It’s not about lead free solder. It’s about air in the epoxy.
My comment was a reply about Greta and how saving the environment didn’t turn out so well for some
bit of a side track to this thread
As for this non start issue, maybe it is indeed air in the epoxy but who really knows unless the chemists and material scientists get involved…
Me, I’d thing fully encapsulated air bubbles wouldn’t be an issue unless it also results in some air pockets over wiring traces which resulted in localised corrosion of those wiring traces… but such should be visible under a microscope…
Where’s NASA when you need them