Hi, wonder if there's someone who can give me an idea of PCB
assembly. Being the holiday season I can't get a hold of any local
mftrs to sound them out, and I'd like to be using the time to move
ahead as far as possible with the layout.

I'm working on a board that has DIP on one side and some SMT
memory on the other. Consequently I need to route many address
lines from counters and data lines to the PICs. I've persisted with it
for a few days as a single-sided board but the time has come when
I realise this is not practical. Too many links and flying leads. So
the only choice I have is to go double-sided. I'm looking at an initial
run of probably 50 and don't want to get bogged down for days
snipping little bits of wire.

The cost of the board is important in that more money will have to
paid up front for the mftr but, as the items are leased and not sold,
in the long run it won't make a lot of difference. What I'm trying to
find out is more along the lines of easy of assembly.

The layout I've got has 250 conventional component holes but many
links and wires (=time). If I used vias or PTH the holes wouldn't go
down by much but the assembly time would. As a rough idea I'd say
there could be 50 vias. A few via connections will be accounted for
by component leads.

Is a via necessarily a PTH (which I know can be expensive) ?

If not, how is one side connected to the other using a via ? I've
seen boards that are obviously PTH and others that have a flat
pad of solder each end of the via, but I can't tell if those too are
PTH or whether they've somehow been filled with solder.

Any suggestions ?

Jinx