Agree with everything you say ....except there are now high resin content
(48%)7628 pre-pregs which means that you can use it facing copper layers.
2116 is definitely the best pre-preg, the glass weave is nice and even and
the resin content is about 55%. It's better for inner layer registration
than 2125.

Geoff Layhe
www.lamar-uk.co.uk

-----Original Message-----
From: Earl Moon [mailto:[log in to unmask]]
Sent: 15 March 2002 10:40
To: [log in to unmask]
Subject: Re: [TN] Prepreg


Again, but I love this stuff, you don't need two ply constructions except
when you need them. You get very well balanced structures, from a resin to
glass ratio point of view, with single ply preg and core material except
when using 7628 types/styles. You never use this facing copper as it only
has about 43% resin content and you may very well find starvation using it.

I feel like I've written this before. Anyway, 2113 and 2116 glass styles
offer the best of both laminate integrity (plenty of resin) and dimensional
stability (plenty of glass). No problem using two plies of these types in
whatever requirement. Two plies of 106 or 1080 isn't appropriate, if
avoidable, because it's two resin rich and makes everything slip and slide
in the press and that's a mess.

As for the shorting issues, that's been resolved even by the
military/aerospace folks for years. How many, I can't even remember. If
you've seen this condition, as voiding and shorting etc., get a photo for us
all to see. If proof exists, it has to be a billion to one shot and
certainly would point to possible process control problems of an other than
preg issue.


MoonMan

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