Method for the deviation inspection of integrated circuit chip pin based on Harr wavelet transform

A fast method for chip pin location inspection based on the Harr wavelet tr ansform is presented. A cross line at the pin tip is analyzed, and the meth od locates the central line of a pin according to the zero crossing positio n of the transform of the 1-D cross line without theoretical error. The req uirement of being theoretically error free is that the constant segment of the pin image is wider than 2 pixels. The experiment shows a measurement pr ecision of 1/40 pixel, (C) 2000 Society of Photo-Optical instrumentation En gineers. [S0091-3286(00)01406-9].