An underfill material is presented that may be used between an electrical
component and a substrate. The underfill material may be a cured epoxy
resin composition comprising a liquid or semisolid epoxy resin and a
polyfunctional anhydride polymer and/or oligomer curing agent. The use of
anhydride polymers and/or oligomers decrease the volatilization of the
composition, thereby reducing the porosity of the underfill material. By
changing substituents of the anhydride polymer and/or oligomer, the
underfill material may be designed to modify viscosity, decrease moisture
adsorption, volatilization and modulus, improve mechanical properties,
and enhance adhesion.