LMZ14202：LMZ14202

Hello.
I posted it because it was told to consult with TI customer support on the defective item, the place to contact on the matter of exchange on this forum.

I bought 1115 pieces of LMZ 14202 TZ-ADJ / NOPB at TISTORE at 2017/9, but errors frequently occurred on parts.

I think whether there was no problem with our method of use, but how is it?

In the board circuit, it is used as a power supply of about 6 V 1 A load from 24 V input.

We completed mass production of 1,100 sheets from 2017/9 after completing preparation and evaluation of prototype board.
We created ten pilots at 2017/10 and completed the reevaluation, there was no problem.

From 2017/12 to 2018/3, we have advanced the schedule of manufacturing, checking and shipping the remaining 1090 sheets.
From 2017 / January mounted products, short circuit between terminals of the device and output voltage shortage were seen.

Initially we confirmed problems in the manufacturing process, mounting process, transportation process and so on.
However, since the number of errors is too large, pay attention to the device itself and only reflow the reflow furnace
Through the terminal resistance measurement (MAX 238 ° C, 7 seconds), the terminal resistance was measured, and the terminal short circuit occurred in 5 out of 8 pieces.

Although it is also an arrival item,

· Date code 2014 reel (250 pieces) Item 3
· Date code 2016 reel (250 pieces) Item 1
The rest was REELCUT.

It is said that error products frequently occurred from 2014 / LOT tape and reel items. 2016 thing has no error.

For these reasons, we believe that there are problems with parts, not usage.
It is very troubled because it can not be manufactured as it is.
Sorry to confirm but please.