August 8, 2012 — Henkel Electronic Materials developed a new underfill system designed to reduce flip chip package stress by controlling die and substrate warpage, LOCTITE ECCOBOND UF 8840.
Flip chip silicon die and package substrates have different coefficients of thermal expansion (CTE). Flip chip die are increasingly thinner, which can lead to warpage during thermal processing. Upward (smiling) and downward (crying) flip chip warpage can reduce package reliability.
LOCTITE ECCOBOND UF 8840 is compatible with various flux systems, has minimum resin bleed out, is compatible with needle dispensing and non-contact dispensing and has a wide dispense process window. LOCTITE ECCOBOND UF 8840, has been formulated to flow consistently with no voids on flip chip die up to 15mm2. It can be used with a variety of die passivations.
Henkel tested the underfill against competitive materials, reporting less warpage and lower stress. The underfill delivered <80