Patent ID: 6815258
Filing Date: 2004-11-09
Classification: H01L

Abstract:
A method for forming an electronic structure, comprising:providing a substrate with a conductive pad coupled to the substrate; providing an electronic device with a solder member coupled to the electronic device; soldering the solder member to the conductive pad to form an electrically conductive interconnect that couples the electronic device to the substrate, wherein the solder member is transformed into a solder portion of the electrically conductive interconnect; dispensing an underfill in a space between the electronic device and the substrate, wherein an upper portion of the underfill is adjacent to the electronic device, wherein a lower portion of the underfill is adjacent to the substrate, wherein the underfill encapsulates the electrically conductive interconnect, wherein the underfill comprises a resin and a filler, and wherein the density of the filler is less than the density of the resin; and curing the underfill after which a weight percent concentration of the filler in the underfill is higher in the upper portion of the underfill than in the lower portion of the underfill.