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Version 3

– April 2022

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6. If higher heating temperatures are desired, consecutive heating commands have to be sent

to the sensor. The heater shall only be operated in ambient temperatures below 65°C else

it could drive the sensor outside of its maximal operating temperature.

5 Physical Specification

5.1 Package Description

SHT4x is provided in an open-cavity dual flat no lead (DFN) package. The humidity sensor opening

is centered on the top side of the package. The sensor chip is made of silicon, hosted on a copper

lead frame and overmolded by an epoxy-based mold compound. Exposed bottom side of the

leadframe with the metallic contacts is Ni/Pd/Au coated, side walls are bare copper.

Moisture sensitivity level (MSL) of 1 according to IPC/JEDEC J-STD-020 is achieved. It is

recommended to process the sensors within one year after date of delivery.

5.2 Package Outline

Figure 12 Dimensional drawing of SHT4x including package tolerances (units mm).

5.3 Land Pattern

The land pattern is recommended to be designed according to the used PCB and soldering process

together with the physical outer dimensions of the sensor. For reference, the land pattern used with

Sensirion’s PCBs and soldering processes is given in Figure 13.

Soldering of the central die pad is optional. Sensirion recommends to not solder the central die pad

because the sensor can reach higher temperatures upon heater activation.