AOpen AOI-702U Especificaciones descargar pdf (Pagina 5)

Theory of Operation

The SCANSPECTION AOI inspection process is based on comparison of PCBs

under test with a known good board with all devices placed correctly. The

setup process involves storing the images of a correctly assembled, good

board. The inspection process compares the images captured from the board

under test with the stored images of the known good board.

In the real world there are three issues that must be addressed regarding

theory of operation:

1. There are appearance variations on good boards. This means all boards

that are considered good do not all look the same. Certain variations on the

board’s appearance do not constitute defects. The system needs to be able

to ignore many areas of the board.

2. In order to inspect all areas of the board, the amount of detail that the vision

system has to extract to detect a small defect is so great that the inspection

process would be very slow.

3. The purpose of the inspection is to identify which devices (or components)

on the board are defective so that a repair can be done. It would be better if

the inspection system associated defects with devices.

The SCANSPECTION AOI’s inspection process is device or component

oriented. The setup process begins by placing a known good board into the

machine. The user defines the board size and positions of the alignment

marks. Device data of each device is then entered either interactively or

automatically extracted from the board’s CAD data. The system learns the

appearance of all the devices. This process is called Template Training. The

system maintains a database of the templates of all the good devices. In

addition to the device’s template, other device data such as device ID, device

name, device location and device size, are also stored in the database.

Usually the setup process needs to be fine tuned with several known good

boards. This allows alternative devices templates to be learned and

inspection parameters to be adjusted.

After setup, the board inspection process can begin. The process starts with

locating the alignment marks. By measuring the positions of the alignment

marks, the system compensates for board placement error, both translational

and rotational. The system then inspects each device in sequence comparing

templates for each and every device as well as performing other visual

measurements. After the entire board is inspected, including all trained

components, the system compiles the inspection results and produces a

report to the user.

1 2 3 4 5 6 7 8 9 10 ... 133 134

Sin comentarios

AOpen AOI-702U Especificaciones Pagina 5