In one of our Temperature Sensor Board, We have chosen P/N#TMP117MAIDRVR. We didn't get the accuracy as as per datasheet (+/-0.3degC). This IC is used for cold Junction reference for Thermocouple Temperature measurement. Thermal Pad is soldered and connected to GND with 2 vias (refer the attached screen shot). Can this impact? TMP117EVM also has the thermal pad connected to GND with 2 vias.
Should we need to make thermal pad as no net and No paste but only Solder mask opening, Will that help in improving accuracy?
What else could impact accuracy? Please suggest if there is any improvement required from design & also from layout point of view?