Notched-Cross Fiducial for Improved Accuracy of Pick-and-Place
Publication Date: 2016-Mar-31
The IP.com Prior Art Database
Described is a method for enhancing the accuracy of the traditional cross-shaped fiducial by adding a small notch on each arm of the cross. This v-shaped notch allows the pick-and-place machine operator to micro adjust the alignment in real time.
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Notched- -Cross Fiducial for Improved Accuracy of Pick
Cross Fiducial for Improved Accuracy of Pick - -and
The assembly of printed circuit boards (PCBs) relies on registration marks to align the equipment. The industry has used a variety of patterns over the years including round circles, squares, double squares, and crosses. The proposed improvement adds a notch on the crosses to improve accuracy by giving an aid to define the center point of the pattern. Starting with a standard cross etch pattern 0.070 inches wide with a 0.070 inches solder mask opening, a notch on each of the arms of the cross was added. The new patterns can be implemented on new products in parallel with existing patterns as new products are released.
Figure 1 shows a traditional cross pattern on the left and the modified notch cross on the right.
compare.gif Figure 1
Figure 2 shows a zoom in of the notched cross pattern.
One drawback of several of the standard patterns, such as the circle and square, is that the machines mistake the patterns with other features on the board like pins, holes, and vias. Another drawback of the standard circle, square, or cross is locating true center. The notched cross improvement gives both an added level of optical alignment accuracy for the machine operator as well as an easily distinguishable pattern from other items on the board.