Reply-To: "Geraldo Sazias"
From: "Geraldo Sazias"
Subject: Re: EDA Software
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
Date: Wed, 25 Sep 2002 09:28:13 GMT
NNTP-Posting-Date: Wed, 25 Sep 2002 11:28:13 MEST
"Ban" wrote in message
> "Geraldo Sazias" schrieb im Newsbeitrag
> > "Trampas" wrote in message
> > news:nw5k9.39716$jF4.firstname.lastname@example.org...
> > > Hi,
> > >
> > > I am new to this group and was getting ready to start a project where
> > will
> > > be designing a PCB as such I was wondering if anyone had any
> > on
> > > PCB and schematic capture programs?
> > >
> > > Basically I will be doing surface mount boards with around 4-6 layers.
> > > will be doing about 3-5 projects per year as such I was figuring I
> > go
> > > with a good system that is easy to learn, even if I have to pay a
> > > more.
> > >
> > > I figure that the price range I will be looking for is the $1k to $10k
> > > range.
> > > Some of the things I will be doing include:
> > > BGA parts
> > > Multilayer boards
> > > FPGAs and CLPDs
> > >
> > > Some of the questions I have are:
> > > Schematic caputre, how easy to use, add parts, etc.
> > > Library editing, how easy is it to understand and add parts and
> > > layouts.
> > > PCB design, how good is the auto router, is their such a thing as a
> > > autorouter.
> > Try Eagle (http://www.cadsoft.de/).
> > There are good autorouters, but the placing of the components is
> > and you have to do that by hand. In general, you should group the
> > as in the schematic, then optimize the placement (keep pressing the
> > 'Ratsnest' button).
> Hi Trampas,
> Eagle is a good advice, I have done all of the above, but the critical
> 1. Use a grid that is not smaller than 1/4 the BGA pitch, place the BGA
> exactly on the grid. Fan out the lines. Change the grid settings to 12.5
> 25mil when doing the normal SMD and change the grid whenever another pitch
> is used. Do small segments to let all lines finish on the routing grid.
> 2. try to find a good placement by hand on a sheet of paper first, or
> with the BGA and other multiple pin parts first. place the parts so there
> are as few crossings as possible.
> 3. Now do the clock lines and other critical lines by hand and place the
> decoupling caps near the supply pins. Then do the power connections.
> 4. save the layout and rename it, then try the autorouter with a grid
> setting around 1/2 of the smallest design rule (trace or space width).
> 5. To make a good library part is not as easy, but with the handbook which
> only comes with the paid versions of Eagle this is not so difficult.
> There are a lot of more tricks to learn, try with a small board first and
> then slowly move to more complex designs, have your schematic and board
> layout inspected by an experienced engineer (BTW: I do this type of
I would place the main components (lC's, transformers, connectors) first and
then put the decoupling caps near the pins (these are of paramount
importance since not placing them close enough to the IC's may make your
design unreliable and prone to 'phantom' failures), then do the power
connections (if you're using power planes you can let the autorouter do this
for you if you set it with the right parameters, see the paperback manual),
then do the critical signal routing by hand and then place the remainder of
the components with as few crossings as possible in a nice and symmetric
layout. Then you can either finish the routing by hand or let the autorouter
take a shot at it. The Eagle autorouter is OK, but not as good as some more
advanced (shape based) routers such as Specttra, so I would prefer doing it