I am working on a few kV PCB design with external voltage connectors (HIGH and GND levels). So user interface connectors are thought to be bananas jacks (they support until 7kV but has soldering terminals).

Now I am searching commercial boxes for packaging the PCB. Providers, that I have consulted, they have boxes with fixed sizes, and they are not much long. Unfortunately I will have exigent area requirements, due components arrays with substantial volumes. So I must face box size limitation and PCB area needs.

The fact or question is that I have found one case that seems to be a solution in terms of long and width. Since we would like to fit bananas on the chasis as you can see at the picture:

enter image description here

I wondered for the minimal distances d1, d2 and d3. Having into account:

  1. Kapton instead solder mask
  2. Conformal coating after soldering
  3. 6kV and 0V wires from PCB (from relays) to banana connectors must be soldered but we will use some suggested silicones for this kind of junction (solder).
  4. I doesn't choose the kind of material of the case, but it seems to be available in aluminium or PVC.
  5. Black banana has 0V and red one is i e 6kV (it can be smaller)

If banana will be into the case surface is the distance between:

  • banana - banana: d2,
  • banana - bare conductor: d3,
  • banana - coated connector (terminal block with screws): d1

considered as the same distances on PCB board? in. ex: if clearance between a copper pad at 6 kV and other one at 0V -with a concrete CTI and pollution degree- must be 32mm, could I apply this distance between banana at 6kV - PCB conductor at 0V or banana at 6kV - banana 0V?


1 Answer 1


Just like on the PCB itself, you need to pay attention to clearance (arcing) and creepage (leakage through surface contamination).

If you use wire with insulation rated for 6 kV, then the only real issues are in the immediate areas around where the wires are terminated on the banana jacks and the PCB connections.

  • \$\begingroup\$ Hi Dave, lot of thanks. I was just talking about needed creepage and clearence distance from conductors at boxes surface. I thought that air gap and box material involved different distance criterion than PCB due PCB sheets composition. Components wires, provides insulation according to the manufacturer. I was especially worried about wire - banana junction, as you said. Some users give me tricks and tips about kind of isolation paste for soldering junctions. \$\endgroup\$
    – Suvi_Eu
    Commented Jul 24, 2019 at 11:50
  • \$\begingroup\$ Heat-shrink tubing is a good idea for any exposed solder. Then slide some silicone tubing over that. I've seen 50kV wire nothing more than 10kV wire in a silicone tube. \$\endgroup\$
    – rdtsc
    Commented Jul 24, 2019 at 12:16

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