GB1191408A - Resistor Tailoring Machine. - Google Patents

Abstract

1,191,408. Blasting. CORNING GLASS WORKS. 31 Oct., 1968, No. 51574/68. Heading B3D. [Also in Division H1] A resistor tailoring machine comprises abrasive blast nozzles 18 controlled by valve assembly 24 (Fig. 2) and adjustably positioned to impinge on a metal oxide film resistor(s) deposited on a substrate 28 mounted on a pad 38 adjustably positioned on a table 14 which is itself movable in the perpendicular directions "X" and "Y" (Fig. 8, not shown) and conducting probes 36 which are movable together vertically to engage conductive portions (30, Fig. 7, not shown) on the substrate 28 to monitor the value of the resistance being tailored with respect to a standard set resistance (R8, Fig. 10(c), not shown). The abrasive blasts removing portions of the resistor films in a preset pattern to alter the resistance values continue till a known value is reached, switchoff being initiated early to compensate for the mechanical lag of the system. After a strip (34, Fig. 7, not shown) of the resistor 32 has been removed while the table 14 slowly moves in the direction " X", the blast stops and the nozzles rise; the probes and the table then move together under numerical control from the unit 16, exposing a new column of metallic film resistors to the abrading action of the nozzles. Controlled reciprocating movement of the probe assembly 22 (Fig. 2) is made possible by a motor (164, Fig. 6, not shown) by means of a gear drive, and other moving parts like the abrasive blast nozzles, table 14 &c. are moved by means using compressed air. Limit switches operate at the extreme ends of the linear movement of the abrading nozzles and the probe assembly. Vacuum is utilized to hold down the substrate on to the pad 38 [which is itself mounted on the table by means of fixed pins (40, 41, 42) and movable pins (44, 45, Fig. 3, not shown)] and also to extract through an inlet 68 into the manifold 66 the abrasive particles after they have been used for blasting. The unit 16 for numerical control of the operation is programmed for moving the work-table, probes and nozzle carrier precisely in a preselected pattern and the whole process may be continuous with circuitry to monitor and control the operation (Figs. 10A, 10B and 10C, not shown) and arrangements to sort the " acceptable " and " to be rejected " finished resistors.