From: Zabinski, Patrick J. (email@example.com)
Date: Wed Oct 11 2000 - 12:36:52 PDT
I do not have any direct experience, but I spoke with
a board fab house recently on this same issue. He
summarized three materials for me from a manufacturing
* Nelco - poor stability in Z (vias tend to
pop after MANY thermal cycles in
* GE-TEK - poor X-Y stability, making alignment
and lamination difficult
* Isola FR408 - good stability in X, Y, and Z
All three materials have very similar dielectric constant
and loss tangent and rely on similar toothing profile
(i.e., surface roughness of metals to ensure adhesion).
The only issue with FR480 the person had was with
thin (<3 mil) dielectric thicknesses. For some reason,
he experienced voltage breakdowns (Shorts) after extended
usage with the thin materials (no problem above 3 mil).
For a recent board (12x24x0.1 inches, 22 layers, 500
watts, 50,000 vias, 4/4 mil rules, etc.) I worked on,
I went with the FR408. We haven't gotten
them back yet, so I cannot give you first-hand notes
on experience. However, the board vendor was
quite adamant in his opinion on the three materials,
and he uses all three regularly.
> -----Original Message-----
> From: Doug Hopperstad [mailto:firstname.lastname@example.org]
> Sent: Wednesday, October 11, 2000 2:00 PM
> To: 'email@example.com'
> Subject: [SI-LIST] : RE: FR408 vs. GETEK
> Does anyone have information on FR408 vs. GETEK for designs
> at the high
> frequencies,1GHz and above.
> Doug Hopperstad
> QLogic Corporation
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