Lead free solder. How do you feel using this?

[luminarium_iaculator]

@Correllux

Not a test, per se, but some of those pertinent qualities are listed here: [Reference] Physical and Mechanical Properties of Solder Alloys

I’m in agreement about source of irritation being the flux rather than the lead. Active fume reduction/movement is pretty much standard at pro benches and you can get decent cheaper units these days for $45 to $80 without going all in on a commercial unit ($$:money_mouth_face:. It’s been a long time since I’ve done enough soldering for a length of time to really bother me, but it used to get me a little with sinuses and a headache…most of that was acid core and non-electronics rosin core, though.

[Reference] Physical and Mechanical Properties of Solder Alloys :+1: , although not all are listed here for example the one I use is Sn60Pb39Cu1 which could be similar to Sn60Pb40 which has melting point 183 / 191 °C, solidus / liquidus and 535 kgf/cm² of Tensile Strength at Break which is one of the best from the table.

Also the one that thefreeman mentioned Sn42/Bi57.6/Ag0.4 could be similar to Bi58Sn42 from mentioned table which has lower melting point 138 / 138 °C solidus / liquidus and 565 kgf/cm² Tensile Strength at Break which seems like the best properties for our modding job if we look the table - very low melting point and excellent tensile strength! But lower thermal conductivity…

The question is: Should we use Bi58Sn42 instead Sn60Pb40? Bi58 has very bad thermal conductivity at 19 W/m⋅K while Sn60 has 49!

So real question: Is thermal conductivity more important than lower melting point and Tensile strength properties? If that is not so important than Bi58Sn42 is winner here?!

@Bob_McBob

@thefreeman

The issue with BiSn is that if it’s contaminated with lead the melting temperature decreases a lot, down to 95°C in the right proportion (rose’s metal) and it makes weak joints, if you plan to solder on existing joint you have to check if it’s leaded or lead free first.

It also has terrible thermal conductivity which may be an issue for LEDs. That’s why Clemence uses indium for his low temp Nichia reflows.

Yes. This certainly is an issue if we repair over existing setup but it should not be an issue if we do build from scratch?