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Hi Bev - in theory, a shrinkage void in a solderball is the same physics
as a shrinkage void in a aluminum or steel casting so no, the shrinkage
void would not have to necessarily always reach a surface. However, after
looking at several hundred SAC BGA/CSP cross-sections, I have nearly
always (99.999%) found a path of a shrinkage void to the solderball
surface. Because we have a very limited and very small molten solder
"volume", I think you will find a surface connection. And I guess I'll
bite - why the question?
Dave Hillman
Rockwell Collins
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Bev Christian <[log in to unmask]>
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04/20/2010 08:16 AM
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[TN] SAC Shrinkage Voids in BGA Balls
TechNetters,
Do all SAC shrinkage voids in BGA balls reach/start at the surface of
the ball? I realize I may be stumped by a 2D cross-section of a 3D
phenomenon, but I thought I would ask this august body.
Bev
RIM
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