ESD issue on LCD controlled by IIC

[Jishnuprakash]

hi,
I work as electronics engineer, recently one of my project failed in ESD test, both is conducted and air discharge
during ESD the LCD turns off and we had to restart entire system to make it run again,
this is the first project i took over in my new company, the designing is done by an external agency who says he is
helpless in mitigating the problem with LCD, please give me any advice on how to mitigate ESD problem up to 16KV
i use i2c to control the  LCD which is connected to the board using 4 pin flat cable, and the screwed on to the plastic container
together , i am providing link to the LCD device i am using (cant share main board circuit, company property)

https://www.roboelements.com/product/16x2-lcd-display-with-i2c-interface/?gclid=CjwKCAjwzt6LBhBeEiwAbPGOgeMW5LfJm_8hCEwY_z1R4JyPBQ4VD9VcgQZ5Je-CEeZOhLQ7Y1g0bhoCxFgQAvD_BwE

[T3sl4co1l]

I2C is an on-board protocol only.  It is not to be used over wiring, at least not without considerable caution.  As you've proved first-hand.  It can be used over modest distances with differential interfaces, or isolators.

Is the LCD bezel/frame exposed (subject to direct ESD strikes)?

Tim

[Jishnuprakash]

no lcd is not subjected to direct ESD strikes

[Jishnuprakash]

the length of iic wire is less than 3CM

[T3sl4co1l]

Are / could those standoffs be grounded, by any chance?  (I think not, they look isolated on the LCD at least.)

Adding those grounds would significantly reduce interference to the signals.

Tim

[Jishnuprakash]

no they are not grounded, i will try grounding them, thank you for information,
also if nylon or PVC Standoffs are used can we avoid this problem

[T3sl4co1l]

Probably not, but plastic spacers could be used instead, and thru screws.

You'll probably have to scrape the soldermask off nearby grounds to test it.  PITA but ok for a test.  Figuring out production is another matter.

Tim