Reaction Kinetics and Rheological Model Coefficient Extraction for Epoxy Mold Compounds

• Published in: 2018 17th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm) pp. 1106 - 1111
• Main Authors: Sakib, A R Nazmus, Jha, Vibhash, Mavinkurve, Amar, Chopin, Sheila
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01.05.2018
• Subjects: Analytical models; Compounds; Conferences; Curing; Curing Kinetics; Instruments; Kinetic theory; Mold Flow Simulation; Reactive Viscosity Model; Viscosity
• ISSN: 2577-0799
• DOI: 10.1109/ITHERM.2018.8419482

Mold compound is used as an encapsulant for semiconductor chips and protecting it from environmental exposure in the forms of moisture, temperature and mechanical shock. Epoxy mold compounds are complex viscoelastic materials that change rheological properties during curing in the transfer molding process. Mold flow simulation requires correct material model parameters for accurate prediction of flow front behavior and other critical packaging issues such as mold voids and wire sweep. This modeling typically requires viscosity as a function of degree of cure, temperature and shear rate. The focus of the paper is to describe methodology to extract coefficient of the Kamal model and Castro-Macosko model that will be used for predictive mold flow finite element simulation. For reaction kinetics parameters, DSC was used to characterize degree of cure at different temperatures. Three different heating rates were used in non-isothermal tests, where the heat of curing reaction is depicted as the exothermic peak in the DSC data. In addition to curing kinetics model, rheology tests are essential to understand variation of viscosity with respect to degree of cure, temperature and shear rate. In this study, curing kinetics and rheological properties were characterized for a commercially available epoxy molding compound that is widely used for encapsulating semiconductor chips.