It is time to choose the proper enclosure for a high voltage PCB. We will need to do holes for LV external connectors and external connectors for high voltage wires. I was looking for standard boxes from different providers' catalog and the most are offered in metallic (aluminium) material. I know that this material is often used due its conductivity. But I'm wondering how it may to have influence on isolation between conductors if I have some case surface connectors (bananas) at HV and the other ones at LV (or 0V). They will connect external wires with board components through internal wires soldered to the bananas copper connector (internal side). In other words, I would like to apply clearance and creepage distances between connectors at case surface, but they depends on kind of surface material, normally air gap or PCB sheets material. I don't know what happen when surface material has high conductivity like aluminium.
I have seen high voltage source (few kV), that has metallic cases and red banana plug is about 3 cm separated from black banana jack datasheet here
So if this is commonly done it would has a coherent explanation for not to use/offer another isolation material, as for example plastic since aluminium conductivity is "similar" to the copper, how can people deal with this? How can it be used for these applications?
If yes, what clearance and creepage distances will we need?
If these boxes were not correct for a portable device like this (V < 7 kV), how does developers get the correct enclosure for a high voltage PCB?
- PCB will be covered by conformal coat
- A kind of silicone paste for coating the banana copper-wire junctions.
- Kapton mask instead of solder mask.