Abstract

Automotive ultrasonic parking sensors were analyzed using X- ray computed tomography (XCT or microtomography), in order to determine if there were internal failures generated on the soldering process between copper wires and piezoelectric ceramic on these sensors. This paper reports the use of X-ray radiography and computer image processing for the study of internal defects. By using X-ray tomography technique, pores, cracks, holes, solder balling, insufficient solder, lead related defects, device related defects, and solder bridging may be identified (1-2). When coupled with a real time radiographic detector and image processor, X-ray technology allows instantaneous radiographic imaging and semi-automatic or totally automatic inspection. Analysis was conducted on six produced test samples showing that the application of XCT as a method of quality control of specimens produced by electronic packaging offers a wide range of possibilities to detect defects within materials. There were determined that five sensors contain internal defects on the soldered joints, between the copper wire, and the piezo electric ceramic covered with silver paint, as shown on the computed tomography. Accuracy of XCT method strongly depends on the size of the samples analyzed, but the possibility of obtaining information in 3D nondestructively shows considerable advantages of XCT method over traditional metallographic cross-sectional analysis.

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