Temperature effects on electrical characterization of high dielectric constant substrates

In this study, the polymer/ceramic composites with high dielectric constant (HK=20 substrate) were prepared to investigate the temperature effects on electrical properties. The material properties of HK substrate were compared with those of FR4 substrate and MLCC-NPO capacitor device. Curie temperature of the HK substrate could be obtained from the curves of current densities varied with temperatures. The dielectric strength of the HK substrate was higher than 200 kV/cm in the temperature range between 25°C and 125°C. The dielectric constants (DK) were slightly decreased but the dielectric losses were increased as the temperature higher than 100°C. Moreover, an effective value near 0.74 eV of the trap depth and barrier height was predicted by Frenkel-poole and Schottky-controlled process. Furthermore, Electrical properties of HK substrate after thermal treatments were also measured in this study. It was found that the variations of capacitance (¿C/C) and dielectric loss (¿DF/DF) of HK substrate were about <±3% and <±20% respectively, after thermal cycle of 85°C for 1000 hrs. The temperature coefficient of capacitance (TCC) of HK substrate near -300 ppm/°C was also obtained as measuring temperatures range from 25 to 125°C. These results indicated that the HK substrates have excellent electrical properties to meet the applications of embedded capacitors via PCB process.