Dear Sir/Madam,
I have a PCA that uses 4x LMZ22008 and 1xLMZ12010.
A high failure rate has been observed on the LMZ22008 (approx 40%).
A low failure rate has been observed on the LMZ12010 (approx 5%).
The failure occur almost always on the same reference designators.
Before the boards are powered they are checked and the two main failures
that I am seeing are:
(1) Pin 10 and 11 “VOUT” is shorted to “GND”.
This can be confirmed when the part is removed and the resistance between Pin 10 and 11 is measured.
(2) Pin 4 is low resistance. Pulls enable low.
There has also been failures after the PCA has been powered.
The part exhibits short circuit shutdown or failure to regulate output.
The PCA manufacturing process is Vapor phase where the board is
in the oven for 7 minutes including ramp time. Approx 5 minutes at
230 degrees.
Any assistance would be greatly appreciated.
Regards Grant
