Patent ID: 9607916
Date: 2017-03-28
CPC Classifications: C09D,H01L

Claim:
1. An encapsulant material for a reflow underfill process welding a flip chip board having a solder ball to a substrate through a single heating cycle, the encapsulant material comprising: an epoxy resin mixture comprising a cycloaliphatic epoxy and a diglycidyl ether bisphenol A or a diglycidyl ether bisphenol F in a weight ratio of 1:3 to 3:1, the cycloaliphatic epoxy being any one or combination of 3,4-epoxycyclohexylmethyl and 3,4-epoxycyclohexanecarboxylate; an anhydride curing compound in an amount of 20 to 80% by weight of the epoxy resin mixture; a catalyst in an amount of 0.2 to 5% by weight of the epoxy resin mixture, the catalysts comprising a metal acetylacetonate, a metal acetate or any combination thereof; a fluxing agent in an amount of 1 to 15% by weight of the epoxy resin mixture, the fluxing agent comprising any one or combination of ethylene glycol, propylene glycol, glycerol, glycerol D-ribose, and diethylene glycol; and a nanoscale inorganic additive in an amount of 1 to 30% by weight of the epoxy resin mixture, the nanoscale inorganic additive being nanoscale alumina, wherein the single heating cycle is enabled by way of providing the encapsulant material to a first interim assembly, which is formed by placing the flip chip with the solder ball in contact with the substrate at a first temperature, to form a second interim assembly in heating at a second temperature and subjecting the second interim assembly to a third temperature sufficient to melt the solder ball, and wherein the second temperature is lower than the melting temperature of the solder ball and at least as high as the first temperature.