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Date: | Wed, 11 Aug 1999 16:15:39 +0100 |
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We are experiencing some bow and twist, greater than 1%, on standard 4 layer
multilayer.
I know that the copper tracks and ground plane is spread quite evenly over
the circuit. Iam also testing a different build from our existing one.
Details as follows:
Existing Build Testing Build
!/2 oz Outer Foil !/2 oz Outer Foil
1 x 2125 pre-preg 1 x 2125
2 x 7628 1 x 2125
0.51mm 1/1 Core 0.93mm 1/1 Core
(Core Tg >125) (Core Tg >140)
2 x 7628 1 x 2125
1 x 2125 1 x 2125
Gel time is short flow: 120 seconds +/- 20
Vacuum press cycle details: 90 mins @ 175 deg C / Heat up rate 6 deg C
per min / 36 min cool down @ 10 tonnes.
I would also be interested in comments on the way panels are thermally cured
at final cure photoimage - racks, Tunnel dry, etc ??
Ian Paterson
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