Curing kinetics and optimal cure schedules for underfill materials

The curing reactions and optimal schedules of three promising flip-chip underfill materials under isothermal and nonisothermal treatments are reported. It is found that curing reactions for three-tested underfill materials are autocatalytic, and the cure rate can be well described by the corresponding model. The activation energy, the rate constants, as well as two reaction orders m and n are determined to describe the curing progress. The temperature dependence of the cure degree for each heating rate is also investigated. It is found that the extent of reactions at a given temperature is a function of the heating rate. The glass transition temperature for the underfill UF-LI is determined as a function of cure degree. It is found that the glass transition temperature increases with the cure time. (C) 2000 Elsevier Science Ltd. All rights reserved.