If there were copper foil inserted between those two prepregs, the board would be a 6-layer one and priced accordingly. Not putting the foil there would spare them a number of technological steps, but the board would be equivalent to a 6-layer PCB with 2 internal layers etched off completely, leaving 4 properly spaced layers for HV routing. But that's not how they make 6-deckers, anyway.
Best regards, Piotr
Who do you get them from?
'T'weren't mine.
Cheers
Phil Hobbs
Thanks John, an excellent good post. But sadly the spec isn't really all that helpful. 0.4 mm is insufficient, and the testing requirement means, for most of us, that we'll use an exact item that somebody else has thoroughly tested (quick HV tests of one batch are not enough). Hah, I'd be looking to use slots, and avoid any mains traces opposite each other. Once the ac power has gotten past the MOV / TVS stage, one can relax the rules a bit.
IIRC that was PNC in New Jersey, whom we no longer use. I checked our recent fave PCBway, and their 4-layers are foil-prepreg-core-prepreg-foil.
Cheers
Phil Hobbs
Hello there, I think Chinese manufacturers are still good!
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