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RnnKrk
RnnKrk
Associate II
June 18, 2018
Question

stm32F301KxUx exposed pad of UFQFPN package connection

  • June 18, 2018
  • 4 replies
  • 1643 views
Posted on June 19, 2018 at 00:24

Hello,

I have just downloaded stm32F301xx (enDM00093332) datasheet - the latest revision (DS9895 Rev 8). But still I have not found a word about how to connect (or not) the exposed pad located beneath UFQFPN package. I guess it can / should be connected to VSS but.... I am afraid not to go wrong.

Could somebody give reliable advice?

Regards

Robert

    This topic has been closed for replies.

    4 replies

    ayarema
    ayarema
    Associate II
    June 18, 2018
    Posted on June 19, 2018 at 00:33

    I dont see an exact part number, but you can go to sites such as snapeda.com and paste your actual MPN to see if that pattern and symbol is available there. If it is see what the pad is connected to. Almost always its Ground but double check yourself.

    waclawek.jan
    waclawek.jan
    Super User
    June 18, 2018
    Posted on June 19, 2018 at 00:48

    https://community.st.com/0D50X00009XkZOtSAN

     
    RnnKrk
    RnnKrkAuthor
    Associate II
    June 19, 2018
    Posted on June 19, 2018 at 12:25

    Andriy and Jan - thank you for quick response.

    But Nov2014 STMicroelectronics promissed to updade the datasheet with this vital information. And has not done it so far.... So it is appreciate to motivate them not to forget it at the next revision again. Otherwise thosuands of engineers will still have this small but nasty trouble.

    Of course I prefere to know from datasheet than guess...

    Regards

    Robert

    T J
    T J
    Senior III
    June 20, 2018
    Posted on June 20, 2018 at 01:59

    Did you check it with a meter ?

    check from the ground pin to the exposed pad.

    sometimes the Die itself is bonded but not connected.

    I would suggest that you connect to ground, but have a trace that you can cut if you have issues.

    Generally, an exposed pad is used as a heat sink and you should be bleeding heat away on the PCB.

    Amel NASRI
    Amel NASRI
    ST Technical Moderator
    June 20, 2018
    Posted on June 20, 2018 at 18:32

    Hello,

    Unfortunately, a confusing note about exposed pad in UFQFPN32 package was added in STM32F301x6/8 datasheets, but later it was removed.

    Now a request is submitted to add the following note bellow the UFQFPN32 package figure: 'There is an exposed die pad on the underside of the UFQFPN package. It is recommended to connect and solder this back-side pad to PCB ground�?.

    Sorry for this inconvenience.

    -Amel

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    RnnKrk
    RnnKrkAuthor
    Associate II
    June 20, 2018
    Posted on June 20, 2018 at 18:47

    Thank you Amel !

    thousands engineers all over the world will keep you in their cordial remembrance for this :)

    Thanks

    Robert

    ps.

    '... to PCB ground' or (better, more precise ?) '... to VSS' as you advised previously...

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