EFFECTIVENESS OF MLC CAPACITORS FOR ELECTROSTATIC DISCHARGE PROTECTIONS IN AUTOMOTIVE ECUs

A simple technique to deal with ESD can be achieved by mounting Multi Layer Ceramic Capacitors (MLCC) at the ECU PCB I/O connector pins which is the ESD entry point. EMC engineers recommend using 0603 MLCC’s placed at the close proximity of each connector pin, mandating low-inductance mounting strategy associated with the PCB traces and vias. When selecting SMD MLCC for ESD protection for automotive ECU I/O pins, specify the ESD capacitor value, its DC voltage rating, and a choice of technology (X7R or C0G). MLCC as an ESD bypass, or shunt device is used to divert the ESD current to ground. ESD protection devices should perform ESD mitigation and should not exhibit degradation and maintain ESD robustness throughout the life span of a product. Nevertheless, post-ESD examination of small foot-print 0603 MLCC’s reveals serious structural damage, manifesting itself electrically in a dramatic change in the impedance characteristics. This is a major departure from a pre-ESD capacitor, thus resulting in excessive low frequency leakage and functional misbehavior