Chuck:
   I'm sorry that I didn't provide enough information. The slippage
happens to 1.5 mm or 1.6 mm double sided laminate during the lamination
process (copper foil, 8 ply 7628 prepreg, copper foil, not PCB
multilayer lamination). It happens from time to time, sometimes zero
percent though we change nothing in our process. We reduce the resin
content of 7628 prepreg, the slippage percentage decrease but lead to
under-thickness problem.

   Thanks and best regards
    William Wang
 ----------
From: Chuck Brummer
To: [log in to unmask]
Subject: Re: [TN] Copper Clad Laminate Slippage
Date: Wednesday, September 01, 1999 10:52PM

Let us count the ways, sorry just a little joke.  In my last bit of
advice I suggested
that the problem could be fixed by increasing the resin to glass ratio.
But too much
resin not enough glass can make your package slip.  When was the last
time you checked
your press for parallelism?  You might be pushing the package to one
side or corner.
If your gel time is off the prepreg can get very slippery.  How many
layers?  Are your
making a multilayer that has little "C" stage core and very much
prepreg.  Do you need
to block the load.  When we last used vacuum assisted lamination I made
some aluminum
frames to assure the load was centered and resisted slippage because we
use some
conformals that can cause slippage when the stack was higher.  When we
do not use the
vacuum assist we reduce the stack height.

Dan Brandler, where are you?  You should probably have some insight for
this guy.

Chuck Brummer
[log in to unmask]

Wang, William (Suzhou Laminate) wrote:

>     I'm a greenhand of copper clad laminate, can anyone tell me why
> copper clad laminate could slip during press and how to prevent from
> slippage? (We use vacuum assisted hydraulic press)
>
> Thanks and best regards
> William Wang
>
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