This size ceramic BGA on FR-4 would only work in very benign environments
(little or no DT). Solder columns would certainly be better, but for this
size BGA that is no guarantee either.  The reliability of your situation
needs to be assessed analytically and/or by accelerated reliability testing.
I recommend you look into J-STD-013, Implementation of Ball Grid Array and
Other High Density Technology, Section 7, Design for Reliability. 
I give a one-day workshop "Solder Joint Reliability for Advanced Packages:
BGAs, CGAs, TSOPs, etc." at conferences and clients as well as directly
consult with clients on solder joint reliability. 

Werner Engelmaier
Engelmaier Associates, Inc.
Electronic Packaging, Interconnection and Reliability Consulting
23 Gunther Street
Mendham, NJ  07945  USA
Phone & Fax: 201-543-2747
E-Mail: [log in to unmask]

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