New 'no flow' flip-chip underfill dramatically improves joint yield
New "no flow" flip-chip underfill dramatically improves joint yield
Keywords Multicore, Underfill
New, pre-deposited,self-fluxing flip-chip underfill from Multicore Solders reduces voids and incomplete filling in the manufacture of flip-chip assemblies while maximising joint yield.
Multicore E/U/1398 series is available for evaluation from Multicore Solders Advanced Products Division. It is pre-deposited as a liquid epoxy and acts as a flux for the solder reflow process. The underfill then cures to act as a high-performance epoxy encapsulant. Underfills enhance the reliability of flip-chip assemblies by preventing the ingress of moisture and other contaminants, and restricting the movement of solder bumps due to differential thermal expansion. Because it is pre-deposited (unlike traditional underfills that rely on capillary action to enter and occupy the gap between die and board), E/U/1398 fills the gap comprehensively, giving greater protection and the benefit of a greatly simplified deposition process.
The pre-deposition process is almost identical to applying die attach adhesive for COB construction, which has long established procedures and dispense patterns achieving thin, void-free bond lines. Continuing the analogy, wire bond yields, thus joint yields for flipchip, are of paramount importance to both the ultimate device yield and the potential reliability. The E/U 1398 series flux chemistry is specifically designed to give perfect soldering while eliminating the premature cure effects often associated with open or intermittent joints. The E/U/1398 series offers the combined benefits of simplified deposition, void-free gap filling and perfect soldering action in one material.
