Increasing Multilayer Ceramic Capacitor Lifetime With Bipolar Voltage Cycling
Year: 2024
Type: article
Abstract: Enhancing the lifetime of multilayer ceramic capacitors (MLCCs) is critical in many aerospace, naval, or electrical grid applications, where device failure could lead to catastrophic consequences. The migration of oxygen vacancies from the ceramic to the electrode interface under constant bias is known to reduce the lifetime of oxide-based MLCCs. Bias cycling presents an opportunity to enhance MLCC lifetime by reducing oxygen vacancy migration. The ideal frequency range is expected to lie between frequencies low enough to avoid self-heating but high enough to avoid interfacial defect formation. However, the impact of low-frequency bipolar voltage cycling (BVC) on MLCC degradation mechanisms has not been well studied. This work investigates the impact of periodic BVC on the degradation of MLCCs through highly accelerated lifetime testing (HALT) on X7R capacitors. HALT tests were conducted at 255 °C and 60 V using different switching frequencies: 0 (dc), 0.1, 2.5, and 10 Hz. BVC was found to improve the lifetime of MLCCs compared to dc test conditions. MLCCs tested at 10-Hz BVC showed a 311% increase in average time to failure compared to the dc case. Impedance spectroscopy shows that BVC decreases the rate of resistance degradation within MLCCs, indicating that oxygen vacancy migration to the electrodes is mitigated. The impedance spectra taken on BVC samples highlight how grain boundaries play a vital role in trapping oxygen vacancies. Periodic cycling causes oxygen vacancies to become trapped at grain boundaries, resulting in oxygen vacancies taking longer to reach the electrode interface and thus increasing MLCC lifetime. This work highlights not only how BVC can be used to increase MLCC lifetime but also how periodically cycling MLCCs could increase lifetime in extreme environments, such as at elevated temperatures and electric fields.
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $2,495
Awards: NEW COMPETITIVE AWARD UNDER DE-FOA-0001953, TOPIC U: SF6-FREE
GEORGIA INSTITUTE OF TECHNOLOGY
CONTROL NUMBER 1953-1924
PROJECT TITLE: TESLA -- TOUGH AND ECOLOGICAL SUPERCRITICAL LINE BREAKER FOR AC, 1979-1524 GEORGIA INSTITUTE OF TECHNOLOGY
''PURE SOLID-STATE CIRCUIT BREAKERS FALL UNDER A NEW CLASS OF SWITCHGEAR WITH FAST SWITCHING SPEED AND FAULT
CURRENT LIMITATION. THESE CIRCUIT BREAKERS CAN BE DESIGNED TO CLEAR FAULTS IN DC OR AC POWER SYSTEMS –
INCLUDING BIDIRECTIONAL OPERATION IN DC POWER SYSTEMS. THEY ARE LESS PRONE TO WEAR THAN THEIR MECHANICAL
COUNTERPARTS, AND OFTEN DO NOT REQUIRE MAINTENANCE. HOWEVER, THESE ADVANTAGES OVER MECHANICAL CIRCUIT
BREAKERS ALSO COME WITH A CRUCIAL DISADVANTAGE: THE ON-STATE LOSSES OF POWER SEMICONDUCTORS DEVICES ARE
MUCH HIGHER THAN THOSE IN MECHANICAL CONTACTS, LEADING TO SIGNIFICANT POWER LOSS AND HEATING IN SOLID-STATE
SWITCHGEAR.''
OpenAlex ID: W4404178653