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From: Joe on 15 Jul 2010 03:54
Why are there these two very similar solders? Is there any situation
where one is better than the other?

I understand the eutectic nature of 63/37, and I wonder if/when 60/40
might ever be better to use.

--- Joe
From: John Doe on 15 Jul 2010 04:04
none given.now (Joe) wrote:

> Why are there these two very similar solders? Is there any
> situation where one is better than the other?

Dunno, but... If you do detail work, try water-soluble flux
solder. You just wipe off the residue for a sparkling clean
circuit.

Good luck and have fun.
From: Smitty Two on 15 Jul 2010 07:22
In article <4c3ec127$0$4762$c3e8da3(a)news.astraweb.com>,
John Doe <jdoe(a)usenetlove.invalid> wrote:

> none given.now (Joe) wrote:
>
> > Why are there these two very similar solders? Is there any
> > situation where one is better than the other?
>
> Dunno, but... If you do detail work, try water-soluble flux
> solder. You just wipe off the residue for a sparkling clean
> circuit.
>
> Good luck and have fun.

60/40 was the standard for many years, until it was learned that 63/37
was more accurately eutectic. 60/40 was kept around as a legacy product
since millions of customers worldwide had written the spec into their
procedural documentation. But distributors (in my part of the world
anyway) stopped stocking much of a 60/40 selection about 20 years ago.

As for water soluble flux, it has at least one significant drawback; it
is corrosive at room temperature (unlike RMA for example which is only
"active" when heated.) Therefore, any flux residue left on the board (or
whatever you're soldering) will lead to corrosion. Without full
immersion in a sonic tank, it can be difficult or impossible to wash it
all away.
From: PeterD on 15 Jul 2010 07:28
On Thu, 15 Jul 2010 00:54:43 -0700, none(a)given.now (Joe) wrote:

>Why are there these two very similar solders? Is there any situation
>where one is better than the other?
>
>I understand the eutectic nature of 63/37, and I wonder if/when 60/40
>might ever be better to use.
>
>--- Joe

The advantage is when you need a lower melting temperature. However,
the difference is slight. 63/37 also does not have as much of a
plastic state when melting.
From: William Sommerwerck on 15 Jul 2010 08:01
As far as I know, no.

63/37 has been "known" to be eutectic for at least 50 years. (I read about
it in "Popular Electronics" as a wee babe.)

The only reason 60/40 was ever manufactured in the first place is that tin
is more expensive than lead, so 63/37 solder costs more. Unless you're
Really Cheap, 63/37 is always preferable. It has slightly greater mechanical
strength, too, though this is rarely a consideration.

J Gordon Holt, who founded "The Stereophile", had his own theories about
soldering. Back in the days when people assembled vacuum-tube equipment from
kits, he recommended simply poking component leads through the lugs, and
soldering them without crimping them. His reasoning was that, if the
component ever needed replacement, you wouldn't have to fiddle with
uncrimping it. (If you've ever unsoldered old equipment, you know what a
tsuris this can be.) The "catch", of course, is that both the lug and the
lead have to be very clean, and you're more likely to get a cold or
incomplete connection. This is a situation where you would /definitely/ want
to use 63/37.

While I'm on the subject... I once asked the late Bob Tucker, * who wrote
the user manuals for Dynaco, why the soldering instructions were, at one
point, obviously in the "wrong" sequence. He explained that Dynaco's
"policy" was that, once a lug had three wires in it, it was to be soldered.
There was otherwise too-great a chance of it being overlooked and remaining
unsoldered, only to cause problems down the line.

* Bob, who passed on in the late '80s, was one of the nicest, most-gracious
people you could ever hope to meet. He was, perhaps surprisingly, also one
of the handsomest men I've ever seen -- by comparison, most actors and
fashion models are plain -- but he didn't seem aware of it.


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