Sender: |
|
X-To: |
|
Date: |
Thu, 26 Sep 2013 15:00:25 -0500 |
Reply-To: |
|
Subject: |
|
From: |
|
Message-ID: |
|
In-Reply-To: |
|
Content-Type: |
text/plain; charset="US-ASCII" |
MIME-Version: |
1.0 |
Parts/Attachments: |
|
|
Gerry,
You are correct. Both silver and silver oxide are conductive. Since my
esteemed colleague Dave is in Texas steering dragonboats right now, I will
pass along his general view that silver tarnish is a cosmetic item only
and does not impact reliability. Of course, that may depend on how the
tarnish is getting there in the first place, but in general, tarnish is
not a functional issue.
Doug Pauls
From: Gerry Gagnon <[log in to unmask]>
To: <[log in to unmask]>
Date: 09/26/2013 02:56 PM
Subject: Re: [TN] Immersion Silver Board Finish Tarnishing
Sent by: TechNet <[log in to unmask]>
Hi Ted,
Not 100% sure, but I believe silver and its' oxide(s) are highly
conductive.
I suspect the "oxide" Ernesto is seeing is not silver or its' oxide.
Just my $0.02.
Gerry
> Date: Thu, 26 Sep 2013 17:47:14 +0000
> From: [log in to unmask]
> Subject: Re: [TN] Immersion Silver Board Finish Tarnishing
> To: [log in to unmask]
>
> Ernesto,
>
> Look at the boards you are having issues with test. Is it possible the
ones you are having problems with went through the reflow process first?
>
> I ask because with an immersion silver finish there is typically an OSP
finish to help prevent the silver from tarnishing. So unless the boards
went through half the SMT process you should have had no problems related
to them being out on the shop floor.
>
> If the boards are having issues at test and you are in fact hitting test
points with silver finish on them I would suggest you change your test
probes to a sharper point or, print paste on the test pads. After the SMT
process the silver finish is going to tarnish creating interment
connections during test. This would also be dependent on how long the
boards have been in process i.e. rework. The longer the boards are in
process prior to testing will increase the problem with interment contact
with test points during test.
>
> Ted T.
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Rueda, Ernesto
> Sent: Thursday, September 26, 2013 12:30 PM
> To: [log in to unmask]
> Subject: [TN] Immersion Silver Board Finish Tarnishing
>
>
> Hi all,
>
> I am seeking recommendations from the experts of this forum about
tarnishing of the PCB board finish with Immersion Silver.
>
> Please enlighten me about the minimum thickness of silver metal on top
of the copper layer.
> What is the maximum process time limitation to build these boards?
>
> Our SMT machine was down for more than 3 days that went through the
weekends and the boards were not completed.
> It is possible that varying temperature and humidity affected some of
the assemblies.
> We have problems with testability at some test points because of the
tarnishing issues.
>
> We are planning to send out some panels for plating thickness test and
contamination tests as well.
> Any provider that you may recommend?
>
>
> Thank you in advance.
>
> Ernesto
>
>
> Ernesto V. Rueda | PELCO by Schneider Electric | SMT Process
Engineer
> Phone: +1 559-292-1981 ext. 3848 | Fax: +1 559-388-3781 | Mobile:
+1 559-333-3913
> Email: [log in to unmask] | Site: www.pelco.com |
Address: 3500 Pelco Way, Clovis, CA 93612-5699 USA
> P please consider the environment before printing this email
>
>
>
>
> ______________________________________________________________________
> This email has been scanned by the Symantec Email Security.cloud
service.
> For more information please contact helpdesk at x2960 or
[log in to unmask]
______________________________________________________________________
>
> ______________________________________________________________________
> This email has been scanned by the Symantec Email Security.cloud
service.
> For more information please contact helpdesk at x2960 or
[log in to unmask]
> ______________________________________________________________________
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
|
|
|