Is IPC-9701 apply to QFN package?

I have a problem recently to qualify QFN package on solder joint reliability. The pcb thickness stated in IPC-9701 is 2.35mm but from the in-house test, QFN surface mount on 2.35mm thickness PCB board have a short cycle to failure due to higher CTE mismatch with about 800cycles MTTF. Is the mismatch valid since it might be overstress.

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