Conductive Coatings for Electromagnetic Interference Shielding of a Time of Flight Sensor
Samuel Hörmann
11:15 - 12:15 Wednesday 02 June 2021 In today’s society, electromagnetic waves are ever-present. Every electronic device unavoidably emits electromagnetic radiation, because any electronic current acts as its source. However, many such building blocks are integrated in a typical application and, therefore, electromagnetic interference (EMI) shielding is often times used to make them compatible. In this thesis, an alternative to the heavy, large and expensive separate shielding caps is investigated. By coating the lid of a time-of-flight sensor with a thin metal layer, the emissions measured in a transverse-electromagnetic (TEM) cell are reduced significantly.
The high shielding effectivity (SE) was traced back to its conductivity, which is confirmed by state-of-the-art literature. The effects of apertures in the lid, and thus the shield, as well as the grounding were researched via trials with copper tape and simulations with Ansys HFSS. It is observed that the SE depends crucially on the quality of the electrical connection between the coating and a ground plane in the integrated circuit of the sensor. Multiple materials from dedicated suppliers and a sputtered layer are compared. Their shielding capabilities are tested in transmission line measurements with coated plates. Furthermore, the TEM cell measurements are compared to a magnetic-dipole source based on the Fourier transform of the vertical cavity surface emitting laser (VCSEL) current.
This work proves the feasibility of the convenient and easily integrateable EMI shielding by a thin deposition film and enables next generation sensors to utilize and improve the established design.
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Institute of Solid State Physics
