Resistor network having horizontal geometry
First Claim
1. A film resistor network geometry having improved trimming and operating characteristics comprising an insulating substrate having at least one film resistor formed thereon and a pair of opposed film conductor electrodes disposed on opposite sides of the film resistor, said film resistor comprising a tapered lower region adjoining a dome-shaped top region, the side edge intercepts of the film resistor engaged by said film conductor electrodes flaring outwardly from the bottom edge of said film resistor at least on one side thereof to form the tapered lower region, said film conductor electrodes terminating at the junction of the tapered lower region with the dome-shaped top region of said film resistor whereby the dome-shaped top region is not engaged by said film conductor electrodes, said film resistor being trimmed by cutting a notch in the film resistor from the bottom edge thereof.
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Accused Products
Abstract
A film resistor network horizontal geometry having extended trim ratio and improved trimming and operating characteristics and method of using the same. The film resistor network comprises an insulating substrate having at least one film resistor formed thereon and a pair of opposed film conductor electrodes disposed on opposite sides of the film resistor. The side edges of the film resistor engaged by the film conductor electrodes flare outwardly from the bottom edge of the film resistor, at least on one side, and terminate in a dome-shaped top region that preferably is elongated semi-cylindrical in configuration. The dome-shaped top region is not engaged by the film conductor electrodes and the film resistor is trimmed by removal of a notch from the film resistor starting from the bottom edge and extending upwardly along a line substantially centered beneath the apex of the dome. With a film resistor thus formed, the trim ratio (TR) will conform to the expression TR=(1+% ΔR/laser bite)n where % ΔR/laser bite is the change in resistance achieved with one pulse of the cutting laser used to trim the resistor and n is the number of laser bites.
13 Citations
30 Claims
- 1. A film resistor network geometry having improved trimming and operating characteristics comprising an insulating substrate having at least one film resistor formed thereon and a pair of opposed film conductor electrodes disposed on opposite sides of the film resistor, said film resistor comprising a tapered lower region adjoining a dome-shaped top region, the side edge intercepts of the film resistor engaged by said film conductor electrodes flaring outwardly from the bottom edge of said film resistor at least on one side thereof to form the tapered lower region, said film conductor electrodes terminating at the junction of the tapered lower region with the dome-shaped top region of said film resistor whereby the dome-shaped top region is not engaged by said film conductor electrodes, said film resistor being trimmed by cutting a notch in the film resistor from the bottom edge thereof.
- 14. A new and improved method of manufacture and trimming film resistor networks having improved horizontal geometry comprising forming on a substrate at least one film resistor having a pair of opposed film conductor electrodes disposed on opposite sides of the film resistor with the film resistor comprising a tapered lower region adjoining a dome-shaped top region, the side edge intercepts of the film resistor engaged by the film conductor electrodes flaring outwardly from the bottom edge of the film resistor at least on one side thereof to form the tapered lower region, said film conductor electrodes terminating at the juncture of the tapered lower region with the dome-shaped top region whereby the dome-shaped top region is not engaged by the film conductor electrodes, and trimming the film resistor network thus formed with a laser beam by cutting a fine slit notch completely through the film resistor starting from the bottom edge thereof along a line substantially centered under the apex of the dome-shaped top whereby a substantially constant rate of change of resistance with trimming is achieved from start to finish, an extended trim ratio is obtained and the mean length of the effective resistor path is increased with increased trim depth.
Specification