A filter cap has been produced by Sensirion for its latest generation of humidity sensors. The SF2 filter cap is made of PBT (polybutylene terephthalate), has an integrated filter membrane, and protects the company's SHT2x humidity and temperature sensor from water, dust, dirt and various contaminants. The filter cap features a filtration efficiency of 99.99% of all particles greater than 0.1μm and is designed to keep response time low. The company claims that protection allows the stable DFN sensors to be used in even the harshest environments and still offer excellent long-term stability and performance. The filter cap can be mounted after reflow soldering. The cap is fixed by plugging the four pins into the PCB. The filter cap also serves as an adaptor for mounting the sensor into the wall of housing.