best low-temp solder?

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

Silver-bearing solder is for use with silver plated terminal strips (such as Tektronix used to use); silver in the solder prevents the silver on the terminals from being dissolved by the solder and ruined.

Isaac

If you say so. That wasn't the question.

No. http://216.239.57.104/search?q=cache:WG_VLmYPkY8J:

No. http://216.239.57.104/search?q=cache:WG_VLmYPkY8J:

Yup--and that's important for good results.

The eutectic alloy is the one which has the right proportions to give it the minimum melting point for a given set of constituent metals. I've only seen the word applied to binary alloys, but I suppose it could be applied to alloys of 3 or more metals, too. I'm not sure if that's a proper use of the term, however.

A side effect of using the eutectic alloy is that there is a distinctive melting point. When the alloy is non-eutectic, there are separate solidus and liquidus points, between which the alloy is just more or less "slushy."

There is no slushy region when a eutectic alloy melts. This sounds like what Hal was describing above.

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----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

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Kester has good stuff,

I've got two spools of Ersin Multicore laying around, I got em when Tabitron closed in Brklyn years ago. But, I always get by pretty well with Chemtronics stuff., I just checked & i have to reorder a spool or deal with the ersin 5core, that stuff is high temp. and somewhat troublesome even for my weller s/gun.

thanks for the posting about this :)

Roy.Q.T. ~ E.E.Tech

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:

lead is lethal, even non leaded solder fumes should be avoided too right, little boys like the smell though }:-o

Lead is very dangerous to the central nervous system, and it is accumulative. Having said that, after years of inhaling solder fumes I thought I'd better get a blood test for lead levels after a bout of ill-health. The results came back with higher levels than the average person, but not high enough to cause concern.

I read somewhere that flux fumes are more dangerous than lead fumes, whether that's true or not I don't know.

Dave

That's messed up, can't you get one of those fumevacs ? I think i saw a few in those popular online tech catalogs.

The stuff is banned in plumbing solder for use in nyc., i don't know how stringent this is in other places.

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.

I'm going back quite a long time, when you either put up with it or look for another job :-) Seriously, lead fumes from solder weren't really given a lot of thought 20 years ago or so, and where I worked although extractors were becoming popular on production lines, the lab and other non-production departments were still a little slow in catching up.

Dave

Also, there are things like stainless steel, and aluminium that don't like regular 60/40 solder-- however silver solder will solder to stainless antenna rods (repair antenna whips, ect). and aluminium is easy to solder to, but consider : 1) that aluminium oxide WON'T allow solder to adhear to it, and that : 2) aluminium oxidizes almost immedietly ! The way to solder to aluminium without special solders/ fluxes is to scrape the surface, and then immediatly apply hot iron and solder. Then solder will adhear to it! As a side note, concerning the oxidation of aluminium, consider that the silver powder in fireworks is powdered aluminium! Have a friend , whose dad told of his experience with it (powdered)-- was used to make aluminium based paint- he was told by his boss to get rid of it-- threw it into an incinerator-- and, KABKOOIE ! as info, Jim NN7K

Isaac W>

IIRC, 'Thermite' is made from Iron Oxide and Aluminium powder, and that burns rather hot!

Dave

| IIRC, 'Thermite' is made from Iron Oxide and Aluminium powder, and that | burns rather hot!

A similar product was used to paint the Hindenburg and it is now believed by many (but not all) that it was this that destroyed it. The film of the flames looks 'wrong' for a hydrogen fire. A sample of the skin, which had been saved for many years, was subjected to a spark test and burned with great enthusiasm.

See

N

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:

It's inevitable that every time this topic comes up, someone confuses the 2 or 3% silver-loaded tin-lead solder with the hard solders known as "silver solder". They're entirely different things. The 2 or 3% silver-loaded tin-lead solder is a soft solder, very similar in use and properties to ordinary tin-lead solder. The "silver solders" used for brazing stainless steel and other materials are hard solders, with a much higher melting point and very different properties.

Roy Lewallen, W7EL

Jim - NN7K wrote:

I guesss. Hydrogen/oxygen burns without a visible flame. The shell of the Hindenburgh was obviously on fire. ...and it was painted with an aluminum paint (Iron??), which was quite normal at the time.

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

Higher melting point and greater strength; specialty applications.