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    BME 680 Gas resistance adc reading 0

    Established Member

    Re: BME 680 Gas resistance adc reading 0

    Hello,

    I had a look to the HSMI document and it states:

    The vent hole of the sensor shall be covered with a silicone-free protective layer during processing (e.g. cleaning, soldering, board wash etc.) to prevent possible contamination

    How is this supposed to be done by the PCBA? If this is a real requirement, shouldn't the BME come with a removable protective cover (like some others Hydro or Baro chips) ?

    Community Moderator

    Re: BME 680 Gas resistance adc reading 0

    This requirement is real, although it may depend on your actual PCBA processes. Unfortunately we do not sell any of our sensors with removable protective covers, therefore one suggestion would be to evaluate for example Kapton tape to cover the hole of the sensor during assembly.

    Established Member

    Re: BME 680 Gas resistance adc reading 0

    Although it could be ok for a small manually placed batch, I don't really see how putting tape on each chip will be feasible for a real assembly run as:

    - getting chips out of the reel for putting the protective tape (cutting it into BME sized pieces beforehand...), then you can not use pick and place machine anymore (reconditionning into reel is not an option).

    - Putting the tape after pick & place will certainly compromise placement.

    I guess that reflow part (not vapour-phase oven) should be harmless for the BME (unlike cleaning/washing), so it might  be enough to put protecting cover after reflow ?

    Don't you have an example of PCBA process flow that is known to work with or without protective cover ?

     

    Community Moderator

    Re: BME 680 Gas resistance adc reading 0


    @The_DudE wrote:

    I guess that reflow part (not vapour-phase oven) should be harmless for the BME (unlike cleaning/washing), so it might  be enough to put protecting cover after reflow ?

    Correct.


    @The_DudE wrote:

    Don't you have an example of PCBA process flow that is known to work with or without protective cover ?


    We would strongly recommend to get in touch directly with your manufacturer about this topic, as they probably already have some experience about this and could recommend the best practices with the tools already available to them.

    Established Member

    Re: BME 680 Gas resistance adc reading 0

    Ok, I'll try the "protect-after- reflow" option in a next proto batch.

    Thanks for your support.

    Laurent

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