Method for detecting missing components at electrical board test using optoelectronic fixture-mounted sensors

摘要

Disclosed is a method and apparatus for determining the presence or absence of a component on a printed circuit board. The method and apparatus utilizes a photo-sensor and photo-detector that are positioned within a predetermined non-contacting distance from the expected location of a given component under test. The photo-emitter emits a controlled amount of light energy on the expected location of the component under test on the printed circuit board. The photo-sensor detects the amount of reflection off the surface of the expected location of the component under test. Because the amount of reflection differs between reflection off the surface of the component under test and reflection off the surface of the bare board, based on the reflection measurement, the component under test can be classified as either present or absent at its expected location on the printed circuit board.