METHOD AND APPARATUS FOR DISTINGUISHING REGIONS WHERE A MATERIAL IS PRESENT ON A SURFACE

摘要

The method searches for regions where a material is present on a surface. A property of the surface such as height is sensed as a function of position on the surface. A statistical spread in said sensed property as a function of the position is computed. Regions where said material is present are distinguished from other regions on the basis of said spread, e.g. conductor tracks on a PCB assembly are distinguished from a PCB substrate by having lower spread.