Copper Foil/Tape with Reinforced Insulation: Does it Exist?

[TimNJ]

Hi everyone,

For those who may work with power electronics, specifically transformer construction, maybe you will have an answer to the following.

I'm trying to meet a very low secondary DCR target on a miniaturized transformer I'm working on. I'm considering using copper foil, but I think it will be impossible to meet the primary-secondary creepage requirements of EN60950. The bobbin winding window width is just shy of 4mm. I also need 4mm creepage for EN60950, so according to my initial analysis, I can't see how that will work. (With a larger bobbin winding dimension, meeting the creepage requirement is much easier.)

Has anyone used any kind of reinforced/triple insulated copper foil in transformer design? Does it exist? If so, how would you terminate to it (flying wires) without violating safety requirements.

I know this is pretty niche, so if you have any other ideas or input, I'd appreciate that too.

Thanks!

[T3sl4co1l]

Possibly.  I'm not sure that I've seen that, but I have seen foil wrapped with tape, which does the same thing of course but with more labor.

Is a planar transformer an option?

Tim

[TimNJ]

Possibly.  I'm not sure that I've seen that, but I have seen foil wrapped with tape, which does the same thing of course but with more labor.

Is a planar transformer an option?

Tim

Thanks for your reply.

I found this supplier: https://en.cmc.de/page/kupfer-abschirmband

But I don't think it's anything more special than pre-cuffed copper foil, using typical PET or Kapton materials. I suppose I was wondering if there was a coated/dipped tape available, similar to triple insulated wire. Looks like probably not.

Planar is looking more and more like the answer. Estimating that I still need to cut the copper losses in half or more, with an already maxed out winding area.

Thanks again.