Characteristics of modern solder mixtures (leadfree)

[nightfire]

Preface: I am living in germany/EU, so due to several reasons, including availibilty of products, leadfree solder is in most cases the way to go for new projects.
I know of the differences to leaded solder (and have some small spools around for repair usage), but would like to condense some knowledge about the characteristics of solder, that might not been clear in the glossy datasheets from the manufacturer.
Basically I see that there are several "families" or approaches to leadfree solder, including flux types (Kolophonium replacements).

From what I have read, two of the prominent families are something around the SAC305 sort of solder, with some percentages of silver in it, and the silver-free stuff like 0,3 CU based stuff. Then comes the Fuji patented SN100NiGe stuff, with its eutectic behaviour.

Actually I stumbled on ebay over some SN100Ag (MA-S) solder, that was described as SAC307- that looked at me with a competetive price, so I am a bit curious what those mixtures can do or how they behave in general.

Are there any ressources on the web available, with some generic comparison chart, that provide information about things like temperature needed, eutectic behaviour, flow characteristics?
Or could we make some generic list of the different families of leadfree solder these days?

[Ungolian]

I'm kind of curious about this too.  I'm currently using Alpha lead-free, and I'd like to find something with a lower reflow temperature.  Without physically going through every brand, it would be nice if that information was on a chart somewhere.

[thm_w]

https://aimsolder.com/technical-articles/lead-free-alloy-development
https://www.eevblog.com/forum/chat/which-type-of-lead-free-solder-is-the-best/
https://www.eevblog.com/forum/manufacture/good-lead-free-solder-for-hand-soldering/
https://www.eevblog.com/forum/chat/do-you-still-use-leaded-solder-i-was-today-refused-to-buy-it/

I'm kind of curious about this too.  I'm currently using Alpha lead-free, and I'd like to find something with a lower reflow temperature.  Without physically going through every brand, it would be nice if that information was on a chart somewhere.

Which specific alpha solder, SAC305? You'd basically have to go to something with bismuth or indium to get anything lower.
AFAIK most leadfree is going to all be 217C or more.

[jonpaul]

SAC305 was an early solution, costly and not optimal.

Most products switched to SN100C.

Patent expired long ago, vendors are AIM, many others.

For repair or DIY, leaded eutectic is far superior, 63/37 leaded.

Ham radio flea markets, estate sales, ebay, good sources.

Jon

[tooki]

I’ve been very happy with SN100NiGe solder.

In Germany, a really affordable option is Felder, which Reichelt sells at excellent prices. I’ve used this one and far preferred it over Stannol: https://www.reichelt.de/ch/de/loetzinn-bleifrei-mit-kupferanteil-0-75-mm-250-g-lz-f4-bf-0-75250-p258991.html

[nightfire]

Yes, this is on the top of my list of solders I want to try in the future, as a member of the SN100 family- also Voelkner has very good conditions for it.
(Will probably be february before I can  give it a try- managed to break my wrist before christmas...)

From what I have seen and read, for the average hobby tinkerer there are basically 4 options that are easy to get (including ebay)

- old stock leaded solder 60/40
- SN100 NiGe (Fuji Patent)
- SAC305 (or similar derivatives)
- Sn/Cu 99,3/0,7

Here probably the type and amount of flux would also make some difference in the behaviour of it.

[tooki]

Yes, flux makes a big difference. (This is where Stannol disappoints: I find it spits a lot, and isn’t the most effective. Tried many different kinds. None is as good as Kester, or even the much cheaper Felder.)

One other avenue to check: US distributors like mouser and Digi-Key. Both of them appear to allow customers in Europe (even non-commercial customers) to order leaded solder, in which case I’d order 63/37, not 60/40. (I’ve asked in other threads if anyone has actually tried this, but got no response. I still have tons of leaded solder left, so I won’t need to order for a while, or else I’d test it myself…)

Both of those distributors offer free shipping to Europe on orders above €50 or so, which is easily met with a 1lb/500g roll of solder and maybe some flux.

[jonpaul]

avoid lead free, 60/40 with rosin flux core or 63 /37 Eutectic leaded

Check ham radio Fleas and surplus outlets.

Jon

[themadhippy]

One other avenue to check: US distributors like mouser and Digi-Key. Both of them appear to allow customers in Europe (even non-commercial customers) to order leaded solder

Also try cpc in the uk ,https://cpc.farnell.com/c/tools-maintenance/soldering/solder/solder-wire?leaded-lead-free=leaded  recently bought a roll of 60-40 ,no questions asked

[nightfire]

Update to the whole stuff, a bit delayed due to my broken wrist...

Got myself a good deal on Felder ISO-Core "Clear" solder. Ordered SN100Ni+ (Fuji Patent) and SAc305 (Sn96,5Ag3,0Cu0,5), both in 1mm diameter and with 3,5% Flux. Flux here is some synthetic new stuff, that is deemed on the rather mild side of agressiveness.
I am still soldering with my classic Ersa 30W iron, so regarding temp regulation nothing to write home about. But does the job...

In some short trial to solder header pins into recently bought breadboard carriers, I noticed not much difference in handling in between those two solders, as I had only small holes to fill.
But the main revelation came to me as I realized that this stuff has some big advantages over the old stock of leaded solder I got on ebay for repairs etc.

- 1mm flows way better than 1,5mm (the standard diameter of solder you always get included with everything)
- the amount of flux is very nice, but makes some puddle around the joint. Looks not nice, has to be cleaned off. Flux does not splatter in those two.
- Synthetic flux is smelling way less aggressive than all that classic stuff inside leaded solder of the past. Not exactly roses, but way nicer than everything I had my iron on or in in the past

For me, as SN100Ni+ is about half price of SAC305, I probably will stick with it, unless special requirements ask for SAC305, like repair work or so.

[jonpaul]

Industry has migrated from SAC305 to SN100C, cheaper, better.

The original patent has expired thus many sources.

We buy AIM and Nathan Trotter bars, in 25# boxes.

For DIY, repair and prototypes, SnPb 63/37 is eutectic, the best.

Most wire solder we have used in USA has a rosin core water based flux, like Kester #44.

fortunately we accumulated boxes of the wire solder in 60/40 and 63/37 decades ago.

Jon

[Karel]

... and have some small spools around for repair usage...

May I ask why?
I have a spool of leadfree solder, tried it once (ten years ago) and never touched it anymore because
I find traditional Sn40/Pb60 rosin core solder much easier to solder and the joints are stronger.

[wraper]

Industry has migrated from SAC305 to SN100C, cheaper, better.

It's not that simple. 10^oC higher melting temperature and somewhat worse wetting than SAC305. And it did not replace SAC305 in solder pastes at all.

[nightfire]

Of course!

As I started my home lab/bench I made some assumptions and set myself some modes I would like to work.
Also some learning curve (partly thanks to knowledge accumulated here @eevblog) settled in.

Due to Europe going leadfree I also decided to try to go leadfree, as lead even in small quantities, if simply kicked out in the trashcan, can poison lots of stuff.
Also I set up my bench to be able to get broken stuff for cheap and fix it, resp. fix my own household appliances if they break. So with repair soldering you should not mix lead/leadfree.
So for new projects I want to go leadfree.

For repair usage I have some amount of old stock 60/40, so that I do not mix different characteristics of stuff. I am aware that leaded solder is somewhat easier to use, but the newer ledfree variants from quality manufacturers with halogen-free flux is a very good alternative. This is valid for me and my setup and things I have to stick my iron in, in different setups it very well might be different.

[nightfire]

... and have some small spools around for repair usage...

May I ask why?
I have a spool of leadfree solder, tried it once (ten years ago) and never touched it anymore because
I find traditional Sn40/Pb60 rosin core solder much easier to solder and the joints are stronger.

Which variant did you got? standard 99.3/0.7 Cu?

[tooki]

Industry has migrated from SAC305 to SN100C, cheaper, better.

It's not that simple. 10^oC higher melting temperature and somewhat worse wetting than SAC305. And it did not replace SAC305 in solder pastes at all.

Worse wetting? I thought it wetted better than SAC305 (and that’s what my experience has been.)

[tooki]

Most wire solder we have used in USA has a rosin core water based flux, like Kester #44.

Kester 44 is a traditional rosin flux, not water based. (I’d also say Kester 44 is the best flux core I’ve ever used.)

[tooki]

- 1mm flows way better than 1,5mm (the standard diameter of solder you always get included with everything)
- the amount of flux is very nice, but makes some puddle around the joint. Looks not nice, has to be cleaned off. Flux does not splatter in those two.

My favorite size for through-hole is now 0.7-0.8mm (about half the cross-sectional area of 1mm). Try that sometime!

That flux is no-clean, so there is no need to clean it except in very special applications.

[nightfire]

I have some 10g package of no-name solder in 0.8mm, and i found out that it is a bit thinner than I like- I have to move too much to put additional material to the tip of the iron, so 0.8 for me is only for some very detailed work.
As I do not work on SMD (at least, not now), it is mostly through-hole which needs some material.

Lets say, with the last job I did the flux is at a visible part, where I do not like it to be there and be visible ;-)

[tooki]

Heh, to me, it’s not “very detailed” work until I need to pull out the 0.2-0.3mm solder!

0.5mm for larger SMD work, 0.7-0.8mm for most through-hole. 1mm for quickly tinning the tip and for large through-hole.

Regardless of diameter, I like to straighten a piece of solder so I’m not having to constantly change the angle of my solder-feeding hand.

[zhir]

If it helps, there is a practical comparison of SAC305 with other mixtures here: