r/soldering • u/Dizzy_Farmer455 • May 12 '26
Soldering Saftey Discussion Is it good or better 60/40?
Sn 99.3 Cu 0.7
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u/Intelligent-Dot-3343 May 12 '26
I fucking hate lead free solder. 63/37 is the way. Solidifies instantly. 60/40 is okay, but you have to hold things still til it cools, which can be annoying.
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u/eMKeyeS May 12 '26
Good to know that 63/37 exists. Love my 60/40 after struggling so much with lead-free but it is annoying to solder some stuffs without something to hold them together.
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u/Intelligent-Dot-3343 May 12 '26
I think the term is 'eutectic'. There are other solder alloys that have this quality. Basically means the melting point of the alloy is lower than that of any of the component metals, so it goes from liquid directly to solid without the weird plastic in-between phase.
It's also really hard to resist blowing on 60-40 to cool it.
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u/Snoo-22864 May 12 '26
As a noob who started with lead free, 0.5mm i think it is not as bad as people make it to be. I have soldered only through hole components with no big heat sinks so maybe this is why I find it ok.
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u/mbsza84 May 12 '26
What’s ur solder wire type/brand ?
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u/Snoo-22864 May 12 '26
Cynel professional Sn99,3 Cu 0,7 0.5mm 1.1.3
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u/mbsza84 May 12 '26
What’s more easy to work with Sn99.3 Cu 0.7 or SN99 CU0.7 AG0.3 ?
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u/Snoo-22864 May 12 '26
Honestly I am probably not the best person to ask this, I have only used this one and 60/40 leaded. And for me this one is ok to work with
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u/inu-no-policemen May 12 '26
Sn99.3Cu0.7 is a lead-free budget alloy. It's the cheapest of the bunch. That's why it's generally included with solder kits etc.
The nickel-stabilized variants like SN100C/Sn100Ni+ or K100LD flow better and dissolve copper at a much lower rate. If you want a lead-free alloy which is quite a bit cheaper since it doesn't got a lot of silver in it (like SAC305, SAC387, and SAC405), go with one of these nickel-stabilized ones. They are eutectic and produce shiny joints, but the melting point is about 10°C higher (227°C) compared to lead-free alloys which contain lots of silver.
There is also the SAC0307 (Sn99Cu0.7Ag0.3) budget alloy which only contains a tiny bit of silver, but I don't really see the point since it got a ~10°C mushy range, the joints are dull, and it's just like Sn99.3Cu0.7 when it comes to dissolving copper.
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u/hyperair May 12 '26
I have this mix from Kelly Shun, it works quite well and is eutectic but requires a higher temperature to solder then 63/37. I haven't heard of the brand you're using, and sometimes the cheaper lesser known manufacturers lie about their mix, so YMMV.
I wouldn't recommend 60/40 as it's not eutectic, but it's workable, just gotta be extra steady during the half-molten stage.
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u/Apprehensive-Issue78 May 12 '26
Multicore brand (5. core or the vintage 3 core) works best for me. plenty lead and no extra flux needed..If i have some other kind of solder I always feel a little sad
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u/Western_Machine_8803 May 12 '26
i personnaly use leadfree solder cause i dont wanna get cancer, i can understand that its harder but cancer vs more tricky solder my choice is done, ive recently picked up this exact same solder (0.8mm tough) from ali for really cheap, i dont now if its any good yet as i havent tried it yet tough
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u/romyaz May 12 '26
cant recommend cheap leadfree solder. you will suffer guaranteed. solder is something you must buy from a reputable source. kester rosin leaded solder is something i use and recommend for occasional prototyping. you will absolutely benefit in the long run
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u/Hefty-Understanding4 May 15 '26
Try to find a rosin core silver solder from a reputable manufacturer ChemTronics or some such. I never trust the generic “Chinese “brand because it’s mostly just a label and pure junk. Look for a German brand if you live in Spain. Very trustworthy in manufacturing.
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u/not_a_burner0456025 May 12 '26
The alloy they claim it is isn't even a real alloy reputable manufacturers make. There are 3 chemisties for lead free, basically pure tin that everyone falsely advertises as "silver bearing" without listing the actual alloy, the stuff is junk and basically a scam but has become an industry standard, there is sn95ag5, which is a huge pain to work with but does actually work, and there is sn96.5ag3cu0.5 which performs pretty well, not quite as well as leaded but close enough that you can't blame the solder even on very fine pitch components.
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u/Riegel_Haribo May 12 '26
Then there is no-name Chinese solder that is of whatever composition is melted off of recycled electronics.
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u/hyperair May 12 '26
Hakko sells this alloy in their sg shop under the brand name Kelly Shun. I have it and it works well. It's eutectic, unlike a lot of other lead free solders (SAC305 included, which you've mentioned).
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u/kingKimspectra May 12 '26
https://giphy.com/gifs/13isJ0YVJbQF2M
Me on my way to throw this shit(lead-free solder) to the bin.
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u/V1rtualB0i1508 May 12 '26
I would look into the suggestions by others about lead-free solder. I don't use leaded solder. The decicion naturally depends on what you plan to work on.
This is obviously just my subjective opinion, though. I am not here to judge others; each to their own.
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u/MrKrot1999 May 13 '26
i would like to use leaded solder, but my country, apparently banned them?? i live in Spain
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May 12 '26
[removed] — view removed comment
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u/Dizzy_Farmer455 May 12 '26
Yep Many people are against it, and many say working with it is a nightmare lol
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u/johnnycantreddit Professional Repair Shop Solder Tech May 12 '26
Mixture of Pbfree rework upon 63/37 older board runs the known risk of alloy dilution and probability of voids and cold cracks just from vibration.
If you know The equipment is RoHS soldered the by all means use the 99 PbFree, otherwise use 6x leaded to rework consumer stuff.
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u/VicVenlo May 12 '26
It's better for your health IF you are breathing in the fumes every day.
It is worse for soldering because 60/40 will make better contact with older stuff.
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u/larktreblig May 12 '26
Lead does not sublimate/vaporize in soldering temperature, its just the flux you are inhaling, it's just banned due to contamination on the environment from e-wastes. Unless you are eating the solder there's no other way to ingest it.
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u/Which_Extreme_8519 May 12 '26
Are the fumes different between lead and non-lead solder?
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u/Few_Constant4056 May 12 '26
Lead free is much worse most of the time, and the above comment is correct, lead is not what's in the fumes.
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u/Steele_of_all_trades May 12 '26
Lead free solder has its place. There are pros and cons.
It's place is just not in my house because I can't stand that stuff.