The peel strengths listed by laminators are on cores, usually .5 oz and
1.0 is listed, and it is usually "standard" profile, which is to say not a
 "low profile" copper. The peels listed should not be viewed as absolute
but as relative; compare within a laminators family of resins to see which
systems may have lower peel strengths, and compare laminate brand  to
"equivalent" laminate brand.

Testing that we have done indicates that the peel strengths listed are
pretty accurate, keeping in mind that there will be some uncertainty
introduced between labs and samples and operators; also, the peel coupons
have widths that are significantly wider than normal signal traces ...
that is done to standardize the test and to get a repeatable result: too
narrow a line would allow etch tolerance to have too great an impact on
the results and obscure the copper peel strength of the resin.

It is only a lab test; it isn't the real world.

But remember that unless you are designing "core" or "cap" laminated
boards, you are going to get foil-lamination: the fabricator will select
the foil to place onto the outermost prepregs for the final lamination -
and that is the foil you care about wrt peels, because that is the copper
that device leads will attach to, and that is the copper which establishes
the "bond" with the resin that will have the impact on any
remove-repair-redress-replace operation.

Of course the resin system makes a difference, but the laminator isn't
controlling the copper selection for the outerlayers.

Valerie



David Greig <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
03/01/2006 09:22 AM
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Subject
Re: [TN] High-frequency losses (e.g., SATA)




Referring to Nelco's web data:

Tg for 13 is higher than 6, T260 is 30+ minutes versus 4-8minutes for 6.
CTE for 13 is lower than 6 in the same conditions.
Moisture absorption similar.
Peel strength for 6 is 1.58N/mm and 13 is 1.31N/mm (IPC-TM-650.2.4.8).

Now how is peel strength really quoted? Are we really comparing peel
strength with the same grade of copper foil (surface treatments and
roughness)? Is this the same foil that actually comes delivered with
cores, or is a manufacturer free to choice particular foils for
measurement ?

The reason for asking this question is that 13 or 13SI is specifically
targeted at low applications and presumably comes normally delivered with
low profile foils. Perhaps the test method should stipulate 2 differing
test, first with a standard foil grade for comparison and secondly with
the explicit foil that the core would be delivered with.


Best Regards

David Greig
______________________________
GigaDyne Ltd
Buchan House
Carnegie Campus
Dunfermline KY11 8PL
United Kingdom
t: +44 (0)1383 624 975
www.gigadyne.co.uk
______________________________


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