Hi Rick,
On several occasions in the past I have been in your shoes.  Although you
may want to check the oven profile and the PCB profile (I'm almost sure
that they are/were in order), cross sections of the delaminated PCBs and
non-processed PCBs (same lot) may reveal the problem.  The problem that I
found was resin starvation.  The starved areas were at locations on the
inner layers where a significant reduction of copper (etched) resided
(i.e. isolation mote for ESD or EMI/EMC).  The fabricator in correcting
the situation was able to use a thicker prepreg to bond the layers
together prior to lamination and also modified the stack and press
parameters.  Hope this sheds some light.

Steve Sauer
Sr. Mfg. Engineer
Xetron Corporation

 ----------
From:  Rick Thompson[SMTP:[log in to unmask]]
Sent:  Monday, August 03, 1998 1:33 PM
To:  [log in to unmask]
Subject:  [TN] PCB Delamination?

Hi,

We recently had a run of PCBA's where round delaminated areas showed up
in
the boards after convection reflow.  The areas are random and up to 2" in
diameter.  They weren't noticeable to visual inspection prior to running
through the oven.  I have 2 questions:

1. What might be the cause of this type of defect in the PCB?

2. Are there any independent test labs that could evaluate this and
verify
the cause?

The reason for the 2nd question is that we're going back and forth with
our
customer and their PCB supplier as to root cause and therefore, whose
responsibility it is.

Any feedback would be appreciated.


                Rick Thompson
                Ventura Electronics Assembly
                2665A Park Center Dr.
                Simi Valley, CA 93065

            [log in to unmask]

                (805) 584-9858 voice
                (805) 584-1529 fax

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