Dave and Bev,
I must confess that this was something that I didn't know.
I guess we learn something new every day.
Thanks for the info.
Doug
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of David Douthit
Sent: Tuesday, December 21, 2004 12:05 PM
To: [log in to unmask]
Subject: Re: [LF] Silver emersion shelf life.
Doug,
Most paper products use sulfur compounds in them (brown cardboard in
particular!).
These compounds (in the form of dust) will reduce to SO2 and H2S very
quickly.
These 2 compounds will vigorously attack silver surfaces.
When dealing with high reliability hardware it is very wise to specify
non-sulfur paper products for shipping and storage.
David A. Douthit
Manager
LoCan LLC
Doug Barnhard wrote:
>Bev,
>
>What is the significance of the cardboard being nearby?
>
>Doug
>
>-----Original Message-----
>From: Leadfree [mailto:[log in to unmask]] On Behalf Of Bev Christian
>Sent: Tuesday, December 21, 2004 11:42 AM
>To: [log in to unmask]
>Subject: Re: [LF] Silver emersion shelf life.
>
>Carol,
>It will also depend on your "air" - how much SO2 and H2S it has in it.
>Any cardboard nearby?
>Bev Christian
>Research in Motion
>
>-----Original Message-----
>From: Leadfree [mailto:[log in to unmask]]On Behalf Of Lee Parker
>Sent: December 21, 2004 11:33 AM
>To: [log in to unmask]
>Subject: Re: [LF] Silver emersion shelf life.
>
>
>Carol
>
>Immersion silver was first introduced into North America by the AT&T
>facility in Richmond, VA. We test the coating in numerous facilities
>across the country prior to production. We found the coating to have at
>least a year of shelf life in these environments. There was also
>extensive laboratory work performed to verify the long term reliability
>of the coating.
>
>Best regards
>
>Lee
>
>-----Original Message-----
>From: Leadfree [mailto:[log in to unmask]] On Behalf Of Carol Spiers
>Sent: Tuesday, December 21, 2004 11:21 AM
>To: [log in to unmask]
>Subject: [LF] Silver emersion shelf life.
>
>Does anyone know the shelf life of unpopulated silver emersion boards
>that are exposed to air. I am concerned about the finish being
>compromised and subsequently affecting solderability in a pbfree
>process. I have been asked specifically if tarnishing over time is an
>issue or will the more highly active fluxes take care of this issue
when
>eventually processing these boards. Also, can anyone suggest an
>appropriate thickness for silver emersion coating on boards. As all I
>can find are cautionary notes stating the "thinness of the coating can
>be an issue as higher soldering temperatures could result in
>out-diffusion of base metals and oxidation, leading to reduced
>solderability."
>Once again, any advise/information provided will be much appreciated.
>Regards
>
>Carol
>C. M. (Carol) Spiers
>Director of Operations
>Interalia Inc.
>
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