Looking for a possibility to check the parts on your board ??? We have the solution! Our application brings a powerful, flexible and affordable solution tailored to your inspection needs. The application runs on a standard PC under Microsoft Windows NT 4.0.

Inspection of small boards:

The camera can see the entire board. Our system can check all the parts of the board for

• Right part
• Existence
• Rotation

The screen shots below are showing an example of the application. In this case the application looks only for the right part and the existence of it. The first image shows the board with all parts on it and the second image shows the system finding a missing part (resistor R12 #1).

Inspection of larger boards:

For inspections of larger boards we add an x/y table to move the board under the camera. The application allows you to train the program where the parts are located and which type of part it should be. That's why the application can be used for almost all types of boards.

Board Inspection: Printed Circuit Boards (PCB) are populated via pick and place machines and/or humans. Many pick and place machines already have built-in machine vision systems to ensure that the components are correctly installed, however some of the pick and place machines only use machine vision to check registration points to figure out where to put the components. Even with pick and place machines, humans often insert the larger components such as large tantalum capacitors, connectors, chips. If the human puts any of these components in backwards and the human inspector doesn't catch it, the next step is usually the wave solder flow station. At this point the component is soldered in place, backwards. If Quality Control catches this, then the PCB is sent to rework and the part is desoldered, reversed and resoldered. If Quality Control doesn't catch it, the PCB won't work upsetting the customer, or worse, the tantalum capacitor might explode.
Although it is possible to use a golden template to automatically learn the board, this will not work in many cases such as: parts of different heights, parts that might differ only in small details, parts that are allowed to move slightly (for example the insertion angle of a voltage regulator with heat sink).
Board Inspection for a larger board requires that the camera be moved over the board typically with an overhead gantry and/or with the board moving on a conveyor or X-Y table under the camera. It is also often necessary to have a remotely controllable zoom and focus lens for the camera. This is because different size and height objects need to be inspected.
Training the system for a new board: The technician commands the gantry to move the camera over the board in a teach mode similar to the teach mode for a robot arm. Using arrow keys on the keyboard or a touch screen computer, the technician tells the system where to stop to make an inspection. Similarly the Technician also tells the system what zoom and focus to use to do the inspection. The Technician then uses the cursor to tell the system which parts to inspect. The system then asks the Technician if this part is already in the library of parts and if not, the name and outline of the part (in order to distinguish between the part and the background or neighboring parts. The Technician can also have the System look for patterns on the part such as a manufacturer's symbol, or "+" or "-" on a capacitor, the key on a connector, or the dot or indent on a chip which indicates pin 1 and orientation. The Technician can also have the System do OCR (optical Character Recognition) to read the text on a component.
The System also understands the concept of modules, sub-modules, components, and sub-components. Thus a section of the PCB which is replicated on other designs can be called a "module", and the parts (ie chips, connectors, etc.) called "components", and distinguishing features such as the keying called "sub-components". This establishes the relationships between the features and allows for easy set-up of inspection of new PCBs.
Changing the inspection is one of the most important parts of the system. In a production environment, even if the PCB Design hasn't changed, a component might change, for example the resistor might have a different color background, or the spacing between the bands might be different, or the text on the chip might differ. In such a case, the Technician tells the System that this other component has the same name, ie it is functionally identical, but has a different pattern "model".
One quick change and the System is ready to inspect the PCB. Since the System uses a library, if the new component has been used before, it just has to be called up from the library, or the Technician can tell the System that any number of variants are acceptable.