Hello Werner,

On Wed, 29 Nov 2006 you posted a message located at 

http://listserv.ipc.org/scripts/wa.exe?A2=ind0611&L=technet&T=0&F=&S=&P=59247

It more or less reads...

> http://www.stevezeva.homestead.com/files/dELAM.doc
>
Hi All,
This may be a copper 4-layer stack-up, but it sure does not look like a
2-laminate layer/1-prepreg layer stack-up. It would be nice to know what the
stack-up is.

Werner

I have looked at the dELAM.doc file and have the same problem with a 4 layer recently built. The board we manufactured is made from IS410 material. Layers 2 and 3 are built on a .028" 2/2 core. The other two dielectric zones were made up with b-stage adding up to .012" in each zone. The image looks very similar to my board. The bare board went through two lead-free smt assembly cycles through a convection oven with a peak temperature of 260 deg C. The entire oven cycle was 4 minutes in length. That being said we built hundreds of boards and the customer has assembled them without a problem.

We now have a board at the customer where the actual core delaminated. To be honest, it doesn't even look like several of the plys of b-stage even laminated in the first place. IE non-lamination. I would be interested in finding out more information on the board from the dELAM.doc file. IE material lot numbers to see if they match any of my material lot numbers. Also, do you know of anyone else having the same problem with IS410 core material?

This is apparently an ISOLA issue that has to my knowledge been a recent development. I've received bad b-stage in the past that did not flow in spot locations. The board I have that failed looks like the inner layer core had an area of non-lamination.

For what it is worth ISOLA provided the core made from 4 plys of 7628. The core in the pictures looks like is was made of the same construction.

Regards,
David Duross
Quality Control Manager
Electropac Co.
252 Willow Street
Manchester, NH 03103-6294 USA
TEL (603) 622-3711
FAX (603) 622-1773
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