I Agree with you Dave. My understanding is that some ImSn have
organic additives that help relax the Tin. What kind of thickness for a
board and component terminations do you use? My understanding is that is
not that much thick. What is the shelf life before it becomes unwateble
due to the IMCs?
Regards,
Ramon
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
Sent: Friday, March 24, 2006 2:09 PM
To: [log in to unmask]
Subject: Re: [TN] Tin Whisker Mitigation
Hi Kevin! As a user of immersion tin and a member of the IPC-4554
committee, I can tell you first hand that immersion tin chemistry
formulations do not promote tin whisker growth. However, all tin
surfaces (e.g. pwbs, components, sheet metal, etc.) should be assessed
for tin whisker risk. Not all immersion tin surface finish chemistries
are created equal.
Dave Hillman
Rockwell Collins
[log in to unmask]
Kevin Glidden
<[log in to unmask]
COM>
To
Sent by: TechNet [log in to unmask]
<[log in to unmask]>
cc
Subject
03/24/2006 11:16 Re: [TN] Tin Whisker Mitigation
AM
Please respond to
[log in to unmask]
om
I believe immersion tin DOES promote whiskers, although not at the same
level as electrolytic tin. Check IPC-4554, especially Appendix 6. "A
potentially significant source for whisker formation are stresses
induced from formation of CuSn IMCs....Whiskers have grown on immersion
tin conductive features. To date, these whiskers have appeared at
ambient conditions..."
As for using cc for mitigation, it has also been found that whiskers
will still grow under (and even penetrate) coating. Check NASA paper
"Effects of Conformal Coat on Tin Whisker Growth".
Regards,
Kevin
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dehoyos, Ramon
Sent: Friday, March 24, 2006 11:34 AM
To: [log in to unmask]
Subject: Re: [TN] Tin Whisker Mitigation
Dewey:
I hear you loud and clear. In the near future thanks to
some crazy fellows that want to save the earth.... We may have to go
that route per customer request. Other choices ensure that the Tin
finish is Matte, bigger grain, instead of bright tin ( do not know yet
how to verify that), have at least 3% Pb or 3-5% Bi( use of XRF) , CC
assembly, annealing components, reflow assembly, immersion Tin
finish.... My understanding of Immersion tin is that it does not
promote Whiskers. The problem that I know about this finish, ImSn, is
that it is too thin and IMC form to make it unwetable.
Thanks for your sharing,
Regards,
Ramon
-----Original Message-----
From: Whittaker, Dewey (AZ75) [mailto:[log in to unmask]]
Sent: Friday, March 24, 2006 10:39 AM
To: TechNet E-Mail Forum; Dehoyos, Ramon
Subject: RE: [TN] Tin Whisker Mitigation
Ramon,
Yes.
Don't do it and spare yourself the cruel and unusual punishment.
Depending on your customers and critical end-use applications, the
amount of effort to do this and control it is incredible. It can be
done, but it extracts a heavy toll. Even meager efforts in-house with
chips is a waste of dough( now class did you catch the joke? Toll house
morsels = Chips(
chocolate) = waste of dough. Good you earned your chocolate chip
cookie).
Dewey
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dehoyos, Ramon
Sent: Friday, March 24, 2006 8:18 AM
To: [log in to unmask]
Subject: [TN] Tin Whisker Mitigation
Hello TechNetters:
Does anyone know of companies that are replating parts with Sn63
and reballing BGAs? Could any one share their experiences in
doing this effort? Things such as: extra time needed, cost,
reliability.......
Regards and TIA,
Ramon Dehoyos,
410.552.2210
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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
-----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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
-----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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
-----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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
-----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
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
-----------------------------------------------------
|
