Hello Tony,

You may wish to look at using components which do not require underfill such
as the compliant package structures manufactured by licensees of Tessera's
technologies
(most of the major semiconductor supplier make such offerings). They are cost
competitive when you consider all of the extra steps you avoid (and in light
of the problems you are experiencing). Sometimes apparently cheaper solutions
are more expensive when viewed at the system level. It is a value/price
consideration. If you are not familiar with their technology you can visit
their web site to learn more.

www.tessera.com.

Kind regards,
Joe