Homebrew PCBs

If you want to do a single sided board with the autorouter, in the
autorouter setup dialog box, look in the preferred directions group
and select N/A for layer 1 Top.  The autorouter will try to do a
single sided board.  Dont be suprised if it gives up, its pretty
stupid (like most autorouters).  You will pretty quickly discover that
some boards simply cant be done single sided. Especially if you do
surface mount stuff.   And of course you have heard dont waste your
time with the autorouter - sage advice.

Its not that bad to do double sided boards, though.  You just have to
lay out your board with what I call "non-plated through hole design
rules".  Basically, where you have an inaccessable pad (like a socket,
relay, crystal, flush mounted LED, etc), you simply put a via to the
solder side.  With eagle, you just drop a via on the trace near the
pin in question and then mirror the trace between the via and the pin.

Vias are easy to do.  Take a thin piece of wire (I use stripped 28 Ga
from discarded cat 5) and thread it through all the via holes.  Then
solder both sides of each via and snip off the wires as flush as you
can.  A quick touch of the iron cleans up the vias but its not
necessary.  You can also use a DMM to buzz out your connections before
you snip off the wire.  With this technique, I can do a lot of vias in
10-15 minutes or so.

Phil

--- In Homebrew_PCBs@yahoogroups.com, "upand_at_them"
<upand_at_them@y...> wrote:
> I just realized something...
> 
> How can I solder a two-sided board if I'm using sockets for the 
> IC's?  Ugh!
> 
> And some of the traces *can* be moved to the bottom, but Eagle is 
> routing them on top.
> 
> Mike