60/40 solder, versus 63/37... ("eutectic" mixture?)

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In comparing the two most popular solder choices, what advantages/disadvantages should be considered?  I'm primarily wondering about durability & reliability over the years.  This is from wiki:

"The greater the tin concentration, the greater the solder’s tensile and shear strengths. At the retail level, the two most common alloys are 60/40 Sn/Pb and 63/37 Sn/Pb used principally in electrical work. The 63/37 ratio is notable in that it is a eutectic mixture, which means:
   1. It has the lowest melting point (183 °C or 361.4 °F) of all the tin/lead alloys; and
   2. The melting point is truly a point — not a range
At an eutectic composition, the liquid solder solidifies as a eutectic, which consists of fine grains of nearly pure lead and nearly pure tin phases, but in no way is it an intermetallic, since there are no tin/lead intermetallics"

So this is basically saying that 63/37 has some advantages over 60/40?  I've noticed that 63/37 is more expensive.  I'm really curious about the last line in the wiki article though: "the liquid solder solidifies as a eutectic, which consists of fine grains of nearly pure lead and nearly pure tin phases, but in no way is it an intermetallic".  Does anyone know exactly what this means to a hobbyist?  Good/bad?

Since you`ve been lurking only since 2004, you may have missed some threads that can be found by advanced
search for: "solder" , by user: "peter snowberg" .

Yeah, of course I've already searched.  Although there are many posts about advantages of 63/37, I'm not clear on any DIS-advantages it might have, versus 60/40.  I've only used 60/40 in the past, and before I drop $26 to Mouser to try the 63/37, I want to make sure there isn't some downside that I'm missing.

And what about my other question (not previously addressed in any topic on this forum):
When wiki says that the eutectic solder "consists of fine grains of nearly pure lead and nearly pure tin phases, but in no way is it an intermetallic", what does that mean??  I already know that the eutectic solder has the lowest melting point/ no plasticy stage.  If you can't answer the question, then just telling me to search isn't necessarily helping!

I didn`t tell you to search, but I searched for you, but this forumboard isn`t able to link to the resultpages
so I had to tell you what to search for so you can find some multiple opinions.
Any disadvantages of the named solder would have surely popped up in one of them posts.

Now again here is what I would search as well, and which I did, but can`t link it to you on a platter again:
The seventh result is a post by R.G. Keen, and though the thread in general is about leadfree solder
(which for itself is interesting enough), it might hold some information you are looking for.

No: I can`t answer your question, since I`m not interested in leaded solder,
and sorry for not having been able to help you.

just my 15 minutes.

If there are more complaints about help with, through and by searching, they can be added in this recent thread:

NASA uses ONLY 63/37 solder (At least when I worked at JPL in the late 80's).
If there was a significant downside to it, I don't think they would be using it.

NASA uses it because of its lower melting point (And maybe other reasons, I don't know), so there is far less chance of heat damage to sensitive components (Kinda hard to repair a solder joint on something thats several million miles away :) )

You could use it for making pedals, but the cost to benefit ratio really doesn't make


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