>"The EU is doing the right thing though. Lead is bad for us and cumulative. And RoHS was about a lot more than just solder."

If you're worried about lead used in electronics and electrical systems, the focus should be lead-acid batteries, which use >10x more lead than circuit assemblies ever did. Lead-acid batteries were, however exempted from RoHS, while circuit assemblies were not.

I've definitely noticed how lead-free solder looks/feel much more brittle. So the EU is basically guilty of vastly increasing E-Waste for most of the electronics made in the last 20 years (which is probably is more than we've made in the time before).

Tin whiskers are absolutely not "ironed out" and there still is not a good answer besides alloying with either lead, or antimony, both of which are toxic.

But it's a tradeoff, because without the lead or the antimony, tin whiskers will eventually form. There is no known way to stop them, on a long enough timescale they will 100% certainly grow whiskers and eventually that will cause a failure.

Conformal coatings can reduce the rate of growth, but they don't stop it, and the conformal coating can itself cause failure as the tin whisker still grows and will exert mechanical pressure as it does.

I thought that as of today only North Korea and a handful of countries (Yemen, Afghanistan...) still use leaded.

Whiskers were an early problem, but the biggest issues right now are:

- Lead-free solders don't wet/flow as well as leaded, which causes lower manufacturing yields.

- Lead-free solders are generally more brittle and subject to earlier fatigue failures than leaded solders, so the lead-free units often fail prematurely (compared to leaded ones).

Solder whiskers are more likely at low pressure and low temp, but they happen with lead-free solder (more slowly and at a lower frequency) under standard conditions as well [1]. Given the number of connections on any given PCB, and that we have no way to prevent or predict whiskers, the failure rate over reasonable time-frames of any ROHS PCBA converges to 100%.

[1] https://nepp.nasa.gov/whisker/reference/tech_papers/2005-dad...

Tin whiskers also occur on earth at ambient temperature and pressure.

I’ve personally experienced tin whiskers growing between adjacent TQFP pins (resulting in product failures).

We successfully mitigated this with (1) electronic redesign so the whisker was likely to fuse (self-destruct melting via resistive heating) if it made contact with the adjacent pin in question, and (2) urethane conformal coating.

NASA studies such as https://nepp.nasa.gov/whisker/reference/tech_papers/2010-Pan... show that urethane conformal coating is effective against tin whiskers. But that does add another chemical and processing step and its own hazards.