MLCC PCB Flexing

Gideon Analytical Laboratories received one MLCC (Multi-Layer Ceramic Capacitor) with a reported short. Ceramic capacitors are the most produced and used capacitors in electronic equipment. An MLCC consists of a number of individual capacitors stacked together in parallel and contacted via the terminal surfaces. Every MLCC basically consists of a ceramic dielectric, a metalized electrode, and connecting terminals. MLCCs can range in capacitance and voltage rating. Many times they serve to function as devices to reduce electrical noise and provide stability in an operating system. The goal was to use failure analysis to determine the cause of the short.

Failure analysis was conducted. There was some residual flux residue on the ceramic surface but this did not cause leakage on the capacitor. The MLCC was cross-sectioned and IR (insulation resistance) tested. After visual examination, the MLCC was found to have bottom cracking which exposed several of the electrodes. There were, in fact, several cracks; one crack ran from the bottom of the terminal to the top of the terminal extending through the entire capacitor width. This was caused by PCB board flexing which severed the ceramic.

There were several reasons for the PCB board cracking, including problems with the termination metal. Gideon Analytical Laboratories can not only diagnose the cause of a failure but advise companies on how to stop the failure recurring in the future. With this expert advice, companies will know if they have problems in-house or with a vendor. This knowledge can prove invaluable to companies and can save them enormous amounts of time, money, and headache in the future.

crack extending throughout the width of the capacitor

crack extending throughout the width of the capacitor

bottom termination and ceramic removed from cap

bottom termination and ceramic removed from cap

residual flux residue on MLCC

residual flux residue on MLCC

multilateral ceramic cracking

multilateral ceramic cracking

cross section reveals terminal cracks

cross section reveals terminal cracks

terminal crack

terminal crack