A package assembly comprises a package base, a sensor die, an isolation plate, and a package interface plate. The isolation plate is bonded to the sensor die and has a plurality of flexible beams. Each flexible beam is configured to deflect under stress such that effects on the sensor die of a thermal mismatch between the package base and the sensor die are reduced. The package interface plate is bonded to the isolation plate and the package base. The package interface plate is configured to limit the maximum distance each flexible beam is able to deflect.