In the solder-mask opening below the sensor, the copper shall not be removed, right?

[rainald]

This is my interpretation of the IIS328DQ Data Sheet, but according to my colleague, the gerber file linked in the answer to "IIS328DQ PCB Design Guidelines Unclear"* shows no copper under the sensor. Thus, the current PCB layout has the copper removed.

What is correct, and is it important?

Thank you.

*) As a new member, I'm not allowed to insert a hyperlink.

[Peter BENSCH]

Welcome, @rainald​, to the community!

You probably meant TN0019, right?

Maybe @Eleon BORLINI​ can make some statement about this.

Regards

/Peter

[rainald]

Yes, same content as in the data sheet.

Section 2, 2nd bullet point: "It is strongly recommended not to place any structure on the top metal layer underneath the sensor (on the same side of the board). This must be defined as a keepout area."

My interpretation of "on the top metal layer" (the data sheet reads "in the top metal layer") is that the copper shall not be removed, while my colleague reads "keepout area" as a fixed term meaning "copper removed".

[Peter BENSCH · Accepted solution]

If you place structures (such as GND plane, vias, tracks...) under the sensor package, this can lead to mechanical stress on the sensor, which in turn worsens the accuracy of the sensor (e.g. increase of offset), but in extreme cases can also damage the sensor.

So please keep this keepout area free not only from tracks etc, but from copper in general.

Does it answer your question?

Regards

/Peter

[rainald]

Yes. Glad to hear that no change is necessary. Thank you.

You may want to improve your documentation (also "PCB thermal pad" is misleading).

[Eleon BORLINI]

@Peter BENSCH​ is right 🙂

-Eleon