Greetings,

I've never done hot-air soldering but am helping set up a lab. I understand
we need solder paste and its shelf life is short. But I just found some
solder paste that has been out of refrigeration more than 7 years, and it
still looks like paste. What quality has it lost? Stickiness?

Thanks!

"mc" wrote in message
news:zqrDh.16146$z6.4928@bigfe9...
Greetings,

I've never done hot-air soldering but am helping set up a lab. I
understand we need solder paste and its shelf life is short. But I just
found some solder paste that has been out of refrigeration more than 7
years, and it still looks like paste. What quality has it lost?
Stickiness?

How important are reliability and traceability (ISO 9000) in your lab?

"Charles Schuler" wrote in message
. ..

"mc" wrote in message
news:zqrDh.16146$z6.4928@bigfe9...
Greetings,

I've never done hot-air soldering but am helping set up a lab. I
understand we need solder paste and its shelf life is short. But I just
found some solder paste that has been out of refrigeration more than 7
years, and it still looks like paste. What quality has it lost?
Stickiness?

How important are reliability and traceability (ISO 9000) in your lab?

So can you tell me what happens to solder paste when it gets old?

"mc" wrote in message
news:jCrDh.16165$z6.9010@bigfe9...

"Charles Schuler" wrote in message
. ..

"mc" wrote in message
news:zqrDh.16146$z6.4928@bigfe9...
Greetings,

I've never done hot-air soldering but am helping set up a lab. I
understand we need solder paste and its shelf life is short. But I just
found some solder paste that has been out of refrigeration more than 7
years, and it still looks like paste. What quality has it lost?
Stickiness?

How important are reliability and traceability (ISO 9000) in your lab?

So can you tell me what happens to solder paste when it gets old?

No, that would be your problem.

I've never done hot-air soldering but am helping set up a lab. I
understand we need solder paste and its shelf life is short. But I
just found some solder paste that has been out of refrigeration more
than 7 years, and it still looks like paste. What quality has it lost?
Stickiness?

How important are reliability and traceability (ISO 9000) in your lab?

So can you tell me what happens to solder paste when it gets old?

No, that would be your problem.

Precisely -- I asked the question because I wanted to know the answer.

Can anyone tell me what happens, physically, to solder paste that gets old,
and why it's no longer considered suitable for use? I know the
specifications say not to use it.

More generally, if I didn't know whether some solder paste was fresh, what
changes should I look for?

"mc" wrote in
news:zqrDh.16146$z6.4928@bigfe9:

Greetings,

I've never done hot-air soldering but am helping set up a lab. I
understand we need solder paste and its shelf life is short. But I
just found some solder paste that has been out of refrigeration more
than 7 years, and it still looks like paste. What quality has it
lost? Stickiness?

Thanks!



IIRC,old solder paste tends to form little balls instead of reflowing
properly. Then you have them getting into the worst places and shorting
things.

--
Jim Yanik
jyanik
at
kua.net

"mc" wrote in
news2sDh.16179$z6.1559@bigfe9:

I've never done hot-air soldering but am helping set up a lab. I
understand we need solder paste and its shelf life is short. But
I just found some solder paste that has been out of refrigeration
more than 7 years, and it still looks like paste. What quality
has it lost? Stickiness?

How important are reliability and traceability (ISO 9000) in your
lab?

So can you tell me what happens to solder paste when it gets old?

No, that would be your problem.

Precisely -- I asked the question because I wanted to know the answer.

Can anyone tell me what happens, physically, to solder paste that gets
old, and why it's no longer considered suitable for use? I know the
specifications say not to use it.

More generally, if I didn't know whether some solder paste was fresh,
what changes should I look for?





perhaps the flux degrades,absorbs O2(oxidizes),loses it's fluxing ability??
It may not be readily apparent from a visual inspection.

--
Jim Yanik
jyanik
at
kua.net

"Jim Yanik" wrote in message
...
"mc" wrote in
news:zqrDh.16146$z6.4928@bigfe9:

Greetings,

I've never done hot-air soldering but am helping set up a lab. I
understand we need solder paste and its shelf life is short. But I
just found some solder paste that has been out of refrigeration more
than 7 years, and it still looks like paste. What quality has it
lost? Stickiness?

Thanks!



IIRC,old solder paste tends to form little balls instead of reflowing
properly. Then you have them getting into the worst places and shorting
things.


Thanks! Just the information I was looking for.

In article p2sDh.16179$z6.1559@bigfe9, ess
(known to some as mc) scribed...

snippety

Precisely -- I asked the question because I wanted to know the answer.

Can anyone tell me what happens, physically, to solder paste that gets old,
and why it's no longer considered suitable for use? I know the
specifications say not to use it.

More generally, if I didn't know whether some solder paste was fresh, what
changes should I look for?

I'd like to know this myself, as I'm in the final stages of getting
set up to do SMD work and I just spent $250 for supplies (solder paste,
flux, wetting solution, tools, etc.)

Simply being told "How important is reliability and traceability?"
doesn't cut it with me, any more than pointing to the expiration date on
a tube of solder paste and saying "Never use this after this date!"

I want to know what, exactly, changes, and how it affects
reliability (I don't give a flying poof-ball about traceability as long
as the solder holds). I also want to know how these alleged changes will
affect the stuff in terms of making simple repairs with (mostly) PLCC's
and QFP's.

I'm not doing mil-spec production here... just trying to do decent
repairs.

Keep the peace(es).



--
Dr. Anton T. Squeegee, Director, Dutch Surrealist Plumbing Institute
(Known to some as Bruce Lane, KC7GR)
http://www.bluefeathertech.com -- kyrrin a/t bluefeathertech d-o=t calm
"Salvadore Dali's computer has surreal ports..."

"Dr. Anton T. Squeegee" wrote in message
...

Simply being told "How important is reliability and traceability?"
doesn't cut it with me, any more than pointing to the expiration date on
a tube of solder paste and saying "Never use this after this date!"

They'd like to sell you new stuff before you use up the old stuff. Try it
and see what happens.

--
..

--
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--

mc wrote in message
news:zqrDh.16146$z6.4928@bigfe9...
Greetings,

I've never done hot-air soldering but am helping set up a lab. I
understand
we need solder paste and its shelf life is short. But I just found some
solder paste that has been out of refrigeration more than 7 years, and it
still looks like paste. What quality has it lost? Stickiness?

Thanks!



Can you try accelerated aging tests.
I remember there was a daily cycle of over-night freezing and (day ) low
oven heating that closely resembled aging for paint, so 1 week accelerated,
simulated about 1 year of normal conditions

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

"mc" wrote in message
...

"Jim Yanik" wrote in message
...
"mc" wrote in
news:zqrDh.16146$z6.4928@bigfe9:

Greetings,

I've never done hot-air soldering but am helping set up a lab. I
understand we need solder paste and its shelf life is short. But I
just found some solder paste that has been out of refrigeration more
than 7 years, and it still looks like paste. What quality has it
lost? Stickiness?

Thanks!



IIRC,old solder paste tends to form little balls instead of reflowing
properly. Then you have them getting into the worst places and shorting
things.


Thanks! Just the information I was looking for.



Why not just contact the solder paste manufacturer's technical department
and ask them ? Most makers of service materials are happy to answer
questions on their products. FWIW, I seem to recall the same as Jim, but it
seems pretty clear that none of us on here *really* know, so we could be
giving you a completely bum steer. If you do find out from the
manufacturers, post back, and tell us all, as it would seem that there is at
least one more in this thread who *needs* to know, and probably a few of us
who would *like* to know.

Arfa

"Dr. Anton T. Squeegee" wrote in message
...
In article p2sDh.16179$z6.1559@bigfe9,
ess
(known to some as mc) scribed...
Simply being told "How important is reliability and traceability?"
doesn't cut it with me, any more than pointing to the expiration
date on
a tube of solder paste and saying "Never use this after this date!"

I want to know what, exactly, changes, and how it affects
reliability (I don't give a flying poof-ball about traceability as
long
as the solder holds). I also want to know how these alleged changes
will
affect the stuff in terms of making simple repairs with (mostly)
PLCC's
and QFP's.

I'm not doing mil-spec production here... just trying to do decent
repairs.

Well done you! There is so much bull**** around these
days...ROHS..Health and Safety...WEE..
compliance this etc., the list goes on and on. The rules and
regulations have gone mad in Europe, they are killing our industries.
Stuff em all I say! Does it do the job? Yes? USE IT. If not DONT.

"Supertech" wrote in message
...

Well done you! There is so much bull**** around these days...ROHS..Health
and Safety...WEE..
compliance this etc., the list goes on and on. The rules and regulations
have gone mad in Europe, they are killing our industries. Stuff em all I
say! Does it do the job? Yes? USE IT. If not DONT.

Meanwhile the Chinese do whatever they like and stick a sticker on that says
they did what YOU wanted.

--
..

--
..
..
..
..
..
..
..
..

--

Simply being told "How important is reliability and traceability?"
doesn't cut it with me, any more than pointing to the expiration date on
a tube of solder paste and saying "Never use this after this date!"

I want to know what, exactly, changes, and how it affects
reliability (I don't give a flying poof-ball about traceability as long
as the solder holds). I also want to know how these alleged changes will
affect the stuff in terms of making simple repairs with (mostly) PLCC's
and QFP's.

Well, then you go elsewhere to determine that (the manufacturer of the paste
seems so dreadfully obvious). Or, you just try the stuff and see what
results you obtain and see how many failures occur that haunt you later.

Geez ... this is a repair group. "What, exactly, changes, reliability" ...
you are expecting too much.

I want to know what, exactly, changes, and how it affects
reliability (I don't give a flying poof-ball about traceability as long
as the solder holds). I also want to know how these alleged changes will
affect the stuff in terms of making simple repairs with (mostly) PLCC's
and QFP's.

Well, then you go elsewhere to determine that (the manufacturer of the
paste seems so dreadfully obvious). Or, you just try the stuff and see
what results you obtain and see how many failures occur that haunt you
later.

Geez ... this is a repair group. "What, exactly, changes, reliability"
... you are expecting too much.

Pardon me for asking a question in a newsgroup, then!

I got a remarkable cascade of "you shouldn't expect us to know" and only one
helpful answer.

I assumed the people in a repair newsgroup would have experience using paste
solder and might be able to tell me about their experiences with it. Or if
they didn't, they wouldn't reply.

"mc" wrote in message
.. .
I want to know what, exactly, changes, and how it affects
reliability (I don't give a flying poof-ball about traceability as long
as the solder holds). I also want to know how these alleged changes will
affect the stuff in terms of making simple repairs with (mostly) PLCC's
and QFP's.

Well, then you go elsewhere to determine that (the manufacturer of the
paste seems so dreadfully obvious). Or, you just try the stuff and see
what results you obtain and see how many failures occur that haunt you
later.

Geez ... this is a repair group. "What, exactly, changes, reliability"
... you are expecting too much.

Pardon me for asking a question in a newsgroup, then!

I got a remarkable cascade of "you shouldn't expect us to know" and only
one helpful answer.

I assumed the people in a repair newsgroup would have experience using
paste solder and might be able to tell me about their experiences with it.
Or if they didn't, they wouldn't reply.



Now now, there's no need to get arsey. I think that you got a number of
reasonable replies amongst them all, not the least of which being, from
several of us, "ask the manufacturer". It's hardly rocket science is it ?
Those of us who use the stuff in our everyday work don't let it get out of
date, so we don't have any direct experience of what goes wrong with it. The
guesses about the flux going bad or maybe the carrier, seem reasonable, but
they are just that - guesses. Probably, nothing much happens. If you keep a
packet of cornflakes past their 'sell by' or 'best by' date, without opening
them, they will probably be ok a year later. If you have opened them, they
won't be. Probably the same with the solder paste, but if you are going to
be using it professionally, do you want to risk it ? Could cause you all
sorts of problems down the line, so I say again, ask the manufacturer, then
you will know for sure, and you can tell the rest of us. If you don't feel
confident enough to talk to them by 'phone, I'm sure that they will have an
e-mail that will reach their technical people ...

Arfa