The Metcal (Menlo Park, CA) division of OK International has developed a flexible optical inspection system for use with large boards measuring up to 36 x 36 in. The VPI-1000-XL system is the latest addition to the company's range of optical inspection systems for inspection of array packages and surface-mount devices.

The system meets all inspection requirements on larger boards, which are becoming increasingly common in applications such as cellular base stations, data communications and network servers. It features four adjustable supports to hold round, rectangular, square or l-shaped printed circuit boards (PCBs) and has an articulating arm capable of spanning up to 24in., allowing it to cover a 36 x 36 in. board without requiring a lens change.

Metcal's NovaScope lens design is capable of moving through 90° left/right and 20° up/down, so operators can inspect under array packages with standoff heights as low as 0.002  in. (0.05 mm) and clearances of just 0.043 in. (1.1 mm) between components. The optical design is sharper and clearer - using 2/3 fewer optical elements to send a direct image to the high-resolution CCD camera.

The integrated optical design is a departure that moves beyond typical endoscopic systems and gradient lenses. While conventional designs relay an internal image repeated throughout the length of the endoscope, an approach requiring multiple sets of complex optical elements to perform the task, NovaScope has only one image: the image in front of the eyepiece.

In operation, the system floods the underside of a component with bright white metal halide light that replicates natural daylight, enhances the color rendering and produces images on the system's color LCD monitor. The lens looks underneath array packages to inspect each ball and its top and bottom connections. With a quick turn of the lens adjustment ring, operators can move through the underside of the device to check for defects such as bridging, cold solder joints, open circuits, excess flux, contamination and other process-related failures.

The unit can also be used for inspecting surface-mount devices and any other board feature without changing lenses. Apertures on stencils can also be inspected with ease.

A software tool completes the package, allowing users to measure, record, annotate, analyze and communicate component information. Images are displayed in real-time for a visual inspection of the soldering process, and they can be captured and stored for future reference or reports. Documents can also be emailed or archived for use in training, research and development or quality insurance.

www.metcal.com

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