Capacitor Failure Analysis
Multilayer Chip Capacitors (MLCCs), Tantalum Capacitors, Aluminum Electrolytic Capacitors, Film Capacitors, Failure Analysis
At SEM Lab, Inc. we perform capacitor failure analysis for several types of capacitors including: Multilayer Chip Capacitors or MLCCs, Tantalum Capacitors, Aluminum Electrolytic Capacitors, and Film Capacitors. The differences in capacitor construction are described below as well as some common failure mechanisms observed during capacitor failure analysis. Failure analysis of capacitors often focuses on the quality of construction techniques used during the manufacture of these devices.
Multilayer Chip or CERAMIC Capacitor (MLCC)
Multilayer chip capacitors (MLCCs) are usually the capacitor of choice when low value capacitances are needed. MLCCs construction consists of a ceramic block with parallel rows of sintered electrodes within, creating alternating layers of ceramic and metal. These metal electrodes come to the surface at the ends of the ceramic block and attach to connecting terminals.
A Tantalum capacitor is an electrolytic capacitor. A piece of tantalum metal acts as an anode and is covered by an insulating oxide layer that forms the dielectric. This is surrounded by liquid or solid electrolyte which acts as a cathode. Tantalum capacitors are usually chosen when high capacitances per volume and lower weight are required.
Aluminum electrolytic capacitor
An aluminum electrolytic capacitor consists of an anode made of thin aluminum foil with an etched surface. Anodization forms a very thin insulating layer of aluminum oxide on the aluminum that acts as a dielectric. Aluminum Electrolytic Capacitors provide the largest capacitance values per unit volume compared to ceramic and plastic film capacitors.
Film capacitors use a thin insulating plastic film as the dielectric with evaporated aluminum conductor on one side of the film. This metallized film along with a counter electrode is rolled into a cylinder. Metal terminations are then added and the assembly is mounted into a protective case. Film Capacitors are chosen when low cost, stability, and low inductance are required. Some types of film capacitors, are metallized polyester, polypropylene, PTFE or polystyrene film. More detail on failure analysis of Film Capacitors can be found here.