SI7013 Datasheet, PDF (19/43 Pages) Silicon Laboratories – I2C HUMIDITY AND TWO-ZONE TEMPERATURE SENSOR

Si7013
4.5. Protecting the Sensor
Because the sensor operates on the principal of measuring a change in capacitance, any changes to the dielectric
constant of the polymer film will be detected as a change in relative humidity. Therefore, it is important to minimize
the probability of contaminants coming into contact with the sensor. Dust and other particles as well as liquids can
affect the RH reading. It is recommended that a cover is employed in the end system that blocks contaminants but
allows water vapor to pass through. Depending on the needs of the application, this can be as simple as plastic or
metallic gauze for basic protection against particulates or something more sophisticated such as a hydrophobic
membrane providing up to IP67 compliant protection.
The Si7013 may be ordered with a factory-fitted, solder-resistant cover that can be left in place for the lifetime of
the product. It is very low-profile, hydrophobic and oleophobic, and excludes particulates down to 0.35 microns in
size. See Section “8. Ordering Guide” for a list of ordering part numbers that include the cover. A dimensioned
drawing of the IC with the cover is included in Section “9. Package Outline ” . Other characteristics of the cover are
listed in Table 12.
Table 12. Specifications of Protective Cover
Parameter
Material
Water Entry Pressure
Pore Size
Operating Temperature
Maximum Reflow Temperature
Oleophobicity (AATCC 118-1992)
IP Rating (per IEC 529)
Value
ePTFE
2.7 bar
0.35 µ
–40 to 125 °C
260 °C
7
IP67
Rev. 0.95
19