There is nothing intrinsic to 6012 class 3 that precludes any feature size.
Rather it is the design for conformant manufacture of the hardware that is the problem.

Many, many designs get you into a situation where there are only a handful of fabricators who have the capability.
I don't think 1.0 or 0.8 BGAs are such a design feature, unless it is a VERY large BGA.

Chris

Chris Mahanna
Robisan Lab

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Whittaker, Dewey (EHCOE)
Sent: 2012/04/12 9:41 AM
To: [log in to unmask]
Subject: Re: [TN] 1.0 and 0.8 mm Pitch BGAs cannot meet Class 3?

Phil,
The only thing I had to give up was the internal MAR requirement. We specify any measurable amount with no breakout allowed. We specify tear-dropping (filleting) for those vias.
Dewey 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Phil Bavaro
Sent: Wednesday, April 11, 2012 4:27 PM
To: [log in to unmask]
Subject: [TN] 1.0 and 0.8 mm Pitch BGAs cannot meet Class 3?

I am being told that it is not possible to layout a BGA for IPC-6012 Class 3 if the pitch is 1.0 or 0.8 mm.

I am not a board designer but this doesn't sound right to me.   I had a
lot of experience with BGAs at 0.5 mm pitch but that was always with Class 2 requirements.

Is anyone laying out PWBs with 0.8 mm pitch BGAs and still meeting Class
3 for spacing?  


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