On Jul 25, 1:48 pm, msg wrote:
Jan Panteltje wrote:

snip

How about conductive glue replacing solder?
Na, will have to wait until the first EU politician's cellphone fails in
some emergency.

What ever happened to 'multiwire' (or some such trade name)? It was
a multilayered weld-bonded wiring alternative to multilayer PCBs
in the '60s and '70s and was very rugged, easily implemented with
NC technology, and used no solder of course.

Since each layer is built up in succession, between power and ground
planes, even BGAs can be accomodated.

You just named the problem with Multiwire--wire is sequentially
applied
to a thermoplastic substrate.

Whatever other advantages or problems it may have, it is a
*prototyping*
process, not a mass production process. It is to PCB production as
e-beam is to photolithography.