Reliability of X7R MLCCs Under Alternating Polarity Highly Accelerated Lifetime Testing

The effect of alternating polarity stressing on the lifetime of X7R multilayer ceramic capacitors (MLCC) was investigated. Lifetimes of MLCC's subject to voltage and temperature acceleration were measured as a function of switching frequency of the applied voltage. A custom-built HALT system capable of performing automated testing with alternating polarity of voltage application was used. Under increased temperature acceleration, it was found that applying alternating polarity bias increased the lifetime of parts in comparison to unipolar DC conditions. Under increased voltage acceleration, the lifetime of MLCC's decreased in comparison to DC conditions. These trends, changes in the failure mode under different conditions, and potential causes are discussed.