Experimental Study Of The SnO₂Gas Sensor Based On ADT

The SnO2gas sensor has the performance of high sensitivity, fast response time,rapid recovery and long-term stability. Because of its excellent performance andcheap price, it is widely used in daily life and industrial production, such asmonitoring the gas leakage, the toxic gas, the fire alarm, etc. Because the failure ofalarm will bring serious consequences, the higher performance of the gas sensor isseriously required. How to quickly and accurately obtain reliability indexes of theSnO2gas sensors becomes a problem needed to solve urgently. With the constantimprovement of science, technology and manufacturing process, the SnO2gas sensorhas the characteristics of high reliability and long life, use the traditional reliabilitytest to evaluate its reliability indexes needs long test time and a lot of test samples.Toshorten the test cycle and reduce the test cost, there is an urgent need to obtain thereliability indexes of the gas sensor in a relatively short period of time.An Accelerated Degradation Testing (ADT)was carried out，in which someSnO2Gas Sensors were chosen and temperature voltage and high-concentrationbutagas was taken as accelerated stress.Then use the reliability evaluation method ofADT and statistical method with acceleration model to assessment the reliability ofSnO2Gas Sensor. The main research content is as follow:First, structure and working principle of SnO2Gas Sensor was introduced andanalyzed. Then reliability analysis of SnO2Gas Sensor is carried out based onFMECA and FTA method to detect the weakness and to analyze the failuremechanism.Second, selecting temperature, voltage, high concentration of butane gas as theaccelerate stress based on the weak link of SnO2gas sensors. formulating theaccelerated degradation test plan include determining the number of samples,accelerated stress type and applied methods, accelerated stress level, the testingparameters of the sample and testing time, etc. completed the accelerated degradation test according to the experiment plan, and obtained the accelerated test data.Finally, this paper studied the accelerated degradation test data statisticalanalysis method. Using the traditional acceleration model andperformance degradation model established the accelerated model. Using the failurethreshold obtained the pseudo failure life distribution. Then using the method ofmaximum likelihood estimation and least squares estimation to estimate the pseudofailure life distribution parameters and obtained the SnO2gas sensor reliabilityfunction which under the normal stress level.