Rapid three-dimensional reconstruction of printed circuit board using femtosecond laser delayering and digital microscopy

Abstract

Reverse Engineering of printed circuit boards (PCBs) has become increasingly critical for quality assurance purposes. Reverse engineering can be accomplished using non-destructive methods such X-ray computed tomography but this faces challenges in terms of the maximum obtainable resolution and the level of details that can be captured from the different materials that are forming the PCB. Destructive methods, which work based on performing consecutive steps of material removal and imaging suffer from a trade-off between throughput and precision/reliability. At one end of the spectrum, use of focused ion beam (FIB) for delayering and scanning electron microscopy (SEM) for imaging can offer high resolution 3D images but is prohibitively slow for addressing large regions of interest (ROIs). On the other hand, use of mechanical and chemical methods for delayering can be fast but faces precision, repeatability and reliability issues. We propose a correlative workflow that combines ultrashort pulsed laser for performing controllable and repeatable material removal and digital microscope imaging for information collection, to offer a fully automated PCB reverse engineering process. We showcase the performance of the proposed workflow on a PCB and we validate the results through comparison with X-ray images.