A customer recently received a sequentially laminated 6 layer board that
failed due to a barrel crack in between L2 and L3. Since we decided not
manufacture this type of structure due to reliability concerns several years
ago, I would like to ask whether anyone can help me respond to my customer.
(of interest, our concern was not for this problem) His question is " does
the relamination of sequential build multilayers require a more ductile
copper to accomodate the stresses of the relamination process?".

The construction of this board is one 4 layer multilayer bonded to a double
sided resulting in a six layer blind via sequential lamination multilayer.
Overall thickness is about 0.070 thick and regular Tg 140 material was used.
I do not know the drill diameter but the aspect ratio stated was about 1.5:1
for the blind via that failed.

If anyone can supply some insights I would appreciate it.

regards

Dave Rooke
Circo Craft - Pointe Claire
A division of Viasystems