| Low temperature cofired ceramic (LTCC) of CaO-B{dollar}sb2{dollar}O{dollar}sb3{dollar}-SiO{dollar}sb2{dollar} offers low loss dielectric characteristics and compatibility with Ag as the best high frequency conductor. Three major issues in applications are addressed, variability, resistance to electromigration, and thermal conductivity. A theoretical model was developed for RF energy loss in LTCC systems and validated. The model enables the determination of loss contributions by the conductor and dielectric over a wide frequency range. The dependence of dielectric loss on microstructure was also established. The model was validated using three ceramic/conductor systems, Al{dollar}sb2{dollar}O{dollar}sb3,{dollar} CaO-B{dollar}sb2{dollar}O{dollar}sb3{dollar}-SiO{dollar}sb2,{dollar} and Al{dollar}sb2{dollar}O{dollar}sb3{dollar}-CaO-SiO{dollar}sb2.{dollar} A mechanism for failure of recrystallizing CaO-B{dollar}sb2{dollar}O{dollar}sb3{dollar}-SiO{dollar}sb2{dollar} LTCC with Ag electrodes under highly-accelerated stress testing was determined and validated. Failure modes observed ranged from increased leakage to catastrophic events. The activation energy for the breakdown mechanism was determined. The thermal conductivity of the LTCC systems is poor. A novel composite approach using diamonds to circumvent this problem in practical applications was demonstrated. |
