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

Hal Rosser wrote:

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

In article ,
Roy Lewallen wrote:

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.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

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

Dave Platt wrote:
. . .

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

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


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

Roy Lewallen, W7EL

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


RST Engineering wrote:
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



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

Roy Lewallen, W7EL

In rec.radio.amateur.antenna Roy Lewallen wrote:
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.

--
Jim Pennino

Remove -spam-sux to reply.

In article ,
Roy Lewallen wrote:

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.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

"Roy Lewallen" wrote in message ...

snip
(and the
terminal strips in very old Tektronix scopes).
snip
Roy Lewallen, W7EL

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

--
Crazy George
Remove N O and S P A M imbedded in return address