I was going to say, my understanding of the P addition was to modify the
grain/plated properties of the NI, to give good mechanical properties rather
than directly as a solderability control, but Werner's answer covers that
and rather more! As is his norm.
There are proprietary "solderable" Ni plates. Solderable meaning less
readily/more slowly passivating, but these are more usually employed on
structural assemblies like large heat sinks, packages rather than PCB
finishes. For regular PCB finishes the N is protected to maintain
solderability with thin Au - to give us ENIG, or sometimes Ag or even Sn.
[I personally do not consider that Pd containing finishes protect or improve
solderability.]
Regards
Mike
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier
Sent: Tuesday, September 21, 2010 3:40 PM
To: [log in to unmask]
Subject: Re: [TN] Solderability of nickel plating
Hi Kevin,
Now my 5 cents.
From my experience, I do not see solderability directly linked to the
concentration of phosphorus co-plated with the nickel-I see however, brittle
interfacial failures between the Ni-P surface and the Ni3Sn4-intermetallic
compound which directly track with P-concentration at that interface. The
presence of Ni3Sn4-IMC is clear evidence that there was no solderability
issue-it is the concentration of the P at the interface which weakens the
interfacial bond.
Because of their superficial appearance, conditions with both too much P and
too little P [causes hyper-galvanic corrosion along the grain boundaries of
the Ni plating] have been termed 'black pad.'
Having too much P at the interface can be the result of improper Ni-plating,
but also the result of too much Ni being dissolved in the Sn of the solder
leaving to much P behind-this can happen from too many soldering operations.
Werner
-----Original Message-----
From: Glidden, Kevin <[log in to unmask]>
To: [log in to unmask]
Sent: Tue, Sep 21, 2010 8:52 am
Subject: [TN] Solderability of nickel plating
All,
Can anyone comment on the solderability of the nickel plate, particularly
with
regard to type of plating: high phosphor / low phosphor, and also storage
conditions:
I've been gathering info, and seen conflicting information.
From one article: http://corrosion-doctors.org/MetalCoatings/Electroless.htm
A paper submitted at the Electroless Nickel conference of 1989 held in
Cincinnati Ohio, Titled "Solderability Parameters of Elecroless Nickel
Bearing
Electronic Finishes" By Louis Kosarek of STB Systems, Inc. report that "An
electroless nickel deposit which contains a concentration of phosphorus
ranging
from 0.1% to 3.0% is readily solderable on an "As-plated Basis" per Mil-Std
883c
method 2003. The frequency of solderability tests which fail per Mil-Std
883c
will increase as the phosphorus content of electroless nickel alloy
increases
from 3.0 to 7.0% phosphorus. A solderability test conducted per Mil-Std 883c
method 2003 incorporating an as-plated surface finish containing phosphorus
in
excess of 7%, the components will consistently fail. The mode of failure is
non-wetting of the surface."
This indicates low phosphorous plating is best for solderability. Many
other
papers seem to agree with this.
----------------------------------------------------------------------------
-----------------------------------------
From another article: http://www.pfonline.com/articles/pfd0024.html
Solderability/Weldability. An important aspect of electroless nickel to the
electronics industry is its solderability. All electroless nickel deposits
are
solderable provided the soldering conditions are matched to the condition of
the
particular electroless nickel deposit. Lower-phosphorus electroless nickel
is
more easily solderable immediately after plating than higher-phosphorus
electroless nickel. However, this advantage disappears after 12 - 24 hrs. At
this point, the ease of solderability depends upon the characteristics of
the
passive layer that forms on the surface of the electroless nickel deposit.
Those
deposits plated from baths containing heavy metal and sulfur-bearing
brighteners
and stabilizers, such as most commercial low- and mid-phosphorus electroless
nickel systems, form a thicker tenacious passive layer than those that do
not,
such as most high-phosphorus electroless nickel systems. High-phosphorus
electroless nickel systems tend to be more solderable in aged deposits.
Other important factors influencing the solderability of electroless nickel
deposits include residual contamination left on the surface after plating
and
storage conditions after drying. Surface contamination and exposure to
environments containing sulfur dioxide, chlorine, high humidity and high
ambient
temperatures will detrimentally affect solderability. Therefore, it is
imperative that parts be thoroughly rinsed in clean DI water, dried and
stored
in a cool, dry atmosphere, preferably nitrogen.
This article indicates high phosphorous plating is best for long term
solderability, and also that parts must be stored carefully (cool, dry,
sealed,
nitrogen). Other articles seem to state this is a highly stable finish and
is
even used as a corrosion inhibitor.
Thanks,
Kevin Glidden
Manufacturing Engineer
Astronics Luminescent Systems Inc.<http://www.astronics.com>
4 Lucent Drive
Lebanon, NH 03766
(603) 643-7766 x3152
Please note, LSI operates on a 9/80 work schedule, and is closed on
alternating
Fridays. Please click the link provided to view the days LSI will be
closed.
http://www.astronics.com/LSI/documents/2010calendar-NH.pdf
NOTICE: This communication is intended specifically for the recipient(s)
named
above and may include proprietary, confidential or privileged information.
If
you are not a named recipient, you should immediately delete or destroy all
electronic and physical copies of this communication. Unintended recipients
also
should not utilize, repeat, publish or relay to any other person the
information
contained herein nor should they take any action based upon, in whole or in
part, such information. If you have received this message in error, you are
requested to contact the sender immediately.
EXPORT COMPLIANCE STATEMENT: The information contained herein is or may be
controlled by the International Traffic in Arms Regulations (ITAR), 22 CFR
120-130, or the Export Administration Regulations (EAR) and may not be
exported,
or disclosed to a foreign person, whether in the United States or abroad,
without prior U.S. Government and Astronics Luminescent Systems written
approval. Violations of these regulations could result in administrative,
civil
or criminal penalties. If you have any questions about the nature of the
material contained in this email please contact the sender immediately.
______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16
for
additional information, or contact Keach Sasamori at [log in to unmask] or
847-615-7100 ext.2815
-----------------------------------------------------
______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16
for additional information, or contact Keach Sasamori at [log in to unmask] or
847-615-7100 ext.2815
-----------------------------------------------------
***This email, its content, and any files transmitted with it, are intended solely for the addressee(s) and may be legally privileged and/or confidential. If you are not the intended recipient, please contact the sender by return and delete the material from any computer. Any review, retransmission, dissemination, or other use of, or taking of any action in reliance upon this information by persons or entities other than the intended recipient is prohibited.
Messages sent via this medium may be subjected to delays, non-delivery, and unauthorized alteration. This email has been prepared using information believed by the author to be reliable and accurate, but Indium Corporation makes no warranty as to accuracy or completeness. Indium Corporation does not accept responsibility for changes made to this email after it was sent. Any opinions or recommendations expressed herein are solely those of the author. They may be subject to change without notice.***
______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------
|