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LMZ12003: should they be baked after long storage?

Viktorija Cecil
Mastermind 18251 points
Part Number: LMZ12003

Team, 

My customer has some inventory of LMZ12003TZ-ADJ, that has been sitting on their shelf for >2 years, and they are seeing a few of them with internally shorted pin 4 to pin 7. Should they bake these parts before they are being used?

Thanks

Viktorija

  • 0
    TI__Guru 50120 points
    Hi Viktorija,

    Let me check with the customer quality engineer to see what procedure/precautions should be taken when using devices after a long storage.

    Regards,
    Jimmy
  • 0 in reply to Jimmy Hua
    TI__Guru 50120 points

    Hi Viktorija,

    I asked the CQE as well as looked around on the E2E post for any similar issues. The LMZ1X device family may experience solder extrusion that could cause failures. Since then with the release of future family devices this has been improved upon. What you see is most likely old datecode material that had that issue. It is recommended to follow the guidelines for handling to prevent movement of solder during mounting. I've attached an application note that further details to minimize extrusion. Some highlights are as described:

    Solder Paste:

                •  TI recommends the use of type 3 or finer solder paste when mounting on the board.

    Reflow Profile:

                •  Measure peak reflow temperature by placing a fine gauge thermocouple (Type K) on top of the package body center.

                •  Ensure the peak reflow temperature does not exceed 245°C max (240°C +/- 5°C). Exceeding the max temperature may damage the part.

                •  Reflow time within 5°C Peak Temp must not exceed 20 seconds

                •  Reflow time above liquidus (217°C) must not exceed 60 seconds

                 •  Max number of reflow cycles seen by the LMZxxx power module is one.

    Moisture Handling:

                •  LMZxxx Power Module is classified as MSL3 and requires special handling due to moisture sensitivity. MSL 3 parts have a max floor life of 168 hours.

                •  Parts must be reflowed prior to 168 hour floor life after removing from the moisture barrier bag.

                •  Parts must be baked per JEDEC recommendations once the 168 hour floor life has been exceeded.

    Regards,

    Jimmy