[sdiy] Transition to Lead-Free Hand Soldering

Mike Beauchamp list at mikebeauchamp.com
Sat Aug 21 05:54:04 CEST 2021

On 8/20/21 5:41 AM, Roman Sowa wrote:
> I have switched to lead-free about year 2006 if not earlier. During that 
> time I was able to notice improvements achieved in lead-free solder. The 
> ones I'm using now are excellent, really easy to use and make nice shiny 
> solder joints, in contrary to widely circulating urban legend that 
> lead-free joints are matt. That was true some time ago, but not anymore. 
> Yes, I'm using it for everything, work, prototyping and home diy fun. 
> It's easier when you don't have to remember what was done with leadfree 
> or leaded, which tip is for which one etc.
> Kester seems to be most popular in US, and I don't think I've ever used 
> it. Likewise, all my suggestions will sound strange to US folks. But 
> anyway, here it goes:
> - Koki Eco+Plus SAC307, that stuff contains a small dose of metal I 
> can't remember (was it cobalt?) that makes tips last longer. I really 
> saw when it literally created new plating on a tip that was so worn out 
> that it changed shape.
> - Felder ISO-Core Sn100Ni+, that's Sn99.3 + CuNiGe, Fuji patent, 
> contains Germanium and Nickel, and that's probably the cause why the 
> joints come out so shiny. No copper here, it eats your tips like Cookie 
> Monster. It's also much cheaper than Koki
> - Stannol Kristall 511, SAC307, got one roll to try, but I think I will 
> get back to Felder. Nearly the same results as Felder, noticeably worse 
> though. But it's half cheaper than Felder.
> - Amtech SAC305, flux NC61, used for manual SMD soldering as it's 10 
> mils diameter. 0.5kg spool may last for ages at this diameter, there's 
> probably milion kilometers in there. It's not as shiny as any other 
> mentioned, but that doesn't mean I should throw it away (or give it 
> someone here?) and buy new Felder.
> I use them in NoClean and RA version. Never used water soluble, and 
> don't plan to. Probably a matter of personal preferences rather than 
> techincal study. Water-clean flux is nasty stuff, and must be washed off 
> pretty quickly, not a month later.
> And there's also of course a small reel of leaded solder for vintage 
> synth repair. Don't put lead-free solder if there was lead, it makes 
> very weak joints, as people smarter than me claim.
> As for temperature, I do it from about 280C with small wires to 350C for 
> quick header soldering. That's roughly 540 to 670F.
> Roman

Thanks Roman, some really good information here. I've never heard of any 
of those solder brands before, but it sounds like the Koki or Felder are 
worth trying. Which Koki are you using:


They also make one that is specifically "High Reliability" for 
automotive aviation and industrial.


I might reach out to them and see if I can get samples to try.

I'm a big fan of water-soluble. Solder a board, run it under warm water 
with a brush and a few seconds later the board looks total pro. I wish i 
could use it on all the joints, including switches and pots just because 
it looks so good after.


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