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Thermography and Complementary Measurements as Tools to Detect Micro-Irregularities in Electronic Components
S. Röhrig, S. Röhrig, I. Petschenig, I. Petschenig, R. Bermejo, M. Hofstätter, F. Aldrian, R. Danzer, P. Supancic, P. Supancic
Abstract
In many ceramic components for electrical applications, small defects in the microstructure may cause an anomalous current flow. Especially in components exhibiting nonlinear electro-thermal properties, such as varistors, positive (PTC) or negative (NTC) temperature coefficient resistors, inhomogeneities lead to high concentrations of current and localized heat generation owing to positive feedback effects. While the integral behaviour of those components is largely unaffected by these defects, the local load at these hot spot regions is extremely high and can even lead to the complete failure of the device. In this work, microanalytical tools are combined to identify the location and type of defects that may cause leakage currents, overheating or other reasons for inhomogeneous current distributions in functional ceramic components. Lock-in thermography is used to localize dominating current paths. This is even possible if the heat sources are in the micrometer range or smaller. Additionally, microsectioning techniques (e.g. Focused Ion Beam) are utilized to expose such regions in order to investigate features of the microstructure and causes for the enhanced current flows. Examples are shown with PTC resistor components as well as Low-Temperature Co-fired Ceramic (LTCC)-based modules.
Keywords
Electroceramics, PTC, LTCC, inhomogeneities, microthermography, focused ion beam
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