반복복원 기법을 이용한 전자회로기판의 납땜부 형상 복원

Abstract

Thia paper presents a shape reconstruction method for automathic inspection of the solder joints on PCBs using X-ray. Shape reconatruction from X-Ray radiographic image has been very important since X-ray equipment was used for improving the reliability of inspection result. for this purpose there have been lots of previous works using tomography, which restructs the correct shape, laminography or tomosynthesis, which are very fast algorithm. Latter two methods show outstanding performance in cross-sectional image reconstruction of lead type component, but they are also known to show some fatal imitations to some kinds of components such as BGA, because of shadow effect. Although conventional tomography dose not have any shadow effect, the shape of PCB prohibits it from being applied to shape reconstruction of solder joints on PCB. This paper show that tomography using Iterative Reconstruction Technique can be applied to this difficult problem without any limitations. This makes conventional radiographic instrument used for shape reconstruction without shadow effect. This means that the new method makes cost down and shadow-free shape reconstruction. To verify the effectiveness of IRT, we develop three dimensional model of BGA solder ball, make projection model to obtain X-ray projection data. and perform a simulation study of shape reconstruction data are reorganized and error analysis between the original model are also performed.