Compositional mapping by laser-induced breakdown spectroscopy

A sensitive optical technique for compositional mapping of solid surfaces using laser-induced breakdown spectroscopy (LIBS) is described. A pulsed Nd:YAG laser with second harmonic module was focused on the solid surface, giving a small ablation area, to produce plasma emission. Copper and magnesium emissions from a standard sample were carefully analyzed and assigned in the wavelength range 500-520 nm. The assigned spectral information was selected to construct an image of 100 x 100 pixels by mapping the measured emission intensity values from the analyzed points. The time required for image construction and image sharpness depends on the number of laser shots per point of analysis and the number of analyzed points per image. A clear image of a copper conductor pattern from a printed circuit board was generated. In addition, some copper contaminations around the conductor area are clearly visible in the scanning LIES map. The contaminated copper salt probably resulted from the incomplete washing step during manufacturing that could cause a short circuit in an electronic device.