Myth #9: A PCB should only be grounded in one place.
Single-point grounding is used to prevent common ground impedance circuit coupling. That is to say, the entire circuit system is regarded as a structural point of ground reference point, and all of the ground connections are connected to this point. Single-point grounding is divided into two types: series and parallel. Because the series type generates common ground coupling, it is better for the low-frequency circuit to use parallel single-point grounding. To prevent power frequency and other interference from stray current in the signal ground line, signal ground and power ground paths should be isolated from the ground and the chassis, and only connected on the safety ground bolt to earth ground wire by power ground, chassis ground (except floating).