Homebrew PCBs

On Thu, 04 Mar 2004 17:52:42 -0000, Phil <phil1960us@...> wrote:

> to continue on this thread.  I've found that if I lay out my board
> and then look at how the traces run, I can make a few tweaks and
> significantly reduce routing complexity.  For example, I put an LCD
> display header on a board I'm doing now.  after first routing, I
> noticed that a couple of the traces were going all over the place.  I
> went back and switched 2 of the control lines going imto the micro-
> controller and rerouted.  wow, what a difference, the traces were
> direct and I was able to get rid of 8 vias (4 top side wires).  Its
> still 2 sided but, my design is now much more manufacturable in my
> little "pcb factory".

there are 2 things:

A) placement of parts

B) exchangeabe pins

Orcad does support exchanging of pins and also of complete function blocks
(like in a logic IC).
This is very handy.


>
> Another thing is that routers are pretty dumb.

I nearly never use a autorouter. only for placement.
sometimes i place the components like i think it is best, then i let
the autorouter work and see where the problems are. then i move parts 
around
to resolve most.
but i always unroute the board and do it myself. the autorouter results i 
get are
simply unuseable.
Only if i know a particular board is "strictly one time only proof of 
concept", just
switched on once and then dumped i will autoroute it completely and then 
never look at it
again.

Autorouter just doesn't match up with my "routing is an art" opinion.
And the result also doesn't match up with what is my minimum demand.

ST