Pragmatic answer.
I don't know if the actual shelf life of electronic grade flux core solder
wire has been established, or ever will be. Nor bar solder for that matter. 

If you wanted to preserve an organic compound packing it in a lead or lead
alloy container would be a good way of doing it, and some activators are not
a million miles from the type of things used as preservatives in foods. So
that's the flux taken care of. So far as the metals are concerned the lead
on our church roof has been there up to eight centuries in all weathers. It
has oxidised a little and this would be the case for high lead alloys. The
wire can be cleaned easily enough by drawing it through a wipe.

For what it's worth I have accumulated a number of odd wire samples over the
years , all perfectly OK. The oldest in my garage dates from the early 70s
and has outlasted its spool which has corroded somewhat, but the wire still
works well, bit smokier than modern types, but that's age of formulation not
age. 

I don't doubt that the IPC has said what it's said because it was under
pressure to say something as people these days want a spec to work to.
Similarly manufacturers will give a shelf life - not as some dastardly plot
to increase sales - but because again people are looking for a number. I
recall telling someone the shelf life of bar solder was effectively forever,
explained why and was pressed for a number as the system required one. So I
said in practical terms it would outlast the records so that's indefinitely,
put what you like. I was then asked to quantify forever/indefinite. So I
said 50 years and was told that that number was too big and asked if I could
agree 5 - which I did to end the call. A week later I was asked to support
the 5 years statement with data by caller's colleague as he said it should
be more. Easier just to write a number to start with.

Regards 
 
Mike 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ricardo Moncaglieri
Sent: Friday, March 13, 2015 1:39 PM
To: [log in to unmask]
Subject: [TN] Solder Wire Due Date

Colleagues,
 
Question:
Is there any specific concern about solder wire due date IPC quality
level 1?
As per J-STD-001 3.2.2 (including J-STD-006) it is not specified any
requirement for Level 1 about solder purity which could be affected from
due date (oxides growing etc). 
Which is the main concern related on solder due date to be taken into
account? 
 
Have been reading some papers beside the specific IPC stds mentioned
upper, and all comments states something like this (or approach similar
concepts):
 
"The presence of additional oxidation may be visible on the surface of
the wire. You may find that the oxidized surfaces are only on the outer
portion of the cored wire, meaning that you could unspool the wire until
you get down to the less oxidized material.


You can determine if the expired cored wire is still usable by simply
trying it - and if you aren't getting the typical amount of soldering
action (wetting speed, spread) that you normally expect, this means that
the age of the cored wire could cause a performance issue.
I have never heard of a reliability issue related to using cored wire
past the expiration date of the cored wire. The caveat to that statement
is that if the solder is excessively oxidized, the operator may feel
forced to supplement the cored wire with more liquid flux than would be
considered typical or acceptable."
Keep awaiting for your comments.
brgds,Ricardo


______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________



______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________