ESD Test- ARM based PCB -Sheetmetal Enclosure

[kmdineshece]

ARM based board design has proper ESD protection, and enclosure is made by sheet metal with powder coating. The unit is passed ESD direct , indirect & Air discharge test upto 8kV on enclosure.
During direct test, the Gun is kept on the RJ45 Ethernet female connector at board, the board is working find upto 4kv test, but it gets hang at 6kV test, let me know how to solve it

 

[KlausST]

Hi,

you should find the path where the high voltage ESD pulse current flows.
Maybe you see marking caused by a spark.

* avoid the spark by isolation
* or use an overvoltage protection circuit that keeps that current away from your microcontroller. This can be a dedicated capacitor or a MOV or similar.

For sure you may improve the microcontroller PCB layout. Using solid GND plane, using HF filters, route your signals as far away as possible fromthe ESD path, even a wtchdog (hardware, software) may cause the circuit to pass the ESD test. When it "hangs" it will be resetted and it will start automatically. A reboot is allowed (but not nice), as long as the total function of the application is guaranteed.

Klaus

 

[kmdineshece]

Hi,

you should find the path where the high voltage ESD pulse current flows.
Maybe you see marking caused by a spark.

* avoid the spark by isolation
* or use an overvoltage protection circuit that keeps that current away from your microcontroller. This can be a dedicated capacitor or a MOV or similar.

For sure you may improve the microcontroller PCB layout. Using solid GND plane, using HF filters, route your signals as far away as possible fromthe ESD path, even a wtchdog (hardware, software) may cause the circuit to pass the ESD test. When it "hangs" it will be resetted and it will start automatically. A reboot is allowed (but not nice), as long as the total function of the application is guaranteed.

Klaus

Thanks for your reply!...
problem only thing at Ethernet connector RJ45...
pls tell any other way,
is it needed to grounding ethernet connector RJ45?

 

[FvM]

The connector case would be usually connected as directly as possible to the metal enclosure. Is it a RJ45 connector with built-in magnetics?

 

[andre_luis]

is it needed to grounding ethernet connector RJ45?

I would say no; likewise the chassis of the equipment must be grounded in another reference, it would not make any sense to put the GND of the board in the same reference of an electric potential that depending on the cable (shielded or not) could put the board electrically connected to an external unknown voltage.