I would agree with Phil.  If you need a controlled dielectric,
     specify that on the print, not the type of prepreg to use.
        1 ply 1080 has a nominal thickness of 3.0 mils (based on resin
     content and glass).  So no, the supplier cannot add as much or little
     resin as they want.  But, there can be up to a 10% variation in this
     thickness.
        Specifying prepreg severely limits the board manufacturer options,
     and increases the chances of the board not meeting your requirements.


     John Anselmo
     Hadco - Tech Center Austin
     512-246-5616


______________________________ Reply Separator _________________________________
Subject: Re: [TN] PREPREG
Author:  Phil Crepeau <[log in to unmask]> at smtplink-hadco
Date:    2/7/00 10:06 AM


hi,

i would strongly recommend that, if at all possible, you leave these details
up to the board fabricator.  and here's why: if the board doesn't meet your
end product requirements you can blame the fabricator.  if you specify the
details, you will be responsible if the board doesn't meet your end product
requirements.

best of all, you should be involving the board fabricator at the initial
stages of you design.  and by the way, i am not involved in the board
fabrication business.

phil

-----Original Message-----
From: Brunker Ed [mailto:[log in to unmask]]
Sent: Monday, February 07, 2000 8:37 AM
To: [log in to unmask]
Subject: [TN] PREPREG


Is there anyone out there who can help me with understanding prepreg. If we
specify a given prepreg, (1080) does that give us any control over board
construction. I'm told that 1080 specifies a glass matt. So does this mean
that for a given glass matt the resin added to it can be as little or as
much as a supplier wants and the characteristics of that resin can be
whatever? So sheets of prepreg can be any thickness and have any flow
characteristics.
Also for mobile phone usage what are people using in FR4 to achieve
approriate dielectric characteristics? Are there a range of prepregs being
used or just 1080?

Regards
Edward Brunker

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