TSDC measurements of underfill encapsulant used in microelectronic packaging

The thermal stimulated depolarization current (TSDC) technique was used to study the dielectric relaxation of underfill encapsulant used in microelectronic packaging. The dependence of electrical properties of the underfill on the polarizing temperature, polarizing field and heating rate were analyzed from the TSDC spectra as a function of temperature. A single α-relaxation peak associated with the glass transition temperature T_g of the underfill was observed. A value of Tg can be estimated which can be compared to the T_g determined by differential scanning calorimetry (DSC). The activation energy and relaxation time of the dielectric relaxation of the underfill were determined from the TSDC measurements.