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Subject:
From:
"David D. Hillman" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Thu, 21 Jan 2010 13:08:14 -0600
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Hi Jon - the IPC JSTD 006 document is a baseline material specification 
with specific solder alloy composition requirements and does not contain 
solder application requirements (that is the responsibility of the user to 
determine if a particular solder alloy is applicable for their product). 
Antimony does inhibit tin pest but so does other solder alloy constituent 
elements (Pb, Bi,) so the historical misrepresentation has been that 
antimony is the element responsible for tin pest elimination which is not 
correct. Don't think of it as our parents lying, our mentors just had a 
skewed perception!  : - )

Dave



"Roberts, Jon (SA-1)" <[log in to unmask]> 
Sent by: TechNet <[log in to unmask]>
01/21/2010 10:35 AM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to
"Roberts, Jon (SA-1)" <[log in to unmask]>


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Subject
Re: [TN] Antimony in solder






Where antimony is reference in IPC and I have one question related to
the ongoing testing. 

Antimony is reference in:

IPC-J-Std-001D in Par 3.2 uses the letter A and B after the three for
solder alloys. The letter ties back to IPC-J-Std-006 Par 3.3.1 through
3.3.3 for maximum amount of antimony. 

Question:

Does the testing included temperature changes with extreme cold
condition?

Just curious.

Technet discussions are extremely valuable to myself.  Finding out the
purpose of antimony to help prevent tin pest is not real is like finding
out your parents lied to you all those years.

I thank all of you for your expertise, Jon


 
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Graham Collins
Sent: Thursday, January 21, 2010 5:23 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
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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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