Electronic article with orientation-identifying surface shape

Details Electronic article with orientation-identifying surface shape Electronic article with orientation-identifying surface shape

1977-12-22

1979-10-02

James, Andrew J.

357 20, 357 68, 357 76, H01L 2906, H01L 2348, H01L 2944

Patent

active

041700210

ABSTRACT:
In the production of varistors, diode chips are cut from a p-n sheet diffused semiconductor wafer. Instead of having conventional rectangular shapes, the chips have a rhomboidal shape. This makes the shape of the chips asymmetric in that one surface of each chip becomes a distinguishable mirror image of its other surface. The direction of the p-n junction in the wafer is oriented with respect to the shape of the chips to be cut to place the same conductivity type region adjacent to the same rhomboidal shape of the surface. As a result, the polarity of the chips, or the direction in which the p-n junctions are oriented within the chips, becomes identifiable by the shape of the chips. This substantially aids in sorting, inspecting, assembling and other handling operations performed on the chip. The chips can, for instance, be inspected visually to determine whether the p-type or the n-type doped portion of the chips are facing away from a supporting surface. Moreover, mechanical means sort the chips into two groups each consisting of chips of the same polarity or orientation of their p-n junctions with respect to a common support plane. Once sorted, the chips are loaded with such known orientation of their p-n junctions into a mass assembly fixture where they become shoulder-bonded to electrical leads to form the varistors.

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Varistor Network Control, by UNO, Electronics, pp. 44-47, Jul. 1961.

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