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January 1998

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Subject:
From:
David Heywood <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 23 Jan 1998 08:16:53 +0000
Content-Type:
text/plain
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text/plain (61 lines)
As a rule of thumb the prepreg pressed thickness should be no less than
double the thickness of the copper to be encapsulated. so one piece of 7628
will barely encapsulate 1 3-ounce layer.
your top and bottom panel note indicates that you may be heating too fast.
If ANY boards are heating at more than 10 degrees C / minute try slowing
things down a bit further.
what do you call high resin content ? Top spec is not high - we would call
high 50% plus.
E-Mail me if I can help further.
Regards,
Dave Heywood.
[log in to unmask]
 ----------
From: [log in to unmask]
To: [log in to unmask]; Dave Heywood
Subject:      [TN] air voids in multi
Date: 23 January 1998 04:51

<<File Attachment: ENVELOPE.TXT>>
Can anyone shed some light on a problem i am having in my lam dept.
We are getting pockets of air (bubbles) trapped in low pressure areas
towards the middle of the panel
Seen only on the top or bottom panel of each book
This only happens on cores with 2-3 oz cu.

So far we have tried
heat rise 12 -16 F /min
b-stage with more resin- we are using 7628 only
vacume assist press and hydrolic
low pressure vs high
no kiss cycle
flatness of plates
not able to modify the pettern

  thank you for any suggestions

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