Kinetic Characterisation of Molding Compounds

During the packaging of electronic components stresses are generated due to curing effects and the difference in thermal shrinkage between molding compound and die. For a reliable simulation of the stresses generated in a package during cure and subsequent cooling it is essential to have accurate data for the thermal and mechanical properties of the molding compound, die, solder and substrate materials. Of these materials the molding compound is by far the most difficult one to model since these properties vary widely and are time, conversion and temperature dependent. The present paper consists of an extensive study on several commercial molding compounds of which the kinetic parameters we obtained by analysing both isothermal and non-isothermal differential scanning calorimetry (DSC) data. For the modelling of the kinetics data it turned out to be necessary to take the diffusion limitation effect (incomplete cure at lower temperatures) into account. The glass transition versus conversion could be modelled satisfactory using the well known DiBenedetto equation.