Hi Richard,
To some degree there is such a classification--it is the properties of the
resins like Tg, Td, and thermal expansion.

I am also proposing a Soldering Temperature Impact Index, defined as

STII = [(Tg+Td)/2] - [% thermal expansion from 50 to 260C]x10
For LF-soldering, a STII>= 215 would be about right.

But then of course, you also have moisture absorption. The delaminated PCBs
most likely had too much moisture in them and were not baked.



Werner

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