Lead-free solder recommendations?

[Datsun]

Hello EEVBlog,

Unfortunately, the college I'm studying at requires the use of lead-free solder for in-class use. I've been issued some generic Sn99.3/Cu0.7 rosin core solder, and to be blunt, it sucks. As a result, I'm hoping to find a better lead-free solder alloy so that my lab sessions are slightly less miserable.

I understand that lead-free solders are generally not as "noob friendly" as their leaded counterparts, but I was wondering if there are any alloys out there that perform better than the low-cost Sn99.3/Cu0.7 stuff?

Any thoughts/recommendations would be very much appreciated.

Thanks for your time.

[deadlylover]

Try SN100C made by Nihon Superior, I think you can find it under a few different brands too.

It's my go-to solder now for general hobby use, and with a good iron, it's not much hardship at all compared to the good ol' leaded stuff.

[Datsun]

Thanks for the suggestion! I'll certainly look into that!

[Augustus]

Best lead-free solder wire i've ever used was Felder Sn100Ni+ "Clear"

http://cdn-reichelt.de/documents/datenblatt/D200/55-ISO-CORECLEARLEADFREE.pdf

It works really well, once you are used to it. Compared to good leaded solder wire it still sucks, of course 

[nanofrog]

Given your location, you'll probably want to look into Kester, Alpha Metals, American Iron & Metals (AIM), Indium, Multicore, and MG Chemicals for quality brands (easy to find in US/CAN market).

You'll need to specify the flux type (I'd suggest skipping the water soluble stuff in favor of no-clean or rosin), flux core size, wire diameter, and alloy. This information would be very helpful in making specific recommendations.

Are there any rules regarding this ^ for your class?

[marshallh]

Get a leadfree solder reel and load on leaded solder? Is there any rationale besides stupid bureaucrats?

The difference between leadfree and leaded is big enough I would consider taking all my work home and doing it there instead of at school.

[tautech]

Get a leadfree solder reel and load on leaded solder? Is there any rationale besides stupid bureaucrats?

The difference between leadfree and leaded is big enough I would consider taking all my work home and doing it there instead of at school.

+1
 

[IconicPCB]

SN100C is the best alternative to eutectic as far as wettability is concerned.

SN100C contains germanium which improves the surface finish and wetting power.

I use both SN100C ( incidentally from AIM ) and eutectic alloy. Both with no clean flux.

Eutectic solderpaste will wet the entire pad as it reflows . SN100C will cover almost all of the pad too, certainly more than the older lead free concoctions.

In fact using a 0.1mm thick stencil and reducing pad apertures by 10% will result in 100 % coverage.
Going to a 0.2mm thick stencil and reducing pad apertures by 30% will result in similar volume of solder and a reduced wet area.
This is not a problem with eutectic alloy but then again I am using a no clean flux.

[andybarrett1]

Get a leadfree solder reel and load on leaded solder? Is there any rationale besides stupid bureaucrats?

The difference between leadfree and leaded is big enough I would consider taking all my work home and doing it there instead of at school.

+2 

[free_electron]

SN100C is the best alternative to eutectic as far as wettability is concerned.

Wrong , SN100c is an eutectic alloy. Being eutectic has nothing to do with wettability.
Being eutectic means it has 1 single transition point from liquid to solid. 63/37 has that point at 183 , SN100c has that point at 227. Not 227.1 or 226.9 but exactly 227.
Non eutectic alloys have a 'band' in where they become in an intermediate syrup state.

SN100C contains germanium which improves the surface finish and wetting power.

Wrong. Yes, it contains germanium but the improved wettability is caused by the addition of nickel, not by the germanium. The germanium is needed to create the right intermetallic compounds to create the solder joint.

Eutectic solderpaste will wet the entire pad as it reflows .

and wrong again Mr bond ... An alloy being eutectic or not has nothing to do with wettability. wettability is an interplay between the flux and the alloy.

[tron9000]

well that sucks! YouR college only uses unleaded?!

We have leaded in our lab and we just tell the students to wash their hands before eating, drinking or smoking!

I was going to suggest using a flux dispensing pen. Seemed to help when I used to solder up boards with lead free solder.

[IconicPCB]

Free electron the discussion was in relation to Tin Lead versus non leaded alloys.

Eutectic is the usual Sn PB alloy and attribute of eutectic was used in that context.

Whether SN100C is or is not an eutectic alloy is something I can not comment on at the moment however to the best of my understanding it is Germanium which acts to modify the surface tension of the alloy thus promoting wetting performance and surface finish of the joint.