best low-temp solder?

[[email protected]]

I've had good luck with the kester 62/36/2% silver stuff, which is
eutectic.

Many many years ago, I had some luck with a indium-bismuth solder paste
in syringes from Indium Corp. Haven't fiddled with any of their stuff
since then.

Radio Shack sells a bag of little peices of tape-form stuff. Never got
it to work well.

Favorites?

 

[Hal Rosser]

I've had good luck with the kester 62/36/2% silver stuff, which is
eutectic.

Many many years ago, I had some luck with a indium-bismuth solder paste
in syringes from Indium Corp. Haven't fiddled with any of their stuff
since then.

Radio Shack sells a bag of little peices of tape-form stuff. Never got
it to work well.

Favorites?

plain old 60-40 rosin-core electrical solder has worked well for me - got
mine at a hamfest on a half-pound roll.
the silver stuff (I believe) melts at higher temperatures - and higher
temperatures are not good for electronics.
eutectic (if my memory serves) just means it's either solid or liquid - and
won't just 'soften' - like ice and water.
hth
Hal w4pmj

 

[Isaac Wingfield]

plain old 60-40 rosin-core electrical solder has worked well for me - got
mine at a hamfest on a half-pound roll.
the silver stuff (I believe) melts at higher temperatures - and higher
temperatures are not good for electronics.

Silver-bearing solder is for use with silver plated terminal strips
(such as Tektronix used to use); silver in the solder prevents the
silver on the terminals from being dissolved by the solder and ruined.

Isaac

 

[JeffM]

I've had good luck with the kester 62/36/2% silver stuff,

plain old 60-40...worked well for me
Hal Rosser

If you say so. That wasn't the question.

the silver stuff (I believe) melts at higher temperatures
No.
http://216.239.57.104/search?q=cach...Electronic.html+62-36-2+179-354+60-40-183-191


the silver stuff (I believe) melts at higher temperatures
No.
http://216.239.57.104/search?q=cach...Electronic.html+62-36-2+179-354+60-40-183-191


eutectic (if my memory serves) just means it's either solid or liquid
--and won't just 'soften' -- like ice and water

Yup--and that's important for good results.

 

[Jim Adney]

eutectic (if my memory serves) just means it's either solid or liquid - and
won't just 'soften' - like ice and water.

The eutectic alloy is the one which has the right proportions to give
it the minimum melting point for a given set of constituent metals.
I've only seen the word applied to binary alloys, but I suppose it
could be applied to alloys of 3 or more metals, too. I'm not sure if
that's a proper use of the term, however.

A side effect of using the eutectic alloy is that there is a
distinctive melting point. When the alloy is non-eutectic, there are
separate solidus and liquidus points, between which the alloy is just
more or less "slushy."

There is no slushy region when a eutectic alloy melts. This sounds
like what Hal was describing above.

-

 

[Roy Lewallen]

The eutectic combination of tin and lead is 63% tin, 37% lead. 60/40 has
a slightly higher melting point, and unlike the eutectic alloy, has a
plastic stage between liquid and solid. Consequently, 63/37 is a better
choice for solder.

Roy Lewallen, W7EL

 

[Dave Platt]

The eutectic combination of tin and lead is 63% tin, 37% lead. 60/40 has
a slightly higher melting point, and unlike the eutectic alloy, has a
plastic stage between liquid and solid. Consequently, 63/37 is a better
choice for solder.

I understand that there's a tradeoff involved. The 63/37 eutectic has
a lower melting point and no plastic stage, and some people feel that
the latter reduces the risk of 'cold' solder joints somewhat. On the
other hand, I've read that the 60/40 alloy is somewhat superior in its
"wetting" property - it adheres and bonds to some base metals better
than the eutectic does, and might make superior joints as a result.

I tend to prefer the eutectic, or a eutectic modified with 2% silver.

 

[Jim - NN7K]

Also, there are things like stainless steel, and aluminium that don't
like regular 60/40 solder-- however silver solder will solder to
stainless antenna rods (repair antenna whips, ect). and aluminium
is easy to solder to, but consider : 1) that aluminium oxide WON'T allow
solder to adhear to it, and that : 2) aluminium oxidizes almost
immedietly ! The way to solder to aluminium without special solders/
fluxes is to scrape the surface, and then immediatly apply hot iron and
solder. Then solder will adhear to it! As a side note, concerning
the oxidation of aluminium, consider that the silver powder in fireworks
is powdered aluminium! Have a friend , whose dad told of his experience
with it (powdered)-- was used to make aluminium based paint- he was told
by his boss to get rid of it-- threw it into an incinerator-- and,
KABKOOIE ! as info, Jim NN7K

 

[Dave D]

As a side note, concerning

the oxidation of aluminium, consider that the silver powder in fireworks
is powdered aluminium! Have a friend , whose dad told of his experience
with it (powdered)-- was used to make aluminium based paint- he was told
by his boss to get rid of it-- threw it into an incinerator-- and,
KABKOOIE ! as info, Jim NN7K

IIRC, 'Thermite' is made from Iron Oxide and Aluminium powder, and that
burns rather hot!

Dave

 

[NSM]

| IIRC, 'Thermite' is made from Iron Oxide and Aluminium powder, and that
| burns rather hot!

A similar product was used to paint the Hindenburg and it is now believed by
many (but not all) that it was this that destroyed it. The film of the
flames looks 'wrong' for a hydrogen fire. A sample of the skin, which had
been saved for many years, was subjected to a spark test and burned with
great enthusiasm.

See http://en.wikipedia.org/wiki/Hindenburg_disaster

N

 

[Roy Lewallen]

2 or 3% silver is added to tin-lead solder to prevent leaching of gold
or silver terminations from certain surface mount components (and the
terminal strips in very old Tektronix scopes). These components are
often used for hybrid circuits, but solder-coated terminations seem a
lot more common for components intended for PCB use. I haven't seen a
leaching problem with the solder-coated terminations using ordinary
tin-lead solder.

Is there some other advantage of a 2 or 3% silver addition?

Roy Lewallen, W7EL

 

[Roy Lewallen]

It's inevitable that every time this topic comes up, someone confuses
the 2 or 3% silver-loaded tin-lead solder with the hard solders known as
"silver solder". They're entirely different things. The 2 or 3%
silver-loaded tin-lead solder is a soft solder, very similar in use and
properties to ordinary tin-lead solder. The "silver solders" used for
brazing stainless steel and other materials are hard solders, with a
much higher melting point and very different properties.

Roy Lewallen, W7EL

 

[keith]

| IIRC, 'Thermite' is made from Iron Oxide and Aluminium powder, and that
| burns rather hot!

A similar product was used to paint the Hindenburg and it is now believed by
many (but not all) that it was this that destroyed it. The film of the
flames looks 'wrong' for a hydrogen fire. A sample of the skin, which had
been saved for many years, was subjected to a spark test and burned with
great enthusiasm.

I guesss. Hydrogen/oxygen burns without a visible flame. The shell of
the Hindenburgh was obviously on fire. ...and it was painted with an
aluminum paint (Iron??), which was quite normal at the time.

 

[RST Engineering]

Yes. This little addition of silver adds a very LARGE amount of strength to
the joint. PLEASE don't ask me to climb up to the top shelf to give you
numbers.... {;-)

Jim

 

[[email protected]]

2 or 3% silver is added to tin-lead solder to prevent leaching of gold
or silver terminations from certain surface mount components (and the
terminal strips in very old Tektronix scopes). These components are
often used for hybrid circuits, but solder-coated terminations seem a
lot more common for components intended for PCB use. I haven't seen a
leaching problem with the solder-coated terminations using ordinary
tin-lead solder.

Is there some other advantage of a 2 or 3% silver addition?

Roy Lewallen, W7EL

Higher melting point and greater strength; specialty applications.

 

[Dave Platt]

2 or 3% silver is added to tin-lead solder to prevent leaching of gold
or silver terminations from certain surface mount components (and the
terminal strips in very old Tektronix scopes). These components are
often used for hybrid circuits, but solder-coated terminations seem a
lot more common for components intended for PCB use. I haven't seen a
leaching problem with the solder-coated terminations using ordinary
tin-lead solder.

Is there some other advantage of a 2 or 3% silver addition?

A fair number of surface-mount components (caps and resistors) use
silvered terminations. Some of them have an anti-leaching coating
over the silver (nickel, or solder with or without silver), others
don't. There's also silver plating on some of the RF connectors I
use. I'm probably being excessively cautious, but figure that it
can't hurt to use a silver-loaded solder and it might save me one or
two failures over time.

 

[NSM]

| I guesss. Hydrogen/oxygen burns without a visible flame. The shell of
| the Hindenburgh was obviously on fire. ...and it was painted with an
| aluminum paint (Iron??), which was quite normal at the time.

Apparently this was the first time this particular product was used - and
the last as the Zeppelin company did further tests on the paint and never
used it again.

N

 

[Crazy George]

terminal strips in very old Tektronix scopes).

Roy Lewallen, W7EL

HEY! I resemble that statement. What do you mean VERY OLD? Seems like just last week.

 

[Roy Lewallen]

Thanks, a web search was educational. Although one or two sources show
only a single melting/solidifying temperature of 179 degrees C for
62Sn/36Pb/2Ag solder, others show a 10 degree C pasty range, with solid
and liquid temperatures of 179 and 189 degrees respectively. This range
is a bit wider than for, say, 60/40 solder which has an 8 degree range.
This would be a disadvantage (probably a minor one) to using the
silver-loaded solder.

I found two different sets of data for strength:

Tensile PSI Shear PSI
63/37 7500 6200
32/36/2 7000 7540

and

Tensile PSI Shear PSI
63/37 7600 5400
32/36/2 8600 6600

So it does appear that the silver-loaded solder has higher shear
strength, and might have greater or less tensile strength, than unloaded
solder. Despite the different numbers, both sources agree that the shear
strength increase is about 22%. I wouldn't call that a "very LARGE
amount" of difference, but that's certainly a matter of opinion.

Perhaps some people will find that the considerably greater expense,
reduced availability, and non-eutectic behavior of silver-loaded solder
is worth the modest increase (my opinion of 22% greater) in shear
strength. But I doubt that many will. I keep a small quantity on hand
for soldering SMD parts which have silver or gold terminations, but am
satisfied with 63/37 for everything else.

Roy Lewallen, W7EL

 

[Hal Rosser]

plain old 60-40...worked well for me

If you say so. That wasn't the question.

**************
Oh contraire Pierre - the question was ...."Favorites ?" (look at the
Original post)
That was mine - because it works for me.. sheesh !
*******************

Yup--and that's important for good results.

*****
I thought so
******