In general, at least one printed circuit board (PCB) is provided in an electronic device, and various circuit components such as a circuit pattern, a connection pad portion, and a driving chip electrically connected to the connection pad portion are mounted on the PCB.
These components are mounted in such a way that the terminals of each component are soldered to the pads of the PCB, and the components need to be inspected whether the components are properly soldered to the PCB or not. In these inspection, it is important to clearly distinguish between the terminal area and the solder area of the component in order to increase the accuracy of the inspection. It is important to find the border of the terminal area of the component, for example the terminal end of the component, in order to clearly distinguish the areas.
Conventionally, a method of finding a terminal end of a component in a two-dimensional image, a method of finding a terminal end by performing rectangle fitting after binarizing a height above a reference height as a threshold value after measuring a height value, etc., have been adopted.
However, there is a problem of highly diffused reflection at the terminal end and a problem of existing inspection noise, so that measurement accuracy and reliability are lowered. In addition, when the size of a component is small, such as a component mounted on a notebook computer, a smart pad, or a mobile phone, the error becomes greater since the size of the component is very small compared to the size of the pixel according to the resolution of the camera.