Patent ID: 8009442

Claim:
A method comprising: providing a semiconductor die and a substrate; coupling the semiconductor die to the substrate, wherein a gap remains between the semiconductor die and the substrate, wherein an open region extends laterally outward on the substrate on four sides of the gap, wherein the open region is not covered by the semiconductor die; placing an underfill material on the substrate, the underfill material comprising a polymer material and magnetic particles; positioning at least part of the underfill material in the gap; controlling the positioning of the underfill material using magnetic force, wherein the controlling the positioning includes controlling the flow of the underfill material so that the flow of the underfill material in the open region on the substrate is controlled by the magnetic force; wherein the flow of the underfill material into the open region is controlled so that the underfill material extends into the open region on the four sides of the gap on the substrate, wherein the underfill material extends no greater than 1 mm into the open region on the substrate on each of the four sides; and solidifying the polymeric material.