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UC3844A: UC3844AD8 fails after about 1 year

user18733
Prodigy 30 points
Part Number: UC3844A
Other Parts Discussed in Thread: UC1844A-EP

Hello,

first I wrote to the support via email and they wrote me that I should ask here for the problem.

We have big problems with the UC3844AD8. The component fails after about 1 year.

We use the UC3844AD8 over 15 years. The main design has not changed. In the design who they fail is nothing change since 6 years.

Now we have from 150 pieces over 20 untill now defect in a short time.

UC3844A 51M are the most who are defect. That must be from end 2016 produce date.

Some UC3844AD8 work short when we make them hot. But after do this 2-3 times they are complete defect.

We think that the UC3844AD8 have a bonding problem.

Have other users the same problem?

After we get more and more from this defects we look to an other component. We find the UC1844AMD REP. This should tested and produced only on one place.

I hope we have in the future not this problem.

  • 0
    TI__Mastermind 34465 points
    Hello user18733,
    Thank you for your interest in the UC3844A.
    There are two analysis pathways that you should investigate here before you arrive at any meaningful fault analysis:
    (1) Find out the source of the failure in your product.
    Even though you say this product has been in use for over 6 years, it is possible that your design is marginal and the failure is due to some component being operated above its absolute maximum operating conditions.
    Failure of the UC3844A is most likely a secondary failure and the primary issue is some other component in your product.
    You should review the schematic, bill of materials, printed circuit board and test and operating conditions.
    If you think there is a temperature issue then you should ensure that the products runs cooler.
    Why do you assume the UC3844A is the cause of failure?
    (2) Something in your manufacturing, assembly process or operating conditions may have changed.
    Semiconductors have pretty much an unlimited lifetime and will not fail after one year.
    Mechanical assemblies, solder joints, bad connector pins or electrolytic caps are much more prone to lifetime degradation.

    Please investigate all of these clues before you focus on the UC3844A as the source of the failure and you will eventually find the root cause.

    Good luck with your investigation and let me know if I can give you further help.
    Regards
    John
  • 0 in reply to John Griffin1
    Prodigy 30 points

    Hello,

    thanks for the quick answer.

    Nothing is change in components or design in the 6 years. And we use this component voer 15 years in other similar designs too.

    The manufacturing is the same.

    The orders before we had no problems and the next orders we have at the moment no problems.

    When we change the UC3844A it works! (now we use UC1844A-EP)

    From our side we see no problem! We had check our side!

    Can you check your side if there where some problems?

    UC3844A 51M the 51M must mean begin of 2015 produce or not? (I had wrote first some wrong about the date) We bought this 08.2016 2 package with 75pieces.

    To find on your homepage a explain what this mean is very difficult! Or an explain what all letters or numbers mean.

    And to point 2 about the pretty unlimited lifetime, 

    we had much fails because of components, resitors, capacitors but semicondoctors too. The most during the first test but some later. From your company and from other.

    With semiconductors only some (1-5) but not in this short time and not so much and from one delivery!

    We have information from other companies (not small) like our cutomers that they have much problems with components! From all manufactors.

    And why you have the UC1844A-EP (UC1844AMDREP) that would special tested and produced on one place?

     

  • 0 in reply to user18733
    TI__Mastermind 34465 points
    Hello user18733,
    If you believe there is a quality issue with this part you should contact the distributor you purchased the parts from and request a parts return request for failure analysis.
    Regards
    John
  • 0 in reply to John Griffin1
    Prodigy 30 points
    Hello,

    thanks.
    We will do this.
    On the board are many other semiconductors. Like microcontroller, OP, AD and DA Converter and ....
    And only the UC3844AD8 are fail.
  • 0 in reply to user18733
    TI__Mastermind 34465 points
    Hello user18733,
    I believe this thread is resolved so I will mark it up as closed.
    Please open a new thread if you have a further query.
    Regards
    John