Macintosh PCB Software FREE Re: [sdiy] Schematic toPCBproblems

[Jim Patchell]

    Flamed....not by me...I would say that is pretty accurate.  I probably spend a
bit more time doing schematic capture, but the board placement is right on...I have
clients that complain about the fact I spend more time on placing the parts on a PC
board than routing.  And the way I generally work it, placement is itterative with
the Schematic Capture...if changing the schematic will make the placement better, I
do it.  I have found if the rats nest looks like...a rats nest, it will be hard to
route.  Nice and clean is the way to go, if you can.

    -Jim

Grant Richter wrote:

> 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...
> >
> >