TECHNET Archives

September 2013

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Gerry Gagnon <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Gerry Gagnon <[log in to unmask]>
Date:
Thu, 26 Sep 2013 15:55:39 -0400
Content-Type:
text/plain
Parts/Attachments:
text/plain (75 lines)
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] 
______________________________________________________________________

ATOM RSS1 RSS2