Electronic Design

Infrared Camera Spots Malfunctions

By photographing a circuit board with an infrared scanning camera, engineers can, within 10 to 60 sec, detect overheated components. This infrared technique is presently being used by engineers at International Business Machines Corp. to measure temperature levels on computer printed-circuit cards.

Designed and manufactured by Barnes Engineering Co., Stamford, Conn., the camera has many applications. For example, IBM engineers say the equipment is extremely effective in testing crowded printed-circuit boards or components that normally are inaccessible when in operation. Immediate effects of such a testing operation would be increased circuit life and reliability, and lower manufacturing costs.

The infrared-camera can check the heat distribution over an entire assembly and indicate if and where modifications should be made to the unit's cooling system. The device readily can indicate that certain heatsinks will be inadequate for keeping over-all temperatures within limits.

The camera's optics system uses a target-scanning mirror, which views the target in small increments, since the field of view of the detector is 1 by 1 milliradian. These increments measure 0.12 by 0.12 in. at a distance of 10 ft from the camera. The mirror moves horizontally from left to right, while slowly tilting in the vertical direction. As the mirror returns quickly to its initial position, the electronic picture is blanked out; thus, the camera produces a horizontal raster similar to that seen on a television receiver. With this technique, the camera will make up to 60,000 individual temperature measurements in the scanning period. (Electronic Design, Dec. 6, 1961, p. 12)

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