International Business Machines Corporation

Norman E Rittenhouse

Peter J Yablonsky

Todd C Fellows

Vincent Charles Conzola

Donald H Canfield

Thomas J Toomey

Robert M Crabb

Steven M DeFoster

Mark A West

Richard A Ziegler

Jeffrey M Solomon

Vincent Caiozza

An optical inspection system is provided in which the background video component of an analog video source which limits imaging integrity is removed enhancing the system's ability to process a wider range of image sources with increase digitizing sensitivity. The overall effects of background and background variations are nulled stabilizing the effective signal to noise ratio, thereby increasing inspection capability of the system and improving the system's process window for effective and efficient inspection.

Analog video processing apparatus and method for eliminating background

An optical imaging surface inspection system and method are provided. The system comprises an illumination source for illuminating an image pattern on a surface to be inspected, a video camera for detecting a portion of the light reflected from the surface and outputting an analog video signal, a dynamic thresholding circuit for converting the analog video signal into a digital representation of the image pattern, and means to compare a known accurate digital representation of the image pattern to the digital representation provided by the dynamic thresholding circuit. The method includes the steps of illuminating the surface, scanning the surface with the video camera, separating the video signal into a black level signal component and a white level signal component, detecting successive peak levels in the white level signal component and outputting a corresponding variable peak voltage. A variable threshold voltage is determined by selecting a percentage of the variable peak voltage. This variable threshold voltage is then compared with a delayed portion of the analog video signal to provide the digital representation of an image pattern on the surface being inspected.

Optical inspection system utilizing dynamic analog-to-digital

The illumination system as a part of an optical inspection system, the total inspection system itself, and the method of illuminating and inspecting a workpiece. The illumination system is computer controlled as to a level of intensity and adjustable as to angle of incidence. The illumination system includes illumination control electronics, a quad quartz halogen lamp array light source, a fiber optic line converter and an illumination collection system, having a collimator lens array and a focusing/field coverage lens. As a result of the present invention, determinations of false defects on the PCB are minimized. Human contact with the PCB is also minimized and the rate of inspections performable is increased.

Computer controlled, multiple angle illumination system

A non-contact system for detecting printed circuit wiring defects and for measuring circuit feature height relative to a substrate. The system has an energy source for illuminating the substrate and circuit features and a scanner for both instantaneously receiving energy reflected from the substrate and circuit features and for generating a signal in response to the reflected energy, which signal is adapted to vary with the intensity of the reflected energy. An analyzer is connected to the scanner for correlating the generated signal to a measurement representative of the height of the circuit features relative to the substrate. Variations and non-uniformity of the substrate surface due to bending, warpage or other causes can be accounted for so as to provide an accurate measurement of the height of a circuit feature relative to the substrate surface on which it is mounted.

System for measuring and detecting printed circuit wiring defects

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Endicott, NY, United States of America

Norman E Rittenhouse