Accelerated Life Test and Identification of Failure Mechanisms of Carbon-Based Planar Heaters

Purpose: In this study, the field failure mode, site, and potential failure mechanisms of carbon-based planar heaters, which are widely used for floor heating, are investigated, and an acceleration model is established.<br/>Methods: By using the two-level quality function deployment (2-level QFD) technique, the potential failure mechanisms of planar heaters were identified, a reliability test method was designed, and a voltage-accelerated life test was performed accordingly. Failure was determined by measuring the uniformity of sheet resistance distribution according to the four-probe method and by measuring temperature uniformity in the images obtained using a thermal camera.<br/>Results: The results of the accelerated life test confirmed that the life distribution followed the Weibull distribution with a shape parameter of 6.7. Moreover, the inverse power model with a material constant of 2.2 was confirmed as a good fit for the acceleration model. Furthermore, according to the failure analysis, it was found to be consistent with the field failure pattern, and therefore, it was judged that the accelerated life test was performed appropriately from the perspective of predicting field life.<br/>Conclusion: In this study, a potential failure mechanism and an accelerated life model for planar heaters were established. This model is expected to contribute toward improving the reliability of planar heaters, the usage of which is anticipated to increase in the future.