Method and apparatus for inspecting surface pattern of object

A method of inspecting a surface shape and pattern on a surface of an object, comprising the steps of:

• providing first and second lighting means for emitting light on an inspected surface side of an object, said first and second lighting means being provided at different heights from the object for illuminating the surface of the object;
• receiving images of reflected light rays from the inspected surface side of the object illuminated by said first and second lighting means;
• separately inputting first image data of the inspected surface side of the object illuminated by the first lighting means and second image data of the inspected surface side of the object illuminated by the second lighting means;
• forming third image data by calculating a ratio of said first image data and said second image data, to obtain a two-dimensional inclination signal corresponding to an inclination of the inspected surface side of the object;
• and
• processing said two-dimensional inclination signal to generate at least a two-dimensional flat area signal or a two-dimensional inclined area signal.

An apparatus for inspecting soldering, comprising:

• an XY table for positioning an object to be inspected, said object being a printed circuit board having an electronic part soldered thereon;
• a plurality of circular illuminating means for respectively illuminating a solder joint in substantially circular shapes, said plurality of circular illuminating means having respectively different inclination angles with respect to a surface of said printed circuit board;
• imaging means for receiving images from reflected light rays from a surface of the solder joint being illuminated individually by said plurality of circular illuminating means, and for outputting a plurality of two-dimensional gray scale image signals, said imaging means receiving said images individually from a direction substantially perpendicular to the surface of said printed circuit board;
• an image memory for storing the two-dimensional gray scale image signals being supplied individually from said imaging means;
• division processing means for calculating a ratio from the two-dimensional gray scale image signals to obtain a two-dimensional inclination image signal corresponding to an inclination of the surface of the solder joint without being affected by a reflectivity of the surface of the solder joint;
• and
• inspection means for generating windows corresponding to portions of an inspected side of the object and for processing said two-dimensional inclination signal to generate at least a two-dimensional flat area signal or a two-dimensional inclined area signal for each of said windows;
• said inspection means judging if each of the portions are flat or inclined in response to said two-dimensional flat signal or said two-dimensional inclined signal.