Solder Melting Point

From: Aaron Christopher Finney <af-list_at_is1.wfi-inc.com>
Date: Fri Dec 3 18:26:40 1999

I had a hell of a time for a while finding solder that I liked to work
with, until someone suggested Kester 44. I paid too much for the first
roll and then stumbled onto 20 large spools of it at a thrift shop for
$.50 each. More than I'll probably use in the next 10 years.

This is related in the way that I did a bunch of research into the
properties of different types of solder, so the discussion on this has
been really interesting. Thanks, Pete...

Cheers,

Aaron


On Fri, 3 Dec 1999, Pete Turnbull wrote:

> On Dec 3, 12:17, Marvin wrote:
> > Philip.Belben_at_pgen.com wrote:
> > >
> > > Eh? Silver solder is certainly very nice, flows well, bonds to a lot
> of metals,
> > > etc., but isn't it usually _higher_ melting point? Conventional solder
> melts at
> > > around 450 F, I think. (Anyone have the exact figure?), silver solder
> typically
> > > at 600.
>
> Yes, yes, no; see below...
>
> > The melting point of solder varies depending on its composition. Eutectic
> > solder (63/37) melts at about 361 degrees F and the melting point raises
> as
> > the percentage of either the lead or tin content raises.
>
> That's not *exactly* true; the solidus point (the temperature at which it
> begins to melt) remains almost exactly the same, but the liquidus point
> rises. In between, though, the solder is rather pasty. That's great for
> old-fashioned plumbing, but it's apt to produce dry joints in electronics,
> so for practical purposes, the useful temperature rises just as Marvin
> says.
>
> For example, 40/60 solder has a liquidus point of 227C (440F) and 60/40 has
> a liquidus point of 188C (370F). Adding certain other metals, especially
> bismuth, lowers the melting point, though many other additives, such as
> antimony, raise it. According to my Multicore Solder list, the recommended
> bit temperature for 40/60 general-purpose electronics solder is 354C
> (670F), and for 60/40 it's 308C (585F). Personally, I'm never that
> precise; I just twist the setscrew on my Oryx TC irons until they work
> right!
>
> "Silver solder" comes in a variety of grades, the ones with the lowest
> melting points are ArgoSwift and EasyFlo2 which melt at 600-610C
> (1100-1130F, that's a dull red heat). EasyFlo2 is 42% silver, 17% copper,
> 16% zinc, and 25% cadmium. Most engineering silver solders are
> silver+brass based like this. A few are silver-bronze (bronze being an
> alloy of copper and tin).
>
> The "silver-loaded" solder Tony and others mentioned is a soft solder
> containing 62% tin, 36% lead, and 2% silver. It has a melting point of
> 179C (354F) and a recommended bit temperature of 300-310C (570-590F).
>
> Other silver/tin/lead solders like Comsol (I bet Tony has come across that)
> and LM5 are high-melting point soft solders, with a high lead content.
> I've seen them used for fusible resistors and the like.
>
> I expect this is at least four times as much as most of you ever wanted to
> know about that silvery-grey stuff that holds the components on...
>
> --
>
> Pete Peter Turnbull
> Dept. of Computer Science
> University of York
>
Received on Fri Dec 03 1999 - 18:26:40 GMT