Nondestructive inspection of packaged microcircuits by aperture-type terahertz near-field imaging

Abstract

Abstract A scanning aperture-type terahertz near-field imaging system is developed to perform precise nondestructive testing on packaged aluminum etched antenna arrays, and surface imaging of a flexible gold electrode array, to obtain subsurface imaging and surface imaging. The resolution of subsurface imaging is 110 and 500 μm when the packaging (polyethylene terephthalate) thickness is 50 and 200 μm respectively, and the surface imaging resolution is 6 μm at 0.11 THz. An adaptive threshold segmentation algorithm of Hilbert scan combined with wavelet transform were employed to successfully suppress the noise of the imaging results due to the change of near-field distance. We also proposed a derivative filtering extremum threshold segmentation algorithm to effectively suppress severely uneven threshold distribution of the packaged aluminum etched antenna arrays.