Pease accept my apologies if these responses seem truncated or out of
sequence, our email has been down I am only now able to respond to emails
posted a few days ago.  I know I have lost some of the responses in this
thread.

In response to Werner's question about a "lamination coupon"; we are testing
a delamination sensing coupon that some may find interesting.


For the past 9 months we have been characterizing a specifically designed
test coupon that enables the detection of material delamination, even to the
extent where and when the dielectric breakdown begins.  The critical
circuits are incorporated into our latest "Generic" test vehicles (IST
coupons).  You do not have to complete "traditional IST" testing to check
for delamination, but simply measuring before and after assembly/rework is
quite sufficient to detect the problem.  You could use the coupon alone and
detect the presence and location (by layer) of delamination.  This
methodology utilizes a capacitance measurement technique that has been
characterized to identify specific electrical changes that are caused by
delamination.  To date excellent correlation has been achieved between this
new technique and standard microsectioning.

The coupon is usually fabricated along the edge of a PWB production panel.
Coupons are initially measured for a combination of resistance and
capacitance readings. The coupons are then subjected to the customer's
specified assembly and rework conditions (E.g. 2 to 6 cycles @ 260C).  A
second measurement is taken which will indicate if delamination occurred
during the assembly and/or rework process.  Please note that we believe the
lead-free assembly and rework process initiates and accelerates delamination
but the propagation is caused in subsequent thermal cycling.

The present methodology uses a static measurement before and after the
thermal excursions, we are now developing the technique to monitor
throughout every cycle.  We expect this capability will be invaluable for
determining when in the thermal cycle, or how many cycles before a material
fails.

A secondary benefit of this design permits the PWB manufacturer (or their
customer) the ability to confirm the precise construction (stack-up) of the
product.  Additionally, knowing the dielectric thickness then affords the
capability to extrapolate Dk and understand how it changes with temperature.
There are further product/material attributes that can be defined, which at
this time are still considered proprietary.

The protocol is titled Dielectric Estimation and Laminate Analysis Method
(DELAM). It is still in the development phase, we need to test a wide
variety of material types, construction and design attributes before we can
make absolute statements related to capability.  We have recently received
confirmation from certain strategic customers that they require their
existing designs should be replaced with the new DELAM coupons.  All
indications are that we have developed a very powerful tool to support us
for the emerging lead-free environment.  We consider that DELAM testing is
essential assessment and a prerequisite to reliability testing.  Any testing
of product that contains delamination may cause a false positive result.



Sincerely,

Paul Reid


Program Coordinator
PWB Interconnect Solutions Inc.

Tel:  613-596-4244 Ext. 229
Fax: 613-596-2200

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