Patent ID: 7279359
Filing Date: 2007-10-09
Classification: H01L

Abstract:
1. A method of attaching a chip to a substrate, comprising: placing an underfill material on the substrate having one or more conductive pads, wherein the underfill material comprises an epoxy resin, an amine-based epoxy hardener, and a fluxing agent that is enclosed into a polymer capsule, wherein the fluxing agent activates at a fluxing temperature and is neutral and does not react with the amine-based epoxy hardener below the fluxing temperature; providing the chip having one or more conductive bumps; pre-heating the chip and the substrate; placing the chip on the substrate such that the one or more conductive bumps are placed on the one or more conductive pads and the underfill material is between the chip and the substrate; increasing the temperature of the chip and the substrate to reach the fluxing temperature to activate the fluxing agent by breaking the polymer capsule; and further increasing the temperature of the chip and the substrate to reach the reflowing temperature to form conductive joints between the one or more conductive bumps and the one or more conductive pads.