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I'm thinking of changing to lead-free solder. I've heard some people prefer a traditional Pb/Sn solder, but haven't heard any specific reasons why.

I'm mostly doing through-hole work, and I have a decent temperature-controlled iron.

So, are there any issues I might encounter with changing over? And are there any situations where I'd want to use a particular type?

Jeremy Kerr
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  • There are different kinds of lead-free solder. For hobbyist use there are also bismuth based solders that have a lower melting point than regular solders and avoid a lot of the issues you have with the normal lead-free (which requires stricter process control). – Simon Richter Sep 27 '21 at 18:50

4 Answers4

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Workmanship is more challening with Pb-free solder, due to degraded wetting and a higher melt point. It is often more difficult to visually verify a cold-solder joint by visual inspection, because most Pb-free solder joints 'look' cold if you judge with the same criteria that is normally used to judge conventional solder joints.

Also, Pb-free is much more prone to tin whiskers than conventional solder - in fact, way back in the day (decades ago) this was one of the reasons lead was added to solder (it's the most effective whiskering inhibitor known). Tin whisker-induced failures are more common with dense layouts and usually happen months or years after assembly.

Adam Lawrence
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DO not use lead free unless you really really need to. And even then consider if anyone's going to find out it's not leadfree. Temeratures are higher, so more risk of part & PCB damage, and it doesn't flow as nicely. Desoldering through-holes with leadfree is a bitch, to the extent that it's easier to first flood it with leaded. It also eats through tips way faster than leaded. The flux fumes are also more unpleasant than leaded fluxes. If you really must do leadfree, use the stuff with 2% silver as this has a lower melting point and produces nicer joints.

mikeselectricstuff
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Well... try by yourself and you'll discover the reason why peoples don't use lead free solder unless they're forced to.

My supplier, when I go buy solder, always asks me "Do you need lead-free solder or do you want the working one?" :-)

Axeman
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I've tried using lead free to see how bad it really is. I got a small roll in my soldering kit and had it stored away and was contemplating to throw it away.

Just recently I decided to try it to see how it really works and to my surprise, it worked quite well. Usually have my station set to 310C and I know that's the correct temperature because I always check it with a tip temperstute tester, and it melted and flowed just fine. My joint wasn't too dull as I thought. So yeah, if the quality of the solder is good, it doesn't matter whether leaded or lead free, it'll still be good. Kester has some top quality lead free solder, so buy and try and see what works for you. I'm switching to lead free, but to beginners, practice with leaded solder

JRE
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Donald Sukhnanan
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