🚀 go-pugleaf

paravia@csd4.csd.uwm.edu (Mark David Kakatsch) writes:
> Does anyone have any techniques or ideas on how to through plate a PC board
> at home, sans expensive equiptment? ...

henry@utzoo.uucp (Henry Spencer)
> As I understand it, if you want reliable results (i.e. you want to use the
> boards, not just play with the technique), there ain't no way.

Henry is right.  Plated through holes are best done by professionals.
I got a tour of a PCB factory through a friend once.  Very interesting.

The bare copper board is drilled with the desired hole pattern.  Then
the photoresist is applied, and the board exposed to a UV source.
The board surface is then developed and the resist is washed away.
Now the copper is etched away.  At this point there are traces on
both sides of the board and holes where the vias should be.  (A via
joins 1 layer to another.)  Now comes the interesting part.

The board is then dunked in polonium.  Polonium is very very sticky,
and coats the copper traces as well as joining the layers together
through the vias.  Now the board is places in a copper ion bath
and electroplated.  The copper will displace the polonium, and
plate through the hole.  All that remains is to add a tin coating
to make soldering easier.

The copper plating baths are very dangerous, both because of
the currents involved as well as because of the copper ions
and catalysts used to make plating easier (cyanide is one.)

Kids, don't try this at home.


Jonathan A. Chandross
Internet: jac@paul.rutgers.edu
UUCP: rutgers!paul.rutgers.edu!jac