Failure Analysis of Capacitors

Multilayer Chip Capacitors (MLCCs), Tantalum Capacitors, Aluminum Electrolytic Capacitors, Film Capacitors

At SEM Lab, Inc. we analyze failures in four types of capacitors: Multilayer Chip Capacitors or MLCCs, Tantalum Capacitors, Aluminum Electrolytic Capacitors, and Film Capacitors. Some common failures are seen in the figures below. The capacitor construction and failure characteristics unique to each device are described in the figure captions..

More detail on failures in Film Capacitors can be found here.

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Other device failure analysis information:


Multilayer Chip Capacitor (MLCC)

Fused Ni and BaTiO3.

Fused Ni and BaTiO3.

The distortion in the plate structure suggests there was a fabrication anomaly associated with this MLCC capacitor.

Distorted electrodes.

This is an apparent “knit line crack”, which is a MLCC manufacturing defect

Knit line failure.

Flexure crack in an MLCC.

Flexure crack in an MLCC.

Tantalum Capacitor

Ta Capacitor

Optical image of the top of a Ta Capacitor. There is a burn mark and fracture visible on this surface..

Breakdown site in a Ta Capacitor

SEM image of the microsection of a Ta Capacitor. The primary failure site is associated with the edge of the slug near the lead attachment at the cathode.

Tantalum-oxide dielectric layer (arrows) in a Ta capacitor.

Tantalum-oxide dielectric layer (arrows) in a Ta capacitor.

The MnO2 deposit region of a Ta Capacitor.

The MnO2 deposit region of a Ta Capacitor. The region appears normal though slightly granular near the outer layers of the deposit.

Aluminum electrolytic capacitor

A dissected Aluminum Electrolytic Capacitor

A dissected Aluminum Electrolytic Capacitor.

FTIR spectrum of the electrolyte from inside an aluminum electrolytic capacitor.

FTIR spectrum of the electrolyte from inside an aluminum electrolytic capacitor.

An aluminum electrolytic capacitor after unrolling. It shows internal the connection of the negative terminal (cathode) to the cathode foil.

An aluminum electrolytic capacitor after unrolling. It shows internal the connection of the negative terminal (cathode) to the cathode foil.

Film capacitor

Secondary Electron SEM image of the end of a film capacitor roll.

Secondary Electron SEM image of the end of a film capacitor roll.

A thicker deposit of evaporated aluminum is applied to one edge of the film to withstand the thermal exposure during flame-spray termination of the capacitor layers during fabrication. The Al-peak is higher in EDS spectra of thicker aluminum deposit and can be used as a measure of aluminum thickness.

A thicker deposit of evaporated aluminum is applied to one edge of the film to withstand the thermal exposure during flame-spray termination of the capacitor layers during fabrication. The Al-peak is higher in EDS spectra of thicker aluminum deposit and can be used as a measure of aluminum thickness.

This is a microsection at the end cap showing a region where the endcap is not connected to the capacitor plates, which would likely result in lower than expected capacitance.

This is a microsection at the end cap showing a region where the endcap is not connected to the capacitor plates, which would likely result in lower than expected capacitance.

The flame-spray end cap is zinc. The termination to the zinc end cap is eutectic tin-lead solder.

The flame-spray end cap is zinc. The termination to the zinc end cap is eutectic tin-lead solder.