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Lead-Free vs. 63/37 tin/lead solder

I don't do much soldering (obviously) but which is better and is less
prone to cracking in the future? The newer Lead-free rosin core or the
63/37 tin/lead rosin core? A store in my town only stocks these two.
This for a small circuit board repair project.

Also, What can I use to cleanup the dried-up rosin residue on the PCB?

Thanks
 
Forgot to mention; Another store nearby stocks 60/40 tin/lead rosin
core (says acid core) and the same kind but its made without the rosin
flux. So many to choose from; they are all around $12.00 a small spool.
 
R

Ralph Mowery

Jan 1, 1970
0
I don't do much soldering (obviously) but which is better and is less
prone to cracking in the future? The newer Lead-free rosin core or the
63/37 tin/lead rosin core? A store in my town only stocks these two.
This for a small circuit board repair project.

Also, What can I use to cleanup the dried-up rosin residue on the PCB?

Thanks

Unless you are working with circuits that have known lead-free solder on it,
go with the 63/37 rosin core. Usually it is more common to find a 60/40
rosin core, but either is fine with a slight preference to the 63/37. If
you look at a chart for the melting and cooling of the solder, you will see
that the 63/37 does not go into what is called a plastic state as it cools.
What that is , as the solder cools and if the joint is moved, the solder
will have a frosted look and will not make a very good joint. It will not
be shinny as it should look.

Never use the acid core for electronic work. The acid left behind will
absorb water from the air and eat away at the circuits. The acid flux is
mainly used for copper water pipes.
 
L

Lionel

Jan 1, 1970
0
I don't do much soldering (obviously) but which is better and is less
prone to cracking in the future? The newer Lead-free rosin core or the
63/37 tin/lead rosin core? A store in my town only stocks these two.
This for a small circuit board repair project.

For repairs, I'd use the lead/tin solder.
Also, What can I use to cleanup the dried-up rosin residue on the PCB?

I've always used methylated spirits (very cheap & easy to find) & a
stiff paintbrush, but any other kind of pure alcohol should work just
as well.
 
I

ian field

Jan 1, 1970
0
I don't do much soldering (obviously) but which is better and is less
prone to cracking in the future? The newer Lead-free rosin core or the
63/37 tin/lead rosin core? A store in my town only stocks these two.
This for a small circuit board repair project.

Also, What can I use to cleanup the dried-up rosin residue on the PCB?

Thanks

Lead free solder is specially formulated to fail after not more than 1 year
because the landfill sites aren't filling up with scrap electronic equipment
fast enough!!!
 
A

Arfa Daily

Jan 1, 1970
0
ian field said:
Lead free solder is specially formulated to fail after not more than 1
year because the landfill sites aren't filling up with scrap electronic
equipment fast enough!!!
As long as that ?? Panasonic and Sony must have got their formulations
wrong. Theirs fail after 6 weeks ...

When looking at how good ( ! ) lead free solder is, you might ask yourself
why the US military refuse to go near the stuff, and the avionics and
medical instrument industries are exempt from the new rules concerning the
hateful stuff, which are now spreading around the world ...

Arfa
 
G

g. beat

Jan 1, 1970
0
I don't do much soldering (obviously) but which is better and is less
prone to cracking in the future? The newer Lead-free rosin core or the
63/37 tin/lead rosin core? A store in my town only stocks these two.
This for a small circuit board repair project.

Also, What can I use to cleanup the dried-up rosin residue on the PCB?

Thanks

Phillip -

NEVER use acid core solder on electronic circuits (or kiss that appliance /
project goodbye).

63 / 37 is the Eutectic of Tin and Lead metals.
Eutectic is an English word that comes from the Greek 'eutektos', meaning
'easily melted.'

The lowest temperature at which a mix of two materials will melt.
Often the temperature is an anomaly, that is, it is much lower than the
melting temperatures of only slightly different mixtures. Lead-tin solder is
an example. Lead melts at 327 C, tin at 231 C.
The lowest melting combination is 67 lead, 33 tin ( 180 C ).

Non-eutectic mixtures have a melting or softening (plastic) range. Such
mixtures do not flow well until thoroughly heated past the softening
(plastic) range. Kester solder Alloy temperature chart
http://www.kester.com/en-us/technical/alloy.aspx

g. beat
 
P

Pooh Bear

Jan 1, 1970
0
I don't do much soldering (obviously) but which is better and is less
prone to cracking in the future? The newer Lead-free rosin core or the
63/37 tin/lead rosin core? A store in my town only stocks these two.
This for a small circuit board repair project.

If you have the choice use tin-lead every day !
Also, What can I use to cleanup the dried-up rosin residue on the PCB?

Do you need to ?

Most of the alcohols work fine for this. Isopropyl alcohol ( aka isopropanol )
is probably best and easy to obtain.

Graham
 
P

Pooh Bear

Jan 1, 1970
0
Forgot to mention; Another store nearby stocks 60/40 tin/lead rosin
core (says acid core) and the same kind but its made without the rosin
flux. So many to choose from; they are all around $12.00 a small spool.

*NEVER* use acid core for electronics.

Graham
 
P

Pooh Bear

Jan 1, 1970
0
Arfa said:
As long as that ?? Panasonic and Sony must have got their formulations
wrong. Theirs fail after 6 weeks ...

When looking at how good ( ! ) lead free solder is, you might ask yourself
why the US military refuse to go near the stuff, and the avionics and
medical instrument industries are exempt from the new rules concerning the
hateful stuff, which are now spreading around the world ...

An exemption has also been applied for regarding pro-audio.

Graham
 
J

James Sweet

Jan 1, 1970
0
I don't do much soldering (obviously) but which is better and is less
prone to cracking in the future? The newer Lead-free rosin core or the
63/37 tin/lead rosin core? A store in my town only stocks these two.
This for a small circuit board repair project.

Also, What can I use to cleanup the dried-up rosin residue on the PCB?

Thanks


Look for the tin/lead stuff, I've used lead free and hate it.
 
D

David Nebenzahl

Jan 1, 1970
0
Pooh Bear spake thus:
*NEVER* use acid core for electronics.

Amen to that.


--
Any system of knowledge that is capable of listing films in order
of use of the word "****" is incapable of writing a good summary
and analysis of the Philippine-American War. And vice-versa.
This is an inviolable rule.

- Matthew White, referring to Wikipedia on his WikiWatch site
(http://users.erols.com/mwhite28/wikiwoo.htm)
 
A

Arfa Daily

Jan 1, 1970
0
g. beat > said:
Phillip -

NEVER use acid core solder on electronic circuits (or kiss that appliance /
project goodbye).

63 / 37 is the Eutectic of Tin and Lead metals.
Eutectic is an English word that comes from the Greek 'eutektos', meaning
'easily melted.'

The lowest temperature at which a mix of two materials will melt.
Often the temperature is an anomaly, that is, it is much lower than the
melting temperatures of only slightly different mixtures. Lead-tin solder is
an example. Lead melts at 327 C, tin at 231 C.
The lowest melting combination is 67 lead, 33 tin ( 180 C ).

Non-eutectic mixtures have a melting or softening (plastic) range. Such
mixtures do not flow well until thoroughly heated past the softening
(plastic) range. Kester solder Alloy temperature chart
http://www.kester.com/en-us/technical/alloy.aspx

g. beat
I'm a bit confused about the talk of not using acid fluxed solders in electronics. Just about all conventional solder wires formulated for electronic work, contain one or more cores of rosin based flux. As far as I am aware, this is a fundamentally acidic material when in its activated state, and in fact its being acidic is how it removes the tarnish and oxidation on the surfaces to be joined.

Recent research that I have done regarding the use of lead free solder wire for repair and rework purposes, suggests that because of the inferior wetting properties of lead free, the fluxes employed are actually more aggressive than those in leaded solder, by virtue of being *more acidic*. This is cited as being a reason that lead free soldering is considered to be potentially more injurious to health than leaded soldering, and that workshops should take steps to improve fume extraction.

I obtained this information on very good authority, directly from a recognised specialist, working for a company whose job it is to recommend on such matters. Comments please ??

Arfa
 
P

Pooh Bear

Jan 1, 1970
0
Arfa said:
Certainly.Please turn off the html ! It's counter to accepted Usenet pactice
and makes replies difficult to quote accurately.

Graham
 
A

Arfa Daily

Jan 1, 1970
0
Sorry, don't know how that got switched on. It's set for " plain text "
again now, as it usually always is ...

So, aside from the formatting gripes, any comments on what I was really
asking :- ) ? It's a serious question that I'm interested in answers to.
There must be some posters who better understand the chemistry of soldering
and flux than I do.

Arfa
 
P

Pooh Bear

Jan 1, 1970
0
Arfa said:
Sorry, don't know how that got switched on. It's set for " plain text "
again now, as it usually always is ...

So, aside from the formatting gripes, any comments on what I was really
asking :- ) ? It's a serious question that I'm interested in answers to.
There must be some posters who better understand the chemistry of soldering
and flux than I do.

IIRC you were commenting on acid fluxes. The difference is that organic acid
fluxes ( like rosin ) are essentially inactive at average 'room' temperatures
AIUI, so present no long term risk.

Graham
 
R

Ralph Mowery

Jan 1, 1970
0
Arfa Daily said:
Sorry, don't know how that got switched on. It's set for " plain text "
again now, as it usually always is ...

So, aside from the formatting gripes, any comments on what I was really
asking :- ) ? It's a serious question that I'm interested in answers to.
There must be some posters who better understand the chemistry of soldering
and flux than I do.

You don't really have to understand it, just use rosin for electronic work.
It is almost nonreactive with the components when not heated. The acid
flux will absorb water from the air and eat the circuits.
 
J

Jim Land

Jan 1, 1970
0
Sorry, don't know how that got switched on. It's set for " plain text
" again now, as it usually always is ...

So, aside from the formatting gripes, any comments on what I was
really asking :- ) ? It's a serious question that I'm interested in
answers to. There must be some posters who better understand the
chemistry of soldering and flux than I do.

It's all a matter of words.

Here's the deal. For decades there have been two classes of flux used
for soldering.

1. Acid. This contains strong chemicals to aggressively clean the metals
and is used only for plumbing and similar soldering. It must be cleaned
from the joint after soldering, or corrosion will occur. It has NEVER
been used for electronic work because of this corrosion.

2. Rosin. This is the only flux used for electronic work. It contains
such mild chemicals that it doesn't need to be cleaned after soldering.

Your worry is about "acidity", which is probably nothing to worry about,
as long as you stick to rosin flux and never, ever, use "acid flux."
 
A

Arfa Daily

Jan 1, 1970
0
Jim Land said:
It's all a matter of words.

Here's the deal. For decades there have been two classes of flux used
for soldering.

1. Acid. This contains strong chemicals to aggressively clean the metals
and is used only for plumbing and similar soldering. It must be cleaned
from the joint after soldering, or corrosion will occur. It has NEVER
been used for electronic work because of this corrosion.

2. Rosin. This is the only flux used for electronic work. It contains
such mild chemicals that it doesn't need to be cleaned after soldering.

Your worry is about "acidity", which is probably nothing to worry about,
as long as you stick to rosin flux and never, ever, use "acid flux."

OK, thanks for the answers. I don't have any " worries " about fluxes. It
was just curiosity as I have never seen anyone making the distinction before
with regard to electronic soldering. I have been soldering virtually every
day of my life for 40 odd years, and have always used 'standard' rosin flux
cored solder, which was the only variety I had ever seen offered for normal
electronic work. I had always understood the material rosin, to be mildly
acidic, at least in its activated form, and that this was the basis of its
deoxidising properties. This was the only reason that I was interested in
comments about " never use acid flux " ( I was not the OP having soldering
problems, incidentally ).

So it would seem that the point is academic anyway, as such fluxes are not
offered for electronic work, and anyone dumb enough to try to use plumber's
flux would deserve all they got ...

Just as a matter of interest, I always remove rosin flux residues from
boards, using a proprietory flux remover from Electrolube. IMHO, post
soldering residues left on boards make the job look scrappy and
unprofessional. A couple of years back, I took over the repair of some
commercial boards from another company, who never cleaned up their work.
Interestingly, when I now see boards in for repair, that they did a couple
of years back, the joints and print area around where they've left flux
residues, often look slightly corroded. The air around them in their normal
working environment, is likely to be slightly moist, and the components that
have been replaced, run hot in normal use, so I wonder if this is slightly
reactivating the flux residues ?

Arfa
 
Good thing I found this group and asked before I bought anything, the
guy at the store counter told me acid core is mainly used for
electronic work and at the other store, the salesperson said to use
rosin core. Thats what confused me; I bought the 63/37 tin/ lead rosin
yesterday and the soldering work turned out OK. Thanks for the help!
Phillip
 
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