Surge test characteristics of high k multilayer ceramic capacitors

A severe under-damped case of surge test on high-K multilayer ceramic capacitors (MLCs), in which the surge current is determined by the inductance of electrical connection and a small current limiting resistor (0.5 Ω) is discussed. At a time scale less than 20 μs upon applying a voltage V₀ (0-275 V), the surge current is oscillatory, with the peak current increasing with V₀. The voltage across the MLC is also oscillatory, with the peak voltage exceeding twice V₀. The impact of surge current, voltage, and power on relaxor and barium titanate MLC under test is discussed. While both types of MLC can sustain similar current and power density, the failure of the relaxor MLC at a lower applied voltage (175 V) is related to the lower breakdown strength of the relaxor dielectrics. For a 50-V rated MLC, the peak transient voltage should not exceed 125 V