Jim Blankenhorn has some excellent books on high density design.
www.smtplus.com


Don't know if you are trying to meet ipc specs.  I would imagine that
Even blankenhorns books are slightly out of touch now. They continue to
improve
Pick and place machines, stencil printing etc etc.  I routinely design
with 16 mils pad to pad and have
Done a lot of high volume production boards with no problems. I know
people who routinely design with 12 mils pad to pad for high volume
production. I think
7351 is head and shoulders above the old 782 spec. It would be
interesting to see
Who was on the committee and came up with the courtyard numbers. 

But I was at a presentation with Tom Hausher one night and that's
exactly what he
Was doing letting the courtyards touch and setting his body to body
clearance rules
To zero.  


-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Dave
Pollum
Sent: Wednesday, October 14, 2009 9:06 AM
To: [log in to unmask]
Subject: Re: [DC] clearance between SMD devices


 >Dave,
 >
 >Check for IPC-7351, the courtyard is what you need. Download the free
landpattern calculator or 
 >viewer from www.pcbmatrix.com and look for this info.
 >
 >Regards,
 >
 >Ioan Tempea, ing.

Ioan;
So does this mean that If select a medium courtyard that I can have one
courtyard touch another 
courtyard and I'll be OK, or do I need a gap between courtyards?
-Dave Pollum

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