why 60-40 solder?

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why is 63-37 eutectic solder not universally preferred?

 

[William Sommerwerck]

<[email protected]>
wrote in message

why is 63-37 eutectic solder not universally preferred?

It costs a bit more.

 

[Smitty Two]

why is 63-37 eutectic solder not universally preferred?

If you're asking why 60-40 still exists, I'd chalk it up to residual
demand from when it *was* the universal standard. I suppose there are
companies around who still have that formulation in their process
specifications and it's easier to keep buying it than to rewrite the
documentation.

 

[mike]

why is 63-37 eutectic solder not universally preferred?

Because you can't sell it in the EU if it's got lead in it.

 

[Smitty Two]

Because you can't sell it in the EU if it's got lead in it.

You better hide under the sheets, now. The Non-Sequitur police are
coming to get you.

 

[William Sommerwerck]

Because you can't sell it in the EU if it's got lead in it.

Uh... 63-37 has lead in it.

The 63 is tin, the 37 lead. Traditionally, tin has been more expensive than
lead, so eutectic solder cost more than 60-40.

 

[TT_Man]

Because you can't sell it in the EU if it's got lead in it.

Not true at all. There are plenty of organisations that are still legally
allowed to use 60/40..... Schools colleges/military/telecoms/space etc. Plus
many more who don't care about lead free....

 

[Andrew Rossmann]

Not true at all. There are plenty of organisations that are still legally
allowed to use 60/40..... Schools colleges/military/telecoms/space etc. Plus
many more who don't care about lead free....

Plus lead helps prevent the formation of 'tin whiskers'.
http://en.wikipedia.org/wiki/Tin_whiskers

 

[Smitty Two]

[email protected] wrote:

Because you can't sell it in the EU if it's got lead in it.

Uh... 63-37 has lead in it.

The 63 is tin, the 37 lead. Traditionally, tin has been more expensive than
lead, so eutectic solder cost more than 60-40.[/QUOTE]

I don't think you'll find that to be true these days (i.e., last twenty
years or so) because solder prices are driven more by volume than the
commodity values of tin and lead. As a WAG, maybe 100 times as much
63/37 as 60/40 is sold, so I believe the premium is on the less common
formulation. If you can show me a cite to the contrary, I *might* be
willing to stand corrected. It has been many years since I priced 60/40.

 

[Ecnerwal]

why is 63-37 eutectic solder not universally preferred?

Because sometimes you want mush.

Eutectic is either solid, or liquid.

Formulations off eutectic have a range of mushiness, which can be of use.

And they have higher melting points, which can be of use in multipart
assemblies, where you might use 50-50, 60-40 and 63-37 to assemble and
solder a series of parts.

 

[Smitty Two]

Because sometimes you want mush.

Eutectic is either solid, or liquid.

Formulations off eutectic have a range of mushiness, which can be of use.

And they have higher melting points, which can be of use in multipart
assemblies, where you might use 50-50, 60-40 and 63-37 to assemble and
solder a series of parts.

Interesting. I've not heard of this before. Do you speak from:

1> experience
2> rumor
3> speculation

Not wanting to be confrontational, just curious. Wikipedia lists melting
points as:

63/37: melts between 180-185°C
60/40: melts between 183-190°C
50/50: melts between 185-215°C

I'm not aware of any soldering process that is able to control
temperature so closely as to not melt one, while melting another of
those formulations. Can you elaborate?

 

[bz]

Interesting. I've not heard of this before. Do you speak from:

1> experience
2> rumor
3> speculation

Not wanting to be confrontational, just curious. Wikipedia lists melting
points as:

63/37: melts between 180-185°C
60/40: melts between 183-190°C
50/50: melts between 185-215°C

I'm not aware of any soldering process that is able to control
temperature so closely as to not melt one, while melting another of
those formulations. Can you elaborate?

When I worked as a process engineer for Sprague Electric Co, in the early
70's, making capacitors and resistors, we used 95/5 solder, I think it was
tin/lead with a small amount of silver, to assemble the capacitors and
resistors.

One reason for that choice was so that the parts would withstand normal
60/40 soldering when boards were assembled.

Like you, I have some doubts about the kind of close control that would be
needed to use mixes as close as the ones given.






--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

[email protected] remove ch100-5 to avoid spam trap

 

[Lostgallifreyan]

When I worked as a process engineer for Sprague Electric Co, in the
early 70's, making capacitors and resistors, we used 95/5 solder, I
think it was tin/lead with a small amount of silver, to assemble the
capacitors and resistors.

One reason for that choice was so that the parts would withstand
normal 60/40 soldering when boards were assembled.

Like you, I have some doubts about the kind of close control that
would be needed to use mixes as close as the ones given.

I doubt it can be that accurately done. I use various indium based solders
for making small assemblies of optics and electronics when I want to get
different melting points, and you need well defined narrow ranges for ech
solder, with at least 10 degrees apart between each rangem ideally, because
an assembly might easily see several degrees variation unless you're
prepared to control the conditions with expensive rigour and to wait a long
time for equlibrium to settle each time you change the temperature. Two
solders wth overlapping ranges for melting would be useless.

 

[Ron(UK)]

Because you can't sell it in the EU if it's got lead in it.

Not true, most if not all UK wholesalers still sell 60/40 leaded solder.

Ron(UK)

 

[mc]

why is 63-37 eutectic solder not universally preferred?

....
Not wanting to be confrontational, just curious. Wikipedia lists melting
points as:

63/37: melts between 180-185°C
60/40: melts between 183-190°C
50/50: melts between 185-215°C

I'm not aware of any soldering process that is able to control
temperature so closely as to not melt one, while melting another of
those formulations. Can you elaborate?

It's not whether you can melt it, it's how it hardens. Eutectic solder
hardens very suddenly. 60/40 solder goes through a fleeting stage of being
viscous but not yet completely hard. I'd like to hear more about this, but
I'm told some people prefer the "feel" of one vs. the other.

 

[Smitty Two]

...
Not wanting to be confrontational, just curious. Wikipedia lists melting
points as:

63/37: melts between 180-185°C
60/40: melts between 183-190°C
50/50: melts between 185-215°C

I'm not aware of any soldering process that is able to control
temperature so closely as to not melt one, while melting another of
those formulations. Can you elaborate?

It's not whether you can melt it, it's how it hardens. Eutectic solder
hardens very suddenly. 60/40 solder goes through a fleeting stage of being
viscous but not yet completely hard. I'd like to hear more about this, but
I'm told some people prefer the "feel" of one vs. the other.[/QUOTE]

If you're going to quote me, I'd appreciate it if you wouldn't snip all
contextual relevance out of the discussion. As it is, your post might
appear to the casual observer as bearing some relevance to the topic at
hand. It may be a response to the OP, but it certainly isn't relevant to
the sub-topic of sequential soldering using a variety of formulations.

 

[mc]

If you're going to quote me, I'd appreciate it if you wouldn't snip all
contextual relevance out of the discussion. As it is, your post might
appear to the casual observer as bearing some relevance to the topic at
hand. It may be a response to the OP, but it certainly isn't relevant to
the sub-topic of sequential soldering using a variety of formulations.

I am indeed trying to discuss the original topic of the thread. The
original poster's question interested me, an nobody has responded to it.

 

[Lostgallifreyan]

[email protected] wrote in [email protected]:

why is 63-37 eutectic solder not universally preferred?

Probably because the gradual solidification makes dry joints less likely.
I'm not even sure it it does make them less likely, but I bet it does
because you're not relying only on ductility of a solid to maintain good
structure during thermal contraction. If the two metals in the alloy don't
solidify together, one can flow to fill pores that might form in the other,
or between the solder and the parts joined with it.

 

[Gordon S. Hlavenka]

Probably because the gradual solidification makes dry joints less likely.
I'm not even sure it it does make them less likely, but I bet it does

If by "dry joints" you mean what I was taught as "cold solder" -- where
the solder crystallizes and looks like the dull side of a sheet of
aluminum foil, then you've got it backwards.

63/37 solder passes from liquid to solid so fast that there's almost no
chance for the solder to crystallize (which is usually caused by
movement during the cooling phase) and so has _less_ chance of forming
cold joints. 63/37 also has a lower melting point than 60/40 which
means that theoretically it puts less heat stress on the component being
soldered.

In practice I don't think the difference in melting points makes much
difference, at least for hand soldering, since the iron's tip
temperature isn't controlled that tightly. But I can definitely say
from personal experience that cold solder joints are much less frequent
with 63/37 than 60/40. Not impossible, though.

 

[Peter A Forbes]

[email protected] wrote in [email protected]:


Probably because the gradual solidification makes dry joints less likely.
I'm not even sure it it does make them less likely, but I bet it does
because you're not relying only on ductility of a solid to maintain good
structure during thermal contraction. If the two metals in the alloy don't
solidify together, one can flow to fill pores that might form in the other,
or between the solder and the parts joined with it.

From my days at Mullard in the early 1960's, I seem to remember that
thermostatically controlled irons were not used, there were horrible large
things like an ice pick!

Multicore set the standard in the UK for many years and what they
suggested/supplied was what industry used. As everything was hand soldered then,
it had to be a solder and flux with as wide an operating temperature range as
possible.

Peter