Just one note on split planes.  High speed signals crossing splits in either power or ground (they're the same for AC), there will be a reflection due to the sharp impedance change.  Of course the effect will vary depending on trace length and split length and locations of nearby bypass caps.  In general you should avoid that situation as it will increase the EMI and reduce the signal integrity.
Tom

Julian Higginson wrote:
From: JaMi Smith [mailto:[EMAIL PROTECTED]]
    

  
While there may be some way somewhere to make Protel ignore 
those dogbones
and vias, DRC wise, I don't think that there is a way to do 
it easily short
of putting them on the schematic, possibly as test points, so 
that each of
them actually becomes a real "net" it the netlist. You could 
turn off some
of your Design Rules, but that would really just be asking 
for more trouble.

    
yeah there is a way:

Don't use synchronisation in the ddb, use NETLIST GENERATION and NETLIST
LOADING. 

In the netlist generation in schematic, you can tell it to include unnamed
single pin nets. You will then get nets assigned to all your unused pins on
your BGA.

  
I would also suggest that you definitely look into using separate 
complete layers for power and ground under your BGA as opposed
to trying to juggle split planes.
    

Jeez. How many layers does he have spare for power planes?? my BGA needed 3
of the buggers. Split planes are the only way to go. Just be really careful
not to bridge them with a through hole pin like I did... 



Julian
(who got his BGA board not reporting errors, and the BGA part of it is fine)



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

  

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

Reply via email to