Statistical Analysis of Thermal Treatment Effect of SMD Ni-RTD Batch Sensors and Its Direct Application Without Packaging for a Contact Thermometer

Thin-film resistive temperature detectors (RTD) are temperature sensors that can be installed on rigid or flexible substrates to meet a wide range of requirements. In this paper, we present a study on the performance of a clinical thermometer and its implementation. The statistical effects of thermal treatment on batch production are presented. Because of localized defects on the film, a non-uniform distribution exists before thermal treatment, which improves after thermal treatment. The data show that thermal treatment reduces the large variation in resistance for as-produced sensors. This annealing is done at 300 degrees C under nitrogen atmosphere which reduces the standard deviation from 177 Omega to 13 Omega, a 5% of its initial value after being fabricated. This reliability increment is obtained due to the crystalline quality improvement which can be done only in the range of 100-300 degrees C. In addition, the RTD sensor was designed with surface-mount technology in mind to avoid post-processing packaging and instead be used directly on a printed circuit board (PCB). A ratiometric circuit was designed to implement the RTD as a contact thermometer prototype; the developed circuit is flexible enough to use the produced RTD with a 5% deviation. The thermometer has an accuracy of 0.095 degrees C in the temperature range of 30-50 degrees C. [GRAPHICS] .

Automated summary

This paper presents a study on the performance and implementation of a clinical thermometer using thin-film resistive temperature detectors (RTD). The study shows that thermal treatment improves the localized defects on the film, reducing the variation in resistance for the produced sensors. The RTD sensor is designed with surface-mount technology and implemented as a contact thermometer prototype using a ratiometric circuit, achieving high accuracy.