Which type of lead-free solder is the best?

[dritech]

Hi all,

I intend to try soldering SMD components using lead-free solder (I know, some will say that I am out of my mind)
I got two different price ranges when filtering for size 0.381 mm (0.015 in) and 63/37 :

Three from AIM (33 euro average price)
Three from Kester (all 69 euro)

I never had any experience with AIM products. Are they any good, or should I just go for the more expensive Kester?
Also, from the three options, which one would you choose? Unfortunately I do not have the knowladge to pick the best one for SMD soldering.
Below are the links for the solder mentioned here:

https://eu.mouser.com/AIM-American-Iron-and-Metal/Tools-Supplies/Soldering/Solder/_/N-b11qq?P=1yzxbyqZ1z0vtnpZ1z0jnibZ1z0zl9f&Ns=Pricing%7c0

https://eu.mouser.com/Kester/Tools-Supplies/Soldering/Solder/_/N-b11qq?P=1yzxbyqZ1z0vtnpZ1z0jnibZ1z0zl9l

[austfox]

Aren’t those links for leaded solder?

[dritech]

 
Okay, that just showed how inexperienced I am when it comes to selecting the correct type of solder. I saw the RoHS compliant symbol and assumed that they are lead free.

Anyways, apparently the only lead free solder from Moser with a diameter close to 0.015" are three below (0.02"):

https://www.digikey.com/products/en/soldering-desoldering-rework-products/solder/262?k=&pkeyword=&sv=0&sf=0&FV=-1%7C117%2C-1%7C82%2C76%7C4859%2C583%7C217368%2C1303%7C364091%2C-8%7C262&quantity=&ColumnSort=1000011&page=1&stock=1&pageSize=25

I also found these from DigiKey

https://www.digikey.com/products/en/soldering-desoldering-rework-products/solder/262?k=&pkeyword=&sv=0&sf=0&FV=-1%7C117%2C-1%7C82%2C76%7C4859%2C583%7C217368%2C1303%7C364091%2C-8%7C262&quantity=&ColumnSort=1000011&page=1&stock=1&pageSize=25

Which type would you recommend for general SMD soldering please?

[austfox]

I’ve been using Multicore (Loctite) branded lead-free for years, but in the 0.56mm size. Mouser sell this, as well as the 0.38mm size that you are after. It’s been fine for me, but I’ve only done a light amount of SMD soldering, mainly through-hole.

I haven’t used any other branded solder so can’t advise you if it is better or worse than the others.

Edit: Should have mentioned I’m using the 99C variant (99.3% tin, 0.7% copper).

[tooki]

For whatever reason, buying lead free solder from USA to Europe is crazy expensive. You’d be much cheaper buying from a European vendor. (Also, for whatever reason, Kester’s price increase for really thin solder is much higher than many other brands.)

I would suggest one of these:

Rosin:
https://www.reichelt.com/it/en/hs10-lead-free-solder-containing-silver-and-copper-0-5-mm-25-sta-hs10-tsc-0-5-p225655.html

More active no-clean:
https://www.reichelt.com/it/en/crystal-511-tsc-sn95-sn95-ag4-0-5-mm-250-g-sta-511-tsc-0-5-p118604.html

Gentler no-clean:
https://www.reichelt.com/it/en/lead-free-solder-containing-silver-and-copper-0-5-mm-250-g-sta-600-tsc-0-5-p217690.html

Those are all 0.5mm. I really don’t recommend going thinner than that, you’ll find that you need ultra thin solder far less often than you might suspect. I have some 0.4mm and almost never use it (still on the roll I bought around 1990, and it’s still almost full!). Even for SMD, I use mostly 0.7-0.8mm, relying on flux and tip choice to ensure the right amount of solder.

P.S. Those solders are all Stannol, which is the same as Multicore/Loctite, as they all belong to Henkel.


December 2022 update: I’ve changed my mind. Having used Stannol a lot at work, I’m just not thrilled with it. Kester and Felder for the win.
Also, it turns out Stannol is no longer affiliated with Multicore/Loctite. They had merged at one point, but Stannol was spun back off as its own company.

[dritech]

I found a Multicore MM01876 which apparently was never used. I believe this is lead free solder, Do you recommend this for SMD? Should I use flux for best results?

[eti]

"Which type of lead-free solder is the best?"

The type that ends up in the trash by the kilo.

All this "eco" horse shit is precisely that. Lead-free solder = unreliable joints = shorter product lifespan = unjustifiable repeat sales = more revenue for the product manufacturer = more tax for the country.

It IS that simple, don't let any "wise" speeches talk you out of it. It's a load of bollocks.

[magic]

That's all nice until you live in the EUSSR and would rather make electronics than drive a truck full of ANFO into the EUSSR Parliament. Some people prefer the former and we respect their choice

Pro tip: buy leaded solder while/if you still can because sales to consumers have been banned a few years ago. And if you are building commercial products, then

And if you think you are clever because you live in the UK, we shall see how your government screws you to stay "harmonized" with the EU because reasons.

[GlennSprigg]

I can't help but generally agree...
To 'me' Solder means 'lead'. I mean, we are talking about tiny amounts compared to the Massive amounts of 'Lead'
used in numerous other types of industry. Does it really matter!!!   
So much MASSIVE reduction in the use of Lead these days, far out weighs the use of 'solder' at Home on a Cct Board.. 
P.S.  A few 'fun-facts'...
The term 'Plumber', meant a Lead Worker, from the word 'Plumb' meaning 'Lead'. And a 'Plumb-Bob' was a 'Lead' weight
hung from a string, in order to check the vertical accuracy, 90 deg from a 'Level'.   Not much Lead work now, but glueing
PVC pipes!!

[tooki]

I found a Multicore MM01876 which apparently was never used. I believe this is lead free solder, Do you recommend this for SMD? Should I use flux for best results?

Looking it up shows it’s a SAC305 lead-free, which is basically the best lead free alloy. The flux is good too, so I’d say that’s a good solder if it’s already there.

P.S. What stopped you from using google to find out this information yourself?


December 2022 update: I’ve changed my mind. The SN100NiGe alloys, despite their higher melting point than SAC305, wet and flow so much better that I prefer using that instead.

[tooki]

"Which type of lead-free solder is the best?"

The type that ends up in the trash by the kilo.

All this "eco" horse shit is precisely that. Lead-free solder = unreliable joints = shorter product lifespan = unjustifiable repeat sales = more revenue for the product manufacturer = more tax for the country.

It IS that simple, don't let any "wise" speeches talk you out of it. It's a load of bollocks.

This kind of hysteria is not helpful. It’s not what the OP was asking about, and it’s not even true. The worries about lead free solder being less robust aren’t proving to matter in the real world, where manufacturers quickly figured out how to use lead free just fine.

Remember that by now, many of the lead free solder exemptions have expired.

Is it as good as leaded? No. But is it the end of the world like you make it out to be? Absolutely not.

[dritech]

Hi Tooki,

Thanks for your reply.
I did some research and many do not recommend using SAC305.
Apparently K100LD and sn100c are better recommended if lead-free solder is required.
Do you have any experience with these please? any advice?

[ebastler]

I did some research and many do not recommend using SAC305.

That sounds a bit enigmatic.
Could you elaborate and ideally provide some sources please?

[Bassman59]

"Which type of lead-free solder is the best?"

The type that ends up in the trash by the kilo.

All this "eco" horse shit is precisely that. Lead-free solder = unreliable joints = shorter product lifespan = unjustifiable repeat sales = more revenue for the product manufacturer = more tax for the country.

It IS that simple, don't let any "wise" speeches talk you out of it. It's a load of bollocks.

OK, Boomer.

[dritech]

Hi ebaster,

Just to clarify, I did not do any scientific research , just reading comments from users (i.e. personal experiences)
Just some highlights from just one forum (link below):

https://www.eevblog.com/forum/beginners/solder-types/

"If you really want to go lead-free in a lab environment get SN99c or SN100c. Stay far away from that SAC305 junk."

"I've had good success with Kester K100LD. It's far better than SAC305 for wire solder."

"It's the most common because it's cheap (certainly not the best performing). SN100C and K100LD are more recent, and the marketing literature insinuates performance is similar to 63/37 (i.e. good wetting, nice and shiny joints, low erosion, and cost effective)."

[magic]

I found a Multicore MM01876 which apparently was never used. I believe this is lead free solder, Do you recommend this for SMD? Should I use flux for best results?

Looking it up shows it’s a SAC305 lead-free, which is basically the best lead free alloy. The flux is good too, so I’d say that’s a good solder if it’s already there.

1% flux content and halide-free?

I have been down that 1.1.3/ROL0 rabbit hole once. It's OK for assembling new boards with new components, less OK when using it on some old crusty equipment, oxidized connector etc. Maybe Multicore's is better but I wonder if your recommendation is based on that sort of use cases.

[tooki]

Hi ebaster,

Just to clarify, I did not do any scientific research , just reading comments from users (i.e. personal experiences)
Just some highlights from just one forum (link below):

https://www.eevblog.com/forum/beginners/solder-types/

"If you really want to go lead-free in a lab environment get SN99c or SN100c. Stay far away from that SAC305 junk."

"I've had good success with Kester K100LD. It's far better than SAC305 for wire solder."

"It's the most common because it's cheap (certainly not the best performing). SN100C and K100LD are more recent, and the marketing literature insinuates performance is similar to 63/37 (i.e. good wetting, nice and shiny joints, low erosion, and cost effective)."

Frankly, I think they’re wrong. Those >99% tin alloys all have appreciably higher melting points than SAC305. Shiny isn’t a useful goal in and of itself. Those solders may perform well in terms of wetting, but the higher melting point is a PITA.

December 2022 update: I’ve changed my mind. The SN100NiGe alloys, despite their higher melting point than SAC305, wet and flow so much better that I prefer using that instead.

[tooki]

I found a Multicore MM01876 which apparently was never used. I believe this is lead free solder, Do you recommend this for SMD? Should I use flux for best results?

Looking it up shows it’s a SAC305 lead-free, which is basically the best lead free alloy. The flux is good too, so I’d say that’s a good solder if it’s already there.

1% flux content and halide-free?

I have been down that 1.1.3/ROL0 rabbit hole once. It's OK for assembling new boards with new components, less OK when using it on some old crusty equipment, oxidized connector etc. Maybe Multicore's is better but I wonder if your recommendation is based on that sort of use cases.

While I agree it won’t be good for old boards, FYI, it’s not a 1%. The datasheet you probably looked at (there are a few) merely states that a 1% version is available, but it’s not saying it’s the default.

This datasheet (https://www.pemro.com/mmpemro/DataSheets/C400DS.pdf ) makes it much clearer: as a 3-core solder, it’s 2% flux.

[peter-h]

For hand soldering, at work we tested many and far out the best was Almit from Japan. Very very expensive... Most of the others were horrible.

For SMT reflow soldering, we use a subcontractor and I don't know what they use.

[newbrain]

Lead-free solder = unreliable joints = shorter product lifespan = unjustifiable repeat sales = more revenue for the product manufacturer = more tax for the country.

Bollocks.

I work in a place that designs and produces electronic equipment which is sold by the million units and used all over the world, in all kind of internal and external environments.
Replacement cycles can be long or short, but we have a lot of very old stuff around.

When we made the move to lead free (and all the rest of Rohs), there were some teething problems - as with any process change: I still remember some early BGA based boards...

To my knowledge, we have not experienced any increased field failure rates or returns due to lead free solder, and I've never seen a recall issued specifically for Rohs related problems on the stuff I worked on.

[Simon]

Lead free is no longer an issue although the old folk like to rat on it. The early days were bad i hear but that's over, we have had years of lead free.

[eti]

Lead-free solder = unreliable joints = shorter product lifespan = unjustifiable repeat sales = more revenue for the product manufacturer = more tax for the country.

Bollocks.

I work in a place that designs and produces electronic equipment which is sold by the million units and used all over the world, in all kind of internal and external environments.
Replacement cycles can be long or short, but we have a lot of very old stuff around.

When we made the move to lead free (and all the rest of Rohs), there were some teething problems - as with any process change: I still remember some early BGA based boards...

To my knowledge, we have not experienced any increased field failure rates or returns due to lead free solder, and I've never seen a recall issued specifically for Rohs related problems on the stuff I worked on.

Okay then 

[peter-h]

The issue of whiskers never actually went away.

I think the reason why it is not a problem today is that packages with pins on the periphery (QFP etc) never went below about 0.5mm pitch. I had seen some 0.35mm but that was in the leaded solder days and it was OK then. The high pin count stuff went to BGA where the balls are not that close so the problem was avoided.

Whiskers could also be avoided with special conformal coatings but they are expensive.

Military and medical still have exemptions. In fact I think the whole "control and monitoring equipment" exemption may still be there; if not then it ended quite recently. A huge raft of small manufacturers were operating under that. And if you are using up old component stock then you have to because the pins can be tin/lead plated.

For hand soldering, leaded solder works much better. However a lot of the challenge is the flux composition and this is where the super pricey Almit solder works quite well. But it works only as well as the cheapest dirtiest no-brand-name leaded solder which is 1/10 of the cost.

The whole ROHS thing is pointless because lead from other sources (e.g. car batteries) is vastly bigger than lead getting into the environment from electronics.

[perieanuo]

hi,
my 2 cents: if the law says you have to work with lead-free, ok.if not, take a good 60/40 Sn-Pb alloy.
I haven't see any lead-free that beats 60/40.
regards

[ebastler]

Military and medical still have exemptions. In fact I think the whole "control and monitoring equipment" exemption may still be there; if not then it ended quite recently. A huge raft of small manufacturers were operating under that. And if you are using up old component stock then you have to because the pins can be tin/lead plated.

RoHS exemptions for medical equipment ended in 2016, and for monitoring/control equipment in 2014 (except industrial instruments) and 2017 respectively (industrial).

You can't legally use up old component stock any longer. The only exception applies to their use as spare parts for units which were placed on the market before the relevant RoHS effective date.