ESD susceptibility evaluation on capacitive fingerprint module

This paper reports on an investigation of ESD stresses on a fingerprint module. It shows that sparking to the flex connector, dielectric breakdown of the insulating layers, and transient electric and magnetic fields can cause damage. Test methods and simulation models are shown. An ESD generator and ESD field probe were used to expose the fingerprint module to currents and electromagnetic fields. Breakdown of the top insulating layer was observed. Damage due to ESD induced H-field injection occurred A 1 kΩ resistively grounded ring is proposed as an ESD protection solution for the fingerprint module system. Its effect on the discharge current is shown via simulation.

I. Introduction

Biometric authentication is a useful method for automatically verifying and recognizing the identity of a person. These systems can control the access to secured areas and devices, such as the bank, personal computers, and smart phones. Compared to other biometric systems, fingerprint modules have the advantage of reliable recognition at a lower component cost.