
Then, the amount you leave on the board will relate to the amount of
pressure you squeegee with.
Be sure to do the requirements analysis and think about any tie wrap
holes or the like you might want the board to have for strain relief of
incoming wires/cables, etc.
Don't count on a large pad area or a soldered edge to be enough to
station an added part. If connectors or other high mechanical stress
components that are typically for plated holes are used, you may need
extra bolstering to keep the soldered connections from failing from
flexure.
Plated holes are relied on for connector stationing in the industry,
and are designed with that in mind, and even your paired faces will
provide nowhere near the same capacity without plated holes. So, I would
think about things like that if you have anything that will be
experiencing any mechanical stresses.
