Jinx wrote:
>
> 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

Makes sense to me.

A via doesn't have to be a PTH, but - if it's not - you'd have to solder
a piece of wire in there, so you want PTH here as otherwise the VIAs
don't gain you much <G>

Those vias that have solder fills, were probably wave soldered or
soldered by dipping in a solder pot.  They're probably PTH, and then
"wicked" themselves full of solder.  Unless someone soldered a wire in
there, lots of work.

Hand-soldering jumpers is good for small or slow production runs, hard
work for fast production.  It's a tradeoff.

  Mark

--
I re-ship for small US & overseas businesses, world-wide.
(For private individuals at cost; ask.)