Graham:
I hereby move that you to summarize all lengthy discussions on important subjects. Very good condensation of the key points of the discussion. Any seconds....
Gregg Owens
Technical Writer - Avionics
Space Exploration Technologies Corporation
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Graham Collins
Sent: Thursday, January 21, 2010 3:23 AM
To: [log in to unmask]
Subject: Re: [TN] Antimony in solder
Technet is a great resource, thanks Dave, Mike, and everyone else who
has chimed in here.
If I'm understanding what has been said here, I am concluding about
Sn63Pb37Sb.4A the following:
1) based on the responses it does not sound like a popular alloy choice
(nobody here has said "I use it because...")
2) Adding antimony improves wetting
3) tribal knowledge suggests other benefits, such as avoidance of Tin
Pest, not substantiated by data.
Am I missing or misunderstanding anything?
regards,
- Graham
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
Sent: Wednesday, January 20, 2010 7:45 PM
To: [log in to unmask]
Subject: Re: [TN] Antimony in solder
Hi folks! Just a couple of comments to add to the discussion. Antimony
gives solder a number of beneficial characteristics including wetting
and
tin pest resistance as has been mentioned in our TechNet discussion. Bev
Christian and I published a paper at the 2006 SMTAI Conference on tin
pest
which did indeed show that the potential of tin pest in a solder joint
is
not very probable. In fact , I am still monitoring those test assemblies
and after 4.5 years, we still have no tin pest phenomena occurring (I
gave
an update of the investigation at the 2008 SMTAI Conference). As part of
the 2006 paper/ investigation, I pulled a bunch of literature references
which turned into a very fascinating tour of the industry solder
specification evolution. Antimony was part of several industry research
projects by Becker and Borneman in the late 1950's. Their data
(including
the role of antimony) was part of the basis for the ASTM and QQ-S-571
specification requirements. When the QQ-S-571 specification was replaced
by the IPC-JSTD-006 specification, there was a huge debate on the
necessity of antimony and unfortunately most of discussions were based
on
tribal knowledge instead of looking at the original investigation
data/results. Some very good summary papers were published by the
International Tin Research Institute (Thwaites, McKay, etc) which
allowed
the industry committees to work out a compromise of "violent agreement".
The literature search was a great demonstration of how industry
investigation results evolve over time and sometimes get
positively/negatively mutated in ways the never imagined.
Dr. Chris Hunt and Dr. William Plumbridge have published some very good
papers in the last couple of years expanding our knowledge of the tin
pest
phenomenon.
Dave Hillman
Rockwell Collins
[log in to unmask]
Mike Fenner <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
01/20/2010 11:19 AM
Please respond to
[log in to unmask]
To
[log in to unmask]
cc
Subject
Re: [TN] Antimony in solder
There are many myths about tin pest, some of them you really want to be
true
like: the reason Napoleon lost against the Russians was that the French
Uniform buttons were made of tin, they succumbed to tin pest and their
trousers all fell down......
Our European office gets about 3 tin pest questions a year, but it never
is.
The failures are due to more boring things like poor wetting,
inappropriate
joint design and so on. Or sometimes people report tin pest when they
mean
tin whiskers.
NPL here did look into this quite thoroughly. You can get their report
on
line, a very nice piece of science. More dramatically satisfying you can
see
video from their research showing tin pest eating a lump of tin. They
concluded tin pest was not a worry and so far as I know there has NEVER
been
a proven case of tin pest in electronics. Presence or absence of 0.X%Sb
in
tin is not significant compared to ~40% Pb. Possibly the Sb made the
solder
harder/stronger, but more likely other changes were made as indicated
above.
Regards
Mike
Mike Fenner, Technical Manager
Indium Corporation
Europe
Mob: + 44 7810 526 317
Skype: mike.fenner
Tel: + 44 1908 580 400
Fax: + 44 1908 580 411
www.indium.com
---------------------
Indium Corporation
Incorporated in New York, USA
Registered office: (Not for correspondence)
77-97 Harpur Street, Bedford , UK
Registered number: fc16473
* Please think before you print
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Roberts, Jon (SA-1)
Sent: Wednesday, January 20, 2010 4:35 PM
To: [log in to unmask]
Subject: Re: [TN] Antimony in solder
I was always trained during my early years working with the Cat A under
the WS6536, DoD Std 2000, etc days that Bev stated to reduce tin pest.
I was informed that during the cold war in the 70's that line of radars
were installed in the northern part of Canada to detect incoming
missiles attacks. The extreme cold temperature caused solder failures
related to tin pest or was attributed to tin pest. I believe my Cat A
without question. Anyone else remember being told that? I am one of the
older ones here. Jon
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bev Christian
Sent: Wednesday, January 20, 2010 9:56 AM
To: [log in to unmask]
Subject: Re: [TN] Antimony in solder
Graham,
I think it was historically added because of a fear of tin pest. Which
is weird since lead is an excellent deterrent to tin pest.
Bev
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Nigel Burtt
Sent: Wednesday, January 20, 2010 10:51 AM
To: [log in to unmask]
Subject: Re: [TN] Antimony in solder
Antimony affects wetting speed
Useful reference here:
http://www.kester.com/en-us/documentation/EffectsofMetallicImpurities.pd
f
Nigel
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