Abstract: In SMT solder paste deposit 3D measurement based on Phase Measurement Profilometry（PMP）, shadow, noise and holes made the conventional phase unwrapping method unable to meet requirement. Considering practical engineering conditions, the phase unwrapping method was improved with 2D image information: the basic principle method was applied to smooth areas while the quality-guided unwrapping and least-square methods were employed in shadow areas, border areas and special solder for phase unwrapping respectively. Experimental results show that the proposed method can ensure the correct and quick unwrapping of desired phases.

Key words: phase unwrapping; phase measurement profilometry; 3D measurement; surface mounted technology; machine vision