Passive component inspection using machine vision

Passive electronic components now make up 50 to 90% of all components on circuit boards and represent more than one-fifth of the board cost. Many of these passive components have been 100% inspected by the manufacturers for electrical properties, but not for mechanical properties. Most manufacturers still measure small samples with micrometers and calipers to verify overall dimensions, although machine vision is beginning to be used for mechanical inspection. In this paper, we investigate machine vision as a technique to enable 100% inspection of such components including properties of size, edge straightness and smoothness, and surface defects for both the component body and terminations. In addition, machine vision is used to derive the component orientation and location. This may have application to the bulk feeding of such components, which is a subject of current research