SBIR-STTR Award

A high spatial resolution and high sensitivity x-ray imaging system has been developed that is appropriate for the in-process inspection of surface mounted printed circuit board assemblies. It is a near real-time system that produces high-quality digital images capable of providing quantitative data for feedback to the assembly soldering and other surface mounted technology manufacturing processes. This technology offers distinct advantages over conventional methods such as film and fluoroscopic x-ray radiography, which has been used in the past. Our approach to scan the article uses a fan beam illumination of the test object and a linear array of detector elements. The patented detector configuration is the key to the system's impressive performance. It has been demonstrated that defects as small as 25 microns (0.001 inch) can be detected. It is our intent under this program, to explore the use of this new and powerful x-ray inspection technology as an important part of a feedback loop in an integrated quality assurance system for overall solder joint evaluation of surface mounted printed circuit board assemblies.

A high-resolution, digital x-ray imaging system has been demonstrated during Phase I to provide extremely high quality images of surface-mount printed circuit boards. Defects in solder joints could in many cases be easily identified through visual image inspection,-and could also be identified and characterized through quantitative image analysis. We propose in phase ii to optimize this powerful x-ray imaging system design and develop image analysis algorithms for automatic identification and characterization of solder joint defects. We will evaluate the possibilities for using a similar system as an important part of a near-real-time feedback loop in an integrated quality assurance system in production-line situations. This approach offers important advantages over other inspection modes. Surface-mount methods make many joints inaccessible for visible-light inspection, and other x-ray imaging methods are either much slower (film), or have much poorer spatial and contrast resolution (fluoroscopy). Our patented detection system provides near-real-time data with high dynamic range (12 bits) and sensitivity to defects as small as 0.001 inches in size.