I suspect that in this case "Dielectric" refers to the superior
dielectric breakdown (electric strength) of polyimide, generically,
over epoxy resins. Since the polyimide has a higher volt/mil of
withstanding voltage rating, for the same degree of protection
from breakdown they can use a thinner separation between plane
layers. Depending on the laminate and the spec, it may not look
better than FR4; but it is.

Polyimide is "94HB" not "94V-0" - that's the way it is.



> The question I have is on IPC-4101/40 material as compared to
> IPC-4101/24 material. Our engineering stated they chose the Polyimide
> material for all the PWB designs because of superior Dielectric
> properties so to make the PWBs as thin as possible. From reading the
> specification sheets for both I do not see where IPC-4101/40 material
> Dielectric properties except for Arc Resistance is any better than
> IPC-4101/24 material. Could someone please help me out in understanding
> this issue with the dielectric properties? I would like to have a
> Flammability rating of V-0 if possible on the PWBs, is there a Polyimide
> material that can give me this property?

 Gary Bremer
> Senior Manufacturing Engineer
>
> Curtiss-Wright Controls Inc.
> Embedded Computing -Subsystem
>
> 28965 Avenue Penn
> Santa Clarita, CA 91355-4185
> Main: 661.257.4430 extension 2170
> Fax: 661.257.4782

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