Hi 'eholton', Marcelo, & Steve,
Lets remember why there are high-melt solder balls and columns on CBGAs; it is
to reduce the strains on the solder joints due to the large thermal expansion
mismatch between the ceramic and the FR-4 by assuring large solder joint
heights (stand-offs). It has nothing to do with cleaning, package weight, or
devices generating heat. For BGAs, particularly CBGAs, a reflow profile with a
peak temperature of 219C is too low even for eutectic Sn/Pb solder.
Even with high-melt solder balls you should get nice fillets because of the
eutectic solder paste.
The reliability of the solder joints goes up roughly with the square of the
stand-off height.

Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL  32174  USA
Phone: 904-437-8747, Fax: 904-437-8737
E-mail: [log in to unmask]

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