Metal working – Means to assemble or disassemble – Means to assemble electrical device
Patent
1979-03-26
1980-11-25
Hall, Carl E.
Metal working
Means to assemble or disassemble
Means to assemble electrical device
29854, 228 6A, 228 49R, H01R 4300, B23K 3704
Patent
active
042350140
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 solder-bonded to electrical leads to form the varistors.
REFERENCES:
patent: 1022818 (1912-04-01), Bogdanffy
patent: 2892530 (1959-06-01), Fox, Jr.
patent: 3341928 (1967-09-01), Naumann
patent: 3589938 (1971-06-01), Blewett et al.
patent: 4125216 (1978-11-01), Ozimec
"Soldering of Leads to Semiconductor Chips", DeMuzio et al., Western Electric Tech. Dig. No. 44, Oct. 1976, pp. 15-16.
"Mass Soldering of Leads to Semiconductor Chips", Bankes et al., Western Electric Tech. Dig. No. 33, Jan. 1974, pp. 9-10.
IBM Tech. Discl. Bulletin, vol. 16, No. 9, Feb. 1974, p. 2800.
DuBois Loring E.
Simpson Lawrence D.
Hall Carl E.
Schellin W. O.
Western Electric Company Inc.
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