To obtain an underfill material which is excellent in preservation stabilty and penetration into gaps and gives a highly reliable cured item by incorporating a liquid epoxy resin, spherical silica prepared by heating and burning spherical polyorganosilsesquioxane particles, and a cure accelerator into the same.
This underfill material for flip-chip semiconductor devices contains 100 pts.wt. liquid epoxy resin; 100-300 pts.wt. spherical silica which is prepared by heating and burning spherical polyorganosilsesquioxane particles, has a max. particle size of 50 μm or lower and an average particle size of 0.5-10 μm, and contains 0.005-0.1 wt.% carbon particles on the surface; and 0.01-10 pts.wt. cure accelerator. A flip-chip semiconductor device has such a structure that a semiconductor chip 3 is mounted, via a plurality of bumps 2, on the wiring pattern face of an organic substrate 1; the gaps between the organic substrate 1 and the semiconductor chip 3 are filled with the underfill material 4; and the side is sealed with a fillet material 5.
SHIOBARA TOSHIO
SUMIDA KAZUMASA
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