Thanks, Karen!

I still suspect that those values were intended for separation ACROSS a
laminate (creepage)
and that the minimum distance THROUGH a laminate should be smaller than
3.25 mm,
I just don't know where to go from there.

The material slash sheets use HUGE numbers,
but I don't think those numbers were intended as design parameters

but thanks,
Jack


On Fri, Jun 20, 2014 at 12:58 PM, Karen Tellefsen <[log in to unmask]>
wrote:

> Maybe this will help
>
> http://www.smps.us/pcbtracespacing.html
>
> It still gives 3.25mm.
>
> Maybe the distance can at an angle within the PCB so the distance is
> sqrt(x^2 + z^2)
>
> Karen Tellefsen - Electrical Testing
> Alpha / 109 Corporate Blvd./ S. Plainfield, NJ 07080
> [log in to unmask]
> 908-791-3069
>
>
>
>
> From:        Jack Olson <[log in to unmask]>
> To:        <[log in to unmask]>,
> Date:        06/20/2014 11:38 AM
> Subject:        [TN] z-axis voltage separation
> Sent by:        TechNet <[log in to unmask]>
> ------------------------------
>
>
>
> maybe I'm having a "not enough coffee yet" morning,
> but I was asked how much separation I need between layers for high voltage.
> I tried to search the TechNet Archives, but it doesn't seem to work as well
> as it used to!
> anyway,
>
> We have a design that may have 1700V in several places.
> Since we are looking at a clearance into the board, layer-to-layer
> I'm pretty sure I can use the "internal" column B1 of Table 6-1 in IPC-2221
> (using Table 6-1 for z-axis was discussed in an IPC committee meeting and
> no one disagreed)
>
> but the number I get for 1700V is =
> (.25 mm for the first 500V) plus (.0025 mm for each of the other 1200V, 3
> mm)
> equals 3.25 mm
>
> For one thing, it already seems like I'm off-track because .25 for 500V
> doesn't correspond very well with 3 mm for 1200V, but if you can't trust
> IPC..... well, let's not go there.
>
> My REAL question is that, although I'm safe using 3.25 mm, my board is not
> that thick!
> Is there a smaller z-axis clearance that can be used for 1700V? across
> typical FR4 material?
> (we are using a RoHS compatible 170Tg /126)
>
> What's the MINIMUM layer spacing I can use for 1700V?
>
> thanks,
> Jack
>
>
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