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June 2009

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From:
"Stadem, Richard D." <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Stadem, Richard D.
Date:
Fri, 5 Jun 2009 13:09:15 -0500
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LOL, agreed, but I would prefer to be holding the test data. Common
sense is still required. I have yet to see any issues with solder paste
whose shelf life was extended 3 months so as to use it up. Trying to
justify use of a three-year-old wire solder, well, that's a little
different.

-----Original Message-----
From: Whittaker, Dewey (EHCOE) [mailto:[log in to unmask]] 
Sent: Friday, June 05, 2009 1:04 PM
To: TechNet E-Mail Forum; Stadem, Richard D.
Subject: RE: [TN] Flux cored wire solder shelf life

While I can't dispute the merit of your logic or argument, when the
proverbial caca hits the rotary device I'd much rather be holding an
umbrella than a light saber.
Dewey 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Friday, June 05, 2009 10:29 AM
To: [log in to unmask]
Subject: Re: [TN] Flux cored wire solder shelf life

I respectfully disagree.
Within J-STD-004, -005, and -006 are specific instructions for
requalification of solder paste, flux-cored wire solder, and fluxes.
An example is J-STD-005 par. 6.2 and 6.3, and Table 4, where it states
"If the stated shelf life on a product is expired, but it meets the
performance test, it may be used. If the material is requalified, the
new shelf life shall be considered to be half the stated shelf life."
This section goes on to provide recommended shelf life extension
inspections (testing methods).
For solder paste, all that is required is a visual inspection and a
viscosity check. 

As a consultant, I have saved a few companies several thousand dollars
in material scrap avoidance by simply documenting the tests to be used
for requalification within their own building. These tests are defined
in IPC-TM-650, along with Test Report forms, such as Table 1 within TM
2.4.34.1, which has specific Inspection Purposes listed on the top of
the page, of which one is "Shelf-life extension". However, for solder
paste I do include a requirement to test the agglomeration and wetting
per the TMs. I don't feel that a visual check and viscosity measurement
alone are sufficient.

My re-qualification procedures include re-labeling and re-stocking
instructions for priority use. 

Nowadays, ten 500 gram cartridges of solder paste costs between
$850-$1000. It takes about 2 hours to requalify a sample if they are all
the same lot code. It saves the company money, allows the use of
perfectly good material, and keeps a lot of waste out of the
environment.

Yes, I know this should not be necessary if the company controlled its
purchases so nothing ever expires. That is sometimes difficult to do
however, and all of the big solder paste, wire solder, and flux vendors
specify minimum lot buys that are sometimes more than a small to medium
size manufacturer can use up before they expire. 

It's called planned obsolescence, and it can be very expensive. This is
why these methods for re-qual were developed.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Whittaker, Dewey
(EHCOE)
Sent: Friday, June 05, 2009 11:29 AM
To: [log in to unmask]
Subject: Re: [TN] Flux cored wire solder shelf life

If the solder was good initially and stored anywhere, except near Doug's
Mountain Dew stash, it will be good for years. The problem is the cost
of having an acceptable process for extending shelf life. In the long
run it is probably more cost effective to discard all materials that
have passed/exceeded their expiration/shelf life dates, then to
acknowledge the non-conformance, segregate, inspect, disposition the
non-conformance ( establish accept/reject criteria, re-test, re-certify,
re-label) and eventually either discard or return the materials to
stock. 
Dewey

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Friday, June 05, 2009 8:38 AM
To: [log in to unmask]
Subject: [TN] Flux cored wire solder shelf life

Well, we made it to Friday!
 
I'm going ask ya'll a couple of question that I think I know the answer
to, but I want to hear what you think.
 
Right now I'm in the midst of gathering up all my solder dross, expired
solder paste, and wire solder for a shipment to my recyclers. I noticed
we had a bunch of wire solder in the locker of our training room that
was really old, like it was manufactured back in February of 1997. The
alloy is 63/37, the flux core is a pretty active water soluble organic
acid.
 
The manufacturer says that shelf life for flux cored wire solder is
3-years. But when I took some of the solder and soldered with it, it
soldered absolutely fine. Wet and flowed out with no problems
whatsoever.
 
So my question is, have any of actually had any problems soldering with
flux cored wire solder because it was too old? Do you think that
manufacturers shelf life is realistic?
 
Steve

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