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Publication Date: 09/1/2008
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Seho Intros Fiducial Recognition and Correction
GoSelective soldering system controlled by new software.
Ashland, VA — Seho has introduced a fiducial recognition and correction function for its selective soldering systems. This new software feature allows optical registration of the PC board to be soldered and to compensate for various types of misalignment such as offset, rotational error and linear shrinkage within the PC board. In addition, incorrectly placed boards are detected and will not be soldered.

Up to three fiducial marks are selected by the operator in a "learning procedure", either globally for the complete board or separately for each sub panel. The software captures exact images of these fiducials and memorizes their precise location. At the beginning of the production cycle, the machine moves to the previously memorized positions automatically and captures an image of the PC board at this point. The correlation between this actual "live" image and the "learned" — ideally positioned — image is calculated and gives a resulting correction value for each fiducial. These values provide for calculating offset, rotation and linear shrinkage of the actual PC board compared to the board used for the "learning procedure". As a result, the software generates a position correction for each production board.

In addition, the fiducial recognition and correction software tool contains an error-proof function which checks the loading of the correct soldering program and controls each board for precise positioning. Because of this, even possible operator faults can be recognized and compensated for.

The new fiducial recognition and correction function makes it possible to perform very accurate and repeatable soldering processes in the most demanding applications.

Contact: Seho North America, Inc., 325 L Hill Carter Parkway, Ashland, VA 23005 804-798-6000 fax: 804-798-5933 E-mail: Web:

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