Abstract

Cracks and other defects in ceramic materials can be difficult or impossible to examine and photograph due to the extreme lack of contrast. A method for inspecting translucent ceramics using scattered light, also known as vicinal illumination, will be described. This method has been known in the ceramics industry for quite some time, but is not well known in the testing and failure analysis community. Electronics applications include substrates, packages, multilayer capacitors, and thin film resistors. Ceramic materials are used in electronic applications as microcircuit packages and substrates which carry signals and power between microcircuits. Fine cracks in ceramic materials can result in mechanical failures, electrical failures, and loss of hermeticity. Often, fine cracks are difficult or impossible to detect using standard nondestructive inspection techniques such as visual inspection, ultrasonic inspection, or vapor crack detection. Dye penetrant inspection is usually effective, but contaminates the part, which is unacceptable for space flight hardware. One effective nondestructive inspection method of detecting cracks involves examining the way in which light scatters through the ceramic material when viewed with a standard bright field reflected light microscope. This method, termed vicinal illumination, has been used for detecting cracks during failure analyses of several part types, and screening of space flight hardware. The technique has proven effective on several different types of ceramic materials as well. A related method for use with dark field equipment has also been used to successfully locate otherwise invisible cracks.

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