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Author Topic: Recommendations on affordable lead free solder? Confused by all the formulas.  (Read 1389 times)
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I've been soldering for many years, first using the radio shack 96sn/4ag lead free solder, and more recently the harbor freight 96sn/4ag solder, .031 in size.  Problem is it comes in such tiny little tubes, I've gone through about 100.  Its got to be cheaper buying a spool, but heres the biggest problems I'm running into.

1.  All the different formulations, and ratios.  Some with "no clean flux", others make no mention of the flux.  Kester has some SN96.3AG3.7 .031 that has my interest a little bit, seems almost the same as what I'm using.  But then I also hear of SAC solder which has mostly tin with a little silver and copper, perhaps its better?  As well as many other formulas.
2. I can't ever find a reasonable size like 1/4 or 1/2 pound.  Its all either super expensive 1lb rolls which I hesitate to buy not knowing if Its right, or else tiny tubes which aren't worth shipping.

I'm not that picky, just want it to work as well or better than the harbor freight stuff, but buy it in slightly bigger amounts to hopefully save money.  But all the different choices are just confusing me.  Any advice?
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My advice: Unless you are soldering something together that -requires- lead-free solder (for instance, the PCB is tinned for lead-free solder), or you are intending to sell your devices to people in countries with the RoHS directive - do yourself a favor and switch to leaded solder. It has a lower melting point, it's easier to use, and is much cheaper - not to mention that it doesn't grow tin whiskers that can later short your project out if you get unlucky.
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Agreed, that solder comes in too many variations.  I have been soldering for a little over 20 years and I have stuck with the same formula, 60/40.  The roll I have now is from Radio Shack and it doesn't say unleaded so I am assuming it's leaded.  I usually don't go over .032" unless I need a mess of solder some where (repairing copper pipes).

So I don't think it makes much difference as long as the solder melts, once cooled it hardens, and conducts electricity.

But, while I'm typing, if anyone has a link to the uses of different formulas, post it up.
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Go here: http://www.kester.com/SideMenu/LeadFreeSolutions.aspx
and click the "Lead free Alloys" button.
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MG Chemicals catalog number 4900-112G...
https://www.google.com/search?q=4900-112G
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Awesome, thanks for the replies.

The link to the kester website was great, providing a description of what the formulations are actually used for.  Now I feel comfortable buying SAC solder.  Either SnAg3.0Cu0.5  or SnAg3.5Cu0.7

And the link to the MG chemicals solder is just the type of quantity I've had a hard time finding, about a $25 spool.

As far as using leaded solder, I have in the past, however I'd like to stick with the less toxic lead free, and although people claim its hard to solder with, I'm able to just fine.

My only last question, is there any vast quality differences between brands, or are they basically the same as long as the formulas are the same.  For example, I found a "Chip Quik" brand, that seems roughly identical to the MG chemicals brand, specs wise, both conforming to rohs for purity, and similar price.  Think anyone would ever see a difference brand wise, or best to go for whichever is cheaper, or less shipping, etc?
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I've been soldering for many years, first using the radio shack 96sn/4ag lead free solder, and more recently the harbor freight 96sn/4ag solder, .031 in size.  Problem is it comes in such tiny little tubes, I've gone through about 100.  Its got to be cheaper buying a spool, but heres the biggest problems I'm running into.

1.  All the different formulations, and ratios.  Some with "no clean flux", others make no mention of the flux.  Kester has some SN96.3AG3.7 .031 that has my interest a little bit, seems almost the same as what I'm using.  But then I also hear of SAC solder which has mostly tin with a little silver and copper, perhaps its better?  As well as many other formulas.
2. I can't ever find a reasonable size like 1/4 or 1/2 pound.  Its all either super expensive 1lb rolls which I hesitate to buy not knowing if Its right, or else tiny tubes which aren't worth shipping.

I'm not that picky, just want it to work as well or better than the harbor freight stuff, but buy it in slightly bigger amounts to hopefully save money.  But all the different choices are just confusing me.  Any advice?

Leaded solder melts at a much lower temperature than lead free. Unless there is a real reason that you NEED lead free, I suggest using lead based solder.

The best solder is a eutectic alloy (an alloy where the melting point is lower than any of the constituent elements). For solder, that ratio is 63/37 or 62/36/2 (2% silver).

An eutectic alloy freeze at one temperature and results in bright, shiny joints. A non-eutectic alloy will have one element freeze first, followed by the other (creating a dull looking joint).

My favorite solder so far, believe it or not, is Radio Shack 62/36/2 "Silver Bearing" solder in 0.022 diameter. It has great wetting flux, cleans up easily with alcohol and makes nice, shiny joints.
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An eutectic alloy freeze at one temperature and results in bright, shiny joints. A non-eutectic alloy will have one element freeze first, followed by the other (creating a dull looking joint).

The solder I referenced is eutectic.
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My only last question, is there any vast quality differences between brands, or are they basically the same as long as the formulas are the same?

Can't help with that one.  I have only ever used MG Chemicals.
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Remember, the "lead-free" solder may be less harmful since there is no Lead in it, but the fluxes in Lead-free solder is _extremely_ aggressive and cause lung diseases if inhaled in larger quantities - As well as the airborne flux-dust that boils off when soldering.

The lead-particles is too heavy to get airborne, so unless you eat it, it won't harm you.

So unless you HAVE to use Lead-free for a reason other than your health, don't...

// Per.
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I fully agree with the statements about using leaded solder. If you'll pardon me for a moment.. I've used all the non lead types of solder and without exception found them more trouble that they are worth. I've used a lot of solder in my life commercially and not so much privately. Without exception soldering with plain old Ersin "Multicore" has been consistently better in all catagories ... Except it's lead content.
From a personal standpoint the law is the law but as I remember it has no provisions for "Hobbyist" use. Were I using more than 250 Gm/year I would be forced to switch by my own conscience, But that is my 'magic number'. When doing commercial soldering Pb Free is the law but personally here in the US..
I am a hobbyist, now. I worked my 45 years and I'll use the solder that works best here at home at my desk and dream of someday designing something that might need Pb Free... solder.

Bob  
« Last Edit: April 07, 2013, 09:12:43 am by Docedison » Logged

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At the moment there is an exemption to Roho for medical equipment and avionics because of the tin whisker problem, but that exemption is set to expire in a year or two.  Anyone know of any solutions on the horizon for the tin whisker problem?
Ciao,
Lenny
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From a personal standpoint the law is the law but as I remember it has no provisions for "Hobbyist" use.

Does RoHS apply to hobbyists? Or are you talking about California law?
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My advice: Unless you are soldering something together that -requires- lead-free solder (for instance, the PCB is tinned for lead-free solder), or you are intending to sell your devices to people in countries with the RoHS directive - do yourself a favor and switch to leaded solder. It has a lower melting point, it's easier to use, and is much cheaper - not to mention that it doesn't grow tin whiskers that can later short your project out if you get unlucky.

No, lead is a pernicious poison - its regulated in many territories and it cannot be washed off the skin with ordinary soaps
or detergents.  Lead-free solder is fine to work with if you set your iron to the right temperature (this is important) and
it doesn't seem to dissolve the copper in bits at all (so damage to the iron coating on bits doesn't cause holes to develop)
- I remember losing many otherwise good bits to this "dental decay" mechanism in the old lead-tin solder days - lead is
a powerful solvent for copper it seems.  I'll admit the higher temperature means you have to scrupulously clean and re-tin
the iron all the time and turn it off when not in use - an oxide layer forms more readily.

One of the reasons the EU has acted to eliminate lead as much as possible is the poisoning of land-fill sites by discarded electronics,
leading to polluted ground water and water courses.

Tin whiskers are a real issue of course, but for hobby electronics the risk of heavy-metal poisoning is surely more important
than failure in 20 years time... (Consumer electronics is always obsolete by then!)

One standard lead-free formulation is 99.3 tin, 0.7 copper - some others use silver and are more expensive - not sure
silver is needed, though it may better electrical conductivity...
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I think it's the tin that dissolves copper.  "Bronze", you know...
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