Modeling the behavior of printed passive components on flexible substrate under environmental loadings

In this study the behavior of silkscreen printed inductors and capacitors on a flexible substrate under environmental loadings are characterized and modeled. Appropriate test setups were used to expose the components to the following loadings: temperature from 0 to 100 °C, relative humidity from 35 to 90% and bending from a flat to a curvilinear structure. The behavior of electrical parameters was measured in-situ by a LCR meter under the described conditions. The results reveal that both inductors and capacitors behave characteristically over the applied range of loading scales. The dominant environmental loading for the inductors was found to be the bending to a curvilinear state, which causes a decrease in inductance of approximately 6-8%. For the capacitors, the major effects were caused by exposure to relative humidity and temperature. The capacitance increased 5-80% in response to the full spectrum of relative humidity loading and 25-35% due to the maximum temperature loading. The behavior is a consequence of the changes in geometrical and material properties due to the applied environmental stresses. Thus, the component electrical behavior under environmental loadings may be modeled as a function temperature, relative humidity and bending radius.