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Optical Inspection of Module Pins

IP.com Disclosure Number: IPCOM000040735D
Original Publication Date: 1987-Dec-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 3 page(s) / 33K

Publishing Venue

IBM

Related People

Bamber, J: AUTHOR [+2]

Abstract

Surface mount modules with multiple thin pins on each of four sides require inspection during automatic assembly to boards. A module is picked up in a horizontal position by a robot and one side viewed by a line array camera with a vertical line array. Within the field of the camera is an end view of a row of pins and via a prism a plan view. Analysis of the resultant video waveform detects pin faults. This inspection is repeated for each of the other three sides. Surface mount modules have pin counts of 80 pin and above, and because of the close spacing the pins are necessarily thin, fragile and very susceptible to damage. As slight pin bending may give problems of pin short-circuits, faulty soldering and solder bridging automatic assembly machines must use some form of on-line inspection.

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Optical Inspection of Module Pins

Surface mount modules with multiple thin pins on each of four sides require inspection during automatic assembly to boards. A module is picked up in a horizontal position by a robot and one side viewed by a line array camera with a vertical line array. Within the field of the camera is an end view of a row of pins and via a prism a plan view. Analysis of the resultant video waveform detects pin faults. This inspection is repeated for each of the other three sides. Surface mount modules have pin counts of 80 pin and above, and because of the close spacing the pins are necessarily thin, fragile and very susceptible to damage. As slight pin bending may give problems of pin short-circuits, faulty soldering and solder bridging automatic assembly machines must use some form of on-line inspection. It is required that the pins be inspected for vertical displacement as well as lateral and obtaining positional data at the same time. The module is presented to the camera in the horizontal position as it is picked by the robot or other handling device. The camera is a line array camera with, for example, 2000 x 1 pixels. An arrangement, as shown in Fig. 1 is used with the camera mounted horizontally with the line array running vertically. Within the field of view of the camera is a right-angle prism and an end view of the row of pins on one side of the module. Reflected in the prism is a plan view of the same line of module pins. Thus, the composite picture obtained is as shown in Fig. 2 of the end view of the pins occupying one end of the line array and the plan view of the pins occupying the rest. It is necessary to ensure that the camera position is...