A method of the measurement of moisture in IC packages using microwaves

A new method to measure the moisture content of integrated circuit (IC) packages is demonstrated. The moisture contained in the encapsulant resin was determined by using microwaves. The microwave signal was transmitted into the encapsulant resin and reflected at the surface of the chip pad. The amplitude and phase of the reflection coefficient of the microwave signal, which varied with the moisture content of the encapsulant resin, were measured in order to determine the moisture content. A preliminary experiment was carried out, and the calibration equation was developed. The present technique indicates the possibility of determining the moisture content directly without drying and weighing IC packages.