I think to get informed answers you need to be more specific in your
question.
By NiAu do you mean ENIG (electroless nickel immersion gold)? The copper
tracks are coated with nickel which is itself then protected with a very
thin layer of gold.
There are several types of tin finish: electroless, electrolytic and
immersion. Which do your people have in mind?
The usual one is immersion and is presumably what is meant by chemical tin.
The advantage of immersion tin is that it is less expensive than alternative
finishes, but no benefit is without a cost.
So immersion tin produces a very thin layer with limited shelf life. The tin
diffuses slowly into the underlying copper to produce an unsolderable
intermetallic. Before that though the protection offered to the copper is
found by some to be limited anyway. It certainly can be supplier dependent
and so a variable finish.
You should also be aware of the problem of tin whiskers. The cause is not
fully understood but is usually attributed to stresses in the tin which
responds by extruding or growing whiskers. These can become random additions
to your circuitry.

Regards 
 
Mike Fenner 
Bonding Services & Products
M: +44 [0] 7810 526 317 
T: +44 [0] 1865 522 663
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Torsten Hagge
Sent: Wednesday, May 29, 2013 12:49 PM
To: [log in to unmask]
Subject: [TN] Difference between chem Sn and NiAu plating

Hi all,

after design validation with NiAu our commercial group would like to
continue a project with chem Sn plating. My question is if anybody has a
study which confirm similar soldering results regarding solder quality,
vibration and thermo cycle results to prevent a new design verification test
(which cost several hundred hours...) if we change plating.

Thanks and best regards,
Torsten

Best Regards

KRISTRONICS GmbH
Torsten Hagge
team leader HW development & 
tech. projectmanager
Gewerbegrund 5-9
24955 Harrislee
Telefon +49 (0) 461 7741-624
Telefax +49 (0) 461 7741-642
[log in to unmask]
www.kristronics.de
Place of jurisdiction: Flensburg, commercial register: HRB 1433 FL
CEO: Dipl.-Ing. oec. Thormod Ohm
VAD-Id: DE 811182059
Bank account: Deutsche Bank AG Flensburg, account 4216610, bank number
21570011
IBAN: DE32 2157 0011 0421 6610 00, BIC: DEUT DE HH 215


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