Abstract:
This work presents a detailed overview ofthe analytic methods for calculating the beam and gaseous thermal
conductance components associated with uncooled VOx microbolometers. The conventional method
to calculate the gaseous component relies on the assumption that the entire plate is maintained at a uniform
temperature,thus the surface area ofthe plate is used for the calculation. We have observed using an
industry leading multiphysics simulator thatthis assumption is not strictly true for VOx microbolometers
as the conduction pattern exhibits an elliptical shape. Based on this, we have developed and propose an
analyticmethod that employs anelliptical surface area scaledappropriately withthedevice dimensions to
obtain an estimate ofthe average temperature conduction pattern. Prototype devices were manufactured
and experimentally characterised. The devices exhibit thermal conduction characteristics comparable to
those in literature and industry, and we could achieve 0.5 W/K under vacuum conditions and 15 W/K
at atmospheric pressure with a TCR of −1%/K. However, both simulated and experimental result sets of
the gaseous thermal conductance exhibit large deviations from the conventional analytic method, on
average approximately 40%. The proposed method reduces this average error significantly to less than
10% when compared to the simulated results.
