Patent ID: 7218007

Claim:
An underfill material for use with a semiconductor die device coupled to a substrate by conductive bumps and ball limiting metallurgy, said underfill material comprising: filler particles, wherein a weight percentage of said filler particles in said underfill material is at least about 60%, wherein a particle size of at least 90wt % of said filler particles is less than about 2 μm or said filler particles are coated by an organic coupling agent, wherein a coefficient of thermal expansion of said underfill material, once fully cured, is no more than 30PPM/° C., wherein if said underfill material is exposed to a temperature of up to 110° C. for no more than 5 minutes, viscosity of said underfill material increases by no more than 20%, wherein if said underfill material is exposed to a temperature below 180° C. for at least 20 minutes, cross-linking density of said underfill material becomes at least 50% or said underfill material does not flow, wherein said underfill material becomes fully cured if exposed to a temperature below 180° C. for less than 3 hours, and wherein a glass transition temperature of said underfill material, once fully cured, is at least 100° C.