Formulation of Mathematical Models for Estimating Residual Strain and Stress Components Correlated with 3-D Flow of Thermosetting Compounds

A method for continuously analyzing three-dimensional flow, variation of strain components and Young's modulus after gelation during the molding process of thermosetting compounds has been developed. In this analysis, Kamal's model was used to calculate the degree of cure and heat generation. A viscosity model was formulated as a function of temperature and degree of cure. Strain components were calculated by adding the contributions due to curing shrinkage and thermal change. The strain component due to curing shrinkage was modeled as a function of degree of cure. The strain component due to the thermal change was calculated as a function of temperature and the coefficient of linear expansion by considering the glass transition temperature. Young's modulus was calculated as a function of the degree of cure and temperature in relation to the glass transition temperature. These models were integrated using FLOW-3D® software, which is typically used for multipurpose 3-D flow analysis. Using the newly developed system, the molding process of a diode package was analyzed. The flow behavior in the mold cavity, the changes in the strain components and Young's modulus after gelation were calculated continuously. The proposed method can be utilized for the prediction of residual strain and residual stress in final products caused by flow and curing behavior during the molding process.