Electrical connection of the bottom plate of Cernox

Hello, I have a question about how the bottom plate of Cernox in SD package is connected to the two leads, if any. In my measurement, the surface that the Cernox is indium soldered to is the system ground, and somehow I'm measuring an additional leakage current. It could be other issues in my setup, but I'm wondering if the bottom plate is electrically connected to the leads. If it's not, how does the electrical resistance senses the temperature?
Thank you.