Typical multilayer ceramic chip capacitors consist of multiple dielectric and electrode layers sandwiched together. Internally, the standard MLCC operates as multiple capacitors connected in parallel. In this arrangement when one of the capacitors experiences insulation breakdown, the entire capacitor bank will short-circuit. However, if two MLCC’s are connected in series and one of them experiences insulation breakdown, the system will continue to operate. TDK's serial design CEU series features a special internal electrode structure similar to two capacitors connected in serial.
The CEU series is also a dual-fail safe design, meaning that it employs not only short-circuit mitigating aspects with its internal serial configuration, but also a flexible termination layer to absorb and soften bending stress of the PCB. In potential PCB flexure situations, the bending of a circuit board can cause cracking and lead to a short-circuit with standard MLCC’s. To contest this problem, design engineers would often employ a two capacitor approach in a real estate consuming, 90° configuration that offers single fail safe security.
The dual-fail safe design of the CEU series is optimal for power supply lines of automotive equipment where safety is of foremost concern. This design can also help to save space on the circuit board as both capacitors are designed into one small package. The combination of these technologies yields improved voltage and ESD performance over standard designs and decreases the risk of short-circuit failures and low IR due to mechanical flex cracks.