Hi Gert,
To Piotr: ESD test are normally carried out on enclosure
and connector shielding, not to internal circuits.
HCP and VCP discharge are designed for this.
My logic is:
The idea of ESD test is to check possible events which can happen in normal
use of device.
The possible source of ESD are human fingers.
Human fingers touches enclosure and not internal circuits because enclosure
is between fingers and internal circuits.
So ESD is tested on enclosure and on HCP and VCP = all expected ESD that can
happen to and near device.
If device has plastic enclosure than in real ESD to something near device
has higher probability than to device (which is close to 0%).
If there is no enclosure than human fingers can touch directly internal
circuits so following the idea of testing all possible ESD events in my
opinion ESD should be also tested to internal circuits. I think that for
such device the ESD to internal circuits has much higher probability than to
something near (HCP and VCP). There is no idea to testing something less
probable and not testing something more probable.
If the prototype board is to be used only in ESD protected environment than
testing ESD to internal circuits can have no sense but testing ESD to HCP
and VCP also has no sense.
But generally I think that prototype board should be excluded from EMC at
all and it should be written in the first EMC directive version long time
ago.
When I first time read EMC (in 2002 - two years before we (Poland) joined
EU) the question about prototype board was my first thought.
Being not clear solved in directive that subject makes me to have clear
opinion about its authors.
Best Regards
Piotr Galka
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