BMP390 encapsulation

[bmckenney]

We plan to use BMP390 pressure sensors in an aerodynamics experiment. To do this, we intend to encapsulate ("pot") a (flexible) PCB holding the sensor, up to the level of the top of the lid, leaving the sensor's top surface exposed in a smooth surface.

The HSMI [BST-BMP3xy-HS000-05, Rev 1.5] (Sec 7.1.4) recommends avoiding "contact" of the encapsulant with the sensor casing, though it also uses the word "un-symmetric". If the encapsulant touches the casing, but on all sides (symmetrically), will that affect the device? We are concerned that a gap around the sensor will cause aerodynamic anomalies.

If it is useful: We have in mind to use as encapsulant 3M's "DP100 Plus", which is quite soft.

Thank you for any suggestions.

[FAE_CA1]

Hi,

Thanks for your inquiry.

BMP390 is a MEMS pressure sensor which is sensitive to mechanical and thermal stress. If you apply encapsulant around BMP390 un-symmetrically or symmetrically there will be some kind of stress applied to it so that the performance will be affected.

For your application, BMP390 doesn't have to be exposed to the surface of your device casing to do measurement. You can place BMP390 inside your device as long as there is a vent hole on your device casing. If you want to protect your device for water-resistant, then you can place a piece of Gore membrane to cover the vent hole of your device casing.

Thanks.