Todays forums are sponsored by Ian Martin Limited
Engineering/Technical Placement Specialists

> Okay, wait a minute here. Protel, PowerPCB, Cadence, Mentor, they are all
> just tools. If you are designing a board outside the limits of any
> "autorouter" then you need to use the "skill sets" that made you able to
> design pcb's in the first place! I've used many different CAD packages and
> NONE of them can route a layout as good as "I" can. I have always routed
> fine pitch fan-outs by hand anyways, then let the router try, when it
> or gets like 98% completion, I know that my job is to make it right! And I
> like it! Any monkey can push a "route all" button!!!!

Well stated Jeff,

I am glad we are on this topic, because this topic is one of the most
important  requirements for any  autoroouter to perform.  As one of the
first functions, it will control how well the  router  later performs.    I
hope Protel is placing much emphasis on this  issue before release of the
new router.

I have found that even with a high end tool like Spectra  , the fan out
interface is clunky, slow  and the graphics is dos looking.  The interface
is not good enough for anyone to look at it for more than 30 minutes.     I
fan out everything  manually in Protel as do some of you .  Protels graphics
are easy on the eyes, commands are at most two keys, and I can hit the
center of every pin.     To  fan out components,  I use that $5000.00 option
(PADS pun intended)   called cut and paste.  Several the reasons  I fan out
in Protel are:   I can control direction of the fan out,  I can control the
length of the fan out, I can inspect my layout to see if decoupling is
installed backwards, ( ie the power node is the furthest from the pin I wish
to decouple ), And most importantly  I can control the size of routing
channels.  This is something that no router with "fan out" takes into
consideration, Size of the routing channel.    I will also manually  route
critical nets, and short stubs that obviously should not drop a layer.
Spectra  has control both in numeric (mils) and scaled  ( 0-256) values  for
different features including fan out. Direction of fannout can also be
controlled,  in verses out. However the size of the routing channel is a
still a  guess as it in Protels router.  Calculating fan out in mils , in
vs. out , etc is awkward and is not of much use.   I know we have all seen
the canned Spectra demos, but in reality I can manually  fanout about 10
times faster in Protel than Spectra.
Neither Spectra and Protel will automatically fanout to the  center of the
pin, though spectra has a command to tell it to hit the center of the pin.
Again awkward,   my cut and paste snaps to center everytime.  Neither router
can fanout a  pattern that is usable for good routing.  A good routing
channels is  open both vertically and horizontally to allow room for tracks
and spacing.  Much has been written about leaving routing channels open. , a
good router should make the calculation before fanning out,   That router
does not yet exist.

Mike Reagan
Frederick MD

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* To post a message: mailto:[EMAIL PROTECTED]
* To leave this list visit:
* http://www.techservinc.com/protelusers/leave.html
* Contact the list manager:
* Forum Guidelines Rules:
* http://www.techservinc.com/protelusers/forumrules.html
* Browse or Search previous postings:
* http://www.mail-archive.com/proteledaforum@techservinc.com
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

Reply via email to