On 02/12/2015 17:42, N_Cook wrote:
On 02/12/2015 16:29, N_Cook wrote:
On 02/12/2015 15:13, wrote:
so would it be a stretch to say that the people who died on that
aircraft may have been victims of RoHs.

Mark


Was there political reasons behind no mention in that report about the
exact nature of the solder crack?
If I was on the analysis team I would have demanded much deeper
exploration of the fault. I assume I'm not unique, so was it done , but
the result supressed in this otherwise thorough report?

This is a macro-pic of a PbF solder ring crack I took a few years ago,
when generally in repair jobs , it started becoming obvious there was a
problem with PbF and vibration or thermal-cycling, in operation, after
just a few years.
Traditional Pb/Sn solder could also get ring cracks but after more like
20 years
http://diverse.4mg.com/talk_crack.jpg
Inappropriate hole dimension wrt to the diameter of a component pin is
far more likely to end up with a ring crack than with traditional
solder, with or without plated through pcb production.


In that pic, X, is the component pin.
I assume the crazing/furrows at different angles, is related to that
sudden freezing optical effect of PbF going solid. Traditional solder
just goes from molten to solid with no visual change to the surface
appearance.
The outer section of the solder blob does not have that crazing, so
perhaps differential stressing is built in , before any operational
stresses.