ESD protection and programming on customized PCB

[User1321]

I am currently designing a customized pcb with the nrf52832 with other two sensors. I have two questions related with the design:

1. I know that the nrf52832 has the HBM ESDprotection, but is this enough when the chip is added to a customized pcb? According to what I have read, it is not. In that case, if I add a couple of ESD Protection Diodes, which pins should I protect? IO pins? power pins? SWD pins? all of them?

2. If I want to program the nrf52832 on the pcb using a nRF52 development board, which pins should i leave open on the pcb so I can connect to them to program the chip on board? SWDCLK and SWDIO? is any other pin necessary?

Thank you in advance!

[FormerMember]

Normally, external ESD protection diodes are not necessary, and most customers don't use it.

However, the on-chip ESD protection is not sufficient for connecting to outside of a product. If you look to end product ESD testing and real world ESD events, the voltages are higher and resistances lower by magnitude. Input pins can easily be protected by adding external series resistor, whereas output and bidirectional pins like USB normally require an active bipolar protection device. 

[User1321]

Thank you, I guess this can be also applied to the SWD pins. In relation with the SWD pins, do I need to add a capacitor, pull-up resistor to any of these pins? or is it enough with the ESD protection device?

[FormerMember]

Yes, it will be the same for the SWD pins!

No, it is not necessary with additional pull-up/pull-down resistors on the SWD pins.