Hi Linda! What a fun topic to start the day with! The belief that we can
use an accelerated conditioning test to mimic X months of natural
solderable surface aging is a widely held urban myth. The JSTD-002 and
JSTD-003 solderability committees have done extensive work demonstrating
that all of the accelerated conditioning tests do not create the same oxide
species/structure/thicknesses that Mother Nature creates. If fact the
JSTD-002/003 specifications no longer use the term "aging" but instead use
the term "conditioning". A conditioning test (such as steam conditioning or
humidity conditioning etc.) will give you a measure of the robustness of a
finish - how that measure of robustness translates into time is a function
of your storage conditions, flux materials, and solder process parameters
(temperatures, times, atmosphere). The one "stake in the ground" you can
use is that a properly applied surface finish (i.e. thickness in accordance
with the vendor's recommendations and meeting JSTD 003 testing) should be
solderable for 12 months in standard storage conditions (75F +/-F, 30-60
%RH). Many surface finishes will be solderable well beyond the 1 year
timeframe (as Gerald O'brien's data demonstrates). Sorry, but no formula is
available.

Dave Hillman
JSTD-003 Chairman
[log in to unmask]




                      Linda Woody
                      <linda.l.woody@LM        To:       [log in to unmask]
                      CO.COM>                  cc:
                      Sent by: TechNet         Subject:  [TN] Steam aging equivalent shelf life extension
                      <[log in to unmask]>


                      05/11/2004 12:34
                      PM
                      Please respond to
                      "TechNet E-Mail
                      Forum."; Please
                      respond to Linda
                      Woody







I'm trying to find out what the equivalent shelf life extension for
solderability is when using steam aging. Does an 8hr. steam aging
correspond to some # of months expectation for good solderability. Is there
a formula for hrs. steam aging vs. months of solderability?

Any/all info. is appreciated.

Linda Woody
Lockheed Martin
Missiles and Fire Control Systems

---------------------------------------------------
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
847-509-9700 ext.5315
-----------------------------------------------------

---------------------------------------------------
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 847-509-9700 ext.5315
-----------------------------------------------------