X-Ray Tomographic Inspection of Printed Wiring Assemblies and Electrical Components

Abstract : The visibility of X-ray tomography techniques for printed wiring assembly (PWA) solder bond evaluation and several categories of electronic components has been studied. The effort was performed as a final testing task assignment in the Advanced Development of X-Ray Computed Tomography Application program. The primary area for testing was surface mount technology solder bonds. During the course of the task assignment several other categories of electronic devices were examined including transformers, connectors, and an optical transducer. Five different X-ray systems for computed tomography (CT), laminography and radioscopy were used. The results of this final task assignment indicate that X-ray tomographic techniques can be useful for solder bond evaluation, and innerlayer trace analysis for PWA's and as a failure analysis tool for a broad range of electrical and electronic components. Investment in PWA solder bond evaluation systems using X-rays commonly show a short term (<1 year) payback. The particular system to be used and the economic payback rate depends on the assembly design and manufacturing throughput. Radioscopy (real- time radiography) and scanned beam laminography are the primary techniques recommended for solder bond evaluation. Printed wiring board innerlayer copper traces were imaged with laminographic inspection using industrial CT systems.