[sdiy] I could use a few pointers on doing a board layout

[harrybissell]

OK I'm in...

1)  YES by all means route power traces and grounds first, along with
decoupling caps.  I prefer to route the +/- and ground beneath each
IC between the .3" dimension  (assuming through hole) on the SOLDER
side of the board.  Youc an fit three .040" traces underneath the IC on
the
solder side. Use small vias to change directions.

2) once you set those power and ground traces, run all lines PARALLEL
to those traces on the Solder side as well

3) Run all traces on the COMPONENT side at 90 degree angle to the solder

side traces.

4) Use VIAS where ever you need to change direction from horizontal to
vertical.
(break this rule ONLY if you are so close to the target pad that you
could not
possibly fit a trace between the via and the pad.

5) I run axial componentsoriented in the direction that pins 1 and 8
would be on the
ICs. This lets you route traces between component leads AND through IC
pins on the
COMPONENT side of the board.  I never run traces between pins on the
solder side
to avoid solder shorts

6) Group all components that go 'with' a particular IC in line with the
pins of that IC...
Picture an 8 pin dual opamp... the feedback resistor goes from pin 1,
the inverting
input resistor goes to pin 2.  Run these on the COMP side.  Keep the
traces on
input pins short.  If you have a long run, run it from an output through
a long trace...
and keep the resistor at the input pin and SHORT. The long run will be
tied to the
output for most of the way and won't pick up noise.

7) The name of the game is ROUTING CHANNELS.  The techniques I've
described
keep the maximum number of options open. DO NOT try to save 'vias'.
They don't
cosr much and the blocking of a routing channel to save one hole will
cost time and
money later.

8) Do complete netlist checking if the program allows it. Make sure that
EVERY
complaint is accounted for (you might say, OK I know that run is close,
or off grid)
but NEVER accept any schematic errors. Resolve them all

9) Fvck autorouting. Need I say more on the subject ???   :^P

10) Spend a couple of hours when you are finished to do clean-up work.
Its called
ARTWORK... and it should be beautiful when its finished. I'll get a
little 'mystic'
on you now and say that if the layout is NOT beautiful when done, look
out for stupid
schematic or design errors.  Now is the time to remove excess vias.
Make sure that you have all the testpoints you'll want... add some extra
holes for power and ground
(you might need to hook up some more panel stuff, right ???)

Rock out !

H^) harry

Jeff Farr wrote:

> While we're talking about eagle, I've still got a few pressing
> questions.  I've got some nice schematics drawn up (like the ARP 4035
> ladder filter module) and believe I'm ready to being making a board.
> And here the process comes to a screeching halt.  I've now made
> several attempts, but really can't get anything remotly exceptable.
> Should I try to lay down traces for the supplies and ground first?
> why don't the icons for supply show up as something on the board
> screen?  I'm using the freeware version so I don't have the
> autorouter, is this worth the money?