Use this link to check the IPC-TN-650 test methods.
2.4.8 discuss Peel strength test
2.4.21 discuss Land bond strength test

To do peel strength, you need a strip of copper on the laminate, typically
0.125" in width.  Peel strength is measured in force/copper strip width
(lb/in).

To do land bond strength test you need to solder a wire to the land before
you pull.  Land bond strength is measured in force/area (lb/sq.in.).

If you really have a problem with copper adhesion, land bond strength tend
to give you very scattered data.  In my mind, it is more qualitative than
quantitative, even though you are getting numbers.  Peel strength, on the
other hand, you get better 'averaging' effect over a wider length and width
and therefore more consistent value.  The problem is on a finished board it
is easier to find pads then long, straight, fat traces to do peel strength
test.

You also need to be careful about how to interpret the results.  When you
peel the copper trace, the energy you put in is both deforming (stretching)
the trace and causing delamination at the interface.  If you have two
differe types of foil, you need to interpret the result carefully,
especially when the peel strength is high.  One good example is the low
peel strength measured in copper traces produced by additive plating.
Plated copper has a much lower yield strength than foil copper.  You should
not expect to see high number with these traces.  In short, use these test
in a comparative study - fix the material you used as much as you can.

Mason Hu

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