A friend descried to me a method for plating through holes. The plating is accomplished by inserting a wire into the hole and applying a high voltage to the wire, exploding it and connecting the layers together. A pdf is available on google. It was too big for yahoo. Despite the questionable looking address, it is real.
https://docs.google.com/open?id=0B9UJMWQidYN0ZE1yNWEzQmluSWc
Curt's description
It involves feeding a thin copper wire through the hole until it touches a massive ground plate which allows a capacitor charged to 300 - 400 volts to discharge and literally melt the wire rapidly enough to cause it to 'explode' and bond to the internal copper layers. I find that 10 to 15 bursts leave enough copper for a sturdy through hole. I use an X Y table to position the board under a chuck that grips the wire and is connected to the high voltage source. A small stepper motor feeds the wire through the chuck from a spool.
Jeff
https://docs.google.com/open?id=0B9UJMWQidYN0ZE1yNWEzQmluSWc
Curt's description
It involves feeding a thin copper wire through the hole until it touches a massive ground plate which allows a capacitor charged to 300 - 400 volts to discharge and literally melt the wire rapidly enough to cause it to 'explode' and bond to the internal copper layers. I find that 10 to 15 bursts leave enough copper for a sturdy through hole. I use an X Y table to position the board under a chuck that grips the wire and is connected to the high voltage source. A small stepper motor feeds the wire through the chuck from a spool.
Jeff