Hi Dave,
>Ioan - I have seen two very distinct camps of though on solder joint voids:
>one camp believes that solder joint voids behave in a classical manner-
>the void "blunts" the crack propagation and slows down the growth of the
>crack; the second camp believes that the solder joint voids do not
>participate in crack propagation in any form.

Actually, the 2 camps you perceive are not mutually exclusive. Chuck Schmidt
of SRI showed that the vois to in fact blunt crack propagation. However, the
blunting is very local--remember, unlike the crack in a bell being stopped by
a hole drilled at the whole of the crack tip--, the void occupies only a
small part of the total crack front. Thus,  the blunting is limited to the
very local area of the void, and as soon as the crack front goes beyond the
void, the crack front retardation at the void rapidly catches up with the
rest of the crack front.
Thus, voids both 'blunt' crack propagation but because of the local and
temporary nature of the 'blunting' they make any real difference.

Best regards,
Werner Engelmaier

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