Macintosh PCB Software FREE Re: [sdiy] Schematic to PCBproblems

[Grant Richter]

This is sure to get flamed, but what the heck...

Here is a schedule for an experienced layout person doing a 4x6 inch PCB
with 15 chips and 100 resistors.

Schematic capture  2 hours
Error Checking     6 hours
Board Placement    6 hours
Routing            4 hours
Build 1st board    2 hours

Total              20 hours

Here is a schedule for an inexperienced board layout person doing the same
board

Schematic Capture  1 hour
Error Checking     0 hours
Board Placement    1 hour
Routing            48 hours
Build 1st board    48 hours

Total              98 hours

I know because both those people are ME.

With CAD systems, if your schematic has errors, your board will have errors.
You will save the most time by checking your schematic until your eyes bleed
(a zero is not an O, and OUTI will not connect to OUT1). Then spend a huge
amount of time improving the parts placement. After that you can pretty much
sleep through routing, because an optimal parts placement will give you the
shortest routing for every trace.

Also route your ground nets first, then the balance of the power nets. THEN
your signal traces. In practice, funky ground and power routing will create
more problems then funky signal routing. Try to avoid running power through
other chips pins. In other words, avoid using chip pins as vias for power
nets. You may need to add additional decoupling to certain chips (hotwire in
a series resistor and tantalum cap), and you can't do that if more than on
chip is connected to the trace.

> From: Joshua Stephen Landau <jslandau at engin.umich.edu>
> Date: Mon, 3 Jun 2002 23:57:34 -0400 (EDT)
> Cc: <synth-diy at dropmix.xs4all.nl>
> Subject: Re: Macintosh PCB Software FREE  Re: [sdiy] Schematic to PCBproblems
> 
> Speaking for myself, there's at least one beginner who would be *very*
> interested in routing lessons.  Sad truth is, at least at UMich, they no
> longer teach PCB design to their electrical students.  So any help that
> can offered, general practice, tips, design theory, etc, would be much
> appreciated.  If I'm the only one, offlist is fine, but I suspect others
> on the list would benefit greatly.
> 
> Josh
> 
>> There are  lots of people on this list who could probably help you get
>> started
>> in manual routing.  Start with some really simple project to get the idea.
>> Then
>> if
>> you want to get an autorouter you'll be better equipped to deal with it. I
>> can
>> give you some tips if you like (offlist) or if there are other beginners we
>> could do a bit
>> of an onlist class.  It would probably benefit a lot of folks out there...
> 
>