Defect Detection of Multilayered Ceramic Capacitors with Resonant Ultrasound Spectroscopy

The performance of capacitors in circuits directly influences the battery life of medical devices used in human implants.  The surface mountable and multilayered capacitors in circuits have been the preferred choice for design requirements in limited space with excellent reliability.  However, some capacitors unexpectedly fail due to defects that typically contain micro-cracks permitting a passageway for migration of conductive metals.  The consequence of excessive leakage-current leads to shorting the circuit or drains battery power prematurely with potentially devastating results.  Using focused ion beam, micro-cracks in capacitors were created to simulate micro-cracks in dielectric filler and in electrode-dielectric interfaces.   The effects of cyclic thermal-and-mechanical treatments on capacitors were also studied.  Macroscopic vibration modes that interact with defects shift their resonant frequencies.   Using resonant ultrasound spectroscopy, the resonant frequencies were nondestructively measured and discussed the results of the frequency shifts.